Effects Of Film Mulching On Ridge And Furrow、Phosphate Fertilizer On Alfalfa Productivity And Soil Quality In The Severe Drought Area Of Semi-arid Areas On The Loess Plateau

Alfalfa grassland is the key component in grassland agriculture, it can control water and soil erosion and improve ecological condition. To investigate the effective way of developing grassland agriculture in the severe drought area of semi-arid areas on the Loess Plateau, we take measures of film mulching on the ridge ang furrow and phosphate fertilizer to research the change of alfalfa productivity and soil quality in GanSu Province, YuZhong county, Zhonglinachuan. We design the experiment use the way of split-plot andrandomized block, and set up2mulching treatments as main treatment:mulching（M） and no mulching（NM）, and4phosphate fertilizer levels as vice treatment:P0,17kg P ha^-1,34kg P ha^-1,51kg P ha^-1. Each treatment has3replicates, and there are24plots in all. The results are as follows:5cm and20cm soil temperature of M treatment is significantly higher than NM treatment overall, but M treatments and NM treatments have no significant difference or NM treatment is significant higher than M treatment before the middle of July. After the first harvesting （August9）,5cm soil temperature of the3phosphate fertilizer （P0, P17and P51） in M treatment respectively increase4.48℃,3.18℃and1.48℃than NM treatment,20cm soil temperature of the3phosphate fertilizer （P0, P17and P51） in M treatment respectively increase2.38℃、3.35℃、2.46℃than NM treatment.Both mulching on the ridge and furrow and phosphate fertilizer significantly increases alfalfa productivity. Alfalfa productivity of P17, P34and P51respectively increase17.6%,29.3%and39.0%than PO in M treatment; P17, P34and P51respectively increase16.5%,35.1%and49.5%than PO in NM treatment; The4phosphate fertilizer levels in M treatment respectively increase46.8%,48.1%,40.4%and36.6%than NM treatment. The total aboveground biomass of two years （2012and2013） in P51of M treatment is13276kg ha^-1（maximum productivity）, but P0of NM treatment is only6505kg ha（-1）（minimum productivity）, and P51in M treatment significantly increase104%than P0in NM treatment.Both mulching on the ridge and furrow and phosphate fertilizer respectively increases the0-5m WUE of alfalfa. The0-5m WUE of P17, P34and P51respectively increase13.2%,25.1%and32.0%than P0in M treatment; P17, P34and P51respectively increase3.31%,17.1%and30.4%than P0in NM treatment; The4phosphate fertilizer levels in M treatment respectively increase32.9%,45.6%,42.0%and34.5%than NM treatment. The total0-5m WUE of two years （2012and2013） in P51of M treatment is14.8kg ha^-1 mm^-1（maximum0-5m WUE）, but P0of NM treatment is only8.43kg ha^-1 mm^-1（minimum0-5m WUE）, and P51in M treatment significantly increase75.6%than P0in NM treatment.Compared with June2011, soil pH of all treatments has the trend of decreasing in October2013, and M treatment has already significantly （p<0.05） decreased. P0, P17, P34and P51in M treatment respectively decreases0.135%,1.63%,2.11%and2.61%than June2011;and P0,P17, P34and P51in NM treatment respectively decreases0.460%,0.519%,1.98%and1.70%than June2011. Until October2013, soil pH of P0, P17, P34and P51in M treatment has the trend of decreasing when it compared with NM treatment, and P0, P17, P34and P51in M treatment respectively decreases0.250%,1.88%,1.82%and1.16%than NM treatment. The soil pH has significantly negative correlation relationship with a lot of soil nutrient indexes in October2013, for example, AP、N0₃^--N、NH4⁺-N、ACP、ALP、SOC and TN.Until October2013, soil AP of P17, P34and P51in M treatment respectively increases5.80%,9.96%and127%than June2011; soil AP of P17, P34and P51in NM treatment respectively increases30.9%,48.2%and83.1%than June2011. In October2013, soil AP of P17, P34and P51in M treatment respectively increases63.5%,66.2%and205%than P0, and soil AP of P17, P34and P51in NM treatment respectively increases74.6%,115%and198%than P0.In conclusion, film mulching on ridge and furrow can increase soil temperature, alfalfa productivity and water use efficiency; promote alfalfa to absorb soil phosphorus; enhance the effectiveness of phosphorus; decrease soil pH; improve the alkaline soil. Putting phosphate fertilizer in the soil can improve alfalfa productivity and water use efficiency, increase soil available phosphorus content, and the effect of P51treatment is the most obviously. So, in our experiment, the P51in M treatment is an ideal alfalfa planting way so far.