PREDICTION OF SOIL WETTING PATTERN FOR THREE SOIL TYPES UNDER DRIP IRRIGATION

Abstract

This study was carried out by identifying and selecting three soil types around the University of Agriculture, Makurdi, Nigeria to determine their physicochemical properties. Drip Irrigation is considered as one of the most efficient irrigation systems, provided the system is designed to meet the soil and plant condition. Information on wetting patterns under point source drip emitters is a prerequisite for the design and operation of the drip systems.  This is to ensure precise placement of water and fertilizer in the active root zone. The objective of this study was to develop models that can help to determine the wetting radius (r), wetting depth (z) from surface point drip irrigation of three soil types (clay loam, sandy loam and sandy clay loam). Water was applied to each soil type using drip irrigation set up at a constant flow rate of 1.3 l/hr. The maximum duration of water application was 10 hrs. At intervals of 30 minutes, there was excavation to monitor the wetted radius and depth. The field data was subjected to statistical analysis using SPSS version 22.0 to formulate the models that relates the duration, flow rate, volume and hydraulic properties to wetted radius and depth. Results show that lateral water movement was highest in the clay loam while vertical movement was highest in sandy loam. The highest wetted depth in clay loam, sandy loam and sandy clay loam were 17, 26, and 25 cm while the wetted radius were 26, 24, and 22 cm, respectively. Models for the three soil types were developed, the R² values for the three soils were between 0.7and0.9 which are close to 1. The ANOVA shows that the models were statistically significant as the P values are less than 0.05.  The results obtained showed that the wetted depth and wetted radius of these soil types are influenced by the flow rate, duration and volume of water application within the range under consideration and can fit into irrigation of vegetable crops.