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Organic/Sustainable Agriculture Section R SWES 316.

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Presentation on theme: "Organic/Sustainable Agriculture Section R SWES 316."— Presentation transcript:

1 Organic/Sustainable Agriculture Section R SWES 316

2 Who do you believe? J. Patrick Madden (World Sustainable Ag. Assoc.): “Healthy soil is the foundation of a healthy society. Just like a healthy person who rarely (if ever) needs medicine, healthy soil rarely (if ever) needs synthetic chemical pesticides and fertilizers.” Dennis Avery (Hudson Institute for Global Food Studies): “Only high-yield farming and the careful use of fertilizer and pesticide can produce enough food for a world population expected to double by 2050. High-yield farming is saving 10 million square miles per year from the plow.”

3 SOME THINGS TO THINK ABOUT Current world population is more than ________________. 75% of that is in “developing” countries. World population in 2030 is projected to be 9-10 billion. Most of that increase will be in “developing” countries. 6,300,000,000

4 MORE THINGS TO THINK ABOUT Production, processing, and sale of food and fiber is _______ % of the U.S. Economy. Slightly less than ____% of the U.S. population is directly involved in agriculture. Agricultural productivity has increased by ______% during the past 30 years. Of the total cost of food in the U.S., about ______% represents a return to the farmer or rancher. 18 2 300 25

5 EVEN MORE THINGS TO THINK ABOUT The _______________ industry is the largest source of non-point source pollution. One-half of irrigated cropland in the U.S. is in areas where groundwater tables are declining by >1 foot/yr. 46% of all U.S. counties are susceptible to groundwater contamination from agriculture. agricultural

6 The Reality Demand for food will increase in coming years, while arable land will decrease. Increased technology in agriculture has greatly increased productivity, but has undoubtedly contributed to pollution. These realities are inescapable.

7 What is Sustainable Agriculture? Sustainable agriculture is a set of practices which, over the long term, enhances environmental quality and the resource base on which agriculture depends, provides for basic human food and fiber needs, is economically viable, and enhances the quality of life for farmers and society as a whole. Sustainable agriculture is agriculture that meets present needs without compromising the ability of future generations to meet their needs.

8 What is Sustainable Agriculture? Exact practices are not defined and are subject to interpretation and argument. To be sustainable, cropping practices must maintain or enhance soil and water quality.

9 Barriers to Sustainability Soil Erosion Water supplies Fossil Fuels ??? Water/Air Pollution Nutrient supplies Pest control Crop Genetics –Monocultures are not sustainable, concerns about GMOs

10 North American phosphate and potash mines

11 World Phosphate Reserves Country2003 Prod- uction ReservesReserve Life Reserve Base Reserve Base Life Million tonnesYearsM tonnesYears U.S.A.331,000304000120 China246,60027013,000540 Morocco & West Sahara 245,70023021,000870 Russia11200181,00090 World Total13818,00013050,000360 Source: USGS Mineral Commodities Summaries, 2004

12 Elements of Sustainability 1.Integrated Pest Management 2.Rotational Grazing 3.Soil Conservation 4.Water Conservation/Protection 5.Cover Crops 6.Crop/Landscape diversity 7.Nutrient Management 8.Agroforestry 9.Marketing According to the “Sustainable Agriculture Network”

13 What is “Organic”? Avoidance of nutrients derived from processed or synthetic sources Avoidance of synthetic pesticides Emphasis on nutrients from N fixation, manures, and non-processed sources Governed by rules established by USDA National Organic Standards National Organic Standards

14 Why “Organic”? Potential for less pollution when using non-processed inputs? Improved sustainability? Improved crop quality for human health enhancement? Improved soil quality Improved water quality? Making money ?


