Impact of manure injection on spatial variability in soil nitrate, carbon, and small grain growth

Manure injection alters the spatial distribution of manure by concentrating it in a subsurface band which can lead to differential soil nutrient distribution and growth in small grains. This study assessed the effects of fall manure applications on soil NO3-N, active carbon, and small grain growth compared to broadcasting and a no manure control. Soil samples were taken to represent whole plot soil means for all treatments, while in-band (IB) and between-band (BB) soil samples were taken in injected plots to assess nutrient spatial distribution after injection. Small grain forage samples were also taken IB and BB to assess the effects of manure injection on small grain growth. Soil samples were analyzed for NO3-N, permanganate oxidizable carbon (POXC), and carbon mineralization (C-min), while small grain dry matter (DM) yield and forage quality parameters were measured from plant samples. Manure injection did not result in any differences between whole plot injection and broadcast soil NO3-N concentrations. However, injection resulted in initially elevated soil NO3-N concentrations IB compared to BB. There were no differences in soil POXC or C-min under manured versus unmanured soils, nor between IB and BB samples. Manure injection did not increase small grain DM yield or forage quality compared to broadcasting, nor were these measurements altered IB and BB. Even though manure injection altered the spatial distribution of soil NO3-N, it did not affect soil C-min, POXC, or small grain growth under the conditions seen in this study. Therefore, differential small grain growth and quality is likely not a concern under injection. Manure injection increased soil NO3-N in the injection band.There were no differences in soil permanganate oxidizable carbon and carbon mineralization between manured and unmanured treatments.Manure application, independent of method, increased small grain dry matter yield compared to no manure control.Small grain dry matter yield was not increased on the injection band compared to between injection bands.