Comparison of Surface and Subsurface Water Distribution Uniformity Under Center Pivot Irrigation System for Sugarcane in Colombia

The objective of this work was to determine the variability in the uniformity of the applied sheet of irrigation, on the surface of the soil, with central pivoting equipment in sugarcane, with the uniformity of humidity that occurs in the soil profile. With ASABE standard S.436.1, as the test procedure, moisture measurements were taken with a TDR equipment in three soil depths of 0–0.2 m, 0.2–0.4 m, and 0.4–0.6 m every 5 m away. Three evaluations were made, in the central pivot of the length of 430 m (58 ha), with two different application sheets, 12 mm and 22 mm, in two different years (2018 and 2019), that is, in two sugarcane production cycles. The crop age of 2–3 months is the same in the two cycles. Comparisons of the sheets on the soil surface are made with those of moisture collected before irrigation (AR), 24 h after irrigation (24hDR), and 48 h after an irrigation (48hDR). The coefficient of uniformity of Christiansen for the sheet on the 75, 78, and 80% was in values of 81.4 and 82.2%, and for the soil moisture at different depths, the applied sheet and the initial soil moisture condition were decisive. The uniformity in the soil profile was never higher than 5% of the presence on the surface, and on occasions, the sheet results became lower. Results showed that under the conditions of the crop and the operation of the equipment, the determination of the uniformity in the surface is a parameter that can be used to define the performance of an irrigation system.