Effects Of Plastic Mulching On Spring Wheat Yield Formation And Phosphorus Distribution Under Different Rainfall Patterns In The Loess Semi-arid Plateau

Little and variable rainfall are the major climate characteristics on the semi-arid regions of Loess Plateau. Majority rainfall is heavy rain, rainstorm and ineffective rainfall. Rainy reason is not in the consistent with crop growing season, about60%rainfall occurred during the July to September. The rainfall is fluctuated in recent year and becoming decreasing with increasing temperature due to the global change which lead to the negative effect on agricultural production. The plastic film mulching is developed in order to use precipitation and increase its use efficiency.Increasing soil temperature and conserving moisture are the major advantage of plastic film mulching. Plastic film mulching can effectively increase soil surface temperature and deplete soil water ineffective evaporation, increase water use efficiency of crop and productivity. The technique of plastic film mulching is widely used in semiarid regions of Loess Plateau. It makes a great contribution to grain yield formation, but there is a little situation to reduce grain yield. Except for temperature, different rainfall patterns are also a key factor to affect crop yield, but we still don’t know the extent. Therefore, Plastic film mulching on spring wheat is effect yield formation and the relationship of the phosphorus distribution in wheat under different rainfall patterns in this study.The thirteen years average annual precipitation from2001to2013years is306mm. The annual precipitation of2009,2010,2012, and2013are238,309,378,357mm, respectively. According to precipitation, the study design to three patterns: dry year (2009), normal year (2010) and rainy year (2012,2013). There were four treatments:(1) spring wheat mulched with plastic (MW),(2) fallow and mulching (MN)(3) spring wheat and non-mulched/bore (BW),(4) fallow and no mulching (BN). Individual plots were replicated three times in randomized complete block design. Some major conclusion can be drawn follows: The plastic mulching can increase wheat yield under different rainfall patterns. Compared to the B treatment, grain yield increased in the M treatment by96%,73%and7%in2009,2010and2012, respectively. On the contrary, grain yield of M treatment decreased by54%than B treatment in2013. Under plastic film mulching, grain yield of dry year (2009) and normal year (2010) were both decreased than rainy year (2012) by27%and30%, respectively. The grain yield of rainy year (2013) significantly decreased by68%,67%,77%than2009,2010and2012in M treatment, respectively.Compared to dry year (2009), Grain P concentration of M treatment increased7.0%in rainy year (2012). But straw P concentration was opposite. The straw P in rainy year (2012) was decreased29%compared to dry year (2009).Therefore, plastic film mulching in rainy year was not always increased yield, and it also result in decrease yield. It implied that plastic film mulching has positive and negative effects to agriculture. Under plastic film mulching, more rainfall made most soil phosphorus to grain, and increased grain yield.