Effects Of Long-term Fertilization On The Spatial Distribution, Availability And Transformation Of Soil Phosphorus In Loess Plateau

Study on the apace distribution and availability of soil total Phosphorus, available Phosphorus, inorganic Phosphorus and organic Phosphorus at different Phosphorus level after long-term fertilization of 21 years, disscuss the effects of reasonable Phosphate fertilization to the soil available Phosphorus, the results show:1 The total Phosphorus, available Phosphorus, organic matter, inorganic Phosphorus properties and moderately labile organic Phosphorus accumulate in the surface layer after long-term fertilization; liable organic Phosphorus, moderately resistant organic Phosphorus and highly resistant organic Phosphorus have not accumulate in the surface layer. The increase of total Phosphorus can be plotted out three soil layers: the cultivated layer (0-20cm), the cultivated-lessen layer (40-80cm), little increase layer (80-100cm); the increase of available Phosphorus also can be plotted out three soil layers: the cultivated layer (0-20cm), the cultivated-lessen layer (40-60cm), little increase layer (>60cm).2 The total Phosphorus, available Phosphorus and inorganic Phosphorus properties increase in the surface layer at different Phosphorus level and moderate Nitrogen level, and the total Phosphorus, available Phosphorus, Ca2-P, Ca8-P, Al-P and Fe-P increase with the raising of Phosphorus fertilization; the total Phosphorus, available Phosphorus, Ca2-P, Ca8-P, Al-P, Fe-P and Ca10-P increase in the sueface layer at different Nitrogen level and moderate Phosphorus level, but the change is not related to the Nitrogen level, which shows that the Nitrogen has light effect to these properties.3 The correlation analysis and path analysis show that Ca₂-P and Ca₈-P are the main sources of available Phosphorus, O-P and Ca₁₀-P are the potential sources of Phosphorus, Al-P and Fe-P are between these two sources, Ca₈-P is the main intermediate form of all the Phosphorus properties to be available Phosphorus. The availability of organic Phosphorus properties can be arranged as follow: highly resistant organic Phosphorus>liable organic Phosphorus>moderately liable organic Phosphorus>moderately resistant organic Phosphorus.4 Analyze the apace distribution of the total Phosphorus, available Phosphorus, Ca₂-P and Ca₈-P and the change of soil Phosphorus properties of different treatments at different fertilization, we can see that at moderate Phosphorus level and moderate Nitrogen level crop can absorb the soil Phosphorus effectively.5 Different soil Phosphorus properties have different mobility, although all the properties transport to deep slightly. Through the analysis of the apace distribution of different soil Phosphorus properties, this paper shows that Ca₈-P, moderately resistant organic phosphorus and highly resistant organic Phosphorus can transport to deep soil easily, other properties are not significant, this can show that fertilizing with plowing deep can increase the content of available Phosphorus in deep soil.