Abstract:

In response to the issues of high nitrogen fertilizer input and declining soil quality in the Hexi Oasis irrigation area for silage maize （Zea mays） production， this study investigated the effects of mixed leguminous forages on soil physicochemical properties and yield of silage maize under reduced nitrogen supply. The aim was to provide a scientific basis and theoretical support for development of recommendations for soil health management and sustainable production of silage maize in this region. The experiment was conducted at the Wuwei Oasis Agricultural Comprehensive Experimental Station from 2023 to 2024 using a split-plot design. The main plots consisted of three crop planting patterns ［M： monoculture of silage maize； MH： mixed of silage maize and soybean （Glycine max）； ML： mixed of silage maize and lablab bean （Dolichos lablab）］， while the subplots comprised three nitrogen application levels （N₃： 360 kg·ha^-1； N₂： 306 kg·ha^-1； N₁： 252 kg·ha^-1）. The results showed that compared to the M planting pattern with a 30% reduction in nitrogen fertilizer， the soil bulk density in MH and ML patterns under the same nitrogen level was reduced by 5.5% and 8.0%， respectively； porosity was increased by 6.6% and 10.8%， respectively； pH was decreased by 0.9% and 1.0%， respectively； organic matter was increased by 3.9% and 5.1%， respectively； total nitrogen content was increased by 9.2% and 10.4%， respectively； total phosphorus content was increased by 8.7% and 10.9%， respectively； total potassium content was increased by 9.4% and 12.0%， respectively； nitrate nitrogen content was increased by 26.4% and 29.8%， respectively； ammonium nitrogen content was increased by 19.1% and 25.1%， respectively； available phosphorus content was increased by 8.8% and 10.6%， respectively； and available potassium content was increased by 5.7% and 10.1%， respectively. In addition， compared to the M planting pattern， the forage yield and energy yield in the MH planting pattern were increased by 23.1% and 25.2%， respectively， and in the ML planting pattern by 30.5% and 33.6%， respectively. Under the MH planting pattern with a 30% reduction in nitrogen， the forage yield and energy yield did not differ significantly from traditional nitrogen application， but under the ML pattern， they were increased by 20.5% and 17.8%， respectively. Moreover， the forage yield and energy yield in the MH planting pattern with a 30% reduction in nitrogen were increased by 15.8% and 17.8%， respectively， compared to the traditional nitrogen application in the M planting pattern， and in the ML pattern with a 30% reduction in nitrogen， they were increased by 23.8% and 28.6%， respectively. Therefore， ML patten combined with a nitrogen application rate of 252 kg·ha^-1 improved soil physicochemical properties and increased forage yield， and can be recommended as a suitable cropping pattern and nitrogen rate for silage maize production in the oasis irrigation area.

Key words: mixed cropping, nitrogen application, silage maize, soil physical and chemical, forage yield