Organic & Low-input Agriculture: Pros and Cons for Soil Health

Transcription

1 Organic & Low-input Agriculture: Pros and Cons for Soil Health Sharon Weyers USDA Agricultural Research Service, Morris MN Iowa Soil Health Conference Feb 16-17, 2017

2 Systems of Management High-input Organic Low-input Agroecology Intensive tillage Conservation till Conservation till Conservation till Low diversity High diversity High diversity High diversity Input intense Fertilizers Herbicides Pesticides Insecticides Cultural and IPM practices Input substitution Organically certified amendments Cultural and IPM practices Input reduction Organic & inorganic as necessary Cultural and IPM practices Internal recycling Organic On-farm innovation

3 Tillage is one of the major practices that reduces the organic matter level in the soil. FAO, The importance of soil organic matter: Key to drought-resistant soil and sustained food production So why is carbon so important? It s the building block for soil health. No-till farmer, It s all about the carbon.

4 National use of no-till = 39% Wade et al. (2015) USDA-ERS EIB 147

5 So, why not no-till? Farmers are highly concerned about yields! Andrews et al. (2013) J. Soil Water Conserv. 68:

6 Does NT really reduce yields? 92% 98% 97% 97% % 98% 97% s Corn Soybean Wheat Cotton Sorghum 92% Oat 147% Adapted from: Toliver et al. (2012) Agron. J. 104:

7 Social The trade-off fear Soil Health! Yields! You? Sustainability

8 Soil Health and Ecosystem Services Figure 1. Impacts of farm management and landscape management on the flow of ecosystem services and disservices to and from agroecosystems Power, A. (2010) Phil. Trans. R. Soc. B 365:

9 Good vs. Poor Management Ecosystem services Products Soil C / enhanced function Resilience to disturbing forces = Pest and disease control; weather changes Energy, nutrients, water conserving Income/Job creating Ecosystem disservices Reduced yields Nutrient losses Poor pest control Higher energy inputs Low aesthetic value Poor resilience to disease and climate variability Microbial biomass C MBC & Soil organic C SOC

10 Farming Systems Morris, MN High intensity CNV CT- 2y YF C-S, moldboard & chisel till, inorganic N-P-K, herbicides, insecticides Low intensity CNV ST 2y, 4y YF, NF C-S or C-S-W/A-A, reduced (strip) till, inorganic N-P-K, chemicals Organic ORG CT, ST 4y YF C-S-W/A-A, intensive till - CT or reduced till (ST); manure N-P-K

11 SOC with Low-input & ST-Organic Mg OC ha Depth 5 cm 10 cm 150

12 mg MBC g -1 soil Microbial C with Low-input & Organic CNV ORG ST -4y ST -2y CT -4y CT -2y Years in production / Sampling year Weyers et al. (2013) Agron. J. 105:

13 MBC with NT over CT MI, ND, PA % MI ND PA ORGANIC C T N T IA MN WI Weyers & Cambardella 2011 ASA Conference

14 MBC with SOC 300 MBC mg kg IA MN WI PA MI ND SOC mg kg -1 Weyers & Cambardella 2011 ASA Conference

15 SAFS - Russel Ranch, UC DAVIS Clark et al. (1999) Am. J. Alter. Ag. 14:

16 SAFS - SOC with Low-input & Organic Doane and Horwath (2004) Global Biogeochem Cycl. doi: /2004gb

17 SAFS Soil health indicators with Organic & Low-input Better nutrient cycling Photo: photos-and-maps Increased microbial biomass Poudel et al. (2001) Outlook on Agriculture 30:

18 DOK Trial Therwil, Switzerland Dynamic Organic Konventionel Image: Google maps, Therwil SUI Rotation, 7 years Potato, winter wheat, fodder crop cabbage/beet/corn, barley, grass-clover x2/x3 Fertility 1.4 or 0.7 livestock units As FYM or inorganic Tillage Plowing cm depth before potato, w. wheat & beet Chemicals/biologicals D- Biodynamic preparations D, O - composted/stacked manure K herbicides, fungicides

19 DOK Trial Therwil Switzerland Fließbach et al. (2007) Agric. Ecosyst. Environ

20 DOK Physical, Chemical, Biological Indicators Biodynamic & Organic Mäder et al. (2002) Science 296:1694

21 Common management Reduced tillage ( no-till, low-disturbance till, rotational till ) Diverse crop rotations ( 3 or more crops + legumes ) Animal manure ( reduced dependence on inorganic N ) Soluble + non-soluble organic matter Soluble = inorganic N ( readily available ) Non-soluble organic matter decomposition ( delayed availability) Large source of C akin to crop residue

22 Broadbalk Wheat Trial, Rothamsted Research, Harpenden, UK High-input continuous wheat, inorganic NPK Low-input continuous/rotated wheat, farm yard manure Moldboard plow yearly all trmts Images: Google maps, Harpenden

23 Broadbalk - SOC Watts et al. (2006) Soil Use Manag. 22:

24 Rotation w/w/w/corn/oats Wheat + straw Wheat - straw Wheat limited fungicides w/w/w/c/o Wheat + fallow herb. Wheat

25 Soil Health Pros Reducing tillage Rotation diversity Organic fertility Perenialization Livestock integration Cons Intensive tillage Low diversity Inorganic fertility Fallow No integration But what about yield?

