Organic/Sustainable Agriculture

Section R

SWES 316

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.”

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

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

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

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.

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.

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.

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

ND

SKMB

ON

BCAB

WA

OR

MT

ID

SD

MN

PQ

NY

PAOHINIL

IA

WIMI

WY

UT

NV

CA

AZ NM

NB

NS

PEI

ME

NH

VT

MA

CTRI

NE

KSMO

KY

WVVA

MD

DE

NJ

NCTN

AROK

TX LA

MS AL GA

SC

FL

CO

Potash mines

Phosphate rock mines

North American phosphate and potash mines

World Phosphate ReservesCountry 2003

Prod-uction

Reserves Reserve Life

Reserve Base

Reserve Base Life

Million tonnes Years M tonnes Years

U.S.A. 33 1,000 30 4000 120

China 24 6,600 270 13,000 540

Morocco & West Sahara

24 5,700 230 21,000 870

Russia 11 200 18 1,000 90

World Total 138 18,000 130 50,000 360

Source: USGS Mineral Commodities Summaries, 2004

Elements of Sustainability1. Integrated Pest Management2. Rotational Grazing3. Soil Conservation4. Water Conservation/Protection5. Cover Crops6. Crop/Landscape diversity7. Nutrient Management8. Agroforestry9. Marketing

According to the “Sustainable Agriculture Network”

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

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?

Growth of Organic Farming

From “Sustainable Agriculture Network”

Organic Production and Plant Nutrients

Crop N Uptake

0

50

100

150

200

250

300

Nit

rogen

upta

ke (

lb/a

cre)

Corn Cotton Soybeans Potatoes Apples

Soybean is a legume

Possible Sources of N for Crops

• Soil Humus N mineralization• Legume N fixation• Manures • Manufactured Fertilizers• Mined Fertilizers (Chilean nitrate)

A Nitrogen Budget for the U.S.

N Need/Source Billion pounds N/yr

U.S. Crop Needs 32.1

Source of N

Legumes 15.6

Manure 2.6

Biosolids 0.6

A Nitrogen Budget for the U.S.

N Need/Source Billion 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

U.S. Fertilizer Use

0

5

10

15

20

25

N (

bill

ion lb

/yr)

Unmet Needs Actual N Applied

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.

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

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.

Mineralization of Organic Fertilizers

Daily N Uptake ofcottonlb/acre

2

1

3

4

0

Mineralization of Organic Fertilizers

The “P problem” in manures

N P N:P

% Moisture (% of dry weight)

Chicken 35 4.4 2.1 2.1 Cattle 80 1.9 0.7 2.7 Hog 72 2.1 0.8 2.6 Horse 63 1.4 0.4 3.5 Municipal solid waste compost 40 1.2 0.3 4.0 Sewage sludge 80 4.5 2.0 2.2

Crop Nutrient UptakeCrop Nutrient Uptake and Removal in Harvest

Nitrogen Phosphorus Potassium

Crop Uptake Removal Uptake Removal Uptake Removal

Corn grain(lb/bu)

1.3 0.75 0.25 0.20 0.95 0.24

Cotton(lb/bale)

72 32 11 6 42 16

Wheat(lb/bu)

2.1 1.3 0.3 0.22 1.9 0.3

Alfalfa(lb/ton)

55 55 6 6 43 43

Cabbage(lb/100lbs)

0.39 0.39 0.04 0.04 0.30 0.30

Oranges(lb/100

lbs)

0.49 0.44 0.04 0.04 0.51 0.45

Source: Plant Nutrient Use in North American Agriculture. Potash and PhosphateInstitute, Norcross, GA 2002.

N/P

5.2

6.5

7.0

9.1

9.8

12.2

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

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)

Ebeling et al., 2002

High P diet: 8.9 g P/kgLow P diet: 4.9 g P/kg

Animal diet directly influences P availability and fate in soil

no difference in STP or cropresponse at equivalent rates

UC-Davis “Sustainability” Experiment

UC-Davis “Sustainability” Experiment

UC-Davis “Sustainability” Experiment

UC-Davis “Sustainability” Experiment

Updated Results

http://safs.ucdavis.ed

Fertilizer vs Food Quality

• How does soil/plant nutrient status affect food quality?

• Does nutrient source affect food quality?

From PPI

Functional food examples

Food Component Possible benefit

Green tea flavanols reduced cancer riskCruciferous veg. indoles,

isothiocyanates, carotenoids

cancer prevention

Flax (seeds,flour) lignands reduced cancer riskBerries

(blueberries, raspberries, etc.)

anthocyanidins, ellagic acid

Cancer and heart disease prevention, lower chosterolWhole grains saponins,

terpenoids, etc.Cancer and heart disease prevention, lower chosterol

From PPI

Phytochemicals

Science 285:377, 1999

Potassium increases total carotenoid content and quality of tomatoes

Trudel and Ozbun. 1971. J. Amer. Soc. Hort. Sci. 96(6)

Nutrient solution Total carotenoids Change Meq K/l ug/g fr. wt. due to K, % Internal External

0.0 71.58 --- 1.86 3.310.5 64.97 -9 1.45 2.951.0 74.86 5 2.19 3.812.0 91.48 28 2.41 3.654.0 91.92 28 2.44 3.986.0 110.5 54 2.51 4.078.0 111.5 56 2.86 4.21

10.0 104.5 46 3.36 3.98Fruit rating 5=no disorders, 1=severly affected

Fruit rating

K influences lycopene and b-carotene content of tomatoes

Nutrient solution Lycopene Change -carotene Change Meq K/l ug/g fr. wt. due to K, % ug/g fr. wt. due to K, %

0.0 36.81 --- 3.48 ---0.5 33.75 -8 3.36 -31.0 41.88 14 3.62 42.0 53.6 46 3.07 -124.0 52.67 43 2.8 -206.0 59.33 61 2.8 -208.0 61.51 67 2.56 -26

10.0 52.39 42 2.36 -32

Trudel and Ozbun. 1971. J. Amer. Soc. Hort. Sci. 96(6)

Effect of KNO3 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-JuneS1-April-June, S2-May-July, S3- July-Sept

From PPI

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).

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.

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.