1. Biomass Yield and Nutrient Accumulation by Four Small Grain Species
Used as a Winter Cover Crop
Dewey Lee and Glen Harris (Crop & Soil Sciences-Tifton)
Julia Gaskin (Biological & Agricultural Engineering – Athens)
Background
Conservation tillage is used on approximately 40 % of row crop acres in Georgia.
Small grain cover crops are recommended for building organic matter, controlling erosion and weed control.
Choice of cover crop and timing of the termination of the cover crop is usually based on which summer crop is planted.
Potential for nutrient recycling is important due to high fertilizer prices.
What We Found
4-Year Average N Uptake
4-Year Average Biomass
4-Year Average K Uptake
4-Year Average P Uptake
Why We Did It
To compare small grain species and determine which is best in terms of biomass accumulation and nutrient uptake for cropping systems in Georgia
What We Think
Biomass and nutrient uptake increased for all species the later the growth stage as expected
Nutrient uptake increased with time due to increasing biomass not % N,P or K in plant
Average N, P, and K % content in tissue at Feekes 6, 9, and 11 were: 2.29.,1.73,1.58; 0.27,0.19,0.18; and 2.55,2.04,1.59, respectively.
Rye and triticale best cover crops for corn since they accumulate more biomass and nutrients early
The later the cover crop is terminated the better the potential for building organic matter and recycling nutrients
How We Did It
Planted rye, wheat, oat and triticale at similar seeding rates in Fall of 2002, 2003, 2004 and 2005
Tifton loamy sand, non-irrigated
Previous Crop:
Pearl Millet: 2002,2004
Soybean “green manure”,2003
Soybean: 2005
Fertilized with lb/a at planting
Aboveground biomass from 0.25 m2 at Feekes 6, 9 and 11
Weighed and analyzed biomass for N, P and K
3-Year Average C:N Ratio
What We Should Do Next
Measure recycling of nutrients in the soil profile
Measure the contribution from nutrients recycled by cover crop into the summer crop
Compare the ability of cover crops terminated at different stages to contribute to soil organic matter based on carbon:nitrogen ratios such as found in this study shown here