Soil spatial variability and the estimation of the irrigation water depth

Abstract

The effects of soil water spatial variability previous to irrigation and of the field capacity on the estimation of irrigation water depth are evaluated. The experiment consisted of a common bean (Phaseolus vulgaris L.) crop established on a Kandiudalfic Eutrudox of Piracicaba, SP, Brazil, irrigated by central pivot, in which soil water contents were evaluated with a depth neutron gauge, in a grid of 20x4 points with lag of 0.5 m. In a given situation, the 80 calculated irrigation water depths presented a coefficient of variation of 29.3%, with an average water value of 18 mm, maximum of 41mm and minimum of 9 mm. It is concluded that the only practical way of irrigation is the use of an average water depth, due to the inherent variability of the soil, and that the search for better field capacity values does not imply in better water depth estimates.

Spatial and Temporal Distribution of Soil Moisture in Drip-irrigated Vineyards

“…Vine-to-vine variability at each site during each sampling time (e.g., Figs. 2 and 3) was much lower than withinfield variability observed in row crops under center pivot irrigation (Reichardt et al, 2001). Thus, all data presented are averaged across vines.…”

Soil Moisture Space-Time Analysis to Support Improved Crop Management

“…This soil moisture distribution is also time dependent (Grego et al, 2006;Herbst;Diekkrüger2003;Hu et al,2010;Reichert et al, 2008;Reichardt et al, 2001;Vinnikov et al, 1996;Mello et al, 2011). Due to the highly intrinsic variability of moisture within the soil profile, time-space variation cannot be simultaneously plotted.…”