Effects of topsoil depth and soil amendments on corn yield and properties of two Alfisols in central Ohio

Abstract

Continued loss of topsoil due to erosion is a threat to sustaining row-crop production in soils of the US Cornbelt. The on-site impacts of soil erosion under natural field conditions, despite the confounding effects of many interacting factors, can be simulated by creating a range of topsoil depths (TSD) through soil removal from or addition to the existing soil surface. Thus, this study was conducted on two Alfisols in central Ohio, located at Waterman Farm of the Ohio State University, Columbus (site 1) and Western Agricultural Experiment Station of the Ohio Agricultural Research and Development Center at South Charleston (site 2) with the objectives to assess (1) impacts of differences in TSD after 10 years of creating simulated erosion on crop yields and soil properties and (2) effectiveness of using organic manure and synthetic fertilizer in restoring the quality of eroded soil. The treatments included (1) three levels of TSD including removal of 20 cm (8 in) of topsoil, undisturbed soil, and addition of 20 cm (8 in) of topsoil; and (2) two amendment types including organic manure and synthetic fertilizer. The results indicated that at site 1, the grain yield response followed the order: topsoil removal (3.1 Mg ha^-1 [1.38 tn ac^-1]) < undisturbed control (5.6 Mg ha^-1 [2.5 tn ac^-1]) < topsoil addition (7.8 Mg ha^-1 [3.48 tn ac^-1]). At site 2, topsoil removal significantly reduced corn grain yield (8.2 Mg ha^-1 [3.66 tn ac^-1]) as compared to topsoil addition (9.3 Mg ha^-1 [4.15 tn ac^-1]). The response of soil organic carbon (SOC) pool to different TSD levels was not statistically significant for 0- to 10-cm (0- to 4-in) depth. However, SOC pool was the lowest for “soil removal” treatment at both sites for 10- to 20-cm (4- to 8-in) depth (15.3 Mg ha^-1 [6.82 tn ac^-1] at site 1 and 13.4 Mg ha^-1 [5.98 tn ac^-1] at site 2) and at site 1 for 20 to 30 cm (8 to 12 in) depth (4.99 Mg ha^-1 [3.66 tn ac^-1]). Across TSD treatments, the SOC pool was significantly higher for plots receiving compost than those receiving synthetic fertilizer: 36.6 Mg ha^-1 (16.3 tn ac^-1) versus 27.8 Mg ha^-1 (12.4 tn ac^-1) for site 1 and 36.2 Mg ha^-1 (16.1 tn ac^-1) versus 22.9 Mg ha^-1 (10.2 tn ac^-1) for site 2. In addition, application of compost decreased soil bulk density, increased SOC concentration in different aggregate size fractions, and retained more soil moisture content when compared with the plots receiving synthetic fertilizer. Among the TSD levels, the exposed subsoil of the desurfaced treatment was more responsive to application of organic manure than synthetic fertilizer, leading to higher mean weight diameter and water stability of aggregates. The soil properties identified as corn grain yield predictors by multiple regression analysis varied only slightly between the two sites. The data obtained enhances the understanding of long-term changes in crop production and soil properties by erosional processes simulated by varying TSD in the US Cornbelt region.