Agriculture and Soil

Green Revolution The Green Revolution was a shift in farming methods from physical labor to mechanized large industrial operations during the 20th century. This also included Fertilization irrigation improved crop varieties. These changes increased food production and more people were fed. (yay! Right?)

Impacts of the Green Revolution Modern agriculture has a greater harmful environmental impact than any human activity. Loss of a variety of genetically different crop and livestock strains might limit raw material needed for future green and gene revolutions. In the U.S., 97% of the food plant varieties available in the 1940 no longer exist in large quantities. Crazy decline in domestic biodiversity!

Industrial Food Production aka: High Input Agriculture About 80% of the world’s food supply is produced by industrialized agriculture. Uses large amounts (high inputs) of fossil fuel Energy Water Commercial fertilizers Pesticides Monocultures (growing only one crop)

Advantages of Intensive Agriculture Maximum yield from minimum land use World grain production has almost tripled in the last 50 years. Higher yield per season Mechanization is efficient and reduces labor costs. Per capita food production has increased, reducing global hunger. The cost of food has declined, and more food is now traded globally. Seeding (top) and planting (below): two practices once exclusively done by hand

Disadvantages of Intensive Agriculture Increases in yields may not be sustainable Pests and diseases spread rapidly in monocultures. Pesticide use is escalating yet its effectiveness is decreasing. Pesticides and fertilizers are energy expensive. Fertilizer use is increasing but soil and water quality continue to decline. Poor countries are reliant financially on outside assistance. Heavy machinery is expensive to purchase, operate, and maintain. Intensive agriculture uses high inputs of energy to achieve high yields

Major Environmental Effects of Food Production: Water Aquifer depletion Increased runoff and flooding from land cleared to grow crops Fish kills from pesticide runoff Surface and groundwater pollution from pesticides and fertilizers Over fertilization of lakes leads to eutrophication You need to be able to clearly explain these examples…

Major Environmental Effects of Food Production: Soil Erosion Loss of soil fertility (leads to less nutrients in food) Salinization Water-logging Desertification Pollution by pesticides You need to be able to clearly explain these examples…

Major Environmental Effects of Food Production: Air Greenhouse gas emissions from fossil fuels Other air pollutants and particulates from fossil fuels Pollution from pesticide sprays You need to be able to clearly explain these examples…

Major Environmental Effects of Food Production: Human Health E. Coli contamination of meat & produce Pesticide residues in drinking water, food, and air Contamination of drinking and swimming water with disease organisms from livestock wastes You need to be able to explain these… “food production decreases biodiversity” Example: pesticide residue, explanation: to reduce pests and increase food production, effect: people working in McFarland CA have cancer and asthma

Major Environmental Effects of Food Production: Biodiversity Loss and degradation of habitat from clearing grasslands and forests and draining wetlands Fish kills from pesticide runoff Killing of wild predators to protect live stock Loss of genetic diversity from replacing thousands of wild crop strains with a few monoculture strains You need to be able to explain these… “food production decreases biodiversity” Example: pesticide residue, explanation: to reduce pests and increase food production, effect: people working in McFarland CA have cancer and asthma

Traditional Agriculture: Low Input Polyculture Research has shown that, on average, low input polyculture (more than one crop planted together) produces higher yields than high-input monoculture. However it takes time and planning

Traditional Agriculture: Low Input Polyculture Many farmers in developing countries use low-input agriculture to grow a variety of crops on each plot of land through: Intercropping: two or more different crops grown at the same time (basically in rows next to eachother). Agroforestry: crops and trees are grown together. Polyculture: different plants are planted together. (beans with corn – beans climb up corn – everyone wins)

Subsistence Agriculture Self-sufficiency farming in which the farmers focus on growing enough food to feed themselves and their families. Typically uses traditional low input agricultural methods Examples: Shifting cultivation Slash and burn agriculture Nomadic herding Intercropping

