Effects Of Green Manures Varieties, Plant Densities And Planting Patterns On Soil Properties In Weibei Rainfed Highland

Synthesized fertilizer industry has been growing drastically since1980s around theworld. The over-use of fertilizer has become more and more popular, which is detrimental toour environment. We have observed a large amount of fertilizer and lack of manure wasapplied into the soil during the winter wheat production in Weibei dry land. Considering thisfact, growing green manure during summer fallow is emerging as an efficient solution tosolve the problems in traditional wheat production. However, many problems, such as,insignificant soil improvement, large water consumption, lower economic efficiency and soforth, were also found in the green manure application. Therefore, this article focused on theeffects of5different green manures (mung bean, changwuhuai bean, hairy vetch, soybean andcanola),2planting methods (growing after wheat and growing with wheat) and4plantingdensity on green manure yield, forage production and soil properties. This will provide insightinto efficient green manure application in Weibei dry land area. Our research has found thefollowing results:(1)The optimal application rates for mung bean, changwuhuai bean, hairy vetch, soybeanand canola were168kg/hm2、225kg/hm2、225kg/hm2、281kg/hm2、22.5kg/hm2.(2)Mungbean has higher protein content and nitrogen-free extract production; Canola has higher crudeprotein but lower fiber content, both of mung bean and canola can be used as forageproduction. Mung bean, shangwuhuai bean and canola have higher biomass, therefore theycan provide more nutrition when returned to the soil.(3) When compared with fallow control,growing canola and changwuhuai bean decreased the soil water content and growing hairyvetch, however, does not has significant difference.(4) Growing mung bean, changwuhuaibean, hairy vetch and soybean significantly increased soil nitrate content, but growing canoladecreased nitrate content significantly. All kinds of green manure increased soil phosphoroussignificantly, among which, canola has the highest improvement; on the contrary, greenmanure decreased soil potassium content significantly. There were no significant differencesbetween4planting density on soil water content, nitrate and phosphorous.(5) Growing huaibean and canola after wheat and growing canola with wheat have significant higher biomassthan any other treatments; averagely, growing green manure after wheat produced higher biomass than growing manure with wheat, especially for larger size green manure seeds.(6)Except for growing huai bean and mung bean with wheat, any other treatments increased soilenzyme activity, soil microbial carbon and soil phosphorous significantly; growing huai beanafter wheat increased soil total nitrogen significantly; growing huai bean, canola after wheatand growing canola with wheat increased soil potassium, water soluble organic carbon andsoil organic carbon; growing huai bean and hairy vetch increased soil mineral nitrogencontent significantly.