Indirect~(15)N isotope techniques for estimating N dynamics and N uptake by rice from poultry manure and sewage sludge

摘要

Sole use of chemical fertilizers as a nutrient source for intensive paddy rice production has likely caused a decline in soil fertility and rice yields. This study examined the effects of poultry manure and sewage sludge application on nitrogen (N) uptake, dynamics and efficiency of usage. A ~(15)N isotope dilution method was used to estimate the amount of N in rice plants derived from the poultry manure and sewage sludge. The results showed that the percentage of ~(15)N recovered from sewage sludge and poultry manure was 19 and 36%, respectively. Most of the N uptake by rice was from the soil and varied from 54-64%. The relative efficiency of poultry manure and sewage sludge was 80 and 85%, respectively. No significant difference was observed in the N loss rate and the N residual into soil post harvesting between the poultry manure and sewage sludge.