When the soil are continuously submerged for whole of the year and only paddy crop is taken, nitrogen and phosphorus may be applied at the rate of 60 kg and 40 kg/ha respectively.
Application of P2O5 and K2O may be avoided if these nutrient were applied to preceeding rabu crops. It the whole quantity of nitrogen is not available as urea or ammonium sulphate, CAN may be used for the split application. But there may be considerable loss of nitrogen when applied through CAN.
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Zinc deficiency
Generally, zinc deficiency is mot wide spread micro-nutrient disorder in paddy crop. The incidence of this deficiency is frequent where top soil has been removed or soils have high pH, high CaCO3 content and high organic matter content. The characteristic symptoms of zinc deficiency in paddy is bloaching of the mid rib of leaves. The symptoms are most marked on the 3rd or 4th basal leaf after 3-4 weeks of transplanting. While the mid ribs becomes yellowish particularly at the base of the leaf, the leaf tip remains normal green.
Besides this, light yellowish spots appear on the leaves, which later enlarge and coalesce and turn deep brown. The entire leaves becomes brown in colour and dries out with the advancement in age. Infact, irrespective of the age of the plant, if the mid rib is lighter colour than lamina, zinc deficiency is suspected. Zinc deficiency can be corrected by application of zinc sulphate @ 25 kg/ha. Soil and plant analysis need to be done for the confirmation of its deficiency and deciding its dose. In transplanted paddy, mid zinc deficiency has also been corrected by dipping seedlings in 1-4% zinc oxide solution prior to transplanting. Zinc sulphate should be applied atleast 2 days after the application of P fertilizer. If the deficiency symptoms appear in the leaves, 0.5 per cent zinc sulphate solution (5 kg zinc sulphate mixed with 2.5 kg calcium hydroxide per ha) could be sprayed.
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