~ CHAPTER 7 ~
THE GREEN REVOLUTION, FERTILIZERS, and PESTICIDES
Edition 9 of March 2010 (
~ TABLE OF CONTENTS ~
(7-A) ~Green Revolution ~ [A1]~General, [A2]~Genetic Resources, [A3]~Corn Belt (US), [A4]~Asian Sub-Continent, [A5]~South America, [A6]~Southeast Asia, ~
(7-B) ~Fertilizer ~
(7-C) ~Pesticides ~ [C1]~General, [C2]~Pesticide Resistance, [C3]~Pesticide Usage, [C4]~Subsidies, [C5]~Integrated Pest Management, [C6]~Health Effects, ~
NOTE: The notation (su1) means that the data is used in the document analyzing the sustainability of the productivity of the world's food, fiber and water supply systems. (See elsewhere in this website.)
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SECTION (7-A) ~ Green Revolution ~ [A1]~General, [A2]~Genetic Resources, [A3]~Corn Belt (US), [A4]~Asian Sub-Continent, [A5]~South America, [A6]~Southeast Asia, ~
Part [A1] ~ Green Revolution ~ General ~
US corn breeders have developed corn varieties that are more drought-tolerant (
By the 1990s, almost 75% of Asian rice areas were sown with "Green Revolution" varieties of rice. The same was true for almost 50% of the wheat planted in Africa, and more than 50% of the wheat planted in Latin America and Asia, and about 70% of the world's corn. Overall, it was estimated that 40% of all farmers in the developing world were using Green Revolution seeds, with the greatest use found in Asia, followed by Latin America (00R1). (Used in (su1).
The miracle that has fed us for a whole generation now was the Green Revolution: higher-yielding crops that enabled us to almost triple world food production between 1950-1990 while increasing the area of farmland by no more than 10% (06D1). The global population more than doubled in that time, so we now live on less than half the land per person than our grandparents needed. That one-time miracle is over. Since the beginning of the 1990s, crop yields (per unit area) have essentially stopped rising (06D1). (su1) (Used in food.html on this website)
U.S. Department of Agriculture plant scientist Thomas R. Sinclair observes that advances in plant physiology now let scientists quantify crop-yield potentials quite precisely. The physiological limits of such metabolic processes as transpiration, respiration, and photosynthesis are well known. He notes "except for a few options which allow small increases in yield ceilings, the physiological limit to crop yields may well have been reached under experimental conditions." In these situations, national or local, where farmers are using the highest-yielding varieties that plant breeders can provide, and the agronomic inputs and practices needed to realize fully their genetic potential, there are few options left for dramatically raising land productivity (Thomas R. Sinclair, "Limits to Crop Yield?" in American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, "Physiology and Determination of Crop Yield", Madison, Wisconsin (1994)) (Lester R. Brown, Gary Gardner, Brian Halweil, "Beyond Malthus: Sixteen Dimensions of the Population Problem", Worldwatch Paper 143 (September 1998) p. 72.).
Scientists estimate that the originally domesticated wheats devoted roughly 20% of their photosynthate to the development of seeds. (20% is the "Harvest Index") Today's wheat, rice and corn devote over 50%. The physiological limit to the Harvest Index is believed to be about 60% (Ref. 68 of (97B3)). Plant breeders have not been able to fundamentally alter the basic process of photosynthesis itself, i.e. to produce more plant mass without added water, fertilizer, etc.(97B3). After 20 years of research, bio-technologists have not produced a single high-yield variety of wheat, rice or corn (97B3).
Plant breeders at CIMMYT and IRRI boosted the "harvest index" - the percentage of the plant's mass that is grain - to about 50%, almost double the previous figure (Science (8/22/97) p.1038) (99M1).
Most plant breeders see little scope in wheat and rice for increasing the harvest index beyond the present value of about 50% (Roger Austin, an agricultural consultant in Cambridge, England) (99M1).
Most plant breeders see little scope for further increases in the harvest index of wheat and rice (up from 20% in the 1950s to around 50% now). (Charles C. Mann, "Crop Scientists Seek a New Revolution", Science, 1/15/99) Comments: Harvest Index = proportion of a plant's biomass that is harvestable yield.
Across all developing countries, modern rice varieties were being grown on 74% of the planted area in 1991, modern wheat on 74% in 1994, and modern maize on 60% in 1992. ((98M2), p. 220).
The Green Revolution was technologically suited to special circumstances: relatively level land with adequate water for irrigation and fertilizer, and in nations that could acquire the other needed resources. The Revolution has been implemented in a manner that has not proved to be environmentally sustainable. The technology has enhanced soil erosion, polluted groundwater and surface-water, and increased pesticide use. This has caused serious public health and environmental problems (79D2), (85D4), (89U5).
With varying degrees of caution, official projections from the World Bank, FAO, and IFPRI assume agricultural researchers can repeat the Green Revolution. But plant breeders themselves are not sanguine. "Those maximum rice yields have been the same for 30 years," says Robert S. Loomis, an agronomist at the University of California, Davis. "We're plateauing out in biomass" (99M1).
The success of the Green Revolution lay primarily in its increased use of fossil energy for fertilizers, pesticides, and irrigation to raise crops as well as in improved seed. It greatly increased the energy-intensiveness of agricultural production, in some cases by 100-fold or more (94K3).
A new rice prototype being developed in the Philippines could raise yields on 2/3 of the world's rice fields by 20%, i.e. increase global rice yields by 50 million tonnes/ year - enough to cover 2 years of global population growth (Ref. 86 of (97B3)).
A new rice under development at IRRI could boost average rice yields by 20-25%. When it becomes available in about 2000, it could add 85 million tonnes of rice/ year - enough to cover 3 years of population growth (Ref.27 of (96B1)).
The IRRI reported (1990) that, during the past 5 years, growth in rice yield has virtually ceased (91B2). The genetic yield potential of rice has not increased significantly since the release of high-yielding varieties in 1966 (89B2) (94B3). In parts of Asia, experimental yields for irrigated wheat and rice seem to have reached a plateau (Ref. 45 of (92N1)). Maximum yields have been static for 10-20 years (92N1). According to agricultural economists Duane Chapman and Randy Barker of Cornell, the genetic yield potential of rice has not increased significantly since the release of the high-yielding varieties in 1966 (Ref. 65 of (88B4)).
A CGIAR study by Donald Plunkett found that wheat, rice, and corn grain yields/ ha/ year continue to increase over the past decade, e.g. (93H3):
IR-8 rice was made available in 1966 by the IRRI. IR-36 was made available in 1982. It has genetic resistance to 15 pests and a growing cycle of 110 days (vs. 180 days for traditional varieties), permitting up to 3 crops/ year (91U1).
The IRRI puts world rice production at nearly 460 million tonnes/ year (91U1).
High-yielding, fertilizer-responsive crop varieties are planted on nearly all suitable land (91B1). In World Agriculture: Toward 2000, Nikos Alexandratos of the FAO reported that 34% of all seeds planted during the mid-1980s were high-yielding varieties (94B5). During 1950-early 1980s, area in high-yielding varieties expanded (world-wide) from under 1% of area planted (and in only 4-5 countries) to over 50% of area planted, and in virtually all countries producing wheat and rice (85O1).
Most high-yield seed varieties of wheat, corn and rice developed by Borlaug et al are inapplicable for large areas of the developing world because of adverse soil conditions such as build-up of salts, iron- or aluminum excesses, or high acidity (82B1). The spread of the Green Revolution is limited to high base-status soil areas of tropical Asia and Tropical America. High base-status soils (18% of the tropics) are already intensively exploited (75S1).
Improved varieties of cassava in the mid-1980s doubled the yield to 1200 tonnes/ km2/ year. A recent development promises a yield of 3000 tonnes/ km2/ year. Cassava (manioc, yucca, tapioca) is the second-most widely used root crop in the world (after potatoes) and is a dietary staple for over 200 million Africans (92I1).
Soils used to yield 2-3 crops/ year rapidly run out of nutrients, while bugs living there thrive. Even on the IRRI's 2.52-km2 model farm, yields are showing a long-term decline (91U1). Comments: IRRI is the International Rice Research Institute.
Corn plant densities in Iowa have nearly tripled since 1930 due to herbicide development that has eliminated plowing for weeds (Ref. 74 of (97B3)).
After 3 decades of continuous increase, crop yields have leveled off or dropped over the past few years. The Green Revolution's limits stem from its reliance on a few high-yield crops strains and intense use of pesticides, fertilizers and irrigation (92M1).
Results of (and issues surrounding) the Green Revolution are discussed in Ref. (82P1). A table is given of the area planted to high-yield wheat and rice in various regions of the world (in ha. and %) (82P1).
Croplands in High-Yield Varieties of Wheat and Rice (1977) (Areas in 1000 km2) (82B1)
Ratio (%) of Cropland Area in High-yielding Varieties to Total Area in 1977(82B1)
Plots of grain yields/ km2 in various nations vs. time (1965-1975), and plots of fraction of croplands planted in genetically superior strains of grain are in Ref. (78W1), p. 48, 52, 53.
Introduction of genetically modified crops is not critical, says the FAO report: "Agricultural production could probably meet expected demand until 2030 even without major advances in modern biotechnology" (03F1).
But if the technology is "affordable and geared towards the needs of the poor", specially engineered crops could help dry, acid, waterlogged or salt-infested soils grow more. There are important exceptions to the FAO's good news on hunger reductions. In south Asia and, especially, Sub-Saharan Africa, poverty will continue to grow. As a result, the number of chronically undernourished people in Africa will only have fallen marginally by 2030, from 194 to 183 million people (03F1).
