| Integration of irrigation and fertilization is one of agricultural technologies which combined irrigation and fertilization as one process, including fertilized water irrigation and fertigation. It is important to maximize water and fertilizer use efficiency and crop production, and to minimize environmental pollution. In order to find a suitable integration of irrigation and fertilization, to establish a reasonable irrigation and fertilization system, field trials and laboratory experiments were conducted, and a combined method of test and simulation was used to study water and nutrients migration in soil under two different irrigation methods, the reclaimed water irrigation in arid and semi arid areas with surface irrigation, and fertigation in arid inland areas with subsurface drip irrigation. Main results obtained are as follows:(1) Take Xinxiang City, Henan as an example, it could meet the water supply and demand balance using reclaimed water irrigation at arid years, and the water environment carrying capacity index would increase to 0.6.(2) In the arid and semi arid areas, surface irrigation with reclaimed water, the migration distance of soil NO3--N, HPO42- and K+ after once irrigation were 80, 60, and 75 cm, respectively, when the quantity was 750 m3/hm2. All NO3--N, HPO42- and K+ in soil could be leached to 100 cm, for the whole year's irrigation quantity up to 5250 m3/hm2, and followed with several heavier rainfall.(3) Compared with conventional water sources, reclaimed water contains more salt, especially Na+ and Cl-, and there SAR is quite different. The impact of water SAR on soil infiltrationin should be considered as the reclaimed water is used for irrigation. In the arid and semi arid areas, effects of reclaimed water surface irrigation on soil salinity, density, pH, fertility are not obvious. Soil salt has no obvious accumulation with reclaimed water irrigation in a whole year.(4) In the arid inland areas, under the condition of fertigation with subsurface drip irrigation, all of soil NH4+-N, NO3--N and K+could reach to the layers below 100 cm, when irrigation quantity up to 4500 m3/hm2, and N, P, K fertilizer were 397.5,62.7,35.7 kg/hm2 respectively. Leaching of soil HPO42- was no obvious. (5) In the arid inland areas, under the condition of fertigation with subsurface drip irrigation, soil density various with the relative distance from the drip line. Throughout the soil profile, soil density distribution characteristics are higher for upper and lower layers, and lower for the middle layers. Soil density at the locations of drip line is lowest. Compared with mulched drip irrigation, the average density for subsurface drip irrigation is smaller above 50 cm layers, higher from 50 to 80 cm, and the deeper levels has no significant difference.(6) Under the condition of fertigation with subsurface drip irrigation, soil salinity increases with the distance from the drip line increasing. Vertical distribution shows that the soil salinity higher for the upper and lower layers than that of middle layers. Distribution of major salt ions SO42- same to the total salt, and Ca2+ did not change at the location below 60 cm. Compared with mulched drip irrigation, soil total salt is lower for subsurface drip irrigation. In production, it shoule be combined with some measures to address the soil salt surface accumulation problem for seedling.(7) Under the condition of fertigation with subsurface drip irrigation, soil alkali dissolved nitrogen and available K content at the soil of 0 to 100 cm increased with distance from the drip line increasing, while the opposite trend of phosphorus. The trend of available K and available P under mulched drip irrigation accord with subsurface drip irrigation, but the trend of alkali dissolved nitrogen was maximum near drip line. After 3 years fertigation, soil N, P and K fertilizer residues at 0 to 100 cm for fertigation with subsurface drip irrigation were lesser than mulched drip irrigation.
|
PDF Full Text Request