| Scant rainfall and poor soil fertility has been the main obstruction of the agriculturaldevelopment in Loess Plateau areas in China for a long time. As is well known, planting andploughing green manure could not only improve soil fertility, but also increase the utilizationof the natural resources in time and space, therefore,3-year field experiments wereundertaken to investigate the effects of leguminous green manure (Huai bean, soybean,mungbean and summer fallow as CK) during summer fallow period and nitrogen fertilizerrates (N0,0kg N·hm-2; N108,108kg N·hm-2; N135,135kg N·hm-2and N162,162kg kg N·hm-2)on winter wheat growth, nutrients uptake efficiency, soil properties and economic efficiency.The study could provide the scientific theory and technical support for renewing anddeveloping the green manure-based system in Weibei area. The main results were as follows:1. There was no significant difference in dry biomass as well as C incorporation, amongthe3leguminous green manures from2009to2011. However, the amount of N, Pincorporation in Huai bean treatment and K incorporation in mungbean treatment were thehighest compared with others, respectively. In general, Huaibean would have the bestinfluence in increasing soil fertility.2. There years incorporation of leguminous green manure during summer fallow periodincreased the winter wheat tillers number, total shoot number, yield, biomass, N, P, K uptakeas well as spike number of winter wheat, compared with the CK treatment. Besides,incorporation of green manure reduced N application and improved N use efficiencysignificantly as its obvious improvement on soil N condition and availability. Incorporating ofHuai bean, soybean and mungbean respectively increased N use efficiency by23.7%,12.9%and13.1%compared with summer fallow treatment, in addition, Huai bean was10.8%and10.6%higher than soybean and mungbean, separately.3. Compared with CK treatment, incorporating leguminous green manure duringsummer fallow period increased soil organic matter by12.5%~16.3%, active organic matterby8.3%~17.9%, total N by8.8%~12.3%, available K by5.1%~23.5%, available P by5.3%~30.1%, soil field capacity by1.2%~5.3%and porosity by5.8%~9.5%in3years, butdecreased soil bulk density by6.2%~10.0%. Green manure consumed much more water during summer fallow period, but the water use efficiency (WUE) was still5.3%~25.2%higher compared to CK treatment due to the higher wheat yield. Besides, WUE in Huai beantreatment was significantly higher than summer fallow treatment.4. Compared with N0treatment, applying N fertilizer significantly increased wheat yield,biomass, spike number, kernels per spike, uptake, nitrogen use efficiency and WUE by21.3%~25.2%, but had no significant effect on soil properties.5. Incorporating leguminous green manure could result in more labor and productioninvestment, and less economic efficiency for local farmers. Compared with CK treatment,incorporating Huai bean, soybean and mungbean during the summer fallow period not onlysignificantly increased the total costs by67.0%,76.8%and94.1%, respectively, but alsoenhanced the gross returns by39.1%,18.6%and22.7%, however, the net benefit in theleguminus green manure treatment was26.4%~145.0%lower than CK from2010to2011. Inthe future, only with the continuous corresponding supporting policies perfected bygovernment, could the green manure-based system been renewed and developed. |
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