Part [A2] ~ Green Revolution ~ Genetic Resources ~
US agricultural production tends to be highly concentrated in a few areas and leans on long-haul travel. Agriculture has relied on biodiversity to adapt to challenges from pests and diseases. To cite an example, potato farmers in Peru have never experienced crop failure, because genetic diversity ensured resistance to pests. In the US and Europe, plant breeders have for a century sought to rationalize biodiversity. Now their goal has been to replace traditional species, which show broad variability, with "pure" hybridized varieties that produce highly uniform results. A study shows that 97% of seed varieties that were available in 1903 had vanished by 1983. Today, the world's key genetic storehouses are the places where our staples originally came under cultivation("Can Industrial Agriculture Withstand Climate Change?" Grist Magazine (10/04/06).).
Chinese farmers were using 10,000 varieties of wheat in 1949. In the 1970s the number was 1000. In 2002 the number was 300. The 14 leading varieties occupy more than 40% of China's wheat fields. Of the 700 crop species that have been domesticated by humans, 30 species now provide 90% of the global caloric intake. Wheat, corn and rice provide more than 50% (FAO, "The State of the World's Plant Genetic Resources for Food and Agriculture," Rome, 1997, p. 14).
According to International Plant Genetic Resources Institute, 25% of all plant species, globally, are threatened in one way or another. This may causes the extinction of 8% of the world's plant species during the next 25 years. At the beginning of the green revolution, India had 30,000 different types of wheat, yet now 90% of the wheat acreage is covered by 10 different, but highly productive, varieties ("Saving Crop Diversity Key to Winning War on Hunger", Reuters, 7/3/01).
UNFAO estimates that, since 1900, about 75% of the world's genetic diversity of domestic agricultural crops has been lost. Without constant infusions of new genes from the wild, geneticists cannot continue to improve domestic crops. Cultivars need to be reinvigorated every 5-15 years in order to give them greater protection against diseases and insects. The most effective way to do this is to interbreed domestic varieties with wild ones (98H1).
In 1970 virulent plague devastated 17% of the US maize crop, wiping out half the harvest in some southern states. Plant breeders found two ancestors of modern maize in Mexico. Once developed, these two varieties of wild maize conveyed resistance to seven of the domestic crop's major diseases. Only a few stalks of these ancient progenitors were found in an abandoned lot slated for development (98H1).
Below is some evidence that wild species and their genetic resources are vital in supporting agriculture.
Although the Green Revolution has significantly increased crop yields, it is not without its costs in terms of increased dependence on fertilizer and a reduction in genetic diversity. One example described in Ref. (79M3) tells what can happen when Man carelessly interferes with genetic variability related to the agricultural practice of hybrid monocultures. One of the prized developments of the Green Revolution was a strain of rice known as IR-8. When it was hit by a mysterious disease in the Philippines, rice growers switched to another form, IR-20, which soon proved fatally vulnerable to grassy stunt virus and brown hopper insects. So farmers switched again, this time to IR-26, a super-hybrid that turned out to be resistant to almost all Philippine diseases and insect pests. But it was too fragile for the island's strong winds. In desperation they turned to an original Taiwanese strain that could stand up to the wind, but it had been all but eliminated by Taiwanese farmers who had converted almost exclusively to an IR-8 strain. Many other examples of the problems of the Green Revolution due to extreme reductions in genetic diversity involved are described by Norman Myers (79M3).
Varieties of asparagus grown in the US in 1903: 46. Number of these varieties surviving by the 1980s, after the advent of large-scale monoculture led to suppression of genetic diversity: 1. Number of varieties of sweet corn grown in the US in 1903: 308. Number of these varieties grown by the 1980s: 12 (Cary Fowler, Pat Mooney, Shattering: Food, Politics and the Loss of Genetic Diversity, University of Arizona Press, Tucson, 1990).
Part [A3] ~ Green Revolution ~ Corn Belt (US) ~
"The current severe nutrient erosion now accelerating in the US Corn Belt under the influence of hybrid grains is another example of a faulty socio-economic farm philosophy . . . " (Ref. (56C1), p. 733). Hybrid corn production in Iowa increased from 5% to 95% of total corn acreage during 1935-1940 (Ref. 19 of (80W4)). By using short-season, early-planted, single cross maize hybrids, commercial production of corn in the US has moved 500 miles further north during the past 50 years. The US winter wheat zone could be moved 200 miles northward using a new level of winter hardiness now genetically available (80W4).
Part [A4] ~ Green Revolution ~ Asian Sub-Continent ~
Share of India's Wheat Land Planted to High-yielding Varieties
(plotted vs. time (1965-83) on p. 68 of (90B2) and in (89B5))
The area of high-yielding wheat varieties in India went from 0 to 82% of total area during 1967-77 (80W4).
Part [A5] ~ Green Revolution ~ South America ~
Rice production increased 40% in each of the past two years with new upland varieties that tolerate aluminum toxicity of soils in the western Amazon Basin ((85A1), p. 409).
Part [A6] ~ Green Revolution ~ Southeast Asia ~
The Rockefeller and Ford Foundations founded IRRI in 1960 with the Philippine government to seek results for rice similar to Green Revolution results on wheat in Mexico (
Some 80% of cultivated land in the Philippines is planted to high yield varieties (80W4).
Go toTop of this Section-Green Revolution
SECTION (7-B) ~ Fertilizer ~
Rock deposits in the US, Morocco, China, and Russia meet two thirds of world phosphate demand, while Canada, Russia, and Belarus account for half of potash mine production worldwide (
See Chapter 11 Section (11-F) (Databases) "World Resources 2005" for a compilation of Fertilizer Applied (kg/ ha) by nation and by region
Part [Ba] ~ Fertilizer ~ Historical and Basics
Since 1950 most livestock manure is not produced on farms in the US
One ton of cow manure has 6 kg of nitrogen, and can only be transported slightly more than 8 km before the nitrogen energy benefits in the manure equal those of inorganic fertilizer. This is why livestock that are grass-fed must be managed on the farm. (Wiens, M. J., Entz, M. H., Wilson, C., and Ominski, K. H. (2008). Energy Requirements for Transport and Surface Application of Liquid Pig Manure in Manitoba, Canada. Agricultural Systems 98(2): pp. 74-81.)
Smil estimated that one-third of the present human population of the earth would not exist were it not for the food derived from synthetic nitrogenous fertilizer a product of the Haber-Bosch process for nitrogen fixation developed in the early 20th century (91S1). Comments: Some authors have noted that synthetic nitrogenous fertilizers were not put into large-scale use until around the middle of the 20th century (after WWII). The same can be said about the large-scale use of genetically modified crops (which are highly dependent on chemical fertilizers) and the construction of large-scale irrigation systems (the economics of which are greatly enhanced by the use of chemical fertilizers). It is not clear whether Smil considered this in his figure of a 50% increase in global population being dependent on synthetic nitrogenous fertilizer. He probably did not. The population of the world has increased by at least 100% since the middle of the 20th century.
Soybeans, alfalfa and clover convert nitrogen into a "fixed" form that can be used by lands, thereby reducing the need for chemical fertilizers. Corn and rice cannot create their own nitrogen (06R1).
Soil bacteria (rhizobium and others) enter the plant root hairs and create nodules in which the bacteria create ammonia (nitrogen usable by plants) and the plant provides sugar to feed the bacteria. (Plants exude flavonoids that attract soil bacteria to the plant's root hairs.) (06R1)
The Haber-Bosch process developed in the early 1900s is an efficient way to synthetically manufacture ammonia. Eventually the Haber-Bosch process was adapted to making nitrogen fertilizer, which helps to grow the food that sustains an estimated 40% of the world's population (06R1). (Lightning also creates ammonia that fertilizes plants (06R1).)
Growing soybeans in a field the year before growing corn can cut the amount of fertilizer needed for the corn by 40% (06R1).
The big breakthrough that made nitrogenous fertilizer comparatively cheap came with the work of the German chemist Fritz Haber (1868-1934). By 1913, Haber found a way to synthesize ammonia from the air, the basis of all subsequent nitrogenous fertilizer. Due to the wars and the Great Depression, Haber's work had limited impact until the 1950s, but ever since, the problem of nitrogen depletion has been treated by various forms of soil chemotherapy, chiefly nitrogenous fertilizer. Without it, the world's farms could feed only 2/3 of today's 6.3 billion people (04M1) (V. Smil, "Enriching the Earth", MIT Press, Cambridge Mass (2001)).
In the 1880s Hermann Hellriegel (1831-1895) and Mikhail Voronin (1838-1903) figured out the process of nitrogen fixation by microorganisms associated with the roots of leguminous plants. In effect they uncovered the hidden pathways of the nitrogen cycle, as von Liebig had discovered hidden limits upon plant growth (04M1).
In the 1840s Justus von Liebig (1803-1873), one of the founders of organic chemistry, developed the idea that minerals such as nitrogen, phosphorous and potassium were required for plant growth (04M1).
In the mid-19th century, Justus von Liebig formulated his law of the minimum that states that plant growth is limited by the availability of whatever nutrient is scarcest (76J1).
The manufacture of nitrogenous fertilizers, burning of fossil fuels and cultivation of leguminous crops have resulted in anthropogenic N fixation exceeding natural N fixation since about 1980, by an increasing margin. Some analysts suggest "over the next few decades this alteration (of the N fixation cycle) will become more severe" (99W2) (03N1).
Fertilizer is most productive in the absence of moisture constraints, i.e. when applied to irrigated crops (03B3).
There is empirical evidence that nutrient budgets change over time, and that higher yields can be achieved through reduction of nutrient losses within cropping systems. That is, increases in food production can be obtained with a less than proportional increase in fertilizer nutrient use (03B3).
