LEAF COLOUR CHART HELPS IN THE RATIONAL USE OF NITROGEN IN RICE AND MAIZE: DR KANG

LUDHIANA, MARCH 10(Anmol Singh)

In a quest to achieve higher yield, farmers have a tendency to apply fertilizer N in excess of crop requirements. Dr. Manjit Singh Kang Vice Chancellor, 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. Expressing concern over the excessive use of urea in rice and maize, he impressed upon the farmers to use Leaf Colour Chart (LCC). Dr Kang urged them to optimize its use which may otherwise lead to harmful effects. He added that the developed countries are using costly \'chlorophyll meter\' and \'green seeker optical sensor\' to optimize nitrogen application in crops, which is beyond the reach of our farmers. Dr Kang appreciated the efforts of PAU soil scientists in recommending an inexpensive LCC technology that can save Rs. 50 crore in one rice season, if adopted by the growers. The LCC recommended by PAU costs only Rs. 35. The technology has also been extended to maize where its use can help need-based nitrogen application in maize. The scientists have recorded a significant saving in nitrogen fertilizer in maize by using LCC.





Dr. Yadvinder Singh, Head, Department of Soil Science, told that LCC is a successful technology which works well in all the coarse grain rice cultivars and the maize varieties, popular in Punjab. He disclosed that technology has been evaluated at 461 farmers' field locations in the state with the average saving of 44 kg urea/acre in rice. Dr Singh advised 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. As the cost of urea has increased by 10 % and may add to increased cost of production with further decrease in fertilizer subsidies, he stressed on the need to adopt LCC technology that ensures maximum yield with minimum use of fertilizer nitrogen.





While explaining the technique of using the LCC, Dr. Varinderpal Singh, PAU Soil scientist, revealed that farmers are already using leaf colour as a visual indicator for urea application but they are using dark green colour threshold for crops that leads to excessive use of urea. Advising the farmers to take help of LCC to know the optimum threshold green colour level in crops, he informed that LCC shade 4 is optimum for rice and LCC shade 5 for maize. LCC recommendation guides to plant rice and maize with the basal application of only half bag of urea per acre and to top-dress half bag of urea per acre whenever colour of first fully exposed leaf from top is below the specified thresholds. He added that 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 the growth stages, emphasised he and stated that nitrogen 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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