Soil cone index and bulk density of a sandy loam under no-till and conventional tillage in a corn-soybean rotation

Tillage practices may have a profound impact on both soil environment and agricultural productivity. A field study was carried out from 2013 to 2019 to investigate the effect of no-till (NT) and conventional tillage (CT) on soil cone index (CI), bulk density (ρb), and gravimetric water content (θm) in a 2-yr corn (Zea mays L.)-soybean (Glycine max [L.]) rotation on a Lihen sandy loam. The study was arranged in a randomized complete block design with five replications. Soil CI was measured with a digital penetrometer to a depth of 0−30-cm after planting in crop rows within each plot. Undisturbed soil cores were sampled at 0–15 and 15–30 cm depths to measure ρb and θm under each tillage. Soil CI was significantly impacted by tillage in the 0–30 cm depth for the period of the study under both corn and soybean. Averaged across 0–30 cm, soil CI values were smaller in CT compared with NT in all 7 years. Soil CI averaged across 0–30 cm depth and 7 years resulted in greater CI of 2.027 and 2.030 MPa for NT compared to 1.118 and 1.137 MPa for CT under corn and soybean, respectively. Tillage had inconsistent effect on bulk density and gravimetric water content at 0–15 cm and 15–30 cm depths under both corn and soybean over a period of six years. Averaged over a 7-year period (2013−19), soil ρb values in the 0–30 cm layer were significantly lower in CT (1.557, 1.578 Mg m–3) that in NT (1.631, 1.635 Mg m–3) under corn and soybean, respectively. There were no differences in soil θm between two tillage systems under both corn and soybean. Smaller CI and ρb values in CT under both corn and soybean may be related to soil disturbance caused by intensive tilling compared to NT management practices.