The EU's net export forecasts are based on cereal yields rising at 1.3%/ year to 2008. This is lower than the historical trend, but still raises the issue of the environmental risks associated with rising yields in the intensively farmed areas that produce much of the EU export surplus, e.g. France. Such risks are mainly related to excessive use of fertilizer and other chemicals. The risk would be certainly increased if the pursuit of higher yields were to be accompanied by inappropriate use of fertilizer leading to increases in the nitrogen balance in the soil (difference between nitrogen inputs into the soil and uptake by crops). Empirical evidence suggests that this need not be so. OECD work on environmental indicators finds that the EU's soil nitrogen balance declined from 69 to 58 kg/ha of agricultural land between 1985/1987 and 1995/1997 ((00O1), Annex Table 1). Over the same period, wheat yield increased from 4.7 to 5.5 tonnes/ha, and that of total cereals from 4.5 to 5.2 tonnes/ha. Changes in the structure of incentives (e.g. reduced support prices), advances in technology (precision agriculture, etc.) and imposition of tighter management regimes concerning use of manure, probably explain much of this phenomenon.
Corn yields in the U.S. in the 1930s were the same as those during the 1860s (the first decade for which reliable estimates are available) (78B2). Comments: Before large-scale fertilizer-use starting in the 1950s, the large-scale use of genetically improved grain in the 1960s, and the large-scale development of irrigation systems in _____, increased needs for food were met by increasing cropland area.
Five references are cited supporting the contention that, on many soils, fertilizer will compensate (fully??) for nutrients carried away by erosion ((83C1), p.10).
Erosion reduces the water-holding capacity of soils, and fertilizer cannot compensate for this (83C1). Comments: This is probably due, in part, to erosion reducing the organic matter content of soils.
Historical: A plot of rice yields in China during 1950-1977 is found on p. 29 of (78B2) (120 tonnes/ km2 in 1950; 180 in 1977).
Historical: Rice yields in Japan during the 19th century were only marginally higher than those during the 14th century (78B2).
Historical: One-third of the increase in cereal production worldwide, and half of the increase in India's grain production, during the 1970s and 1980s have been attributed to increased fertilizer consumption (03B3).
Historical: The first big increase in crop yields due to fertilizer came from the use of super-phosphates in the mid-19th century. Super-phosphates were made by treating bones with sulfuric acid (83H2).
Historical: For centuries, most fertilizer came from animal manure and crop rotation. In the 1950s, cheap chemical fertilizers were substituted. Their use expanded 600% in the first 30 post- WWII war years -the single most important factor in cropland productivity growth. But without organic input from livestock and crops, physical properties of soil deteriorate, and soil becomes more susceptible to water- and wind erosion, and are less able to detoxify chemical herbicides and pesticides. They need more and more energy inputs in the form of chemical fertilizers to maintain productivity. It is a cycle that is at once productive and destructive (80B1).
PART [Bb] ~ Fertilizer ~ Marginal Productivity of Fertilizer ~
Grain yields (tons/ unit area/ year) increased half as fast in the 1990s as they did in the 1960s (globally?) (
Between 1950 and 1990, world grain yields per acre increased by 2.1%/ year. From 1990 to 2008 it rose by 1.3%/ year (09B6).
In India, adoption of "Green Revolution" seeds was accompanied by a six-fold rise in fertilizer use per unit area. Yet the quantity of agricultural production per tonne of chemical fertilizer dropped by a factor of 2/3 during the "Green Revolution" years. Over the past 30 years, the annual growth of chemical fertilizer consumption on Asian rice fields has been from 3 to 40 times faster than the growth of rice yields. In Central Luzon, Philippines, rice yield increased 13% during the 1980s, while chemical fertilizer consumption increased by 21%. In the Central Plains of the Philippines, rice yields increased by 6.5% while chemical fertilizer consumption increased by 24% and pesticides increased by 53%. In West Java, a 23% increase in rice yield required a 65% increase in chemical fertilizer consumption and a 69% increase in pesticide consumption (00R1). Comments: These data cannot be used to illustrate diminishing marginal productivities of chemical fertilizers.
*Grain yields (production per unit area of cropland) increased half as fast in the 1990s as in the 1960s (08B3). Comments: This trend can be attributed to at least three processes: (1) Declining marginal productivities of chemical fertilizers reflecting von Liebig's "Law of the Minimum," (2) Saturation in the percent of the world's grain lands that have been converted to miracle strains of wheat, rice and corn, and (3) The green revolution hitting up against its theoretical limits.
*World soybean production has quadrupled since 1977 (08B3).
Worldwide, farmers use 10 times more fertilizer in 2001 than in 1950. That 10-fold increase in fertilizer consumption has coincided with just a threefold increase in food production (FAO, Fertilizer Yearbook, Rome (various years)) (K. G. Soh, M. Prud'homme, "Fertilizer Consumption Report: World and Regional Overview and Country Reports," Paris: International Fertilizer Industry Association (December 2000)).
US farmers have discovered that there are optimal levels beyond which further applications of fertilizer are not cost-effective, and so are using less fertilizer in the mid-1990s than in the early 1980s. This trend is now evident in Western Europe and in Japan (Ref. 71 of (97B3)).
USSR fertilizer consumption dropped precipitously after subsidies were dropped in 1988 (97B3).
A US National Academy of Science report is cited as showing that the yield response to additional fertilizer declined as the amount of fertilizer per acre rose during 1910-69. Fertilizer-use increased 20% during 1975-1976, but yields remained unchanged (Ref. 9 of (79C3)).
If global fertilizer-use were halted, global food output would drop 40% (89B5).
While one lb. of fertilizer nutrients probably led to a yield increase of 10 lb. of non-milled rice in 1972, this ratio is now about 1:5 (89B5).
Marginal Fertilizer Productivity
(1) Ref. 20, Chapter 9 of Ref. (94B4)
(2) Ref. 22, Chapter 9 of Ref. (94B4)
Fertilizer Use and Grain Production in 1986 (90B2)
(Grain and fertilizer are in units of millions of tons/ year.)
During the 1960s, an additional ton of fertilizer boosted corn output by as much as 20 tons. Today, another ton of fertilizer may boost output by only a few tons. For rice, one ton of fertilizer boosted rice output by 10 tons (unmilled) in 1972. Today the ratio is about 1:5 (91B1).
Marginal productivity of fertilizer: see (81B3), p. 119.
Ratio of Incremental Grain Production to Incremental Fertilizer Use (tonnes of grain/ tonne of fertilizer) (81B3) (FAO- and USDA data)
A US National Academy of Science report indicates that the yield response to additional fertilizer declined as the amount of fertilizer/ acre rose during 1910-1969. Fertilizer-use increased 20% during 1975-1976, but yields remained unchanged (79C3).
During 1959-1964, each added lb. of fertilizer applied to US cornfields bought an average of 0.77 added bushel of corn. During 1964-1970, each added pound of fertilizer increased US corn production by 0.13 bushel (82W1).
Cereal yield in the US is plotted vs. time (1950-1977) on p. 28 of (78B2) (170 tonnes/ km2 in 1950; 370 in 1977). A reduced marginal productivity of fertilizer is seen.
There does not seem to be any diminishing returns from the application of fertilizer in the range of 2 tonnes/ km2 in India to 50 tonnes/ km2 in the Netherlands (80S1). The effects of fertilizers on crop yields (especially "miracle" strains) and related issues are discussed in (82B1).
PART [Bc] ~ Fertilizer ~ Fertilizer Consumption ~ [Bc1]~Global, [Bc2]~Africa, [Bc3]~Asia (East), [Bc4]~China, [Bc5]~Europe, [Bc6]~Asian Sub-Continent, [Bc7]~US, [Bc8]~USSR (former), [Bc9]~South America, ~
Sub-Part [Bc1] ~ Fertilizer Consumption ~ Global
Globally, fertilizer production has declined per capita by more than 22% since 1991, especially in developing countries, due to fossil fuel shortages and the high prices of natural gas
Globally, chemical fertilizer supplies essential for food production have been declining since 1989 (10P1).
Between 1981 and 1991, the world's annual use of fertilizers increased from 81 to 96 kg/ ha of cropland. Zimbabwe, one of Africa's higher users, used 56 kg./ ha/ year in 1989-1991 (99F1).
See Chapter 11, Section (F) for a compilation of large databases on:
~~ fertilizer consumption in 2001.
~~ fertilizer applied (kg/ha) in 2001.
World chemical fertilizer consumption has increased dramatically since the 1950s when it first started to get popular. China is now the top consumer of chemical fertilizers, with use rising beyond 40 million tons in 2004. Fertilizer use has leveled off in the US, staying near 19 million tons per year since 1984. India's use also has stabilized at around 16 million tons per year since 1998. More energy-efficient fertilizer production technology and precision monitoring of soil nutrient needs have cut the amount of energy needed to fertilize crops (05M1).
Global fertilizer consumption in 2000 was 136 million tons(International Fertilizer Development Center (IFDC), World Fertilizer Consumption (IFDC, Muscle Shoals AL 2000).) (04L1).
Some annual rates of depletion for the principal plant nutrients (nitrogen, phosphorous and potassium):
40-60 kg/ ha in Latin America, well above 60 Kg./ ha in parts of Africa (Julio Henao and Carlos Baanante, "Nutrient Depletion in the Agricultural Soils of Africa, IFPRI, Washington DC, October 1999) (Stanley Wood et al, Agro-ecosystems: Pilot Analysis of Global Ecosystems, IFPRI and World Resources Institute (2000) p. 52).
Poor farmers in various parts of the world are mining soil nutrients because they lack access to sufficient organic manure or mineral fertilizer (01B3). Their land use practices cause environmental damage that may ultimately endanger future food security, but immediate food needs take priority (01M3) (03N1). Comments: Organic manure is often used for fuel for heating and cooking in developing nations, compounding the nutrient-mining problem.
