Abstract
In maize-based cropping systems, leaching of nitrate-nitrogen (NO3-N) to drainage tile and groundwater is a significant problem. The purpose of this study was to assess whether a winter rye cover crop planted after silage maize or soybean harvest and injected with liquid manure could decrease soil NO3-N without reducing the yield of the following maize crop. An experiment was conducted at 19 sites with predominant occurrence of Mollisols (15 out of 19 sites) in the upper Midwest USA immediately after soybean or maize silage harvest to compare a drilled rye cover crop and a non-cover crop control. Later in the fall, liquid swine or dairy manure was injected into the cover crop and control plots. Rye was terminated the following spring using herbicide, usually before reaching 20 to 25 cm in height, and incorporated with tillage at most sites, after which maize was planted and harvested as silage or grain. Across sites, soil NO3-N at rye termination was reduced by 36% (range = 4% to 67%) with rye compared to no rye. Nitrogen in aboveground rye biomass at termination ranged from 5 to 114 kg N ha−1 (mean = 51 kg N ha−1). Across sites, there was no significant difference in yield of maize silage or grain between treatments. These results demonstrate in a Mollisol-dominated region the potential of a winter rye cover crop planted before manure application to effectively reduce soil NO3-N without impacting yield of the following maize crop, thereby reducing risk of negative environmental impacts.
Highlights
Agricultural intensification over the past few decades has led to degradation of aquatic systems, and the impact of downstream nutrient export from agricultural lands continues to be of concern.Nitrate-nitrogen (NO3 -N) is troublesome as it leaches through the soil into subsurface drainage or groundwater, which leads to surface waters
While temperatures were warmer than the 30-year average in the fall of 2016, harvest of the crop prior to the cover crop was delayed in many fields due to excessively wet conditions, delaying planting of the cover crop
More research is needed to understand the dynamics of nutrient release from cover crops in a manured system. In these 19 trials conducted in the upper Midwest USA, 15 of which were carried out by commercial growers with their own equipment and management, a rye cover crop was successfully established by drill-seeding following harvest of maize for silage or soybean
Summary
Agricultural intensification over the past few decades has led to degradation of aquatic systems, and the impact of downstream nutrient export from agricultural lands continues to be of concern.Nitrate-nitrogen (NO3 -N) is troublesome as it leaches through the soil into subsurface drainage or groundwater, which leads to surface waters. Agricultural intensification over the past few decades has led to degradation of aquatic systems, and the impact of downstream nutrient export from agricultural lands continues to be of concern. In the Midwest region of the United States, nutrient losses have been exacerbated by both intensified crop and livestock production. This has led to a large hypoxic, or dead, zone forming annually in the Gulf of Mexico [2,3]. The use of commercial fertilizers along with increased mineralization of nitrogen from drained soils is problematic [4,5,6].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
