Rate and Management Effects of An Alkaline Stabilized Biosolid On Soil Mineral Nitrogen and pH.

Alkaline stabilized biosolids, such as N-Viro Soil^® (NVS), are increasingly applied in agricultural land as a lime substitute and a nitrogen (N) source. A three-year field experiment, 2008-2010, was conducted to determine effects of application rates of NVS (0, 7, 14, 28 and 42 Mg ha^-1) and management practice (NVS annual vs NVS single application) on soil nitrate N (NO₃^—-N), soil ammonium N (NH₄⁺-N) and soil pH.  One reference plot receiving lime at the recommended rate was included. Application rates of NVS significantly increased soil NO₃^—-N compared with the control treatment; however, at most samplings there were no differences in soil NO₃^—-N between the 28 and 42 Mg ha^-1 treatments. At peak samplings in July of 2009 and 2010, average soil NO₃^—-N was 27%, 31%, 45% and 48% higher in the 7, 14, 28 and 42 Mg ha^-1 treatments, respectively, than in the control treatment. Reapplication of NVS at rates of 14 Mg ha^-1 or higher significantly increased soil NO₃^—-N relative to the single application plots. However, when the application rate was 14 Mg ha^-1 or lower, no residual effects of NVS on soil NO₃^—-N were observed. Over all sampling periods after the first NVS application, soil pH was 4%, 7%, 11% and 14% higher in the 7, 14, 28 and 42 Mg ha^-1 treatments, respectively, than in the control treatment.