| 【Object】Low phosphorous(P) use efficiency is a hard issue in China. Studying of efficient utilization of P resource is very important. The objectives of our study were to explore the effect of mono-ammonium phosphate(MAP), phosphoric acid(PA) and polyphosphoric acid(PPA) with two application methods on P mobility, transformation and availability on calcareous soils, and to study the effect of those on P nutrition and P use efficiency of wheat, corn. It was aim to provide a theoretical support for efficient use of P sources in arid region in Xinjiang and to provide the maintenance logistic for integrated management of P sources and high yield of crops in Xinjiang.【Method】 1. The soil column experiment was set up to study the downward movement of three types P sources including MAP, PA, PPA and two application methods by determinating both water soluble P and Olsen P in diffrernt depth of soil column profiles under drip irrigation condition.2. Employed a laboratory simulating experiment and pot experiment along with the Guppy fractionation method to study the effect of different P sources and application methods on transformation of each P fraction in soil and the distribution characteristics of inorganic phosphorus pool.3. Using network chamber pot experiment to study the biological effects and P use efficiency of P fertilizer due to different P application methods under drip irrigation with planting wheat and corn.【Results】 1. The results in soil column experiment were as follows, compared with orthophosphate fertilizer, polyphosphate increased P mobility in soil at vertical direction. When P fertilizer was applied basically in soil, the vertical average distance of P movement in PPA, MAP and PA treatments were 81.5mm, 61.0 mm and 45.0 mm, respectively. Namely, PPA treatment averagely increased distance of P movement by 33.6% and 81.1% compared with MAP and PA treatments, respectively. Repeated application method could increase vertical distance of P movement in soil by 21.2% compared with single application method, averagely.2. Compared with MAP and PA fertilizer, PPA fertilizer could increase soil available P and decrease the transformation to non-available P, reduce the P fixation in soil. PPA fertilizer increased available P fractions(resin-P and Na HCO3-P) by 50% and 145.9%, respectively, meanwhile, decreased non-available P fractions(HCl-P and residue-P) by 37.9% and 26.1%, respectively, compared with MAP and PA fertilizer. Repeated application method reduced the transformation to non-available P, which increased resin-P and Na HCO3-P by 127% and 60.4% compared with single application method.3. After sterilization on soil by high temperature, some physicochemical properties might be changed in soil,which increased resin-P and Na HCO3-P and decreased residue-P in soil, which led to high available P pool in soil.4. Under drip irrigation, repeated application method treatment could enhance P nutrition of wheat and corn.Repeated application method treatment increased the biomass of stem and leaf of corn by 11.9% and 17.3%,increased P uptake of stem and leaf of corn by 26.8% and 37.1% compared with single application method,respectively. Compared to single application method, repeated application method treatment also increased PUE by 100% and 48.8% averagely in two types of soils, respctively. Repeated application of P fertilizer coupling with drip-irrigation achieved high use efficiency of P nutrient.【Conclusion】 1. Appling of polyphosphate increased P mobility, availability and decreased the transformation to non-available P fractions, thus to improve the availability of P supplying in soil.2. Compared with single application, repeated application treatment increased vertical distance of P movement in soil and the proportion of available P fractions.3. Repeated application of P fertilizer coupling with drip-irrigation improved the soil P supply condition and promoted the absorption of P to plant. It also increased bio-availability and efficient utilization of P fertilizer. |
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