Biosolids application to no-till dryland and crop rotations: 2006 results

Biosolids recycling on dryland winter wheat (Triticum aestivum, L.) can supply a reliable, slow?release source of nitrogen (N) and organic material (Barbarick et al., 1992). Barbarick and Ippolito (2000, 2007) found that continuous application of biosolids from the Littleton/Englewood, CO wastewater treatment facility to dryland winter wheat?fallow rotation provides 16 to 18 lbs N per dry ton. This research involved tilling the biosolids into the top 8 inches of soil. A new question related to soil management in a biosolids beneficial?use program is: How much N would be available if the biosolids were surface?applied in a no?till dryland agroecosystem with winter wheat?fallow (WF) and winter wheat?corn (Zea mays, L.)?fallow (WCF) crop rotations? Our objective was to compare agronomic rates of commercial N fertilizer to an equivalent rate of biosolids in combination with WF and WCF crop rotations. Our hypotheses were that biosolids addition, compared to N fertilizer, will: 1. Produce similar crop yields; 2. Not differ in grain P, Zn, and Cu levels (Ippolito and Barbarick, 2000) or soil P, Zn, and Cu AB?DTPA extractable concentrations, a measure of plant availability (Barbarick and Workman, 1987); and 3. Not affect soil salinity (electrical conductivity of saturated soil?paste extract, EC) or soil accumulation of nitrate?N (NO3?N)