بررسي بيلان نيترات در سيستم هاي مديريت سطح ايستايي

چكيده انگليسي :

Investigation of Nitrate Balance in Water Table Management Systems Ali Parvaresh Rizi a parvareshrizi@ag iut ac ir September 16 2012 Department of Water Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Sayed Farhad Mousavi mousavi@cc iut ac ir Abdolmajid Liaghat aliaghat@ut ac ir Abstract Agricultural intensification and high rate of application of nitrogen fertilizers are recognized as major sources of nitrate contamination of surface and groundwater resources Thus using proper management practices is important to increase water and fertilizer use efficiencies and preventing environmental pollution Water table management systems including sub irrigation and controlled drainage are the most effective methods to reduce quantity of drainage water and its nitrate concentration and to improve yield The objectives of this study were to determine the effects of water table management systems on nitrate distribution and its concentration in soil and evaluating the impacts of using the nitrate enriched water resources in conjunction with water table management systems on yield and quality of drainage effluent Using drainage water in this systems could lead to recover soluble nutrients due to plant uptake Hence a lysimeter study was conducted in Karaj Iran The treatments included sub irrigation controlled drainage and free drainage Each treatment applied in two groups with plant silage corn and without plant All lysimeters were irrigated with nitrate enriched water 50 mg NO3 L Nitrate concentration in soil was measured in 6 periods and 3 depths Also crop yield water and fertilizer use efficiency and drainage volume were evaluated The results indicated that nitrate concentration in soil was significantly affected by drainage systems for planted lysimeters P 0 05 and non planted lysimeters P 0 01 and each one of these systems had different effect on nitrate distribution in soil The results of nitrate distribution in soil for sub irrigation systems showed that upward movement of nitrate via the capillary rise of moisture is significant and its concentration has been increased at the top of the saturated zone Also the nitrate concentration in non planted treatments was more than planted The controlled drainage systems had the most effect on reducing nitrate concentration of drainage water Also investigation of nitrate balance showed that nitrate consumption by plant in sub irrigation treatment was more than other systems The best corn yield belongs to sub irrigation The fresh plant weight in the sub irrigation treatment was 28 3 and 24 2 more than controlled drainage and free drainage treatments respectively Water use efficiency WUE and fertilizer use efficiency FUE for sub irrigation treatment is significantly higher than other treatments P 0 01 WUE for sub irrigation was 20 2 more than controlled drainage and 37 8 more than free drainage Also FUE for sub irrigation was 19 2 and 37 6 more than controlled drainage and free drainage respectively The results of the experiment indicated that nitrate concentration in the root zone of water table management treatments near the water table has increased This could be accomplished by sub irrigating with nitrate enriched water This practice could significantly increase crop yield and reduce the use of fertilizers Moreover sub irrigation systems could be used to minimize the nitrate concentration in drainage water This could provide an opportunity to recycle large quantities of drainage water by repeating sub irrigation cycles thereby minimizing pollution This system may thus prove to be an environmentally friendly dual purpose system for pollution control and enhancement of the efficiency of fertilizer use Keywords Nitrate balance water table management sub irrigation controlled drainage

پرورش ريزي، علي

بررسي بيلان نيترات در سيستم هاي مديريت سطح ايستايي

آبياري زيرزميني , زهكشي كنترل شده