Integrated nutrient management by using farmyard manure and fertilizers inpotato-sunflower-paddy rice rotation in the Punjab

A rotation experiment was conducted on an alluvial soil at Central Potato R esearch Station, Jalandhar, India between 1994 and 1999 to develop an integ rated nutrient management programme for a potato-sunflower-paddy rice rotat ion. It tested 10 fertilizer treatments that combined application of 50, 10 0 and 150% of the recommended rates of inorganic nitrogen (N), phosphorus ( P) and potassium (K) with farmyard manure (FYM) and in some cases zinc. Pot atoes were the most nutrient-responsive crop followed by paddy rice and sun flower. The responses of potatoes to both P and K were greater in frost and late blight years. In these experiments potatoes required NPK at 150% of t he currently recommended rate for maximum tuber production (i.e. they requi red 270 kg N, 52 kg P and 150 kg K/ha). Application of FYM at 30 t/ha with 270 kg of inorganic N/ha (FYM + N) was less effective than the use of NPK a t 150% of the currently recommended rate. Application of K to replace that removed in the harvested crop was more effective in potatoes than giving K at 100 or 150% of the currently recommended rate. Sunflowers grown after potatoes that had received NPK at 150% of the curren tly recommended rate or with the FYM + N treatment required only half of th e currently recommended rate of NPK for maximum yield (i.e. they required 2 3 kg N, 7 kg P and 13 kg K/ha), whereas paddy rice, grown as a third crop, required the full amount of NPK at the currently recommended rate (i.e. 120 kg N, 26 kg P and 67 kg K/ha). Application of K to adjust for its removal did not benefit sunflowers or paddy rice. Zinc had no direct effect on pota toes or any residual effects on the succeeding sunflower and paddy rice cro ps. The effects of the FYM + N treatment were cumulative, especially on pot atoes which were the most responsive crop, whereas those involving the appl ication of NPK at 150% of the currently recommended rate were not. Also, th e NPK fertility of the soil was enhanced and more organic carbon was presen t following the FYM + N treatment than with NPK fertilizers applied at the currently recommended rate. Application of P resulted in a build-up of P bu t none of the treatments, even the applications of K to adjust for its remo val, maintained the K status of the soil at its initial level.