Effects of Soil Water Conditions, Sewage Sludge, Poultry Manure and Chemical Fertilizers on the Growth Characteristics and Water Use Efficiency of Rice Plant in a Calcareous Soil

Rice is one of the most important agricultural crops in Iran that needs much water and mainly cultivated in waterlogged conditions. In order to increase water use efficiency and yield of rice, reduce environmental pollution with chemical fertilizers and increase organic matter of paddy soils application of organic fertilizers is recommended. This investigation was conducted to study the effects of soil water conditions, sewage sludge, poultry manure and chemical fertilizers on the growth characteristics and water use efficiency of rice plant (Oryza sativa L. cv. Ali Kazemi) in a calcareous clay loam soil under greenhouse conditions. The study was performed as a factorial experiment in a randomized complete blocks design including soil water conditions at three levels (continuous submergence, alternate submergence and alternate saturation) and source and amount of organic and chemical fertilizers in 10 levels (control, 100% chemical fertilizers (456.5 mg urea, 66.4 mg Ca(H2PO4)2.H2Oand 22 mg ZnSO4.7H2O /kg of soil), 6g sewage sludge per kg of soil with and without 50% chemical fertilizers, 20g sewage sludge per kg of soil with and without 50% chemical fertilizers, 3g poultry manure per kg of soil with and without 50% chemical fertilizers and 6g poultry manure per kg of soil with and without 50% chemical fertilizers) with three replications. Results showed that the tiller and leaf number per plant, leaf area index and shoot and root dry matter in continuous submergence and alternate submergence were greater than alternate saturation. The effect of soil water conditions on water use efficiency of rice plant was not significant. Application of organic and chemical fertilizers increased the above mentioned characteristics and water use efficiency as compared to the control treatment. With increasing the level of sewage sludge, tiller and leaf number per plant, stem length, shoot and root dry matter, the ratio of shoot dry matter to that of root, leaf area index, leaves chlorophyll index and water use efficiency increased but by increasing amount of poultry manure from 3 to 6 g per kg of soil the above mentioned plant characteristics decreased. In general, alternative submergence with application of 20 g sewage sludge per kg of soil to achieve the optimum growth of rice and increase water use efficiency in greenhouse conditions is recommended.