The Response Of Crop Yield, Soil Phosphorus And Phosphorus Fractions Of Rotating System To Conservation Tillage On The Loess Plateau

Phosphorus is a necessary element of plant growth. It is easily fixed in the soils leading to a low use efficiency use of phosphate fertilizer. A field experiment was featuring three conservation treatments:conventional tillage with stubble retention (ts), no-till (nt) and no-till with stubble retention (nts), with conventional tillage(t) as a control. The dynamic of soil total phosphorus, soil available phosphorus, plant phosphorus of grain and stubble, and phosphorus fraction under top soil were measured. The main results were as follows:1. Stubble retention could significantly improve soybean yield from the rotation system.The highest grain yield and stubble yields were under nts treatment, which were increased by91.4%and16.2%respectively compared to conventional tillage. The yield of maize, wheat and total yield of the rotation system differed, but not significantly so.2. Tillage and stubble retention treatment resulted in the greatest increase to the content of phosphorus in maize grain. It was significantly increased by36.2%. No tillage and stubble retention treatment alone could also significantly promote maize stubble phosphorus and soybean grain phosphorus contents, but there was no significantly difference to the content of wheat grain and stubble under these treatments.3. Conservation tillage could improve crop mycorhiza colonization rate. At the flowering stage of maize, the mycorhiza colonization rate was higher under the nt and nts treatments, increased by16.5%～20.8%.4. The three conservation tillage treatments could signicantly improve the total phosphorus content of the0～5cm layer and the5～10cm layer. At the harvesting of maize, wheat and soybean, the total phosphorus under conservation tillage was significantly increased by11.9%,29.9%and11.2%respectively in the0～5cm layer; In the5～10cm layer, the total phosphorus under conservation tillage was significantly increased by1.0%,3.7%,24.3%at the harvest of manze, wheat and soybena respectively.The available phosphorus content at the0-5cm layer was higher than the5～10cm layer and the available phosphorus under maize and wheat in no tillage and stubble retntion treatments were higher than under conventional tillage, being increased by87.6%and83.4%.5. The content of phosphorus fractions under the nt and nts treatments were higher than the t and ts treatments. Content decreased with soil depth. The content of inorganic phosphorus fraction was DHC1-Pi> HHCl-Pi> NaOH-Pi> NaHCO3-Pi> H2O-P. The content of organic phosphorus fraction was:HHCl-Po> NaOH-Po> NaHCO3-Po. The content of H2O-P and NaHCO3-Pi accounted for6.5%～12.5%of the total inorganic phosphorus under the rotation system. The content of NaOH-Pi accounted for4.8-7.8%of total inorganic phosphorus. The content of NaHCO3-Po accounted for8.1%～10.5%of total organic phosphorus; The content of NaOH-Po was took for11.3%of total organic phosphorus.6. There was a significantly correlation between total phosphorus and available phosphorus. The H2O-Pi, NaHCO3-Pi, NaOH-Pi were signicantly correlated with soil total phosphorus and available phosphorus, and plant phosphorus was also correlated with phosphorus fraction.