USE LEAF COLOUR CHART FOR RATIONAL APPLICATION OF UREA TO PADDY AND MAIZE: PAU SOIL SCIENTISTS

LUDHIANA, MAY 26:--------



To achieve higher yield, farmers have a tendency to apply fertilizer N in excess of the crop requirements. Dr. Bijay Singh, ICAR National Professor, at PAU, informed that farmers have a practice of applying 150-180 kg urea/acre in rice, however, maximum yields can be achieved only by optimizing the nitrogen supply at right time and in right dose with the use of only 90-120 kg urea/acre. He advised the farmers to use Leaf Colour Chart (LCC) to avoid excessive use of urea both in rice and maize. With a deep concern regarding the excessive use of urea, he cautioned the farmers to optimize its use that may otherwise lead to harmful effects on quality of underground water due to high nitrate contamination. The excessive use may also impact the ozone layer, in the long run, said he. Dr Singh told that LCC technology can cause huge saving to the tune of Rs. 50 crore in one paddy season if adopted in rice by the growers in the state. A single LCC costs only Rs. 35. Moreover, PAU has also recommended the LCC technology for need based fertilizer nitrogen application in maize, said Dr Singh.



Dr. Charnjeet Singh Sethi, Head Department of Soil Science, told that LCC is a successful technology that works well for all the coarse grain rice cultivars and the maize varieties commercially grown in Punjab. He told that technology has been evaluated at more than 400 farmers' field locations in the state with the average saving of 44 kg urea/acre in rice. He suggested the farmers to optimize the application of fertilizers to reduce the cost of production, insect-pest attack, lodging losses and also for the benefit of environment. He told that cost of urea has already increased by 10 % and may add to the cost of production with further decrease in fertilizer subsidies. He suggested the farmers to adopt LCC technology that ensures maximum yield with minimum use of fertilizer nitrogen.



Another soil scientist, Dr. Varinderpal Singh, explained that farmers use apparent leaf colour as a visual indicator for urea application adding that they often draw on dark green colour threshold for applying urea to crops that leads to excessive use. To make out the optimum threshold green colour level in crops, the farmers should take help of LCC, he said adding that LCC shade 4 is best for rice and LCC shade 5 for maize. He added that LCC recommendation guides to plant rice and maize with the basal application of only half bag of urea per acre and to top-dress the half bag of urea per acre whenever colour of first fully exposed leaf from top is below the specified threshold. The leaf colour should always be matched with LCC in shade starting from 14 days after translating to the initiation of flowering at 7-10 day intervals in rice and staring from 21 days after sowing to initiation of silking at 10 day interval in maize. No urea should be applied after these growth stages, he said adding that the N supplied through phosphatic fertilizer di-ammonium phosphate (DAP) should also be adjusted while calculating the dose of urea that is generally ignored by the farmers.


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