Carbon and Nitrogen Mineralization Kinetics for Poultry Litter1
- P. M. Gale and
- J. T. Gilmour2
An incubation study was conducted to evaluate the relationship between net C and net N mineralized during the decomposition of surface-applied poultry (Gallus gallus) litter. The two litters studied were passed through a 2-mm sieve and comparisons were made among the fine and coarse fractions, and a 50:50 mixture of these fractions. Carbon mineralization for the fine fraction, as measured by CO2 evolution, followed first-order kinetics. Three distinct phases of decomposition were observed. Rapid phase rate constants followed the Arrheniuns equation for the 11 to 25°C temperature range, while slow and intermediate phase rate constants at 18 and 25°C were temperature independent. The fine fraction C mineralization rate constants for the rapid phase were 0.018, 0.038, and 0.049 d−1 at temperatures of 11, 18, and 25°C, respectively. For the intermediate and slow phases, rate constants at 25°C were 0.011 and 0.006 d−1, respectively. At 25°C, the rapid phase rate constant for the course fraction was 0.041 d−1 and that of the mixture was 0.046 d−1 . No effect due to size fraction was observed for the intermediate and slow phases. During the rapid phase, net N mineralization paralleled net C mineralization after an initial flush of N mineralization at 1 d. In a comparison among temperatures, the linear relationship between net N mineralized and net C mineralized had a slope of 0.62 for the fine fraction of both litters. The parallel intercepts for this relationship, 160 g N (kg N)−1, for pine (Pinus spp.) shavings and 116 g N (kg N)−1 for wheat (Triticum aestivum L.) straw litter, correlated well with the N mineralized in 1 d, as determined in a separate experiment. In a comparison among fractions, coarse, fine, and mixed fractions had slopes of 0.52, 0.64, and 0.25, respectively, at 25°C. The intercept for the coarse fraction was 65 g N (kg N)−1 with no differences due to litter type. However, differences due to litter type were observed for the fine and mixed fractions.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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