Tillage and drainage impact on soil quality: II. Tensile strength of aggregates, moisture retention and water infiltration

Tillage-induced changes in soil quality are important to understanding soil strength and water retention and transmission properties. Thus, this study was conducted to assess the effects of two tillage systems under un-drained and drained conditions on tensile strength (TS) of 5-8 mm, aggregates, soil water characteristics (SWC), plant available water (PAW), and the water infiltration rate (i). Soil properties were determined mainly in the surface (0-10 cm) layer on a Crosby (fine, mixed, mesic, Aeric Ochraqualf) silt loam soil at the Waterman Farm of the Ohio State University, Columbus, OH on a 14-year-old field study. Effect of two tillage treatments comprising no-tillage (NT) and conventional tillage (CT) were studied for two levels of drainage: un-drained (UD) and tile drained (D). The TS for 0-10 cm depth was significantly (P <= 0.01) affected by tillage and drainage treatments, and was higher in CT than NT by 61% in UD and by 48% in D soil. In comparison, TS increased by 13% in NT and 4% in CT in D compared with the UD treatments. Soil organic carbon (SOC) in 0-10 cm depth of NT-UD treatment was 23% higher than CT-UD treatment and 38% more than NT-D treatments. Tillage and drainage impact on SWC was non-significant at 0 kPa suction, but significant (P <= 0.1) at -3, -6. -10, -30, -100 and -300 kPa suctions indicating that water was retained more in NT-UD than CT-UD soil. The PAW was significantly influenced by drainage (P <= 0.01) but not by tillage treatments. Yet, there existed a general trend of about 8% more PAW in NT-UD than CT-UD treatments. In contrast, PAW was 48% more in soil from NT-UD than NT-D treatments. PAW increased with increase in the SOC concentration (R-2 = 0.89; P <= 0.01). There were also differences in soil water sorptivity (S), and equilibrium infiltration rate (i,) in NT-UD compared with CT-UD treatments. A positive and significant correlation (r = 0.57, P <= 0.05) occurred between i(c) and SOC concentration. The value of S was more in NT-UD by 70% than CT-UD, and 46% in NT-D than CT-D. Similarly, the i(c) was more in NT than CT by 119% in UD compared with 82% in D soil. The value of A in NT was higher than that in CT by 39% and 12% in UD and D treatments. respectively. The mean cumulative infiltration (1) in 3 h was 71.4 cm in NT versus 44.0 cm in CT in UD compared with 62.1 cm in NT and 48.4 cm in CT for the D treatment. The I was positively and significantly correlated with SOC concentration (r = 0.32, n = 12, P <= 0.1) indicating improvement of I with increase in SOC concentration. Results of this study suggest that conversion from CT to NT management system may reduce the risk of surface runoff, increase soil aggregation, and improve soil hydrological properties. (C) 2009 Published by Elsevier B.V.