Effects of Biosolids Types On Nitrogen Availability Under Varying Tillage Practices.

Biosolids are typically injected or incorporated into soils by tillage; however, little research has been conducted on biosolids effects on nitrogen (N) availability, with the elimination of tillage for crop production. We conducted a three-year field study to investigate the effects of lime-stabilized and anaerobically digested biosolids on crop yield and N availability in a corn (Zea mays L.)-soybean (Glycine max L.) rotation under both conventional and no-tillage practices. Research was established on an Orangeburg loamy sand (Fine-loamy, kaolinitic, thermic Typic Kandiudults) soil in 2009-2011. During each growing season, pre-sidedress nitrate test, corn ear leaf total Kjeldahl N, corn and soybean grain yield, end-of-season corn nitrate test, soil total N were determined to reveal biosolids effects. Both biosolids treatments increased soil inorganic N immediately prior to the high N uptake period by corn, plant tissue N at silking, post-season corn stalk nitrate N , grain yield and soil total N by the end of the growing season. Biosolids N availability were influenced by tillage practices, as no-till apparently slowed down the mineralization of biosolids organic N, and incorporation of biosolids into soil could reduce ammonia volatilization. These results indicated that both biosolids types could maintain high N availability under no-tillage practices.