<p>Soil quality on irrigated farmland is declining due to intensive agricultural activities and inappropriate agricultural inputs. This study aimed to analyze the effects of agricultural inputs (fertilizer and irrigation input) on soil quality and quantify the relationship between soil quality and resource use and yield formation under two irrigation patterns [border irrigation (BI) and drip irrigation (DI)] in the Hetao Irrigation District of China. We identified nine soil indexes [clay, sand, bulk density, pH, soil organic matter (SOM), electrical conductivity of saturated extract, structural stability index (SSI), soil water content, NH4+-N] as the minimum dataset (MDS) in topsoil (0&#8211;30 cm) and subsoil (30&#8211;60 cm). The results showed that the soil quality indicator (SQI) calculated using multi-linear regression (SQI-M) qualified the relationship between soil quality and crop yield better than the SQI calculated using factor analysis (SQI-F), especially for subsoil. The variation in soil quality was related to soil depth, with the SQIs in topsoil decreasing and subsoil increasing with increasing soil depth. The SQI variation was due to decreased SOM and SSI in topsoil and increased sand content in subsoil. The ANOVA and linear mixed-effects model (LMM) had high predictive performance, the LMM method quantified management, environment and SQIs factors to accurately estimate yield. In addition, the reduction in soil quality decreased the crop water and fertilizer use capacities and soil carbon sequestration capacity. Our study provides a quantitative tool for assessing soil quality in farmland and develops an LMM model to estimate yield considering soul quality. Overall, our findings suggest that continuous irrigation agricultural practices decrease soil quality, limit crop resource use and yield formation, and decrease agricultural sustainability.</p>
<p>Agroforestry systems (AFS) have been realized as a sustainable alternative for food production to adopt climate warming, but a quantitative analysis of the radiation use mechanism of converted farmland from previous desert grassland is missing. Thus, this study aimed to assess the dynamics of interception and absorption of photosynthetically active radiation (fIPAR and fAPAR), intercepted and absorbed radiation use efficiency (RUEi and RUEa), growth and productivity of spring maize grown in AFS. A two-year field experiment was conducted using a factorial combination of two fertilization levels (high and low) and three plastic film mulching (PM) (transparent film, black film, and no film). The observed parameters were: leaf area index (LAI), relative chlorophyll content (SPAD), canopy light use characteristics (fIPAR and fAPAR), soil temperature and maize productive performance. We calculated RUEi and RUEa, and quantified the contribution of light use characteristics and net photosynthetic rate (A) to yield. The results showed that fIPAR and fAPAR increased by 3.4&#8211;22.2% and 3.4&#8211;14.7% in transparent film mulching (TM) and 3.3&#8211;15.7% and 3.3&#8211;10.6% in black film mulching (BM) from jointing to grain-filling, respectively, relative to no mulching (NM). Nitrogen application positively affected fIPAR and fAPAR. And, we developing an empirical regression function to calculate the canopy fAPAR. The increased soil temperatures under PM advanced crop development. PM improved LAI, SPAD, A and prolonged the grain-filling duration. TM and BM increased RUEi by 11.7% and 4.4% and RUEa by 12.0% and 3.6% relative to NM, respectively. fIPAR and fAPAR had higher proportional contributions to yield than A, which both decreased slightly with increasing nitrogen application. LAI positively correlated with fIPAR, fAPAR, RUEi and RUEa, which were positively correlated with yield. Thus, TM combined with high nitrogen is recommended to produce high yields and resources use efficiency by maintaining high LAI.</p>
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