Abstract:

The environmental pressures caused by nitrogen-intensive agriculture have accelerated the promotion of a system combining leguminous green manure (GM) with chemical nitrogen fertilizers. Although leguminous green manure can maintain crop yields with moderate nitrogen inputs, the mechanism of its yield increase is still unclear, especially how changes in soil properties drive improvements in photosynthetic efficiency, which ultimately increase crop yields. Field experiments were conducted at the Wuwei Oasis Agricultural Experimental Station in China from 2020 to 2022, with five treatments: GM incorporation with traditional nitrogen application (N360, 360 kg N ha⁻¹), nitrogen reduction by 10 % (N324, 324 kg N ha⁻¹), nitrogen reduction by 20 % (N288, 288 kg N ha⁻¹), nitrogen reduction by 30 % (N252, 252 kg N ha⁻¹), and nitrogen reduction by 40 % (N216, 216 kg N ha⁻¹). The results showed that compared with the N360 treatment, the N288 and N324 treatments increased soil bulk density (SBD) by 8.3 % while ensuring that soil organic matter (SOM), total nitrogen (TN), and C/N did not decrease. Moreover, this model has the advantages of increasing soil moisture content and regulating soil temperature reasonably. In addition, N288 treatment ensured that the leaf area index (LAI), relative chlorophyll content, biomass accumulation (BA), and photosynthetic physiological characteristics (Pn, Tr, Gs, and Ci) of maize did not decrease. Through structural equation modeling (SEM), it was found that nitrogen reduction with green manure incorporation mainly optimizes the photosynthetic physiological characteristics of maize by improving soil chemical properties, thereby increasing maize grain yield (GY). It can be seen that GM incorporation with nitrogen reduction by 20 % can be a feasible fertilization strategy for achieving high-yield maize production.