Effect of monocrotophos on soil microflora in a ricefield ecosystem.
1994
Moldez A.G.
The soil physico-chemical properties of irrigated soil from a ricefield were characterized as to its pH, moisture content, organic matter and waterholding capacity. The range of values for soil pH, moisture content, organic matter and waterholding capacity were: 6-7.35, 26-122.31%, 2.15-5.07%, and 93.74-114.61%, respectively. These values served as baseline information about the soil being used in the study. Monocrotophos did not affect these properties since the time frame of gathering samples was too short to warrant any detectable change in the physico-chemical properties of the soil. The rapid hydrolysis and short half-life of monocrotophos also account for the inability to detect its presence easily in the soil. Biochemical activities were also measured in terms of ammonia, nitrate content and dehydrogenase activity. There was no marked change in the mean values for nitrate and dehydrogenase activity for both treatments in all depths but ammonia content showed a marked increase for the monocrotophos-treated sample. Monocrotophos increased ammonium content of the soil. The mean values of the microbial population per gram of the soil sample for bacteria, actinomycetes and fungi were decreasing at increasing depth for both monocrotophos-treated and control samples. Monocrotophos treatment effected increase in the populations of bacteria. It, severely affected fungal population but had the least effect on actinomycetes population. Benefit cost analysis showed that the net return of the treated plot is greater than the control taking into account yield and cost of production.
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