Opportunities for increased nitrogen-use efficiency from improved resource management in irrigated rice systems

Cassman, K. G. and et al, . (1998) Opportunities for increased nitrogen-use efficiency from improved resource management in irrigated rice systems. Field Crops Research, 56 (1-2). pp. 7-39.

[img] PDF - Published Version
Restricted to ICRISAT researchers only


Research and extension work to improve nitrogen (N) management of irrigated rice has received considerable investment because yield levels presently achieved by Asian farmers depend on large amounts of N fertilizer. Most work has focused on placement, form, and timing of applied N to reduce losses from volatilization and denitrification. In contrast, less emphasis has been given to development of methods to adjust N rates in relation to the amount of N supplied by indigenous soil resources. As a result, N fertilizer recommendations are typically made for districts or regions with the implicit assumption that soil N supply is relatively uniform within these domains. Recent studies, however, document tremendous variation in soil N supply among lowland rice fields with similar soil types or in the same field over time. Despite these differences, rice farmers do not adjust applied N rates to account for the wide range in soil N supply, and the resulting imbalance contributes to low N-use efficiency. A model for calculating N-use efficiency is proposed that explicitly accounts for contributions from both indigenous and applied N to plant uptake and yield. We argue that increased N-use efficiency will depend on field-specific N management tactics that are responsive to soil N supply and plant N status. N fertilizer losses are thus considered a symptom of incongruence between N supply and crop demand rather than a driving force of N efficiency. Recent knowledge of process controls on N cycling, microbial populations, and soil organic matter (SOM) formation and decomposition in flooded soils are discussed in relation to N-use efficiency. We conclude that the intrinsic capacity of wetland rice systems to conserve N and the rapid N uptake potential of the rice plant provide opportunities for significant increases in N efficiency by improved management and monitoring of indigenous N resources, straw residues, plant N status, and N fertilizer

Item Type: Article
Author Affiliation: Agronomy Department, 279 Plant Science Building, University of Nebraska, Lincoln, NE 68583-0915, USA
Subjects: Plant Protection
Statistics and Experimentation > Experimentation
Crop Improvement
Divisions: Other Crops
Depositing User: Mr. SanatKumar Behera
Date Deposited: 05 Mar 2012 03:01
Last Modified: 05 Mar 2012 03:01
Official URL: http://dx.doi.org/10.1016/S0378-4290(97)00140-8
URI: http://eprints.icrisat.ac.in/id/eprint/3067

Actions (login required)

View Item View Item