Temporal stability of soil moisture in an experimental watershed in the Pernambuco semi-arid region

Soil moisture estimation is very important in decision making regarding agricultural practices and investigations in hydrology. The aim of the study was to evaluate surface soil moisture temporal stability under two cover crop conditions in an experimental watershed in the Brazilian semi-arid region, aiming to identify stable points, thus reducing monitoring costs and highlighting the importance of temporal stability in a watershed. Fourty five soil moisture monitoring campaigns in the layers of 0-0.10 and 0.10-0.20 m were conducted using a capacitance probe (Diviner - 2000 (R)) during the period from 10/07/2010 to 03/25/2014, with soil cover under native bushy vegetation and degraded pasture, predominantly Brachiaria decumbens. Temporal stability was evaluated through the mean relative difference technique. The point located at the middle of a slope under pasture and bushes was the most stable, with determination coefficient of 90 and 92% for both layers.