Abuja Journal of Agriculture and Environment (AJAE)

TESTING OF SOIL INFILTRATION RATE AND SOIL WATER CHARACTERISTIC CURVE MODELS FOR DESIGNING AND SCHEDULING IRRIGATION ON SANDY LOAM SOILS OF MAIDUGURI, SEMI-ARID NIGERIA.
Author(s): Ali Umar Bashir and Adam Lawan Ngala
Volume/Issue: Volume 2 , Issue 1 (2022)

ABSTRACT:

The high temperature, high soil evaporation rate, poor water holding capacity of soils and the vagaries of climate change are among many factors responsible for reducing water availability to crops in the semi-arid region of Nigeria. But an adequate amount of water in the soil is necessary for optimum growth and yield of crops Two field experiments were conducted in the2014 and 2015 seasons to determine irrigation scheduling on sandy loam soils. The study involved testing of different infiltration rates and soil water characteristic curve models for designing and scheduling irrigation. Infiltration rate of the soil was measured using double ring infiltrometer. Four (4) commonly used empirical infiltration models (Kostiacov, modifiedKostiacov, Kostiacov-Lewis and Philips models) were evaluated and compared with the measured values. Field soil water characteristics were also determined based on measurement of soil water tension using tensio meter and gravimetric soil water content. Three empirical models(Van Genuchten, Brooks-Corey and Gardner’s models) suitable for sandy soils were evaluated to select the model that can best interpret the field measured soil characteristics of the study area. The study established infiltration models which are useful in designing irrigation and drainagesystems; soil and water characteristics models for scheduling irrigation and production model for describing the relationship between yield and actual evapotranspiration for making sound management decisions by farmers for optimum production. For predicting infiltration rate the Kostiakov or the Modified kostiakov models using the relationship between cumulative infiltration and time given by and can be used. For soil water characteristics models the soil water characteristics curve can best be described using the expressions given by Van Genuchten and Brooks-Corey models using the relationship between the volumetric water content and pressure head of 0 = 0.065 + and 0 = 0.041+ (0.0410 – 0.041) X (2.023xh)- 0.210 can be used.

KEYWORDS:

Infiltration rate, water characteristic curve, infiltration models, irrigation schedules, sandy loam soils.