Effects Of The Rotation Of Different Green Manures And Wheat On Soil Water-fertility And Growth Of Wheat

Aiming at the drought, barren soil of the Loess Plateau, and in order to make theoptimum use of the light, heat and water resources during summer fallow period, improve soilphysical-chemical properties and increase the productive potential of cropland in arid andsemiarid areas, a field rotation experiment of different green manures and wheat, wasconducted to study the soil nutrients, soil water content, growth-physiological indicators andyield of subsequent winter wheat, with bare fallow as control (CK) during summer fallow.The study aimed to provide theoretical basis for green manure-wheat rotation systemaccording to four green manures as Smooth Vetch, Hairy Vetch, Milk Vetch, Sweet Clover.The main conclusions are as follows:1. The soil nutrient contents in the depth of0-60cm were mainly controlled by thenutrient returning of different green manures. The effect of soil nutrients content of theSmooth Vetch and Hairy Vetch treatments were the highest. After the green manures planted intwo years, the soil Total P, Total N, organic matter, Hydro-N content in the depth of0-60cmof Smooth Vetch were increased, the content of Available P and Available K weresignificantly higher than that of other treatments; Hairy Vetch treatment increased the contentof Available P and Hydro-N; Milk Vetch treatment had a stronger effect on the content ofTotal K, Total N, Available K in the depth of0-60cm and Available P in the depth of0-40cmof the winter wheat sowing; Sweet Clover treatment could obviously improve the content ofHydro-N.The content of NO3--N in the depth of0-60cm were decreased after green manuresplanted, but green manures treatments were higher than the control, there was a increase onthe content of NH4+-N, but not obvious. The content of NO3--N in the depth of0-60cm werereduced after Smooth Vetch, Hairy Vetch, Sweet Clover planted, when they were returning tofield, the content of NO3--N recover. The content of NH4+-N of Smooth Vetch, Hairy Vetch,Milk Vetch were11.37%,26.14%,9.55%higher than before green manures planted, SweetClover and the control were reduced by3.26%,3.52%.2. Planting green manure crops consumed a lot of soil moisture, in the main periods ofsubsequent winter wheat growth, the soil moisture content of each green manure treatmentswere lower than the control in the depth of0-200cm. On the growth period of green manures in three years, the water consumption of Smooth Vetch, Hairy Vetch, Sweet Clover in0-200cm soil layer were4.1%,5.7%(P＜0.05),1.5%higher than the control. On the growthperiod of winter wheat in two years, the water consumption in0-200cm soil layer of HairyVetch, Milk Vetch, Sweet Clover were respectively higher than the control by2.3%,3.0%,2.1%. The soil water storage of four green manure treatments were significantly lower thanthe control, but the difference decreased of the winter wheat sowing and harvesting in threeyears. The effect on soil moisture of shallow layer (0-60cm) was the greatest, in the depth of60-120cm was the smallest, and each green manure treatments were lower than the control inthe depth of120-200cm. The average moisture content of the0-200cm soil layer of SmoothVetch and Hairy Vetch treatments were significantly lower than the control, but the differenceof that decreased gradually with the growth of wheat; Milk Vetch treatment has the lestinfluence on soil moisture compared with the control.3. The plant height, flag leaf area and dry matter accumulation volume of subsequentwinter wheat has increased after planting different green manures, the flag leaf area of greenmanure treatments had no significant difference.The plant height of Sweet Clover treatmentincreased by8.69%(P＜0.05) compared with the control in winter wheat filling, the othergreen manure treatments had no significant difference. The dry matter accumulation of HairyVetch treatment in winter wheat heading was increased by55.40%(P＜0.05) compared to thecontrol, and had difference with the other treatments significantly. The net photosyntheticrates (Pn), transpiration rate (Tr), stomatal conductance (Cs) of flag leaf in green manuretreatments were higher than the control. The rotation of different green manures and winterwheat could increase the chlorophyll content of subsequent winter wheat flag leaf.4. The grains per ear, ear number per unit area and1000-grain weight of winter wheat inrotation with different green manures were increased by5.63%～12.12%,28.2%～43.0%（P＜0.05）,1.70%～3.84%respectively, there were not significantly different between eachgreen manure treatments. The biomass and grain yield of subsequent winter wheat in SmoothVetch, Hairy Vetch, Sweet Clover treatments were significantly(P＜0.05) increased by18.0%、32.5%、19.8%and25.71%、28.90%、25.97%compared with the control. There wasno significant difference between Milk Vetch treatment with the control. The order of wateruse efficiency was concordance with the biomass and grain yield of each treatment. The wateruse efficiency of Smooth Vetch, Hairy Vetch, Sweet Clover treatments were25.71%～28.90%(P＜0.05) higher than the control significantly, the Milk Vetch treatment was no significantdifference compared with the control.