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Article Nitrogen Balance in a Highly Fertilized Rice–Wheat Double-Cr...

Article Water and nitrogen-balance and -use efficiency in a rice (Or...

DNDC model was generally able to capture the

major effects of N and water on rice and wheat crop

performance and balances of N in the rice–wheat systems.

. Patahk et al (Soil Sci. Soc. Am. J. 70:1612–1622 ,2006) showed that 30.4% of applied N was lost from the system and NH3 volatilization

was the major loss mechanism, followed by leaching and

denitrification. The simulated balance of N was negative.

This shows the vulnerability of the system

and calls for improved N management to stop the

depletion of soil N. This is particularly true for the states

of Bihar and Uttar Pradesh, where the depletion of

soil N is the largest and immediate attention needs to

be paid to minimize this depletion. The application of a

higher amount of chemical N, substitution of a part of

chemical N by organic N, and use of better management

techniques to increase N use efficiency have been found

to reduce the depletion and improve soil N status; however,

higher fertilizer N use leads to more losses of N,

which may cause environmental pollution. New tools for

fertilizer management are therefore needed to reconcile

the legitimate aims of improving N management and

reducing losses and optimizing N application (Ladha

et al., 2005). The analysis suggests that models such as

the DNDC could be applied for studying N-related

issues in the rice–wheat cropping systems of India and

would be very useful to accelerate the application of

available knowledge at field, farm, and regional levels

for quantifying N losses and optimizing N management.

Planning and agricultural extension personnel can use

this tool for optimizing fertilizer availability and

distribution in the various states, while the farmers can

use it for improved fertilizer management. This model

can also be used as a regulatory tool to make projections

of future outcomes of fertilizer management scenarios

with respect to key environmental areas such as N leaching and environmental pollution.