How Do Cover Crops Affect Fertilizer Recommendations?

Transcription

1 How Do Cover Crops Affect Fertilizer Recommendations? Newell Kitchen USDA-ARS Cropping Systems and Water Quality Research Unit, Columbia, MO 2014 Advanced Nutrient Management Course Bradford Technology Transfer Center Feb

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3 Summary of Typical Positive Impacts from Cover Crops on Soil Physical/Chemical Properties 1. Greatly reduced erosion 2. Increased soil organic matter 3. Enhanced infiltration 4. Enhanced aeration with improved soil structure/aggregation 5. Preventive of soil compaction 6. Reduced evaporation potential 7. Recycle nutrients 8. Fix N with legumes

4 Summary of Typical Positive Impacts from Cover Crops on Soil Physical/Chemical Properties 1. Greatly reduced erosion

5 What nutrient losses should we be concerned about? 70% of N and P transported in the basis are tied to agricultural sources (Alexander et al., 2008). 52% of N and 25% of P come from corn and soybean production; 37% of P from animal manure on pasture and rangeland.

6 Percent Reduction in Phosphorus in Runoff (summary of studies; Sharpley and Smith; 1991)

7 Summary of Typical Positive Impacts from Cover Crops on Soil Physical/Chemical Properties 1. Greatly reduced erosion 2. Increased soil organic matter

8 Cover Crop Effects on Soil Quality Indicators Property and units ph P, mg/kg K, mg/kg SOC, g/kg POM-C, g/kg MnOxC, g/kg Total N, g/kg POM-N, g/kg Highlighted items are significantly different between samplings

9 Role of Organic Matter on Nutrients Organic matter is a reservoir of nutrients that can be released to the soil. Each percent of organic matter in the soil releases 20 to 30 pounds of N, 4.5 to 6.6 pounds of P 2 O 5, and 2 to 3 pounds of sulfur per year. The nutrient release occurs predominantly in the spring and summer, so summer crops benefit more from organic-matter mineralization than winter crops.

10 Summary of Typical Positive Impacts from Cover Crops on Soil Physical/Chemical Properties 1. Greatly reduced erosion 2. Increased soil organic matter 3. Enhanced infiltration

11 Improved Water Infiltration

12 Summary of Typical Positive Impacts from Cover Crops on Soil Physical/Chemical Properties 1. Greatly reduced erosion 2. Increased soil organic matter 3. Enhanced infiltration 4. Enhanced aeration with improved soil structure/aggregation

13 Soil Aggregate Stability Min. Till CS (1) No Till CS (2) ICM No Till CSW (5) CRP (6) Aggregate stability, % With Cover Crop Without Cover Crop 10 0 Footslope Backslope Summit Landscape

14 Summary of Typical Positive Impacts from Cover Crops on Soil Physical/Chemical Properties 1. Greatly reduced erosion 2. Increased soil organic matter 3. Enhanced infiltration 4. Enhanced aeration with improved soil structure/aggregation 5. Preventive of soil compaction

15 Cover Crops and Soil Compaction

16 Do Cover Crops Always Reduce Compaction?

17 Summary of Typical Positive Impacts from Cover Crops on Soil Physical/Chemical Properties 1. Greatly reduced erosion 2. Increased soil organic matter 3. Enhanced infiltration 4. Enhanced aeration with improved soil structure/aggregation 5. Preventive of soil compaction 6. Reduced evaporation potential

18 Effect of Cover on Evaporation

19 Summary of Typical Positive Impacts from Cover Crops on Soil Physical/Chemical Properties 1. Greatly reduced erosion 2. Increased soil organic matter 3. Enhanced infiltration 4. Enhanced aeration with improved soil structure/aggregation 5. Preventive of soil compaction 6. Reduced evaporation potential 7. Recycle nutrients

20 Cover Crop Effects on Soil Quality Indicators Property and units ph P, mg/kg K, mg/kg SOC, g/kg POM-C, g/kg MnOxC, g/kg Total N, g/kg POM-N, g/kg Highlighted items are significantly different between samplings

21 Recovered Nitrogen after Drought 0 Profile Depth (cm) lbs/a captured If 50% of captured N available $27/A of N $.60/lb N Avg. NO 3 -N (kg ha -1 90cm -1 ) Cover: 16.7 No-Cover: $2,430 of N for 90 acre field NO3-N (kg ha -1 )

22 Percent Reduction in Nitrate Leaching (summary of studies; Meisinger et al., 1991)

23 Summary of Typical Positive Impacts from Cover Crops on Soil Physical/Chemical Properties 1. Greatly reduced erosion 2. Increased soil organic matter 3. Enhanced infiltration 4. Enhanced aeration with improved soil structure/aggregation 5. Preventive of soil compaction 6. Reduced evaporation potential 7. Recycle nutrients 8. Fix N with legumes

24 Cover Crop and Kill Date on Plant Available N Source: D. Sullivan.

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27 1. Greatly reduced erosion 2. Increased soil organic matter 3. Enhanced infiltration 4. Enhanced aeration with improved soil structure/aggregation 5. Preventive of soil compaction 6. Reduced evaporation potential 7. Recycle nutrients 8. Fix N with legumes

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