Irrigation Practices as Alternative Means of Supporting Rain-fed Agriculture: A Case Study of Potato (Solanum tuberosum L.)

Solomon Yirga

doi:10.7176/jaas/55-03

Abstract

Estimation of evapotranspiration is important for study, design, determining crop water requirement and management of irrigation systems. Also it’s important for determining irrigation water requirement during dry spell and water shortage i.e. when the evapotranspiration is greater than effective rainfall. Based on this, the study was conducted in Cheha district, Gurage Zone with determine crop water requirement of potato. In line to this, ten years climatological recorded data (2008-2017) for Indibir station on (sunshine duration hr /day), maximum and minimum temperature ( O C), humidity (%) and wind speed (km/day) at 2 meters height were used to determine ET o using Penman combination method. Secondary data were used to collect important soil parameters required for determination of crop water requirement. Lengths of growing periods, planting date and crop varieties data were received from the validation value of the local farmers and CDAO. Crop coefficients (kc), rooting depth, critical depletion fractions, yield response factors and crop height were obtained from food and agriculture organization of the United Nations guidelines (No. 56). The analyzed data indicated that reference crop evapotranspiration ranged from 2.40 to 4.73 mm with a mean of 3.56mm. The assessment has showed that the water requirement of potato is 63.2, 84.1, 145.8 and 77.2mm during initial, development, mid and late growth stages, respectively. The effective rainfall contribution throughout the growing stage of potato in the area is 8.5, 23, 187.2 and 158.1mm all through initial, development, mid and late growth stages, whereas the net irrigation requirement of potato throughout the dry spell period is 52.9, 61.3, 14.9 and 0mm in initial, development, mid and late growth stages, respectively. Soil and water conservation management practice, water harvesting technology and agronomic practices should be applied, principally mulching is very important to save soil moisture during high heat stress and dry spell or water shortage. Key terms: reference evapotranspiration, crop water requirement, potato DOI : 10.7176/JAAS/55-03 Publication date :May 31 st 2019

Highlights

The importance of rain-fed agriculture varies regionally but produces most food for poor communities in developing countries
The proportion of variation (R2) in mean monthly reference evapotranspiration explained by the year/month oscillated from 1 - 29 % in the study area (Table 2)
The Water requirement satisfaction index (WRSI) for a 145 day to maturity potato variety planted between March-3 and Agust-1 period shows that an initial and development stage has 13.5 and 27.4% indices respectively, indicating a great coincidental of total failure for a 145 day to maturity potato grown under rain-fed condition in the area (Table 6)

Summary

Introduction

The importance of rain-fed agriculture varies regionally but produces most food for poor communities in developing countries. In the domain of agriculture sector, potato is one of the dominant tuber crops in Cheha district, it’s used as food crop and economic value for the farmers. In addition to the above motive, lack of information on evapotranspiration, crop water requirement and net irrigation requirement are causes for low potato production in the area. This finding will tried to make information available on evapotranspiration, crop water requirement and net irrigation requirement for the farmers, NGOs, investor’s and government who want to involve in the potato production in the area. The objective of the research is to determine crop water requirement, net irrigation requirement and water requirement satisfaction index of potato production in the area

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Conclusion