Submitted to: American Society of Agronomy Abstracts
Publication Type: Abstract only
Publication Acceptance Date: 9/1/2004
Publication Date: 11/4/2004
Citation: Starr, G.C. 2004. Implications of soil water temporal stability for precision water management. American Society of Agronomy Abstracts. cd-rom Interpretive Summary:
Technical Abstract: The temporal stability of soil water content patterns may have profound implications for precision irrigation. However, the scale of spatio-temporal variability and the yield response to stable soil water content must be determined. A hammer driven time domain reflectometry probe was used to measure soil water content along ten transects covering four fields in a two year potato-barley rotation. Irrigated, un-irrigated, and late irrigated treatments were employed. The stable soil water pattern was compared with elevation and soil particle size classifications. A temporal stability model explained 47% of the observed variability in soil water content. An additional 20% of the variability was attributed to random measurement error. Calibrated in 2002, the model predicted water content (+/- 0.05 m3m-3) along transects in 2003. Field-scale trends and extended (>100m) wet and dry segments were observed. Coarser particle size class soils were drier. Potato yield increased linearly with water content in un-irrigated areas. Yield was consistently high in the drier areas for the irrigated treatment but was highly variable in the wetter areas. For the Late Irrigated treatment, a strong yield response to added water was evident in the dry areas; however, the yield response was neutral to negative in the wetter areas. There appear to be advantages in both water savings and yield if a pattern of precision irrigation is designed to fit the underlying stable soil water distribution.