Fertilizer consumption and fertilizer-use efficiency are projected to rise. This will bring benefits in terms of higher soil fertility and soil organic matter levels. Soil erosion will diminish because of the positive impact on root proliferation, plant growth and ground cover of increased phosphate and potassium (associated with more balanced fertilizer inputs) (03N1). Comments: Soil organic matter levels tend to decrease with increased use of chemical fertilizers - see elsewhere in this document. Fertilizer-use efficiency in terms of wasting less fertilizer will probably increase, but the marginal productivity of fertilizers has been dropping over the years, and the basic science of plant growth says it must.
~ Fertilizer consumption: past and projected (03B3) (1998 is average of 1997-1999)
Table Note: Kg./ ha for 1997/1999 are for developing countries calculated on the basis of "adjusted" arable land data. For industrial and transition countries no projections of arable land were made.
North America + Western Europe + East- and South Asia accounted for over 80% of all fertilizer consumption in 1997/1999 (03B3).
Aggregated over all crops, fertilizer consumption is expected to increase by 1.0%/ year, rising from 138 million tonnes/ year in 1997/1999 to 188 million tonnes/ year in 2030 (Table 4.14) (03B3).
Fertilizer Consumption (kg./ ha. of Cropland) ((00W1) Table AF.2) (A breakdown by nation is shown in Table AF.2)
Comments:"Oceania" apparently includes Australia and New Zealand. The 1987 fertilizer-consumption figure for the "Developed" world appears to be in error since it exceeds that in all component regions.
Use of commercial fertilizer (1995-1997) is charted for 10 regions of the world in Ref. (00W1), p. 58.
A table and graph of fertilizer consumption in 13 regions of the globe during 1951-1975 (USDA data) are in (81B2), p.100-102.
During 1950-1984 global fertilizer consumption increased by a factor of 9. Irrigated land acreage nearly tripled during this same period (91B2).
Between 1961-1996, global fertilizer consumption went from 31 to 135 million tonnes (FAO data). This trend is now stalling (99M1). Comments: Elimination of subsidies explains much of the stalling of recent years.
Fertilizer and Pesticide Consumption ~ Global Data ((90W1), Table 18.2)
Col.2= Cropland area (1000 km2)
Col.3= Ave. fertilizer consumption, tonnes/ km2 cropland/ year, 1975-1977
Col.4= Ave. fertilizer consumption, tonnes/ km2 cropland/ year, 1985-1987
Col.5= Ave. pesticide consumption, tonnes active ingredients/ year, 1975-1977
Col.6= Ave. pesticide consumption, tonnes active ingredients/ year, 1982-1984
Fertilizer Consumption, Global totals(81B2)
Growth in (global??) Fertilizer Consumption (91B2)
Comments:The above growth figures seem to be in units of %/ year, not in % during the period indicated.
See a plot of (global?) fertilizer consumption vs. time (1930-1990) on p. 12 of Ref. (91B2.).
A plot of fertilizer consumption in various regions of the globe vs. time (1961-1977) is in (80S1) (based on Strout's analysis of FAO data).
Global Fertilizer Consumption (millions of tonnes/ year) (95B1)
Global Chemical Nutrient Production(millions of tons/ year) (76W1) (Obsolete data - for historical purposes only)
Global Fertilizer Consumption data(FAO data, (97B1))
Global Fertilizer Consumption(in Millions of tonnes/ year)
* Half of this was synthetic-fixed nitrogen.
World Fertilizer Consumption (88B4) (million tonnes total, and kg./ capita)
In 1975 global fertilizer consumption was 90 million tonnes (K2O, N, P2O5) ((80W2), p. 230).
Fertilizer Consumption in Various Regions (tonnes/ km2
of cropland) (1975?) (76M1)
Fertilizer consumption/ km2 of cropland in 1972-1973 in various nations is tabulated in (78W1), p. 68.
In 1950, worldwide fertilizer consumption: 5.6 kg/ capita/ year. By 1980 it was 25.6 kg/ capita/ year (81B3), p.103). 16 kg. of NPK fertilizers are needed to produce food for one person for one year (Schuffelen (1965)) (78B3).
World fertilizer consumption/ capita, and world grain-area/ capita are plotted vs. time (1950-88) in (89B2). Fertilizer consumption increased by a factor of 4, while grain-area/ capita decreased by 1/3 (89B2).
An international report on fertilizers indicates that per-capita fertilizer consumption during the past decade has decreased 23% (98P2).
During 1984-1989, (global?) fertilizer consumption increased by 18 million tons (14%) (90B1).
Global fertilizer consumption is plotted vs. time (1950-1991) is found in (91B1).
Global fertilizer consumption increased at +6.7%/ year during 1950-1984, and by +0.7%/ year during 1984-1992 (93B1).
World fertilizer consumption (total and per-capita) (1950-1992) is tabulated on p. 43 of Ref. (93B3).
World fertilizer consumption increased 10-fold during 1950-1989 (14 to 146 million tons/ year). Fertilizer consumption declined in the 4 years since 1989 (Ref.11 of (94B4)).
Global fertilizer consumption: 146 million tons in 1989 (peak), 126 million tons in 1993 (94B4). This decline is largely due to reductions in fertilizer subsidies in the former USSR, India, and China (94B4).
Fertilizer consumption per-capita (1950-1993) is plotted vs. time in Fig. 9-2 of (94B4).
Fertilizer consumption per unit-area of grain land is plotted vs. time in Fig. 9-3 of (94B4).
A farmer from Manchester, Iowa, holds the national record for dry land corn yield, 394 bushels from one acre. These techniques, however, come with high environmental impacts ~ plowing deep into the ground, leaving topsoil highly vulnerable to erosion, douse heavily with fertilizers and pesticides (400 pounds/ acre of nitrogen, three times the average corn application in Iowa), use genetically modified varieties, do not rotate corn with soybeans or any other crops. $650/ acre is spent on fertilizer, pesticides, seed and fuel, twice the Iowa average. (Scott Kilman, Wall Street Journal (1/28/00); Ag Week, 3/27/00).
Sub-Part [Bc2] ~ Fertilizer Consumption ~Africa
Cereal yields in sub-Saharan Africa are barely 1 tonne/ ha (vs. over 3 tonnes/ ha in Asia) (
Cereal yields in other developing regions increased by 1.2-2.3%/ year during 1980-2000 while yields in Africa increased by 0.7%/ year (World Bank data) (08F1). Comments: In a plot, yield growth in developed countries and Asian developing countries leveled off during around 1996-2003.
(Sub-Saharan) Africa loses about 8 million tonnes of soil nutrients/ year. More than 950,000 km2 of land in (sub-Saharan) Africa have been degraded (over the decades) to the point where productivity has been greatly reduced (data of the International Center for Soil Fertility and Agricultural Development) (08F1). Comments: The very low rates of consumption of both chemical fertilizers and organic fertilizers in Africa is a result of (1) extremely high prices of chemical fertilizers, (2) the diversion of animal dung to cooking fuel and (3) the inability of sub-Saharan Africa's poor soils to hold much fertilizer due to its low organic matter content.
Sub-Saharan African soils cannot hold much fertilizer because nutrient retention is so poor (i.e. organic matter content is low) (08F1).
Sub-Saharan Africa accounts for 2.5% of global fertilizer consumption and 2% of the world's irrigated lands (04L1).
The depletion rate of soil nutrients for Sub-Saharan Africa caused by low-input/ subsistence farming is estimated to be 40 kg. of NPK/ ha./ year (P. A. Sanchez, Science 295 (2002) p.2019.) (04L1).
In the early 1960s, fertilizer use in Sub-Saharan Africa was about 5 kg./ ha/ year, compared to 10 in India and China. In the 1990s, China was using 240 kg./ ha/ year and India about 110, but Sub-Saharan Africa was using about 8. But in a number of Sub-Saharan African countries, nutrient losses exceed 60 kg./ ha/ year of nitrogen, phosphorus and potassium (NPK) (02F1).
In Europe, urea costs about US$90/ tonne. Shipping it to a port in Kenya or Mozambique raises the price to about US$120/ tonne. Getting it into the African interior raises the price to $500/ tonne in eastern Uganda, and $770 in Malawi. These rates are 6 times greater than prices in Asia, Europe and North America. Infrastructure is the cause of much of the problem. Much of Africa has less than 10% of the road density of India. India has 1004 km. of paved road per million people, China has 803; Ghana has 494; Uganda has 94; Ethiopia has 66 (02F1). Taxes on imported fertilizer worsen the situation (02F1). Organic soil amendments lack some nutrients such as phosphorus. Manures have only 2% nitrogen (02F1). Sub-Saharan African farm soils are poor in organic matter, making them less fertile and more erosion-prone, but farmers cannot raise livestock (an organic matter [manure]~source) because of population pressures on the land. Also, instead of putting manure and crop residue in soils, people burn them for fuel because they cannot afford to import oil (02F1).
Shortage of organic matter in soils reduces drought resistance and increases inorganic fertilizer runoff. For this and other reason, low organic matter worsens the economics of inorganic (chemical) fertilizer use (02F1). Shortages of organic matter and nutrients also greatly reduce the efficiency of water use, making the economics of irrigation marginal (02F1).
The fundamental biophysical cause of stagnant per-capita food production in Africa is soil fertility depletion. Since mineral fertilizers cost 2-6 times more than world market prices, a soil fertility replenishment approach has been developed based on naturally available resources: nitrogen-fixing leguminous tree fallows that accumulate 100-200 kg. N/ ha, indigenous rock phosphate applications and biomass transfers of the nutrient-accumulating shrub Tithonia diversifolia. Tens of thousands of farmers in East and Southern Africa are becoming food secure with these technologies. (Sanchez, P., Science 295: pp. 2019-20 (3/15/02)).
Fertilizer consumption in Africa is 1.1 tonnes/ km2/ year (90C1). Comments: This is far less than in India or China.
[Bc2a] ~ Fertilizer Consumption ~ Sub-Saharan Africa ~
Fertilizer consumption in Sub-Saharan Africa is 1.4 tonnes/ km2/ year (Ref. 48 of Ref. (97P2)).
