Cropping system effects of maize on infiltration, runoff and erosion on loess soils in South-Limbourg (The Netherlands): A comparison of two rainfall events

Abstract

Two natural rainfall events are compared to evaluate the effects of three cropping systems of silage maize on soil moisture content, infiltration, runoff and erosion. Both rainfall events took place in early summer. One was a low intensity event with 27.6 mm of rain in 9 hours, and the other a high intensity event with 33.4 mm in 42 minutes. Cropping systems were: 1. (I) a spring tilled system (conventional), 2. (II) an autumn and spring tilled system with summer barley as spring cover crop, and 3. (III) an autumn tilled system with winter rye as winter cover crop and direct drilling of silage maize. During the low intensity event, soil moisture content of the top 5 cm rose to field capacity on all three cropping systems. No runoff was generated. During the high intensity event, soil moisture content rose to field capacity on the two spring tilled cropping systems but was only slightly raised in the direct drill system, in spite of 17.7 mm of infiltrated rain. Runoff coefficients of the high intensity event were 41.7% (conventional system), 14.9% (autumn and spring tilled system) and 47.0% (direct drill system). The direct drill system showed a severely slaked soil surface in early summer, caused by winter rain. The response to rainfall of soil moisture content is ascribed to: 1. (I) a predominance of matrix infiltration on all cropping systems during the low intensity event and on the spring tilled systems during the high intensity event, and 2. (II) a predominance of infiltration via continuous macropores, open to the surface (of biologic origin), by-passing the soil matrix, on the direct drill system during the high intensity event. The presence of continuous, vertical macropores on the direct drill system explains its surprisingly high infiltration capacity, considering its strongly slaked appearance. The smooth soil surface of the direct drill cropping system may have delayed infiltration during the flooded stage of the high intensity event by not providing vent points for the escape of soil air. Soil loss from the direct drill system during the high intensity event was only 15.6% of that from the conventional system. This is ascribed to low detachment rates of soil material by drop impact and/or overland flow, due to the presence of winter rye remains and, especially, the relatively high soil surface shear strength of the direct drill cropping system in early summer.