Enhancing Water and Nitrogen Use Efficiency in Soybean-Corn Rotations with Winter Cover Crops.

2017 ASA, CSSS, SSSA Annual Meeting

October 22-25, 2017 – Tampa, FL

“Managing Global Resources for a Secure Future”

Alexander Hummel Jr., Jeffrey A. Coulter, and Axel Garcia y Garcia

Enhancing Water and Nitrogen Use Efficiency in Soybean-Corn Rotations with Winter Cover Crops

Soybean [Glycine max (L.) Merr.] and corn (Zea mays L.) are the dominant crops in the midwestern United States; however, concern over water and N use and losses during their production urge the development of cropping systems for enhanced sustainability. This research aims to achieve greater efficiency of water and N use. A 2-yr soybean-corn rotation experiment through integration of winter annual cover crops [camelina (Camelina sativa L. Crantz), field pennycress (Thlaspi arvense L.), and winter rye (Secale cereal L.)] was conducted in southwest Minnesota. Soybean-fallow-corn, soybean-winter rye-corn, soybean-field pennycress-corn, and soybean-camelina-corn rotations were evaluated. Cover crops were interseeded into soybean at the full seed stage and into corn at the dent stage in 2015 and at full physiological maturity for both soybean and corn in 2016. Total water and N use of crops and cover crops as well as nitrate N concentration in the leachate were evaluated. Water use of soybean and corn showed a gradual increase early in the growing season, mid-season high values followed by decreasing values associated with the onset of senescence.  Winter annual cover crops used less water in fall than in spring; following a water use pattern of winter rye > winter camelina > field pennycress. There was a reduction of [NO₃-N] with the use of cover crops following soybean and corn compared to fallow, particularly in the spring. Our results showed that winter cover crops did not affect the grain yield of soybean and corn.