Abstract:
This work focuses on evaluating a simple on-farm water optimization technology called
Wetting Front Detector (WFD). The work compared WFD against computer based tools to
estimate Crop Water Requirement (CWR) and subsequent application and farmers practice. A
field experiment was designed in Randomized Complete Block Design, replicated six times for
pepper and five times for onion on farmers' fields. Results were compared on the basis of
application, distribution storage and water use efficiencies, and water productivity. The results
illustrate that there was a significant difference between the water used in the CWR, WFD and
Farmer Practice (FP). In comparison with FP, CWR saved irrigation water by 37% under
pepper and 35% under onion fields. The WFD technology also saved the irrigation water by
about 16% than the farmer method. The differences between the water optimization techniques
can be accounted for by to differences in the efficiencies of application (Ea), storage (Er) and
irrigation water use which vary considerably from one type of irrigation water management to
another at p<0.05. Generally, CWR technique is more efficient (Ea is 59.06 under onion and
66.76% under pepper), followed by the WFD technique (Ea is 53.78% under onion and 62.32%
under pepper) and farmer practice (Ea is 49.26% under onion and 55.74% under pepper). On
the basis of these values, the water saved by the CWR technique could irrigate 16.5% and the
WFD 6-8% more area than the FP. Implicitly better crop production, also less competition
between head and tail irrigators. The mean IWUE of CWR, WFD and FP were 114.79, 78.38
and 54.38 respectively for onion and 3.67, 3.08 and 1.52 for pepper. Based on this study, CWR
technique appears to be a promising alternative for water saving without negligible trade-off
in yield. The CWR had an Er of 65.09% and 66.42% under onion and pepper respectively
which can be beneficially used by the crops while the WFD of 59.78% (Onion) and 50.85%
(Pepper). As a result, yield of the crops from the CWR exceeds both techniques as it can
provide sufficient amount of water for plants at their root zones. Considerable amount of water
in FP is lost to Deep Percolation (Dp) and this has environmental and economic implications.
Although many indicators confirm the importance of CWR approaches, its practicality at
farmers level is questioning as it is computer based. Thus, WFD would be an important tool to
be considered to improve the current on farm water optimization by smallholder irrigators.
