Assessment of Low Head Drip Irrigation Systems Uniformity of Application
Water application uniformity (EU) is an important performance criterion that must be considered in the design, operation and management of irrigation systems for increasing agricultural productivity. This research study was as a result of the previous studies done by Hassan F.A, Kabutha, et al. and Nyakwara et al., which reported about poor/non-uniformity of water application by low-head drip irrigation systems. The study identified systems widely adopted by the smallholder farmers alongside low-cost greenhouse farming technology, categorized and coded them using letter T based on layout configuration; height of stand for water tank, length of lateral, type of drip tube, size and number of emitters per spacing and assessed their water application uniformities using American Society of Agricultural Engineers (ASAE) standards 1996(a) for line-source drip irrigation systems performance rating. This was done in order to check/compare their EU performances and diagnose constraints to enhance agricultural productivity. This research was done in Trans Nzoia West; Sub-Counties of Saboti and Kiminini of Trans Nzoia County, Kenya. Four replications of each identified six design configuration categories in operation (with crop in season) were selected by simple random sampling. Sampling of data points of each system was done using a pattern guide developed for sampling data points to improve fairness of sampling in the irrigation area. Water discharges filling a 10 ml cup (medicine dispenser) were timed from each of the thirty sampled emitters. The data collected was processed and Analysis of variance (ANOVA) procedure was used to statistically test for equality of the EU means between the categories as a way of checking/comparing their performances at a confidence level of 95%. The result obtained together with observations and the information gathered through semi-structured interviews was used in the conclusions and recommendations. The result from this study showed that the uniformity of water application performance rating for common low-head drip irrigation systems are marginally fair (71%) on average except for the two categories,T2 and T5, with v double emitters whose performances are very poor (< 65%). The result from ANOVA showed that EU means for T1, T3, T4 and T6 are statistically equal at 95% confidence level. Also there is a significant difference between the sample means (F-ratio >> F-table) attributed to differences in systems design configurations. Therefore choice of design configuration whose mean water application uniformity are statistically equal at 95% confidence level coupled with proper installation and management is needed for enhancement of agricultural productivity. The categorized design configurations whose water application performance ratings are very poor should not be promoted by extension providers and are recommended for further hydraulic uniformity test.
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