Sustainable Agriculture Industrial agriculture may seem necessary, but less-intensive agricultural methods may be better in the long run Sustainable agriculture = does not deplete soil, pollute water, or decrease genetic diversity Low-input agriculture = uses smaller amounts of pesticide, fertilizers, growth hormones, water, and fossil fuel energy than industrial agriculture Organic agriculture = Uses no synthetic fertilizers, insecticides, fungicides, or herbicides Relies on biological approaches (composting and biocontrol)

A standardized meaning for “organic” People debate the meaning of the word “organic” Organic Food Production Act (1990) establishes national standards for organic products The USDA issued criteria in 2000 by which food could be labeled organic Some states pass even stricter guidelines for labeling

The market for organic food is increasing Sales increased 20% per year in Canada and the U.S. from 1989-2005 Expanded by a factor of 40 in Europe Amount of land for organic farming is increasing 10-35% per year in the U.S. and Canada In 2005 the U.S. had 1.7 million acres of organic cropland and 2.3 million acres of organic pastureland

The benefits of organic farming For farmers: Lower input costs, enhanced income from higher-value products, reduced chemical costs and pollution Obstacles include the risks and costs of switching to new farming methods and less market infrastructure For consumers: Concern about pesticide’s health risks A desire to improve environmental quality Obstacles include the added expense and less aesthetically appealing appearance of the product

The U.S. doesn’t financially support organic farmers In 1993, the European Union adopted a policy to support farmers financially during conversion to organic farming The U.S. offers no such support Organic production lags in the U.S. Farmers can’t switch, because they can’t afford the temporary loss of income In the long run, organic farming is more profitable

Locally supported agriculture is growing In developed nations, farmers and consumers are supporting local small-scale agriculture Fresh, local produce in season Community-supported agriculture = consumers pay farmers in advance for a share of their yield Consumers get fresh food Farmers get a guaranteed income Farmers Markets—growing and becoming more popular locally.

Soil Uppermost layer of earth’s crust that supports plants, animals and microbes Soil Forming Factors Parent Material Time Climate Vegetation & Organisms Topography

Soil Problems Soil Erosion Wearing away or removal of soil from the land Caused primarily by water and wind Why a problem? Causes a loss in soil fertility as organic material and nutrients are eroded More fertilizers must be used to replace nutrients lost to erosion Accelerated by poor soil management practices

Salinization & Waterlogging

Soil Salinization Gradual accumulation of salt in the soil, usually due to improper irrigation techniques Often in arid and semi-arid areas The little precipitation that falls is quickly evaporated Leaves behind salts Salt concentrations get to levels toxic to plants

Desertification Degradation of once-fertile rangeland, agricultural land, or tropical dry forest into nonproductive desert Typically a human-induced condition Change in vegetation changes climate, further decreasing precipitation levels (usually in a positive feedback loop scenario) Asia and Africa – largest areas – many droughts

Soil Conservation Policies in US Soil Conservation Act 1935 Authorized formation of Soil Conservation Service, now called Natural Resource Conservation Service (NRCS) Assess soil damage and develop policies to improve soil Food Security Act (Farm Bill) 1985 Required farmers with highly erodible soil had to change their farming practices Instituted Conservation Reserve Program (CRP) Pays farmers to stop farming highly erodible land

Soil Conservation Practices Conservation Tillage Residues from previous year’s crops are left in place to prevent soil erosion Includes no till agriculture

Soil Conservation Practices Crop Rotation Planting a series of different crops in the same field over a period of years Lessens pest and insect disease Lets nutrients specific for certain plants naturally replenish

Soil Conservation Practices Contour Plowing Plowing around hill (following natural contour of land) instead of up-down Decreases soil erosion

Soil Conservation Practices Strip Cropping Alternating strips of different crops along natural contours

Soil Conservation Practices Terracing Creating terraces on steep slopes to prevent erosion

Soil Conservation Practices Agroforestry Trees and crops are planted together to improve soil fertility in degraded soils Trees grow much longer and provide many soil benefits: - reduces soil erosion - regulates water - provides habitat for natural enemies of crop pests - leaf litter regenerates soil - shade Example: Acacia trees and millet

Soil Reclamation Two steps Stabilize land to prevent further erosion Restoring soil to former fertility Best way to do this is to plant shelterbelts Row of trees planted to reduce wind erosion of soil