Evaluation of Rice Plant Response to Nitrogen, Phosphours and Potassium Based on Site-Specific Nutrient Management (SSNM)

Site specific nutrient management technique can increase nutrients use efficiency, prevent non-selective use of fertilizers and provide better performance of fertilizers. Optimizing fertilizer application was used in this study by site specific nutrient management technique through indigenous soil nutrient supply, crop nutrient demand (expected yield) and nutrients recovery. Twenty two selected farms were located in west Guilan and varied widly in soil properties, and agricultural practice management. In each research area were divided into four plots (each plot had 12 square meters). The fertilizers treatments determined through Doberman method (N0, P0, K0, and NPK). Morphological characters, yield and yield components and nitrogen, phosphorus and potassium in soil and plants after harvest were meseared. Also provided indigenous nutrition elements to consider the yield were calculated. The results showed in 6 farms (27%), applied nitrogen were more and in 14 farms (63%) were less than the recommended dose. Furthermore only 2 farms were in recommended range. Phosphorus supply in all fields was more than the recommended dose. This increased consumption ranged from 52 to 85 kg.ha-1 P2O5. Also according to site specific nutrient management, 10 farms had more potassium intake equivalent to 95 to 129 kg.ha-1 than the recommended dose and in 12 farms the recommended dose was high and must consume less potassium to achieve optimal yield.The results indicate that current fertilizer recommendations based on testing in a region can not be justified for other areas.