Increasing Nitrogen Use Efficiency in Rice (Oryza Sativa L.) with Chlorophyll Meter and Leaf Color Chart
The IUP Journal of Soil and Water Sciences, Vol. II, No. 4, pp. 36-54, November 2009
Posted: 28 Nov 2009
Date Written: November 25, 2009
Abstract
Low Nitrogen Use Efficiency (NUE) continues to be a problem in wetland rice situation as nitrogen (N) is subjected to several transformation losses in the rice ecosystem. Chlorophyll meter (SPAD) and Leaf Color Chart (LCC) can be potentially employed for the precise N measurement, which is based on the leaf N status to synchronize the timely N application with the crop demand. Two field experiments were conducted during 1998 and 1999 at Coimbatore, India with the rice (Oryza sativa L.) cultivars of ADT 36 (short duration) and ASD 19 (long duration) respectively for efficient N management based on the leaf N status of rice. The experiments consisted of four SPAD and LCC-N regimes, blanket N recommendation, green manure N regime and Controlled Release N (CRN) fertilizer regimes, which were compared with the zero-N regime. The technology involves the indirect measurement of leaf N status by the chlorophyll meter and LCC and N application only if the measured meter value is below the predetermined threshold value. The study reveals that N requirement with LCC was higher than SPAD for all the time intervals of measurements. In terms of NUE parameters, LCC was inferior to SPAD-N management, but the lesser cost of LCC, when compared to SPAD meter, provides an opportunity as a simple tool for the individual rice farmers to own it. The study also reveals that the application of controlled release N fertilizer as polymer coatings at the rate of 60% of blanket N recommendation would save 40% of fertilizer N.
Keywords: Chlorophyll meter, Controlled release N fertilizer, Leaf Color Chart (LCC), Nitrogen Use Efficiency (NUE), Oryza sativa L
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