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Building Soil Quality with No-Till, Crop Rotations & Cover Crops. $. $. $. $. D. Wayne Reeves J. Phil Campbell Sr. Natural Resource Conservation Center. “Soil degradation prevents the full use of the soil resource to meet human needs and impacts ecosystem functions.”.
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Building Soil Quality with No-Till, Crop Rotations & Cover Crops $ $ $ $ D. Wayne Reeves J. Phil Campbell Sr. Natural Resource Conservation Center
“Soil degradation prevents the full use of the soil resource to meet human needs and impacts ecosystem functions.” USDA-ARS Soil Resource Management National Program
“Agricultural mismanagement is the most important causative factor of soil degradation . . . . .” Oldeman, 1994 United Nations Environment Programme (UNEP), Global Assessment of Soil Degradtion (GlASOD)
“Perhaps the most dominant soil degradative processes are soil erosion and organicmatterdecline.” B.A. Stewart, R. Lal, and S.A. El-Swaify. Sustaining the Resource Base of an Expanding World Agriculture. In:Soil Management for Sustainability. R. Lal and F.J. Pierce (eds.), 1991.
Soil Quality Agricultural Productivity Soil Quality is the Converse of Degradation Health/Habitation Environmental Quality
Soil c web Soil C is basis of Soil Quality/Productivity NH and NO , NH and NO , 3 4 3 4 Aggregate P, K, Ca, Al, P, K, Ca, Al, Stability CEC CEC Microbial Biomass C and N capacity Soil retention Respiration content Respiration to Biomass ratio Biomass C Water to TOC ratio Total Organic C and N C Size Distribution Bulk Density N mineralized Soil Strength Infiltration from Doran et al., 1993 from Doran et al., 1993
Soil c web Soil C is the basis of Agricultural Sustainability . . . . SOM=SOC (x2)
Evidence for Sustainability: SOM from ancient agricultural sites diverse rotations, green & animal manures continuous corn New Mexico 1000-1150 AD Peru 400 AD-present Sandor and Eash, 1991
Evidence for Sustainability: SOM from ancient agricultural sites 4 Continuous Corn Rotation+Manures 3 2 SOM (%) 1 0 New Mexico 1000-1150 AD Peru 400 AD-present Cultivated Uncultivated Sandor and Eash, 1991
How to increase soil C and improve soil quality? Conservation Tillage!
Tillage impact on SOM after 10 y on a sandy soil SOM (%) 0 1 2 3 4 5 0 5 Depth (cm) 10 No-Till Conventional 15 20 Compass loamy sand
GA corn erosion pic Conservation tillage alone does not work !
Attitude adjustment Attitude Adjustment . . . Soil C and crop residues are the key to making conservation tillage work. It’s not “the lack of tillage” but the production & conservation of crop residues which offers the most benefit to productivity.
Brazilian Model . . . 60 40 (%) Adoption 20 0 USA Brazil Argentina Paraguay Derpsch, 2004
Need for crop residues to sustain soil resource as affected by climate. Need for Residue Hot Wet Cool Dry
Conservation tillage – key component . . . cover crops/residue
Effect of cover crop on SOM in no-till corn after 5 years . . . SOM (%) 0.5 1.5 2.5 3.5 0-3 Depth (cm) 3-6 clover 6-12 fallow Reeves and Wood, 1994
Effect of tillage/rye cover crop on SOM after 5 y SOM (%) 0 1 2 3 4 5 0 5 10 Depth (cm) No-Till w/o cover Conventional w/o cover 15 No-Till w/ cover 20 Fall Paratill w/ cover 25 Decatur silt loam
Crop Rotation “Here is my Farm Relief Bill: Every time a Southerner plants nothing on his farm but cotton year after year, and the Northerner nothing but wheat or corn, why, take a hammer and hit him twice right between the eyes. You may dent your hammer, but it will do more real good than all the bills you can pass in a year.” -Will Rogers, ca. 1931
Old Rotation Experiment Cotton every year No legume/no N (1, 6) Winter legumes (2,3, 8) 120 lbs. N/acre/yr (13) Cotton-corn rotation Winter legume (4,7) Winter legume + 120 lbs. N/acre/yr (5,9) 3-year rotation Cotton (legumes)-Corn (small grain for grain)soybean (10,11,12)
1996-2005 “Old Rotation” cotton yield increase from first ten years (1896-1905) 1986-1995 250 200 150 Yield Increase (%) 100 50 0 Cot Cot/Corn (Leg) Cot(Leg) Cot/Corn (Leg+134 kg N/ha/yr)
1996-2005 1986-1995 Corn/Cot (Leg) Cot/Corn (Leg +134 kg N/ha/yr) Cot/Corn/Wht-Soy (Leg +60 kg N/ha on wheat) “Old Rotation” corn yield increase from first ten years (1896-1905) 600 500 Yield Increase (%) 400 300 200
Conservation Tillage-constraints… Cooler, Wetter Soils
Manage constraints . . . 65 oF @ 8:00 a.m. MAY 1 50 DD60’s
Manage constraints . . . 50 -55 oF @ 8:00 a.m. MAY 2800 GDD
Conservation Tillage-constraints… Poor Seed-Soil Contact
Conservation Tillage-constraints… Soil Compaction/Crusting
Manage compaction . . . Non-Inversion Tillage
Cover Crops/ Residue Conservation tillage – key components . . . Manage soil compaction Cover Crops/ Residue
Conservation tillage – key components . . . Manage soil compaction No Cover Crop or Rotation !
Tillage negates cropping system effects! Health/Habitation Agricultural Productivity Soil Quality Environmental Quality
Effect of cropping/tillage system on SOC (0-15 cm) from an eroded Ultisol conversion to conventional till soybean Grain sorghum no-till into crimson clover 30 25 20 Soil Carbon (g kg –1) 15 10 5 1984 1986 1988 1990 Year Bruce et al., 1995
Top 2-cm of soil after 6 y of corn-soybean with clover cover crop No-tillage Conventional tillage
Water is key pics $ $ $ $ Water is THEkey!
Surface soil effects pic Residues/Soil C: Surface soil effects are most critical
Rainfall sim pic lead-in Rainfall Simulation Study . . . Tillage Systems 12 yr old +/- residue removed
Tillage and residue effects on infiltration of a Coastal Plain Soil (50-mm rain event) 100 11 days 80 60 Rainfall (%) 6 days 40 3 days 20 0 No Till w/ residue No Till w/o residue Conventional Tillage
Limestone Valleys – Clay Soils Conservation Tillage Systems are Site-Specific. . . ..
Coastal Plain – Sandy Soils Conservation Tillage Systems are Site-Specific. . . ..
The Future: Site Specific Soil Management GPS Guidance System
2 4 5 . 5 7 8 . 5 Electrical Conductivity Map 32.4245 32.4240 32.4235 32.4230 32.4225 32.4220 32.4215 -85.8995 -85.899 -85.8985 -85.898 -85.8975 -85.897 -85.8965 -85.896 -85.8955
No-tillage improves degraded soils andreduces spatial and temporal yield variablility Conservation Tillage (+16%) Conventional Tillage (+11%)
Conclusions… Soil degradation is the problem . . .