Impact of 15N-labeled rice straw and rice straw compost application on N mineralization and N uptake by rice

Document Type: Research Paper

Author

Rice Research & Training Center, Field Crops Research Institute, Agricultural Research Center, Egypt.

Abstract

Incorporation of plant residues in soil affects N and C content and dynamics. This study
determined the effects of short-term alternative rice (Oryza sativa L.) residue management on N
mineralization and uptake by rice. Pot and laboratory incubation experiments were established by
incorporating 15N-labeled rice straw and rice straw compost in paddy soil. The 15N recovered by rice
averaged 16.6%; most of this recovered 15N-fertilizer was cycled through soil pools and only small
amounts originated from labeled rice residues. At harvest, denitrification rate of rice straw and rice
straw compost was 27.2% and 38.5%, respectively in the pot experiment, while residual N in soil
ranged from 56.2% and 55.1%, respectively. The incubation study showed that about 22-26% of N
from 15N-labeled rice straw was mineralized over a period of 105 days. Recovery of residual 15Nfertilizer
appears to contribute little to total inorganic N. The results showed that rice residues exerted
a small and short-term positive effect on N mineralization and N uptake.

Keywords