effect of partial root-zone drying (prd) and deficit irrigation on nitrogen uptake and leaching in maize

the effect of full irrigation (fi), partial root-zone drying at two levels (receiving 75 percent of et (prd75), 55 percent of et (prd55)) and deficit irrigation treatments at the same levels (75 percent (di75) and 55 percent (di55)) under drip irrigation on nitrogen uptake and leaching in a maize field in sari agricultural sciences and natural resources university were carried out during years 2010 to 2011. tdr access tubes were installed in the soil profile to measure soil water content for deep percolation measurement. the results demonstrated a significant decrease (p< 0.05) in the values of leaf nitrogen and total nitrogen uptake by plant in di75, di55 and prd55 treatments as decreasing irrigation depths. there was no significant difference in the values of leaf nitrogen and total nitrogen uptake between prd75 and fi treatments. although, nitrate leaching potential was more in prd treatments than di treatments, residual nitrogen in soil in prd treatments at the end of growing season (in 0-80 cm of soil depth) was about 20 to 60 percent less than those of di treatments due to more nitrogen uptake in prd than di treatments. also, the results showed that yield in prd55, di55 and di75 treatments were 54, 52 and 17 percent lower than those in fi treatment in 2010 and 26, 14 and 20 percent less than that in fi treatment in 2011, respectively. finally, there was no significant difference found in the values of yield between prd75 and fi treatments. therefore, by considering both environmental and economic issues, it could be concluded that prd75 treatment was a promising irrigation strategy to reach a sustainable condition.