Pennycress as a cash cover-crop: Improving the sustainability of sweet corn production systems

Authors: MOORE, SARAH - University Of Minnesota; WELLS, M - University Of Minnesota; Gesch, Russell - Russ; BECKER, ROGER - University Of Minnesota; ROSEN, CARL - University Of Minnesota; WILSON, MELISSA - University Of Minnesota

Submitted to: Agronomy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/22/2020
Publication Date: 4/25/2020
Citation: Moore, S.A., Wells, M.S., Gesch, R.W., Becker, R.L., Rosen, C.J., Wilson, M.L. 2020. Pennycress as a cash cover-crop: Improving the sustainability of sweet corn production systems. Agronomy. 10:614. https://doi.org/10.3390/agronomy10050614.
DOI: https://doi.org/10.3390/agronomy10050614

Interpretive Summary: A large amount of nitrogen fertilizer is required to optimize sweetcorn yield. Because of its short growing season there is great potential for loss of unused nitrogen from sweetcorn fields into ground and surface water where it then becomes a pollutant. Pennycress is a newly developed oilseed cash cover crop that could be planted following sweetcorn harvest to utilize much of the remaining soil nitrogen, thereby reducing the amount available for loss. Field studies were conducted in southern Minnesota to evaluate the yield of pennycress when grown as a cover crop following sweetcorn with no additional fertilizer and to determine its potential to reduce the amount of soil nitrogen susceptible to loss. Five nitrogen rates ranging from 0 and 200 lbs/acre were applied to the soil before planting sweetcorn. After harvesting the sweetcorn, pennycress was planted. Soil nitrogen was measured before planting pennycress and then again after it was harvested the following summer. Even though more nitrogen was left in the soil after sweetcorn harvest for the highest nitrogen rate used, it had no effect on pennycress growth and yield. However, in control plots without pennycress growing, the soil nitrogen was 27 to 42% higher. These results showed that pennycress can scavenge the excess nitrogen left following sweetcorn and can produce seed yields without any additional nitrogen fertilizer. This information will be useful to those studying the environmental impacts of using winter oilseed cover crops and will also benefit extension specialists, agricultural consultants, and farmers interested in growing pennycress as a cash cover crop.

Technical Abstract: Commercial sweetcorn (Zea mays convar. Saccharata var. rugosa) production has a proportionally high potential for nutrient loss to waterways due to its high nitrogen (N) requirements and low N use efficiency. Cover crops planted after sweetcorn can help ameliorate N lost from the field, but farmers are reluctant to utilize cover crops due to lack of economic incentive. Pennycress (Thlaspi arvense) is a winter annual that can provide both economic and environmental benefits. Five N-rates (0, 65, 135, 135 split, 200) were applied pre-plant to sweetcorn. After sweetcorn harvest, pennycress was planted into the sweetcorn residue with two planting methods and harvested for seed the following spring. Residual inorganic soil N (Nmin), pennycress biomass, biomass N, and yield were measured. Nitrogen rate and planting method had no effect on pennycress yield, biomass, or biomass N content. Nitrogen rate positively affected Nmin at pennycress planting, wherein 200N plots had 38-80% higher Nmin than 0N plots, but had no effect on Nmin at pennycress harvest. Control treatments without pennycress had an average of 27-42% greater Nmin. In conclusion, pennycress can act as an effective N catch crop and produce an adequate seed yield after sweetcorn without the need for supplemental fertilization.