Martinez-Feria R.A., R. Dietzel, M. Liebman, M.J. Helmers, S.V. Archontoulis (2016) Rye cover crop effects on maize: A system-level analysis, Field Crops Research. doi: 10.1016/j.fcr.2016.06.016.
The effect of rye cover crop on corn yield, water and nitrate leaching in subsurface drainage is proportional to the amount of rye biomass produced at termination.
We tested the hypothesis by synthesizing experimental, literature and APSIM model results to perform a comprehensive systems level analysis and shed light into the underlying mechanisms by which rye affects corn-based systems in Iowa (Fig. 1). We considered six years of data on soil moisture, soil temperature, water and nitrogen leaching, rye above and below ground biomass and its carbon and nitrogen concentration, corn yields and N uptake at harvest. We supplement these data with 30-yr APSIM model simulations and literature data to develop robust relationships to support deeper understanding and decision making.
- Experimentally, rye cover crop reduced drainage by 12% and NO3-N losses by 20% (or 31% per unit of N applied), and corn yields by 6%.
- We also found minimal effects on soil temperature, water deficits that reduced yields only during drought years (2012 and 2013), and lower NO3-N losses that were related to reduced NO3-N concentrations in drainage.
- APSIM model scenario analysis (4 termination dates × 30 years) indicated that rye cover crop decreases NO3-N losses (-25.5 ± 26%) but does not always reduce drainage water (-3.9 ± 13%) or grain yields (-1.84 ± 6%), which is consistent with experimental and literature results. However, analysis of the synthesized measured and simulated dataset do not support a strong relationship between these variables and rye biomass (Fig. 2).
Read more here.