Sub-Part [Bc3] ~ Fertilizer Consumption ~ Asia (Eastern) ~
Fertilizer consumption in Eastern Asia is 20 tonnes/ km2/ year (Ref. 48 of Ref. (97P2)).
Sub-Part [Bc4] ~ Fertilizer Consumption ~ China
China's grain production and nitrogen fertilizer use hit 502 million tonnes of grain and 32.6 million tonnes of nitrogen fertilizer in 2007, up 54% and 191% respectively compared to 1981 (
Fertilizer consumption, in thousands of metric tonnes/ year (http://apps.fao.org)
Comments:Much of this is chemical fertilizer, since manure must often be used as fuel for cooking and heating. This runs the risk of organic matter depletion in the soil.
In parts of China fertilizer consumption is even more extreme than in the UK, with some rice farmers applying over 870 kg. N/ ha/ year, almost four times the national average (03N1).
About 30% of N, and 22% of K in applied fertilizer in China goes to replace nutrients that have eroded away (95W1).
Fertilizer Consumption: US and China (in units of millions of tons/ year)
(from plot in World Watch 9(5) (1996))
China'sfertilizer consumption (1997): 26 million tonnes/ year (vs. 19 tonnes/ year in the US) (98B1).
Sub-Part [Bc5] ~ Fertilizer Consumption ~ Europe
In the UK, the present average fertilizer application rate for all arable crops is about 150 kg. N/ ha/ year, but the range is 25-275 kg. N/ ha with application rates of more than 150 kg. on over 35% of arable land (
Manure is estimated to provide almost half of all external nutrient inputs in the EU (03B3). Comments: This helps to explain how Europe can use so much inorganic fertilizer without losing organic matter content of soils.
Crop subsidies are high in the EU, so applications of fertilizers are 2-4 times those in the US (90M2) (e.g. 70 tonnes/ km2/ year in the Netherlands (90C1)). Most developing countries use under 3 tonnes/ km2/ year of N, P, and K of arable land (82B1). This compares with 10 tonnes/ km2/ year in the US, and over 20 tonnes/ km2/ year in Japan and the more populous countries of Europe (82B1).
Sub-Part [Bc6] ~ Fertilizer Consumption ~ Asian Sub-Continent ~
In 1967 India imported 18,000 tons of hybrid wheat seeds from Mexico. In the 1970s, India dramatically increased food production to the point of being able to export food instead of importing it. But the heavy government subsidies on nitrogen fertilizer (urea) for over the past three decades caused over-consumption of urea to damage cropland soils, and this caused crop yields to decline. Declining yields caused farmers to add even larger doses of urea. This forced India to resume importing food. India's rice yields are now 340 tons per km2 compared to Pakistan's 350, Sri Lanka's 370, Bangladesh's 390 and China's 650 tons per km2 (FAO data of 2008). India has now eliminated subsidies for all fertilizer except for Urea (for political reasons). India's urea subsidies pay about half the domestic industry's cost of production. India's wheat imports were 1.7 million tons in 2008, vs. 1,300 tons in 2002. Too much urea over-saturates plants with nitrogen without replenishing phosphorous, potassium, sulfur, magnesium and calcium. India's fertilizer subsidies cost $20 billion/ year, vs. $640 million in 1976. In one Indian state, farmers used 32 times more nitrogen than potassium in the fiscal year ending March 2009, vs. the recommended 4-1 ratio. Croplands need more water when fertilizer is used. This is partly responsible for India's water tables dropping dramatically (
Fertilizer consumption, in thousands of metric tonnes/ year (http://apps.fao.org)
Comments:Much of this is chemical fertilizer, since manure must often be used as fuel for cooking and heating. This runs the risk of organic matter depletion in the soil and degradation of soil chemistry.
Fertilizer consumption in India was once heavily subsidized. Subsidies ceased in the early 1990s, and growth in fertilizer consumption slowed significantly (Ref. 14 of (93B3)).
Fertilizer-consumption in the US and India is plotted vs. time (1950-1993) in Figure 9-5 (Ref. 16, Chapter 9 of Ref. (94B4)).
Sub-Part [Bc7] ~ Fertilizer Consumption ~ US ~
Fertilizer consumption in the US peaked in 1980 and has dropped since then (95B1). Comments: Falling crop prices may have had some role in this.
Fertilizer consumption in the US during early 1990s was 21 million tons/ year (22 million tons/ year in early 1980s) (93B1).
Fertilizer-consumption in US and India plotted vs. time (1950-1993) in Fig. 9-5 (Ref.16, Chapter 9 of Ref. (94B4)).
US fertilizer consumption increased 15 times between the 1930s and the 1970s. Nitrogen fertilizer applications in the US increased over 17 times in that period ((83C1), p.10).
US fertilizer consumption increased by 4 times between 1950-1981. Since then it has fallen. 1989 consumption was lower that 1980 consumption (90B2). Comments: Fertilizer consumption tends to be highest in nations that provide crop subsidies, e.g. Europe and the US. It is not clear that these high levels of fertilizer use are economically viable under free market conditions. E.g., during 1988-91 Soviet fertilizer consumption fell 23% as fertilizer prices rose toward free market prices (93B1).
World Bank efforts to eliminate fertilizer subsidies in countries like Mexico and Indonesia have added to the trend of lower fertilizer consumption (93B1).
Sub-Part [Bc8] ~ Fertilizer Consumption ~ USSR (former) ~
The total amount of mineral fertilizers applied under Russia's crops made up 1.539 million tonnes (in terms of 100%-nutrients), or 18 kg./ ha in 1997. The amount of organic fertilizers was 67 million tonnes. Thus, 27% of the total arable area was fertilized by mineral fertilizers and 3% by organic fertilizers. Chemical melioration covered 10,000 km2 in 1997 (
(Chemical) fertilizer consumption in the former USSR dropped 60% during 1988-1995 due to reductions in subsidies (95B1).
Sub-Part [Bc9] ~ Fertilizer Consumption ~ South America ~
Argentina Fertilizer Consumption (in millions of tonnes.) (From charts in the
Go toTop of this Section-Fertilizer
Part [Bd] ~ Environmental Effects and Energy Requirements of Fertilizers ~ [Bd1]~Water Quality, [Bd2]~Soils, [Bd3]~Energy Requirements, [Bd4]~Excess Consumption, [Bd5]~Health Effects, [Bd6]~Dead Zones, ~
Sub-Part [Bd1] ~ Environmental Effects of Fertilizer ~ Water Quality
Nitrogen and phosphate enrichment of lakes, reservoirs and ponds can lead to eutrophication, resulting in high fish mortality and algae blooms. This is important because of the growing importance of aquaculture. Algae blooms release toxins that are poisonous to fish and humans (03N1). Comments: Also see [Bd6]~on Dead Zones.
Fixed nitrogen compounds are water-soluble, and hence tend to leak into ground water (90M2).
The National Water Quality Inventory: 1996 Report to Congress Executive Summary found that phosphorus and nitrogen caused impairment to 40% of US rivers, 51% of surveyed lakes, and 57% of surveyed estuaries. (EPA Holds Public Stakeholders Meeting on Nutrient Criteria, Clean Water Network, June/July 1999, Status Report (6/30/00)).
The small size of the 2000 hypoxic area at the mouth of the Mississippi River is consistent with observations since 1985, when scientific measurements began. When river levels are low, nutrient runoff is usually lower, and the hypoxic zone tends to be smaller. There are exceptions, however, which demonstrate the pivotal role that nutrient runoff plays, e.g. 1999 when heavy rains upriver early in the spring resulted in a record-size Dead Zone, even though it was a drought year. There is a strong consensus among scientists conducting research on Gulf hypoxia that loading of nutrients, in particular nitrogen is the driving force behind hypoxia. Midwest farm runoff, as well as municipal wastewater from Chicago, has been identified as key sources of nitrogen by the US Geological Survey and a 6-volume report commissioned by a federal-state Task Force working to address Gulf hypoxia. (00D1) (See http://www.riverwise.org/hypoxia/hypoxia.html).
Trends in nitrate concentrations in the Des Moines and Raccoon Rivers (Des Moines IA water supply) have been significantly upward. Ammonia and nitrites (resulting from nitrate) have been found in Iowa's shallow aquifers. Both chemicals are suspected cancer-causing chemicals and are believed to cause other illnesses. (99U2).
Iowa and Illinois are credited with as much as 35% of the nitrogen pollution ending up in the Gulf. Nitrogen pollution is a leading cause of water pollution in Iowa rivers and lakes as well. 11,000 miles of Illinois streams are impaired by agricultural runoff (00D1).
A plot of phosphorus pollution in Lake Pepin (On the Mississippi in SE Minnesota) since 1830 clearly showed the rapid increase due to the "Green Revolution" and its dependence on fertilizers (00A1).
The nitrogen in the 8 billion gallons of livestock waste produced in Minnesota annually is equivalent to the domestic waste of 77 million people - over 17 times the population of Minnesota. (00D1)
Sources of nitrate (NO3) in water supplies: nitrogen fertilizers, crop residues, livestock waste, septic systems, organic matter from soil. Nitrate forms when nitrogen fertilizers, decaying plants, manures and other organic residues are broken down by microorganisms (99W1).
There is no scientifically identifiable link between farmers' use of fertilizer in the Mississippi River Basin and the appearance of a low-oxygen (hypoxia) zone in some waters of the Gulf of Mexico, according to the American Farm Bureau Federation. In comments filed today regarding a government-commissioned report, Farm Bureau stated that any hypoxia-related mandate to curtail the farm use of nitrogen fertilizer in the Mississippi River Basin is not supported by science or economics. A hypoxic zone of water with low oxygen concentration typically forms in the Gulf of Mexico each summer for about 3 months. Cited in Farm Bureau's comments are conclusions by scientists who worked on the CENR report that stated, "there is no discernable, measurable, or documentable detrimental ecological and economic effects" to the Gulf environment or its fisheries from hypoxia. Even during recent extremes in hypoxic conditions (1993-97), CENR scientists concluded that Louisiana's coastal fisheries flourished. US farmers have improved their nitrogen fertilizer-use efficiency by 29% since 1983. (Farm Bureau Comments On Gulf of Mexico Report, 8/10/99).
