Assessment of the mechanism for conserving nitrogen in fall-applied manure in combination with paper-mill biosolids
This thesis reports an investigation of a combination of paper-mill biosolids (PMB) with fall-applied manure to identify whether the combined application of PMB and fall-applied manure-N would benefit corn yield in the following growing season. This investigation included a field and two laboratory studies. The field experiment consisted of 5 rates of PMB (0, 30, 60, 120, 150 Mg ha -1) and 4 rates manure-N (0, 50, 100 or 200 kg ha -1). N mineralization was studied using 'in situ' incubation of soil cores set on ion exchange resin bags. In the first laboratory study CO2 evolution from PMB-amended soil was compared with unamended for periods up to 35 days. In the second laboratory study, the release of CO2 from PMB was assessed anaerobicaly using rumen microflora. PMB did not benefit corn grain yield. The laboratory study suggested the absence of any effect from adding PMB was because its decomposition rate was too slow to release significant N to the corn crop.