Drip irrigation frequency for sugarcane in the tropics.

DRIP IRRIGATION was a system initially developed for desert areas where the sandy soils have low water retention capacity and rainfall is limited. In the Cauca river valley, located in south-western Colombia, soils have a high water retention capacity and frequent irrigation results in excess moisture and poor root development, which affects crop development. The frequent application of water in the sugarcane soils of the Cauca River Valley results in excess soil water and little use of natural precipitation. The current study was conducted at the Malimbu Sugarcane Plantation, located in the driest area of the Cauca River Valley where annual precipitation is below 800 mm and soils are loamy to clayey in texture. The effect of irrigation frequency (daily, twice a week, weekly) was studied in drip-irrigated plots. A gravity irrigation system was used as check. In three consecutive cuts (plant crop and two ratoons), sugarcane production in drip-irrigated plots was 160 t/ha with daily irrigation (483 mm water applied), 165 t/ha when irrigated twice a week (356 mm water applied), and 166 t/ha when irrigated weekly (264 mm water applied). Gravity-irrigated cane produced 157 t/ha, with an average of 465 mm water applied. Average precipitation during the three cuts reached 984 mm. Results highlight the importance of taking advantage not only of the soil’s capacity to store available water but also of actual precipitation, scheduling the weekly drip irrigation of sugarcane fields in the Cauca River Valley without adversely affecting cane production