Dexter Watts, Auburn Univ, 3003 Lafayette Ave, Muscle Shoals, AL 35661, H. A. Torbert, USDA-ARS, 411 South Donahue Drive, Auburn, AL 36832, and Stephen Prior, USDA-ARS, Nat'l Soil Dynamics Lab, 411 S. Donahue Dr., Auburn, AL 36832.
An in situ study was conducted to evaluate N mineralization patterns using three different soil types located in close proximity of each other during the summer and winter months. Three Coastal Plain soils investigated were Bama (Ultisol), Lynchburg (Ultisol) and Goldsboro (Ultisol). Dairy composted manure was incorporated into in situ soil cores at a rate of 350 kg N ha-1 and compared to an unamended control. Dairy composted manure significantly affected mineralization of N. This was most evident during summer months. Suggesting seasonal timing of application influences mineralization. Theses seasonal patterns in N mineralization were mostly affected by temperature. During winter (temperature ~ 10° C) N mineralization was minimal where as during summer N mineralization was greater due to higher temperatures (25-30°C). Landscape and soil texture also played an important role in mineralization. During winter months the soil type with the greatest % sand located in a low lying area lost most of the added N from compost compared to other soils. However, during summer the loam soil with the greatest field capacity mineralized the most N. It was also noted that the soil with the highest bulk density was more effective in retaining N in the soil compartment of the in situ core. These results show that when applying manure for crop production field scale variability of soils and landscapes needs to be taken into account.
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