Residue Decomposition and Prediction of Carbon and Nitrogen Release Rates Based on Biochemical Fractions Using Principal-Component Regression
2003
Ruffo, Matías L. | Bollero, Germán A.
The successful use of winter cover crops (WCCs) in short rotations depends on adequate management of their residues. To improve management decisions, there is a need to understand the factors controlling WCC residue decomposition rates and nutrient release rates. A 2-yr study was conducted to estimate residue decomposition and C and N release rates using principal-component regression (PCR) based on WCC biochemical fractions at the time of WCC killing. Rye (Secale cereale L.), hairy vetch (Vicia villosa L.), and rye–hairy vetch biculture were planted as WCCs in the fall and chemically killed in the spring before no-till–planting corn (Zea mays L.). At killing time, residues were analyzed for total C and total N concentrations, neutral detergent fiber (NDF) and acid detergent fiber (ADF), and C and N concentration in the NDF and ADF. Concentration of C and N in neutral detergent soluble fractions (NDSOLC and NDSOLN, respectively) and acid detergent soluble fractions (ADSOLC and ADSOLN, respectively) were calculated. Principal components (PCs) 1, 4, 5, and 7 were selected as significant predictor variables for biomass decomposition and C and N release rates. The PC1 scores suggest that large concentrations of NDF and ADF are associated with low biomass decomposition and slow C and N release rates. Other important fractions are C and N concentration in the NDF and NDSOLC, NDSOLN, ADSOLC, and ADSOLN. The availabilities of C and N, rather than their total concentration in the residue, play a critical role in residue decomposition and nutrient release.
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