Anisotropy of Saturated Hydraulic Conductivity in a soil under conservation and no-till treatments

Abstract

Saturated Hydraulic Conductivity (Ks) is an important parameter for agriculture. Some authors have studied Ks anisotropy in soils with different results. Several methods have been developed and modified with time for the determination of Ks. The aim of this study was to determine Ks anisotropy of a typic Argiudoll under conservation (T2) and no-till (T1) treatments by laboratory measurements on samples extracted in vertical and horizontal directions and to compare them with those obtained from field measurements with a tension disc infitrometer. In order to determine Ks anisotropy undisturbed samples were collected at different depths (0–15 cm and 15–30 cm) and orientation (vertical and horizontal). Ks was also determined from field infiltration tests. Additionally bulk density (rb) was determined by gravimetric methods. Ks was anisotropic at 0–15 cm in both treatments (horizontal Ks was about five times larger than vertical Ks in both treatments), and isotropic at 15–30 cm. Ks determined from field infiltration tests did not differ from vertical Ks for all treatment-depth combinations. To summarize, mean values of Ks varied between 0.51 and 9.48 cm h1. Mean values of bulk density (rb) ranged from0.98 (T2, surface) to 1.23 (T2, subsurface). The rb values were significantly greater at subsurface for both tillage systems. At this depth rb was significantly greater for T2. Water entry into the soil profile was conditioned by vertical Ks values. The values obtained from field measurements with a tension disc infiltrometer were similar to vertical Ks measured in laboratory in all cases.