16 Growth of Organic Farming From “Sustainable Agriculture Network”

17 Organic Production and Plant Nutrients

18 Crop N Uptake Soybean is a legume

19 Possible Sources of N for Crops Soil Humus N mineralization Legume N fixation Manures Manufactured Fertilizers Mined Fertilizers (Chilean nitrate)

20 A Nitrogen Budget for the U.S. N Need/SourceBillion pounds N/yr U.S. Crop Needs 32.1 Source of N Legumes 15.6 Manure 2.6 Biosolids 0.6

21 A Nitrogen Budget for the U.S. N Need/SourceBillion pounds N/yr U.S. Crop Needs 32.1 Source of N Legumes 15.6 Manure 2.6 Biosolids 0.6 Unmet N Needs 13.3

22 U.S. Fertilizer Use


24 Nutrient Facts Even the most optimistic calculation of manure usage in the U.S. yields only about 10 kg N/ha/yr from manure available for croplands. Sewage sludge provides even less N, plus associated health concerns. 25 - 33% of U.S. food production is due to the use of synthetic N fertilizers.

25 Nutrient Facts (cont.) An organic farm that is self-contained with respect to N will have to set aside _____% of its land for legumes in crop rotations. It is impossible to be self-sufficient with respect to P. No major food crops are legumes. Legume yields are usually much less than that of non-legumes. 40

26 Notes About Organic Fertilizers Organic Fertilizers vary in N content, but are usually <5% by weight. Composts are usually not very effective fertilizers. It is critical to synchronize N release from the fertilizer with N demand by the plant. Organic fertilizers are not necessarily more “environmentally safe” than inorganic fertilizers.

27 Mineralization of Organic Fertilizers

28 Daily N Uptake of cotton lb/acre 2 1 3 4 0 Mineralization of Organic Fertilizers

29 The “P problem” in manures

30 Crop Nutrient Uptake N/P 5.2 6.5 7.0 9.1 9.8 12.2

31 The P Problem in Manures Manures contain too much P in comparison to the N content. –Animals inefficiently use most plant P (phytic acid). Traditionally, manure application rates have been determined according to crop N requirement. –This results in: Over-application of P, buildup of P in the soil

32 The P Problem in Manures (2) Applying manure based on crop P need will result in: –Under-application of N Other possible solutions –Animal diet supplementation with phytase, enzyme that breaks down phytic acid –Low-phytate corn (GMO)

33 Ebeling et al., 2002 High P diet: 8.9 g P/kg Low P diet: 4.9 g P/kg Animal diet directly influences P availability and fate in soil no difference in STP or crop response at equivalent rates

34 UC-Davis “Sustainability” Experiment




38 Updated Results http://safs.ucdavis.ed

39 Fertilizer vs Food Quality How does soil/plant nutrient status affect food quality? Does nutrient source affect food quality? From PPI

40 Functional food examples From PPI

41 Phytochemicals Science 285:377, 1999

42 Potassium increases total carotenoid content and quality of tomatoes Trudel and Ozbun. 1971. J. Amer. Soc. Hort. Sci. 96(6)

43 K influences lycopene and  -carotene content of tomatoes Trudel and Ozbun. 1971. J. Amer. Soc. Hort. Sci. 96(6)

44 Effect of KNO 3 on grapefruit carotenoids B. Patil, 2001 (one year data) Texas Rio Grande Valley Treatments: F= fertigation, S= foliar F1-Jan-Mar, F2-Feb-April, F3-April-June S1-April-June, S2-May-July, S3- July-Sept From PPI






50 Article in Nature


52 Nutrient Challenges for Organic Agriculture Need for providing N Impossible to be self-sufficient in P Problems using manures Problems synchronizing N release from mineralization of organic materials with crop N demand. Note: It is usually easier to supply N to perennials organically than to annuals (lower peak N demand in perennials).

53 The Final Word? There is incomplete scientific data to support many claims of organic agriculture’s proponents: –Improved soil quality –Safer, more nutritious food –Reduced pollution –Enhanced sustainability A true evaluation of the benefits of organic farming cannot be made until rigorous scientific studies are completed.

54 The Final Word? (2) Organic agriculture is not sustainable as an answer to society’s food needs: –Not enough organic nutrients –Too little arable land, fresh water Organic agriculture can be both successful and profitable under certain conditions. The organic/sustainable agriculture movement has helped to focus attention on the shortcomings of “conventional” agriculture, and ultimately will result in improved, more sustainable agriculture.

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