Management of nitrogen through the use of leaf color chart (LCC) and soil plant analysis development (SPAD) or chlorophyll meter in rice under irrigated ecosystem.

Debtanu Maiti,Mahua Banerjee,D K Das,Tanmoy Karak

doi:10.1100/tsw.2004.137

Abstract

A field experiment was conducted in a farmers field in the district of Nadia, West Bengal, India to study the management of N through leaf color chart (LCC) and soil plant analysis development (SPAD) or chlorophyll meter in rice (cv. IET-4094) during the Kharif (wet season) of 2001—2002 and 2002—2003 by taking the treatment combinations based on different levels of N at fixed schedule and through LCC and SPAD. The experimental soil (0—15 cm) had pH 7.33; organic C 0.43%; available N 408.70 kg ha−1; available P 6.92 kg ha−1; and available K 66.31 kg ha−1. The results of LCC and SPAD or chlorophyll meter for the N management in rice show that values of both LCC and SPAD significantly increased with an increasing level of N. The mean values of LCC and SPAD varied from 3.19—5.31 and 27.36—39.26, respectively, in rice. The results show that the amount of N can be saved as 20—42.5 and 27.5—47.5 kg N ha−1 through the use of LCC and SPAD in rice over the fixed-timing N treatment T7 where 150 kg N ha−1 was applied in three (3) splits without reduction in the yield. The SPAD- and LCC-treated N plot showed higher N-use efficiency over fixed-scheduling N treatment in rice. The results further show that SPAD value of 37 and LCC value of 5 have been proved to be superior treatments over SPAD (35) and LCC (4) for the best management of N in rice in an Inceptisol.

Highlights

For achieving high yields of rice (Oryza sativa L.), farmers in many parts of the world tend to apply N in excess of the requirements
The recorded leaf color chart (LCC) values did not show any particular trend with the progress of crop growth, but mostly the LCC values increased up to 63 days after transplanting (DAT) of rice and thereafter, decreased at 84 DAT
Singh et al.[7] indicated that with the application of 30 kg N ha–1 each time, the soil plant analysis development (SPAD) value fell below the critical value of 37.5, which resulted in application of 90 kg N ha–1, which produced rice yields equivalent to those with 120 kg N ha–1 applied in three splits

Summary

INTRODUCTION

For achieving high yields of rice (Oryza sativa L.), farmers in many parts of the world tend to apply N in excess of the requirements. The chlorophyll meter, known as SPAD (soil plant analysis development), can quickly and reliably assess the N status of a crop based on leaf area. It has been successfully used for rice[2]. The leaf N content is closely related to photosynthetic rate[3] and the N concentration on a dry weight basis of the topmost fully expanded leaf has been used as an index to determine the N topdressing Use of this approach in developing countries of Asia is very limited. The present investigation was conducted to evaluate need-based N management strategies for rice using LCC and SPAD with the following objectives: (1) to save N without decreasing yield of rice, (2) to avoid expenditure on soil test for the recommendation of N fertilizers, and (3) to find out the relative efficiency of LCC and SPAD for the N economy as well as increasing yield

EXPERIMENTAL METHODS

RESULTS AND DISCUSSION

CONCLUSIONS