بررسي پتانسيل شستشوي نيترات و آمونيوم در پروفيل خاك تحت تاثير كم آبياري

Evaluation of potential nitrate and ammonium leaching under deficit irrigation in soil profile

Nitrate (NO3-N) and ammonium (NH4-N) leaching from agricultural soils can represent a substantial loss of fertilizer nitrogen (N), but a large variation in losses has been reported. The objectives of this study were to assess die accumulation and movement of nitrate and ammonium in the soil profile over studying period under deficit irrigation conditions. We report N concentration and leaching losses under three N fertilizer and three irrigations treatments in Khuzestan. Irrigation treatments consisted of full irrigation (II) and others were 80 (12) and 75 (13) percent of II treatment Urea application consist of 150 (Nl), 250 (N2) and 350 (N3) kg/ha. Leachate from the farm was extracted from a depth of 1.2 m and soil samples were collected from field plots in 0.3 m depth increments to 1.2 m on a periodic basis. NO3-N values increased with rise of fertilizer consuming and decreasing of water application. It depended to NH4-N transformation and irrigation regimes. In all treatments, NH4-N decreased from the surface to 120 cm depth. Maximum concentration of NO3-N and NH4-N accrued in I3N3 and I3N2 treatments respectively. Temporal variability in nitrogen concentrations in the soil depths were mainly the result of different irrigation and fertilizer regimes. Our results indicated that the irrigation regimes in this study lead to relatively N leaching losses, appropriate fertilizer application with enough irrigation can substantially reduce these losses.