Crop management effects on water infiltration for claypan soils

ABSTRACT:

Plant water and nutrient use for claypan soils are restricted by an argillic horizon (clay content > 500 g kg⁻¹) that typically occurs 20 to 40 cm (8 to 16 in) below the soil surface. Identifying water infiltration characteristics for claypan soils under different management provides crucial information needed to optimize crop management and estimate watershed hydrology. The objectives of the study were: 1) to evaluate the influence of long-term annual cropping system (ACS) and perennial cropping system management (PCS) [such as Conservation Reservation Program (CRP) and hay crop] on water infiltration, and 2) to examine relationships between apparent soil electrical conductivity (EC_a) and other claypan soil properties with water infiltration parameters. The effects of the ACS and PCS management on water infiltration parameters were evaluated using ponded water infiltration measurements in the field. Water infiltration parameters were estimated using the Green-Ampt infiltration equation. Apparent profile soil electrical conductivity was obtained using an EM38 sensor. Analysis of variance and orthogonal contrasts were used to determine effects of management treatments on water infiltration parameters and associated soil properties. Soil organic carbon and aggregate stability were significantly (P < 0.05) improved after 12 years of CRP management compared to 12 years of ACS management. Antecedent soil water content and ECa were lower and water infiltration was greater for PCS than for the ACS. For a hay crop treatment (PCS), water infiltration was greatly improved when compared to any ACS or other PCS management treatments. Antecedent soil water content and soil organic carbon were significantly correlated with the water infiltration parameters. Soil ECa was significantly correlated with infiltration-estimated saturated hydraulic conductivity (Ks). This relationship may be useful for mapping spatially-variable water infiltration within fields. In summary, PCS contributed to improved water infiltration as well as to increased soil organic carbon and soil aggregate stability. Soil ECa may be useful for characterizing management influence on water infiltration without labor intensive sampling.