Soil water repellency and micro-aggregate fractions in response to crop growth periods in a sloping cropland subjecting to long-term fertilization management

Fertilization management and crop growth can affect soil water repellency (SWR) through altering other soil properties such as micro-aggregate, soil organic carbon (SOC) and total nitrogen (TN). However, the extents and magnitudes of these effects remain unclear. This study aimed to determine the effects of different crop growth periods and long-term fertilization managements on SWR and selected soil physicochemical properties and their linkages. Soil samples were collected from agricultural plots experiencing different maize growth periods (ES, elongation stage; TS, tasseling stages; FS, filling stage; and MS, maturity stage) and fertilization managements (CK, no fertilizer with downslope cultivation; T1, combined manure and chemical fertilizers with downslope cultivation; T2, chemical fertilizer with downslope cultivation; T3, 1.5-fold chemical fertilizer with downslope cultivation; T4, chemical fertilizer with contour cultivation) in a representative sloping cropland with Entisols, southwest China. SWR, micro-aggregate fractions, and other physiochemical properties like soil organic carbon (SOC) and total nitrogen (TN) were determined. Results showed that SWR increased by 64.93% in T1 than in CK, and fertilization managements (i.e., T1, T2, T3, and T4) markedly increased soil 1000-250 μm fraction by 34.50-50.74% and reduced 250-50 μm fraction by 22.95-48.87% than CK did. SWR was 27.35%-78.74% higher in ES than that in other growth periods. The highest soil 250-50 fractions (30.80%) and the lowest <50 μm fractions (43.95%) both appeared in TS. SOC was both differed by fertilization management and growth period, while TN was only affected by the former. SWR was predicted well by TN alone. Our results indicate that long-term fertilizer application enhances SWR and have great significance for optimizing sustainable agricultural management in the similar sloping croplands.