Poor physical structural components restrict soil fertility and crop productivity for wheat-maize cropping

Improving poor physical structural components has been gaining increasing recognition for its role in enhancing soil fertility. This study was conducted to identify the key physical structural barriers for soil fertility and their effects on crop productivity in Aquic Inceptisol. Based on the strip sampling in Fengqiu County, arable soils from 0-0.40 m profile pits were collected to determine the physical structural components including plough layer thickness, textural composition, soil aggregation and bulk density, as well as stocks of soil organic matter (SOM), total nitrogen (TN) and total phosphorus (TP). The grain yields of wheat and maize and amounts of fertilizer applications were also investigated. The tested soil was dominated by a plough layer of 0.15-0.18 m and sandy loam texture, which constituted 50% and 59%, respectively, of the studied profile pits. Compared to the soil with < 0.15 m plough layer, the bulk density was 4-11% lower in the plough layer and 4-12% lower in subsoil with increasing the thickness of plough layer. The soil with >= 0.15 m plough layer had over 21-fold macroaggregation at the expense of microaggregation, whereas the high content of sand particle in soil restrained macroaggregation. Increasing the plough layer thickness averagely improved the stocks by 176% in SOM, 153% in TN and 59% in TP at the 0-0.40 m depth. Soil macroaggregation was also significantly positively correlated with these nutrient accumulations. The factor analysis revealed that soil fertility was significantly influenced by the plough layer thickness and soil texture. The soil with 0.20-0.25 m plough layer and loam clay texture displayed the highest integrated fertility index and consequently, was beneficial to increasing the grain yields of wheat and maize and nutrient use efficiency from applied N fertilizer in the study area. These results would be informative to improve soil fertility and then crop productivity during a long-term cultivation.