5. Influence of Method of Residue Application and Moisture Content on Water Soluble Nitrogen in a RhodicKandiustalf Amended with Different Fallow Plant Materials

Abstract

Use of plant residues as nutrient sources presents a viable option to resource poor farmers who sparsely use mineral fertilizer in crop production. A study was conducted to gain an insight into how different application methods of residues from different fallow management systems under two moisture regimes would affect soluble N release in a Rhodic Kandiustalf. Three residue types viz, elephant grass from a natural fallow (T1) and another as a fallow following a previously fertilized maize (T2) and a fallow legume (T3) were surface applied and incorporated in a Rhodic Kandiustalf at both field capacity (FC) and 60% field capacity over a sixteen-week period. Incorporation of mucuna residues and elephant grass from previously fertilized maize fallow released similar soluble N levels which were higher than levels from the natural elephant grass amendments. At 60% FC, both mucuna and elephant grass from the fertilized maize fields that were surface applied had slower N releases than the grass from the natural fallow, suggesting the elephant grass from the natural fallow field could be used as an N source amidst light watering to avoid leaching in the dry season.