2What are the environmental effects of producing food? Modern agriculture has a greater harmful environmental impact than any other human activity, and these effects may limit future food production
3Agricultural Revolution The Agricultural Revolution took place 10,000 years agoCroplands- 77% 2) Rangelands-16%3)Ocean Fisheries- 7%
4Three most important crops (feeds 2/3 of the world) WheatRiceCornThese crops providemore than half thecalories people consume
5What Plants and Animals Feed the World? Out of 10,000 species of plants that have been used for food only 14 plants and 8 animals species provide 90% of global intake of calories!
6How has the Green Revolution Increased Food Production? Develop and plant monocultures cultivation of single cropsProduce high yields by using large inputs of fertilizers, pesticides, and waterMultiple cropping
7How serious is soil erosion? Soil is being eroded faster than it is being formedWaterWindpeople
8Soil Erosion (cont’d) Nature’s Lesson: Dust Bowl of 1930s Bad cultivation technique and drought
9Methods of Soil Conservation Using ways to reduce soil erosion and restore soil fertilityTerracingContour planting and strip croppingAlley cropping or agro forestryWindbreaks
10TerracingReduces soil erosion on steep slopes by series of broad terraces that run across land contour
11Contour Planting and Strip Cropping Planting in rows across the slope of the land rather than up and down. Each row acts as a small dam to hold soil and slow water runoff.
12Alley CroppingSeveral crops are planted together in strips between alleys of trees and shrubs
13WindbreaksReduces wind erosion and provides habitat for birds, pest eating and pollinating insects, and animals.
14Conservation-Tillage Farming To disturb the soil as little as possible while plantingAdvantagesReduces erosionSaves fuelCuts costsHolds more soil waterAllows several crops per seasonDoes not reduce crop yieldsReduces CO2 release from soilDisadvantagesCan increase herbicide use for some cropsLeaves stalks that can harbor stalk pests and fungal diseaseRequires investment in expensive equipment
15How can we maintain and restore soil fertility? Organic FertilizerAnimal manureGreen manureCompostCrop rotation: corn→ soybeans (legumes)→ oats→ alfalfa (legumes)
16Can Inorganic Fertilizers Save The Soil? AdvantagesEasy to transport, apply, storeInexpensive to produceHelp feed one in every three people in the worldWithout it food crop output would drop 40%DisadvantagesDoes not add humus to soilReduces ability of soil to hold waterLowers oxygen content in soilSupplies only 2-3 of the 20 or so nutrients neededReleases greenhouse gas nitrous oxide(N2O)Runoff can kill fish
17GOOD NEWSFarm Act (1985)Farmers received subsides for planting eroded land with soil saving grass or trees for yearsForgive all or part of farmer’s debts if they agree not to farm erodible cropland/ wetlands for 50 yearsErosion cut by 2/3
19How do we feed the world?Overnutrition: When food energy intake exceeds energy use and causes excess body fatUndernutrition: Consuming insufficient food to meet one’s minimum daily energy needsMalnutrition: Deficiency of protein and other key nutrients
20How do we develop sustainable agriculture? Good News! We produce more than enough food to meet the basic nutritional needs of every person on the planet.Produce more grain by reducing meat productionBeef (7kg grain for 1kg of meat)Pigs (4 kg)Chicken (2.2 kg)Fish ( 2 kg)Top priority is the soil.Minimize erosionLimit pesticide & fertilizer use (IPM & crop rotation)Stop pollution & remediate soil & water