Abstract

Field experiment was conducted at farmers’ field of old alluvial zone (Manikchak, Malda) of West Bengal, India during winters of 2007-2009 to study the effect of water management practices with different combinations of integrated plant nutrient supply including lathyrus green manure, vermicompost, poultry manure, chopped rice straw on productivity and nitrogen use efficiency of irrigated rice (Oryza sativa L.). Growth and yield attributes of rice, viz, effective tillers/m², panicle length, number of grains/ panicle and 1000-grain weight were significantly highest in saturation from 15 to 35 days after transplanting followed by continuous ponding, among the water regimes and lathyrus green manuring 10 t ha^-1, among the organic sources of nutrients. Similarly highest grain yield was recorded in saturation of top soil (0-40 cm) (4.26 and 4.32 tones ha^-1) and lathyrus green manuring 10 t ha^-1 (4.70 and 4.78 t ha^-1), which was at par with the combined application of lathyrus green manuring  5 t ha^-1 + vermicompost 2.5 t ha^-1  + poultry manure 2.5 t ha^-1  (4.66 and 4.75 t ha^-1) and chopped rice straw 5 t ha^-1 + lathyrus green manuring 5 t ha^-1 (4.64 and 4.73 t ha^-1). Irrespective of organic nutrients sources, saturation of top soil (0-40 cm) recorded highest net return (Rs 19613/- and 20281) and benefit:cost ratio (1.76 and 1.78) and the treatment lathyrus green manuring 10 t ha^-1 (Rs 24592/- and 25484/- and 1.98 and 2.02) recorded among the organic nutrient management.  Irrespective of water regimes,  statistically highest N and K uptake were found in lathyrus green manuring 10 t ha^-1 (115.59 to 118.39 kg ha^-1) and (67.17 to 70.80 kg ha^-1), respectively; however, highest P uptake was found in lathyrus green manuring 5 t ha^-1 + vermicompost 2.5 t ha^-1 + poultry manure 2.5 t ha^-1 (49.24 to 50.57 kg ha^-1). The nitrogen use efficiency indices such as agronomic efficiency, physiological efficiency, internal efficiency, recovery efficiency and partial factor productivity might be influenced when a part of nitrogen was supplied through organic sources. The highest water expanses efficiency was recorded in saturation of top soil (0 to 40 cm) (26.68 and 27.22 kg ha^-1 mm^-1), however, highest water saving (5.45 and 5.70%) was found in intermittent ponding of water.

Key words: Lathyrus, nitrogen use efficiency, poultry manure, vermicompost, water expanses efficiency, water regimes.