26 Grain t ha -1 (85% DM) Broadbalk Wheat Yields No fertilizer continuous wheat FYM continuous wheat 144 kg N ha -1 yr -1 continuous wheat Best NPK rate with rotation FYM + 96 kg N ha -1 yr -1 rotation *Fallow *Herbicides *Modern cultivars *Fungicides *Rotations 0 Modified from: Rothamsted Research, 2012;

27 Farming Systems - ST reduced corn yields Mg ha CT - 2 CT - 4 ST - 2 ST - 4 YF NF YF NF CNV ORG In non-fertilized and organic systems differences were linked to weeds Bu ac -1 Weyers et al. (2017) RAFS in press

28 ST reduced soybean yields only under organic management Weeds! n.s. n.s. CT - 2 CT - 4 ST - 2 ST Mg ha Bu ac YF NF YF NF CNV ORG Diverse rotations can boost yields Weyers et al. (2017) RAFS in press

29 SAFS Crop Yields + 6% +3% +12% +12% Poudel et al. (2001) Outlook on Agriculture

30 DOK - Yield 11% 37% 13% Mäder et al. (2002) Science 296:1694

31 But, Yield gaps Economics High input $495 ha -1 CT 2y High input $787 ha -1 CT 2y Costs Low input $471 ha -1 ST 4y $428 ha -1 ST 2y Net Returns Low input = $502 ha -1 ST 4y = $703 ha -1 ST 2y Organic $561 ha -1 CT 2y $459 ha -1 CT 4y $482 ha -1 ST 4y Organic ( with premiums ) $1029 ha -1 CT 2y $567 ha -1 CT 4y -$331 ha -1 ST 4y FS Archer et al. (2007) Agronomy J. 99:

32 SAFS Costs & Returns, US $/ha Clark et al. (1999) Am. J. Alt. Ag. 14:

33 Productivity Low High Production Efficiency LOW EFFICIENCY HIGH EFFICIENCY High inputs, industrial monocultures High Input Low external inputs, high recycling rates, croplivestock integration Agroecology MEDIUM EFFICIENCY MEDIUM-LOW EFFICIENCY Specialized systems with low external inputs Low - Input & Organic Low external inputs, diversified with low levels of integration Low High Agroecosystem Diversity Adapted from: Altieri et al. (2012) Agron Sustain Dev 32:1-13.

34 Metabolic quotient Biological efficiency increases with diversity More respiration/less biomass Less respiration/more biomass Mäder et al Science 296:1694

35 Metabolic quotient Biological efficiency increases with diversity More respiration/less biomass Less respiration/more biomass Mäder et al Science 296:1694

36 Farming Systems Average Annual Energy Use Energy Use (GJ ha -1 ) YF NF YF NF YF NF YF NF 2YR 4YR 2YR 4YR CT ST CNV Seed, Chem. CNV LP CNV Diesel ORG Seed, Chem. ORG LP ORG Diesel Archer & Weyers 2008 ASA Conf.

37 Low-input and ~ organic systems can be equally or more efficient! 2.5 Energy Intensity (MJ Mg -1 ) CNV ORG 0.0 YF NF YF NF YF NF YF NF 2YR 4YR 2YR 4YR CT Energy used per unit of production ST Archer & Weyers 2008 ASA Conf.

38 DOK Inputs and energy equivalents Mäder et al. (2002) Science 296:1694 The energy input per unit of yield (harvested crop) in the period was 19% lower in the organic systems than that of their conventional counterpart, and 30-50% lower per unit area

39 Low-input & Organic management practices support soil health! We have high yields! We can get more $$ for our products We use less energy Our system is efficient

40 Gabe Brown Brown s Ranch, ND Soil Health is a priority No-till farming since 1993 High diversity system No synthetic fertilizers, fungicides, pesticides Close to eliminating herbicides No GMO/glyphosate Production Profits Quality of life Photo and information:

41 Fernado Funes-Monzote, Finca Marta, Cuba Images:

42 Agroecology at Finca Marta

43 Will this be you? Photos: Robin Moore, Land Stewardship Project & Chippewa 10% Cover Crop Network