| dc.description.abstract | In this study, the impacts of irrigation water quality, soil characteristics and on-farm practices
on paddy yields were investigated. Standard spectroscopy and spectrometry methods were used
to analyze irrigation water and irrigated soil samples. The irrigation water had sodium
adsorption (SAR) values ranging from 0 to 3. The corresponding electrical conductivity (EC)
values were between 0.2 and 0.7 dS/m and accounted for 14% of all samples hence posing
slight to moderate infiltration problem. Neither sodium nor chloride levels were high enough
to cause toxicity problems in the irrigation water. For boron, 54% of the samples was found to
have moderate toxicity whereas ~14% of the samples indicated severe boron toxicity in the
irrigation water. For bicarbonate, about 86 and 14% of the irrigation water indicated slight-to moderate and severe potential detrimental effect to plant growth, respectively. The trace
elements Fe2+, Zn2+, Cu2+, Mn2+, B, As, Cd, Cr2+, Pb2+, Ni2+, and Al3+ in the irrigation water
samples were too low to cause any harmful effect. Although soil EC (0.2 to 1.9dS/m), organic
carbon (OC) (0.1 to 2.4%) and pH (6.0 to 8.5) indicated favorable levels, there were significant
variations in soil Fe (2.6 to 169.5 mg/kg) and Zn (3.9 to 204.1 mg/kg). The mean value of Fe
in soils was 19.8 mg/kg. Soils indicated signs of Fe-deficiency. High variabilities were also
found in the total N (86 to 2155 mg/kg) content of the studied paddy soils. The levels of
phosphorus (Olson P, mean 224.2 ± 149.4 mg/kg) were found to be too high compared to what
is reported as normal in similar studies. There might be unsustainable and excessive application
of P-containing inputs in the studied area. Furthermore, a low soil K content was observed in
the analyzed soil samples. The present study recommends that regular control of irrigation
water HCO3
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, EC and controlling soil pH levels as well as adoption of standard on-farm
practices following of crop calendar, proper application of fertilizers. Availability of extension
officers to advice farmers is highly recommended. | en_US |
