Soil, Agriculture and Food Production: sustaining Earth to sustain us.

Transcription

1 Soil, Agriculture and Food Production: sustaining Earth to sustain us. Key points: Although grain production is at record highs it has not kept up w/population increase, despite the green revolution Climate change is/will affect this Food distribution is an issue Opportunities and problems facing a growing population in the face of environmental, social, and economic change Many deaths, esp. in children from malnutrition Developing countries suffer from overnutrition Role of mycorhizzal fungi and nitrogen fixing bacteria Pesticides can be helpful, but harmful too We need more food Soil Resources Soil: probably most valuable natural resource after water although renewable, it is produced very slowly, years to form 1 inch of topsoil; if topsoil erodes faster than it is renewed, soil becomes a nonrenewable resource. Nitrogen is often the mineral that has the greatest effect on plant growth Plants require nitrogen as a component of proteins, nucleic acids, chlorophyll, and other important organic molecules most of the world s crops are grown on cleared grassland (e.g. US midwest) and deciduous forest soils. Why?? Soil fertility and topsoil 1

2 Symbiotic Nitrogen Fixation and Agriculture Topsoil is a mixture of rock (inorganic) and organic material (breakdown of humus) The agriculture benefits of symbiotic nitrogen fixation underlie crop rotation In this practice a non-legume such as maize is planted one year, and the following year a legume is planted to restore the concentration of nitrogen in the soil Topsoil loss ranges from t/km2/yr Accumulation rates are highest in grasslands - 100t/Km2/yr 50,000 km2/ year of arable land are lost to wind- and water erosion, salination, sodification, and desertification Soil cover and erosion Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Areas of serious concern Areas of some concern Stable or non-vegetative areas Before Humans: ~9 billion metric tons/yr Current estimates ~24 billion metric tons/yr

3 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. EROSION: causes Soil degradation mechanisms Wind and water are the major forces Exacerbated by Overgrazing Deforestation Cultivating marginal farmlands Poor farming techniques Source: Data from UNEP Preventing erosion Terracing Contour farming Crop rotation Never leave fields bare! Use cover crops Organic fertilizers Wind breaks Stop deforestation Stop overgrazing Table 5-2, p.143 3

4 Now on to eating kcal per capita per day (world health organization) What we eat global food sources (2004) Vegetables and fruit 1206 MMT Grains (Barley, oats, sorghum, rye, millet) 1013 MMT Meat and milk 870 MMT Corn 643 MMT Wheat 620 MMT Rice 610 MMT **The wealthier a country gets, the more meat its citizens eat World food production faces a serious decline within the century due to climate change Undernourishment is a serious problem UN FAO Sept 2007 special session 2080 s 5-20% decline in agricultural output. IMPORTANT: % in India, 20-30% in Africa, with some countries experiencing some gain (mostly temperate countries). Sudan and Senegal could experience collapse: >50% decline FAO-13-14% of the world s population is undernourished 4

5 And then there was drought: U.S Crop production Source: 2011 ARMS; U.S. Drought Monitor (August 14, 2012 drought status). Drought status is designated by the highest level of drought affecting at least 1/3 of a county. 5

6 US drought summer 2012 Percentage experiencing severe or greater drought Percentage of: June 19 July 17 August 14 Farms Acres of Cropland Value of Crops Value of Cattle Values are percentage of national total. Source: ERS calculations based on 2010 data from the Agricultural Resource Management Survey (ARMS) and county-level U.S. Drought Monitor data reflecting drought status as of August 14, Cline, 2007 *Rice may be particularly hard hit Climate change will have an effect on agricultural output, but how? Climate Change and rainfall: projections average to average (%change) Central Asia, Canada, East coast US South Eastern Africa: % Southwest and Northern Africa, Southern US, Australia, China: % *Parts of the Sahara Desert will green a bit! See National Geographic, April 2009 issue Cline Projections for 2080 (Global) 6

7 undernourishment Soil loss Agricultural productivity Feeding the world Corn used to make a 25 gallon tank of ethanol would feed one person for a year. China raises half of the world s pigs, and imports tons of grain to feed them In the Philippines, record harvests have not been enough to feed 90 million people. It is now one of the leading rice importers Grain production has generally kept up with demand. BUT, consumption was greater than production in 7 of the past 9 years. Low stockpiles (for emergencies) and high grain prices Agricultural output and the Green Revolution 7

8 The green revolution Producing more food per hectare agricultural output. Became important in the 1960 s Development of high yielding varieties Use of synthetic fertilizers and pesticides It was not without its problems We need a new green revolution in half the time it took us in the 70 s Before: Irrigation Dwarf varieties (fertilizers) Pesticides Synthetic fertilizers Now: Breeding (and GM) for drought tolerance, pests photosynthetic rates Sustainable farming: increasing soil fertility Smart irrigation: mulch, drip irrigation, cover crops Fertilizer use and green rev. 8

9 GMO: Genetically Modified Organisms Feeding more people Less expense More profit Efficiency Fewer chemicals? Medicines? Vitamins? New allergens? Antibiotic resistance? New Toxins? Immunosuppression? Weediness? Gene transfer? Gene splicing: merging DNA from different organisms generally that do NOT occur in nature Goats that spin silk GM crops GMO World Grain Supplies Will Barely Meet Demand Despite Record Harvests Food demand competes with biofuel demand Over the past several years, grain harvests have consistently fallen short of consumption, reducing carryover stocks--our only buffer against unanticipated crop failure--to their lowest levels since the 1980s. At the same time, international cereal prices have soared to their highest levels in a decade, creating concern for lowincome food deficit countries and hunger hotspots such as Sub-Saharan Africa. 9

10 TYPES OF AGICULTURE: Industrialized: Primarily MDC's. High Fossil Fuel use, oil, Nat gas, solar and oil. Single crop or livestock. Intensive breeding/selection through (MDCs) genetic engineering. Plantation agriculture: $$Cash crops for MDCs,export: Bananas, coffee, pinapples, tobacco (LDCs) Traditional: Used on about 70% of the worlds lands, by 2.9 bill people (1/2 of earth!) Intensive (large farm) (LDCs) Subsistence (Family) The good news is that food production has kept up with population increases. The bad news is that (WHO) 15 million children die of hunger each year ~1/3 world is well fed, 1/3 underfed, 1/3 starving Social justice issue too? In the US, approx 42 % of African America children hungry, 35% Latino, 15% Caucasian At what price agricultural output? What about genetically modified crops/meats? CH3Br: methyl bromide The United States has successfully lobbied for critical-use exemptions. In 2004, over 7 million pounds of bromomethane were applied to California. Applications include tomato, strawberry, and ornamental shrub growers, and fumigation of ham/pork products. Also exempt is the treatment of solid wood packaging (forklift pallets, crates, bracing). Respiratory, kidney, and neurological effects are of the greatest concern. Watsonville Castroville Your home What does it all mean?? Population growth rates are going down Food/grain production is increasing Per capita food production is going down in high population growth rate regions Global warming will most likely have an effect on crop production Food shortages are likely (and happening) around the globe Arable land is decreasing (per capita)-448 million people live without enough of it Clear more land? Grow different crops? Consequences? 10

11 Pesticides..use, misuse, and issues Integrated Pest Management IPM Using several techniques: Crop rotation Interplanting Combine natural and chemical pest control Requires knowledge of fields and natural cycles 11