Sub-Part [Bd2] ~ Environmental Effects of Fertilizer ~ Soil
It is generally perceived that chemical (inorganic) nitrogen fertilizers sequester soil organic carbon by increasing the input of crop residues. This perception is shown to be false, and the opposite is found to be true. After 40 years of synthetic (chemical) fertilization in which inputs of fertilizer nitrogen exceed grain (crop) nitrogen removal by 60 to 190%, a net decline occurred in soil carbon despite massive residual carbon incorporation into the soil (07K1). These findings implicate chemical (fertilizer) nitrogen in promoting the decomposition of crop residues and soil organic matter. The results are consistent with data from numerous cropping experiments involving synthetic nitrogen fertilization in the US Corn Belt and elsewhere (07K1). (Continued below)
Despite the use of forage legumes, many Midwestern US soils had suffered serious declines in both nitrogen content and soil organic matter by 1950, except in cases involving regular applications of manure. There are good reasons for being concerned that these declines could adversely affect both agricultural productivity and the sustainability of cropland productivity because soil organic matter plays a key role in maintaining soil aggregation and aeration, hydraulic conductivity, water availability, cation-exchange, buffer capacity, and the supply of mineralizable nutrients. Numerous 15N-tracer studies have found that the nitrogen found in grain (crops) originates largely from soil nitrogen (the nitrogen stored in soil organic matter) rather than from the nitrogen supplied by chemical fertilizers (07K1). (Continued below)
The common practice of applying chemical fertilizer nitrogen in ever increasing excesses relative to crop (grain) nitrogen also carries serious implications for atmospheric CO2 enrichment because soils represent the Earth's major surface-carbon reservoir. (Mineralization of soil organic carbon to produce atmospheric CO2 is speeded up by chemical fertilizer nitrogen, and this does double damage: depleting soil organic matter and increasing atmospheric CO2.) Also, application of chemical fertilizers beyond crop nitrogen requirements contributes to anthropogenic production of N2O, a potent greenhouse gas and a gas with adverse implications for stratospheric ozone. In addition, excessive chemical fertilizer nitrogen promotes NO3- pollution of surface water and ground water (07K1). Excessive chemical fertilizer nitrogen applications can be reduced or eliminated by extensive use of forage legumes and applications of livestock manure (as is done in Europe and in "mixed agriculture" in Wisconsin) (07K1). ("Mixed agriculture" commonly refers to farms that produce both livestock and crops. This form of agriculture is most commonly practiced on smaller farms.)
Further intensification of chemical fertilizer use may also add to widespread problems of soil acidification (99S1) (03N1).
A University of Wisconsin study found that excessive applications of chemical fertilizers are rapidly aging temperate agricultural soils. Researchers found soil that aged the equivalent of 5000 years after 30 years of normal chemical fertilizer application. The soil had lost much of its ability to hold calcium, magnesium and potassium because of increased acidity. Soil acidity increases when excess nitrogen from the chemical fertilizer becomes nitric acid. (Only about half of the applied nitrogen is actually taken up by plants.) As a result of this soil acidity increase, rich northern soils are becoming more like the sandy, less productive soils of the south (99U2).
Globally, one third of tropical soils have sufficiently acid conditions to cause soluble aluminum to be toxic for most crops. Soil acidity increases when excess nitrogen from chemical fertilizer applications becomes nitric acid. (Only about half of the applied nitrogen is actually taken up by plants.). So additions of chemical fertilizers to tropical soils carry the potential adverse side effect of increasing the likelihood of tropical soils showing aluminum-toxicity for crops (99S2).
Sub-Part [Bd3] ~ Fertilizer ~ Energy Requirements
According to the Fertilizer Institute (http:www.tfi.org) during 6/30/01 to 6/30/02, the US used 12,009,300 short tons of nitrogen fertilizer (
Using the low figure of 1.4 liters of diesel equivalent per kg. of nitrogen, this equates to the energy content of 15.3 billion liters of diesel fuel or 96.2 million barrels (00M1).
Production of one kg. of nitrogen for fertilizer requires the energy equivalent of 1.4-1.8 liters of diesel fuel. This is not considering the natural gas feedstock (00M1).
By 2000, 160 million tons of chemically fixed nitrogen (4 times 1974 usage) will be used in world agriculture. This will require 250-300 million tons of fossil fuels (4% of present-day fossil fuels consumption) (76R1). Synthesis of a ton of anhydrous ammonia requires 30,000 ft3 of natural gas (76J1). Production of one ton of nitrogen requires the energy equivalent of 7 barrels of oil (82B1). If the world's 4 billion people all consumed energy at the US per-capita rate, world consumption would increase by six times. If the world's petroleum resources (1.7 trillion barrels) were consumed at 6 times current rate, they would be exhausted by 1997 (82U1, p. 95).
A chart is given of energy use in US agriculture in 1974 (BTU and %). Energy invested in fertilizer, pesticides, herbicides and fungicides (700 trillion BTU) was 34% of total energy used in agriculture ((81B2), p. 87).
In world agriculture, synthetically fixed nitrogen represents only about 30% of the total fixed nitrogen metabolized by crop plants. Some 40 million tons of synthetically fixed nitrogen were applied worldwide in 1974. Biological fixation in agricultural soils amounted to 90 million tons (35 in crop legumes, 9 in non-legume food crops, 45 in permanent meadows and grass-lands) (76R1). World demand for nitrogen-containing fertilizers: 80 million tonnes/ year (92M1).
Sub-Part [Bd4] ~ Environmental Effects of Fertilizer ~ Excessive Consumption ~
Heavy use of nitrogen fertilizer in China since the 1980s has resulted in severe acidification of its cropland soils. Farmers used cheap nitrogen fertilizer like urea and ammonium carbonate. As a result, some croplands in southern China can no longer be used. The pH has dropped to 3-4 in some places. So maize, tobacco and tea cannot be grown. (Most plants grow best in neutral soils with a pH of 6-8 because the availability of essential nutrients is usually optimal in this range. A lot of trees cannot grow in soils with a pH of under 4.) The average pH of all (cropland) soils in China decreased by 0.5 in the past 20 years. Under natural conditions a single unit change needs somewhere between hundreds of years or thousands of years. Reversing soil acidification can be accomplished quickly with lime, but that is expensive and labor-intensive. A cheaper option is to return crop residues to the soil. Crop residues are usually burned, in part because returning them to the soil is labor intensive and machinery intensive (
A 1977 (1997?) University of Minnesota study found that nitrogen applications on croplands exceed University of Minnesota recommendations by 53 lb./ acre (largely at the behest of fertilizer dealers and crop consultants) (99U2). Comments: This figure needs to be in percent to be meaningful. The average corn application in Iowa is about 130 lb./ acre/ year.
When nitrogen was cheap, US farmers would apply it in the winter, so lots of it was lost in spring run-offs. Now, with the price up 4-5x, US farmers apply it in spring and summer, but even then, nearly half of it leaks away or is oxidized by micro-organisms (81W1).
Sub-Part [Bd5] ~ Environmental Effects of Fertilizer ~ Health Effects ~
More nitrogen is now fixed synthetically and applied as fertilizers in agriculture than is fixed naturally in all terrestrial ecosystems. Over-application of nitrogen fertilizers in agriculture and its concentration in domestic animal manure have led to eutrophication of surface waters and groundwater in numerous locations around the world. Nitrogen fertilizers also lead to the microbiological production of N2O, a greenhouse gas. They are also a source of NO in the stratosphere where it is strongly involved in ozone chemistry (
It is not nitrate per se that is a health concern, rather nitrites and N-nitroso compounds (NOCs) that are produced from nitrates by a series of complex chemical reactions. The historic area of concern with respect to nitrates is methemoglobinemia ("blue baby syndrome"). Blue-baby syndrome has rarely been diagnosed in the US in recent years. Alex Avery (Hudson Inst.) contends that the USEPA limit of 10 ppm for NO3-N (45 p.p.m. for NO3) in drinking water is too stringent. Ref. (99W1) lists numerous studies of the health effects of nitrate, other than blue-baby syndrome (99W1).
In Des Moines, officials with the city's Water Works department recorded (May 2000) the highest-ever nitrate level in the Raccoon River, the source of the city's drinking water. Federal guidelines say that the water is safe as long as the level of nitrates doesn't reach 10 ppm. The nitrates were registering at 17.5 p.p.m. in May, forcing Des Moines to switch to the Des Moines River for its drinking water (01U2).
Sub-Part [Bd6] ~ Environmental Effects of Fertilizer ~ Dead Zones ~
Nitrogen and phosphate farm runoffs and untreated sewage are creating "dead zones" in oceans around the world and the problem is likely to increase by 2/3 by 2050. There are already more than 50 dead zones - including the Gulf of Mexico, Chesapeake Bay and Puget Sound in the US - caused by an over-abundance of nutrients choking off oxygen (
Part [Be] ~ Fertilizer ~ Phosphate and Potash Reserves ~
Phosphorus makes up 1% of your body weight. Most economists see global trade as a win-win proposition, but resource limitation turns it into a win-lose, zero-sum contest. "The faster China grows, the higher grain prices go, the more people in China or India who upgrade to meat, the higher the tendency for Africa to starve (11R1).
