SPRINKLER APPLICATION EFFICIENCY AND STEMFLOW EFFECTS ESTIMATION BY SOIL WATER CONTENT MONITORING AND AN INFILTRATION MODEL

Sprinkler irrigation application efficiency in corn crops is influenced by soil water distribution through crop canopy water partitioning. The aim of this work was to develop a methodology to evaluate sprinkler irrigation application efficiency considering stemflow effects on soil water distribution profiles. Soil moisture monitoring was carried out on eight points for a center pivot irrigation. Three water distribution estimation methods were employed: the raw measured soil moisture values, the spline interpolation of measured data and the simulation of the infiltration processes. The infiltration process was modeled by means of the two dimensional (2D) Richards equation. The simulations were calibrated on the eight measured data points. The stemflow was obtained as additional model fitting parameter. During center pivot irrigation, 34% of the water delivered in the interrow was conveyed in the row. Soil water distributions calculated from measured and interpolated data overestimated and underestimated the irrigation application efficiency by approximately 15% and 30%, respectively. The water application efficiency obtained from simulation of water infiltration processes was 99.6%. The proposed simulation method evaluates stemflow effects on the water distribution profile, leading to accurate application efficiency calculations.