Improvements in urban sanitation eventually led to a resumption of population growth, one results of which was an increase in the area of farmland. Food now had to be transported over greater distances from farms to cities. That, together with the development of sewers, meant that food wastes and human excrement, which formerly had been returned to farmland, were no longer recycled but, for the most part, at least in the case of sewage, were discharged ultimately into the sea. As a result, some essential nutrient elements came to be used in a way that was, and is, irreversible. The most vulnerable of these elements is phosphorus, reserves of which, allowing for the inevitable uncertainties, will probably last somewhere between 85-190 years. Is a substitute for phosphorus available? The problem there is that the element whose chemical properties are closest to those of phosphorus is arsenic. The concentration of phosphorus in the sea is such that, to meet current rates of fertilizer application, seawater would have to be processed at a rate of 646 km3/day. That rate is more than 50 times the global rate of consumption of fresh water (04B2).
In 2007 the price of phosphate fertilizer shot to $300 and then to $400/ ton, and is expected to hit $800/ ton in 2008 (08U3).
Global consumption of phosphate rock is projected to grow 2.3%/ year (08U3).
Out of 50 billion tons of potential phosphate rock reserves worldwide, the USGS estimates that the US holds 3.4 billion tons, Morocco owns 21 billion tons, and China owns 13 billion tons (08U3).
The deep red color of (sub-Saharan) Africa's soils means that they are rich in iron that renders phosphorous unavailable to plants (08F1). (Also in food.html in this website)
Phosphate Uptake by Common Crops (94D1)
A consumption rate of 30 million tons/ year gives at least a 400-year supply of phosphate (Gruhl, 1975) ((78B3), p.125). A consumption rate of 20 million tons/ year gives at least a 400-year supply of potassium (78B3). Potash reserves and resources in various regions of the globe are tabulated. World reserves = 10 billion tons; Resource = 69.1 billion tons ((78W1), p. 71). Phosphate rock resources in various nations are tabulated (78W1). Known world reserves of phosphate = 16.1 billion tons (78W1).
About 80% of the world's resources and reserves of phosphates are in Africa (78W1). Developing countries, containing 80% of the Earth's population, used only 20% of the phosphate fertilizer in 1977 that were used in the developed countries ((83H1), p. 8).
Phosphorous apparently is the most deficient plant nutrient in eroded soils (Ref.63 of (81N1)). The problem is compounded if sub-soil contains more clay than topsoil. Clay tends to transform applied phosphorous quickly into forms not readily available to plants (81N1).
Part [Bf] ~ Fertilizer ~ Gross Effects on Food Production ~
An 18-year experiment in Kenya showed that the yield of maize and beans was 1.4 tons/ ha/ year without external input, and 6.0 tons/ ha/ year when stover was retained and fertilizer and manure were applied (
CGIAR has estimated that land saved through yield gains over the past 30 years from CGIAR research on 7 major crops is equivalent to 2.3-3.4 million km2 of forest and grassland that would have been converted to cropland in the absence of these gains (01N1). Their estimate excludes land savings stemming from research on other crops, from national and private research systems and from farmers' own research and development. Some estimates of land savings resulting from all past research efforts and agricultural intensification amount to more than 4 million km2 (99G2) (03N1).
To get world food production to double over the past 35 years, farmers have had to use seven times as much nitrogen as they used to, effectively doubling the amount that already comes in from the atmosphere. By 2050, the use of nitrogen may quadruple with the projected increase in the world population by almost 50%, and if it becomes increasingly affluent with a buying power 2.4 times that of today's population and producing a demand for twice as much food. The study recommends timing applications of fertilizer better and doing a better job of removing it from sewage. (MSNBC, 2/21/00 http://www.msnbc.com/news/372766.asp).
If fertilizer consumption were stopped, food output would drop about 40% (90B2) (at least 1/3 according to (81B3). Fertilizer caused 40% of the increase in crop output between the early 1960s and the mid-1970s. In that period, fertilizer use in developing countries increased by 4 times (80S1).
In 1983, one pound of nitrogen fertilizer produced approximately 0.75 bushel of corn. Today, one pound of nitrogen fertilizer produces about a bushel of corn. (Farm Bureau Comments On Gulf Of Mexico Report, 8/10/99) Comments: Is this gross or marginal fertilizer productivity?
During 1935-1975, New York State wheat production/ acre increased 100%; 50% of this was attributed to genetics; 50% to fertilizer, herbicides, pesticides, machinery, etc. (78J2).
In India and Pakistan, 50-60% of all animal manure is used for fuel for cooking, etc. ((80W1), p. 572). Comments: This causes soils to become depleted in organic matter content, making the soil less fertile.
Egyptian cereal yields doubled during 1951-1971; but they have not increased since (78B2).
French cereal yields tripled (160 tonnes/ km2 to 440) during 1950-1973. But during the four years since 1973, yields fluctuated between 340 and 420 tonnes/ km2/ year (78B2).
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SECTION (7-C) ~ Pesticides ~ [C1]~General, [C2]~Pesticide Resistance and non-Specificity, [C3]~Pesticide Usage, [C4]~Subsidies, [C5]~Integrated Pest Management, [C6]~Health Effects, ~
Part [C1] ~ Pesticides ~ General ~
Despite the yearly use of 3.0 million tons of pesticides and other controls worldwide, about 40% of all potential crop production is lost to pests. (
Globally, loss of food to pests has not decreased below 52% since 1990 (10P1).
Crying not for Argentina but for lost patent fees, Monsanto's legal hacks are in European courts suing to block millions of tons of Argentine soybean meal from docking on the continent. Monsanto says that much of the meal crossing the Atlantic to feed Europe's cows and pigs contains traces of its genetically modified Roundup Ready Soybeans. Known as RR, the soybeans are tweaked to withstand the company's "Roundup herbicide. This resistance lets farmers blanket entire fields with the chemical mixture rather than surgically applying it to kill off weeds. Monsanto holds a patent for the seed in Europe, but not in Argentina, where a dispute over technology rights keeps the US-based agri-giant from collecting technology fees on RR seed sales. By using its European patent to disrupt Argentina's lucrative soy-meal trade with Europe, the company hopes to strong-arm Argentine farmers into paying up. (Continued below)
Argentina first approved RR seeds in 1996, and Monsanto tried to build its royalty fees into the price, but a thriving black market kept the seed prices too low for Monsanto to recoup the fees. US farmers were paying a $6.50 patent-based technology fee every time they bought a 50-pound bag of RR seed. Around that time, seeds that sold for $9 a bag in Argentina were going for $21.50 in the US. A report issued at the time by the US government's General Accounting Office blamed the price difference on lack of property-rights enforcement in Argentina. The American Soybean Association asked Monsanto to refund more than $300 million to US farmers. The company refused. (Continued below)
As Argentina struggled to recover from a devastating economic collapse that hit in 2001, the illegal trade in RR seeds grew. By 2005, according to one estimate, only 20% of Argentina's $1 billion annual soybean seed trade was legal. Monsanto had had enough. It stopped direct seed sales in 2003, though Argentine companies continued to sell seeds containing RR genes and paid some licensing fees. (Continued below)
Having missed out on the chance to collect fees at the point of sale, Monsanto lawyers in 2004 said the company would charge a $1/ ton export fee on Argentine soy and soy derivatives shipped abroad (and $2.50/ ton between 2006-2011). Argentina's farmers and government officials refused. (Continued below)
The astounding rate at which the RR soybean took hold, and the repercussions it has wrought are becoming clearer. Since RR was approved for use in Argentina in 1996, Argentine jungles and savannas have been cleared to make room for 34 million acres of soybeans. The rate at which forests in northern Argentina are being turned into soy plantations is 3-6 times higher than the world average. Argentina now ranks second only to the US as the biggest producer of GM crops in the world. (Continued below)
GM cheerleaders say the crops enhance food security. But statistics fall crossways. Walter Pengue of the University of Buenos Aires and Miguel Altieri of the University of California-Berkeley report that wheat, dairy, and fruit production has dropped significantly in Argentina as farmland has turned to soybean monocultures. (Continued below)
Monsanto claims RR soybeans decrease the need for repeated herbicide applications. But some weeds build resistance to herbicides, and when they do, different herbicides are needed in the mix. Pengue and Altieri report that in the Argentinean pampas, 8 species of weeds exhibit resistance to glyphosate, the active ingredient in Roundup. The fear: the more plants become resistant, the more farmers turn to different pesticides, further complicating the soup of poisons being spread through the country's fields. *(Continued below)
There are also concerns that all this genetic tinkering is causing GM soy to have lower protein levels than regular varieties. A study published in the Journal of Agricultural and Food Chemistry in 2004 analyzed soybeans and soybean meal from the world's top producers: Argentina, Brazil, China, India, and the US. Those from Argentina, which Benbrook says at the time were 98% Roundup Ready, had the lowest crude protein content. Those from China, which grew no GM soy at the time, had the highest. "This points directly to the possibility that RR has resulted in significant decline in protein level," Benbrook said, adding that it mirrors concerns that protein levels in soy and corn in the US are decreasing ("Is Monsanto playing fast and loose with Roundup Ready Soybeans in Argentina? By Kelly Hearn (9/22/06).).
Birds, bats, bees and other species that pollinate North American plant life are losing population. 75% of all flowering plants depend on pollinators for fertilization. (Other pollinators include butterflies and wild bees.) (06E1) (su1).
American honeybees, which pollinate more than 90 domestic commercial crops have declined by 30% in the last 20 years. Pesticides and introduced parasites, such as the varrora mite, have hurt honeybee population (06E1). Bats, which carry pollen to a variety of crops, have declined as cave vandalism and development destroyed some of their key cave roosts (06E1) (su1).
Animal pollinators fertilize more than 187,500 flowering plants, called angnosperms, gained ecological dominance more than 70 million years ago (06E1) (su1).
Evidence from the fields shows Monsanto's claims about its BT cotton variety to be spurious. A study of 481 Chinese farmers in five provinces found that after 7 years of cultivation they had to spray up to 20 times to deal with secondary insects, bringing a net income of 8% less than conventional cotton farmers. Failure of BT cotton crops in India resulted in the suicides of an estimated 700 farmers in the Vidarbha region of Maharashtra, to escape debt incurred by buying the expensive GM seed. BT crops have been attacked by a disease unseen before which affected BT more than the non-BT cotton crop. Genetic engineering and BT cotton will neither revolutionize the countryside nor improve food security, but a new farm economy based on the principle of food sovereignty and farmers' rights as the centerpiece of the country's economic development model will("The New Harvest of GM Cotton," IPS News (6/1/05)).
Developed countries are increasingly using taxes and regulatory measures to reduce pesticide use (99D4) (99D3) (03N1). However, shortages of farm labor (in developed economies), reduced use of flood-irrigation for rice, and expanding minimal tillage systems tend to increase the use of herbicides and herbicide-resistant crops (03N1).
Pesticide use has increased considerably over the past 35 years. Recent regional growth rates have ranged between 4.0-5.4%/ year (98Y1). This has led to serious water pollution in OECD countries (01O1) (03N1).
Insects, diseases, and weeds collectively destroy about 35% of potential pre-harvest crop production in the world (91P2).
Between 40 and 80% of agricultural pests are biological invaders (invasive species), and despite the 5 billion pounds of pesticide applied worldwide over 40% of potential food is destroyed by pests each year. (David Pimentel, "How Many Americans can the Earth Support?", Population Press (4/99)).
Development of a new pesticide requires 10 years, on average, and can cost $20-45 million (Ref. 42 of Ref. (96G1)).
Part [C2] ~ Pesticides ~ Pesticide Resistance and non-Specificity ~
Farmers spend about 17 times as much, adjusting for inflation, on pesticides (than on ?????). Yet the effectiveness of these applications is dropping. The share of harvest lost to pest remains largely the same as in 1950, despite the use of much greater quantities of pesticides (Montague Yudelman et al, "Pest Management and Food Production", Food, Agriculture and the Environment Discussion Paper 25, Washington DC, IFPRI, Sept. 1998).
During 1945-89 in the US, insecticide applications increased 10-fold, but crop losses to insects increased from 7% to 13% of the harvest (96G1). Monocropping explains part of the higher losses (96G1). Comments: This loss is probably in addition to the global loss of over 20% of harvested food because of spoilage, spillage, and losses to rodents and insects (96G1). Comments: The decreasing genetic diversity of crops also aids pests and increases pesticide usage.
Species resistant to common pesticides now number over 900 (vs. 182 in 1965) (96G1) (See plot for the period 1908-present in (96G1).)
Pesticides tend to be "non-specific" meaning that they oftenkill non-target organisms, including natural enemies of pests. Because of the disruption of natural enemies of pests, there have been resurgences of existing pests and outbreaks of new ones (03B4). Almost all economically significant pests are resistant to at least one chemical pesticide (03B4). Over 400 species of agricultural pests are now resistant to one or more pesticides. In the 1940s, 7% of US crops were lost to insects. In the mid-1980s, 13% were lost to insects (86P3). Pesticide resistance continued to grow after the banning of persistent pesticides, and now pesticide resistance is the highest ever in history (86P1).
Genetic resistance bred into wheat crops 40 years ago has begun to break down. A new, mutated form of the stem-rust fungus - a disease that virtually disappeared from the face of the Earth after destroying as much as half of wheat yields decades ago - reappeared several weeks ago at an experimental farm in Uganda. Most affected would be eastern and southern Africa, where many crops depend solely on the sr-31 resistance gene. But the sr-2 gene complex, used throughout much of the rest of the world and which is still able to prevent the fungus, may not work as effectively against the mutated spores. The last major outbreak, which occurred in the US in the mid-1950s, destroyed up to 50% of wheat crops on many US farms. (Mark Stevenson, Wheat Disease Resistance Weakening, AP, Mexico City, early 1999).
Part [C3] ~ Pesticides ~ Usage ~
In the US, about 0.5 million tons of pesticides are applied each year, yet pests still destroy about 37% of all potential crop production. Estimates suggest that pesticide use could be reduced by 50% or more, without any reduction in pest control and/or any change in cosmetic standards of crops, through the implementation of sound ecological pest controls, such as crop rotations and biocontrols (
GE crops of corn, soybeans and cotton have increased use of weed-killing herbicides by 383 million pounds from 1996 to 2008; 46% of the total increase occurred in 2007 and 2008. However, GE corn and cotton have reduced insecticide use by 64 million pounds, resulting in an overall increase of 318 million pounds of pesticides over the first 13 years of commercial use (09U1). (Continued)
A U.S. Department of Agriculture (USDA) report links the increase in pesticide use on GE, "herbicide-tolerant" (HT) crops to the emergence and spread of herbicide-resistant weeds. Farmers are already critical of GE crops because of drastically rising biotech seed prices (09U1). (Continued)
The agricultural biotechnology industry claims that the higher costs of GE seeds are justified by the decreased spending on pesticides. But the need to make additional herbicide applications in an effort to keep up with resistant weeds is also increasing cash production costs. Corn farmers planting GE hybrids in 2010 will spend around $124 per acre for seed, almost three times the cost of conventional corn seed. A new-generation "Roundup Ready" (RR) 2 soybean seed will cost 42% more than the original RR seeds they are displacing (09U1). (Continued)
Glyphosate, the active ingredient in Monsanto's Roundup herbicide, is now being resisted by weeds which are starting to infest millions of acres; farmers face rising costs coupled with sometimes major yield losses (09U1).
The annual crop loss due to insects in Bangladesh is 16% for rice, 11% for wheat, 20% for sugarcane, 25% for vegetables, 15% for jute and 25% for pulses. In 2003, 3866 metric tons of ingredients of pesticides were used in Bangladesh, "Pest" refers to insects, pathogens, weeds, nematodes, mites, rodents and birds.("Integrated Pest Management in Agriculture", The Daily Star, (8/31/04)).
Global salesof pesticides in 1994 were $25 billion. Industrial countries consumed 80% of pesticides, but sales there have plateaued (96G1).
Pesticide exports have increased by a factor of almost 9 since 1961, to $11.4 billion in 1998. (Hilary French, Vanishing Borders: Protecting the Planet in the Age of Globalization, World Watch (3/27/00)).
During 1970-1990, global pesticide use rose from 1.3 to 2.9 million tonnes/ year (92M2). Pesticides were used at a rate of 1.5 million tonnes/ year in the late 1960s, and the rate is increasing by 10%/ year (FAO data) ((80W2), p.230). As a group, less-developed countries use 20% of the world's pesticides (86P1). US pesticide use in agriculture nearly tripled during 1965-1985 to 390,000 tons/ year (280 kg./ km2/ year) (See plot) (Ref. 5 of Ref.(88P2)).
Global use of agricultural pesticides rose from 50,000 tonnes/ year in 1945 to current application rates of approximately 2.5 million tonnes/ year. Most modern pesticides are more than 10 times as toxic to living organisms than those used in the 1950s (98P3).
Part [C4] ~ Pesticides ~ Subsidies ~
Pesticide subsidies in the early 1980s ranged from 19% of unsubsidized retail cost in China to 89% in Senegal (44% in Colombia, 83% in Egypt) (Ref. 31 of (91P1)).
Part [C5] ~ Pesticides ~ Integrated Pest Management (IPM) ~
Indonesia's switch from pesticides to IPM is described in (90S1).
Part [C6] ~ Pesticides ~ Health Effects ~
Expanded use of pesticides: Pesticide-use has been growing rapidly, both in tonnage and in toxicity per tonne, but without having achieved any clear reduction in the loss of crops to pests. Pests have the ability to evolve their pesticide-resistance about as rapidly as new pesticides can be developed. There is evidence now that pests may win this deadly race with humankind in the end, since humans apparently have limits to their ability to tolerate pesticides -limits that probably cannot be raised sufficiently rapidly via human evolution. In a study, researchers followed the health of 143,000 people since 1982, trying to pick out the factors that lead to diseases. They found that people regularly exposed to pesticides had a 70% higher incidence of Parkinson's disease. Gardeners who used such chemicals were as much at risk as farm workers. The findings support the idea that exposure to pesticides is a risk factor for Parkinson's that is a brain disease that afflicts about 150,000 Britons, with nearly 10,000 new cases per year. Scientists have suspected a link between pesticides and Parkinson's since 1983 when Californian drug addicts were diagnosed with the disease after taking impure drugs. Since then, epidemiological studies have hinted at links but few have been large enough to extract meaningful figures. The latest research is big enough to get around that problem but raises new questions, especially which pesticides might be causing this effect. In Britain 31,000 tons of pesticides are applied to gardens and farms each year. Many pesticides are designed to be toxic to animals' nervous systems, so a link with Parkinson's is not surprising
A more recent study (09M1) found much the link. The study compared 368 long-time residents who lived within 500 yards of fields in California's Central Valley where the fungicide maneb and herbicide paraquat had been sprayed and compared them with 341 carefully matched controls who did not live near the fields. The results were reported in the April 2009 American Journal of Epidemiology. People who lived next to the fields where maneb and paraquat had been sprayed were, on average, about 75% more likely to develop Parkinson's disease. Those who developed the early-onset form of the disease (contacting it before age 60) had double the risk of contacting the disease if they were exposed to either maneb or paraquat alone, and four times the risk if they were exposed to both. (Parkinson's disease has been recognized since the Middle Ages, but became more prevalent in the 20th century. As many as 180 of every 100,000 Americans develop it.) (su1)
Of the 80,000 pesticides and other chemicals in use today, 10% are recognized as carcinogens. Cancer-related deaths in the US increased from 331,000 in 1970 to 521,000 in 1992, with 30,000 deaths attributed to chemical exposure (98P3).
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