Influence of carbaryl on nitrogenase activity and combinations of butachlor and carbofuran on nitrogen-fixing micro-organisms in paddy soils (original) (raw)
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Journal of Pesticide Science, 1981
Butachlor [2-chloro-2', 6'-diethyl-N-(butoxymethyl)acetanilide] was applied at the recommended rate, and at ten and fifty times the recommended rate to samples of silty clay loam and then compared with untreated samples incubated at 15°C or 30°C under waterlogged conditions. The effects of the herbicide on ammonification and nitrification were studied by adding 100 ppm NH2-N as CO(NH2)2 or NH4-N as (NH4)2SO4 respectively, at pH 6. 8 by the addition of CaCO3 to the soil. Butachlor at all doses inhibited the rate of ammonification and stimulated the rate of nitrification slightly at 30°C when pH was adjusted from the original 4. 9 to 6. 8. At ten and fifty times the recommended rate, butachlor delayed the maximum rate of ammonification of CO(NH2)2, and at the fifty fold dose inhibited the nitrification of (NH4)2SO4 at 30C when pH was not adjusted. The effects of butachlor on ammonification and nitrification were not significant compared to those of the control at 15C. One of the major metabolites of butachlor by soil microbes, 2-chloro-2', 6'-diethylacetanilide, delayed the rate of utilization of NH4-N, and inhibited NO2-oxidation at 1, 000 ppm concentration. Butachlor mixed with Biphenyl ether type herbicides, nitrofen (2, 4-dichlorophenyl 4'-nitrophenyl ether), chloronitrofen (2, 4, 6-trichlorophenyl 4'-nitrophenyl ether and chlomethoxynil (2, 4-dichlorophenyl 4'-nitro-3'-methoxyphenyl ether) at either normal or ten fold the recommended rate, did not significantly affect the rate of ammonification and nitrification. Cation exchange capacity of the soil was not affected by the application of butachlor after incubation for 7 weeks. Butachlor applied at the normal rate stimulated soil respiration in the initial stage, but at ten and fifty times the recommended rate, inhibitory phenomena were observed. The inhibitory effects seemed to be transitory and disappeared rapidly. Application of butachlor at all rates increased the population of fungi, actinomycetes and bacteria compared to those of the control after incubation for one week. The higher doses of butachlor caused the population of soil microbes to be greater than those of the control up to 4 weeks after incubation.
Microbiological Research, 1999
Four insecticides, viz. HCH, phorate, carbofuran and fenvalerate @ 7.5, 1.5, 1.0 and 0.35 kg a.i. ha' respectively, were applied to the rice fields to investigate their effects on the availability of nutrients, Nz-fixation andphosphate solubilization in the rhizospere soilof rice in relation to the yield of the crop. HCH highly stimulated the mineralization of organic C. Fenvalerate and HCH reduced the total N content to thehighest extent. HCH and phorateliberated more available N (NH 4 + and N0 3-) ascompared to carbofuranand fenvalerate. Phorate, however, released maximum amount of available P. Application of different insecticides accentuated the proliferation of aerobic non-symbioticNz-fixing bacteria and phosphate solubilizing microorganisms and also their biochemical activities such as, non-symbiotic Nz-fixi ng and phosphate solubilizing capacities of the rhizosphere soil resulting in greater yield of crop.
Journal of Agricultural and Food Chemistry, 2000
Four insecticides, viz., BHC, phorate, carbofuran, and fenvalerate, were applied at the rate of 7.5, 1.5, 1.0, and 0.35 kg a.i. ha-1 , respectively, to investigate their effects on the growth and activities of N 2-fixing and phosphate-solubilizing microorganisms in relation to the availability of N and P in laterite (Typic Orchragualf) soil. Insecticides in general, and BHC and phorate in particular, stimulated the proliferation of aerobic nonsymbiotic N 2-fixing bacteria and phosphate-solubilizing microorganisms and also their biochemical activities, such as nonsymbiotic N 2-fixing and phosphatesolubilizing capacities, which resulted in greater release of available N (NH 4 + and NO 3-) and P in soil. All the insecticides were persistent in soil for a short period of time, and the rate of dissipation was highest for fenvalerate followed by phorate, carbofuran, and BHC, depicting the half-lives (T 1/2) 8.8, 9.7, 16.9, and 20.6 days, respectively. The insecticides followed first-order reaction kinetics during their dissipation in soil.
Effects of Pesticides, Temperature, Light, and Chemical Constituents of Soil on Nitrogen Fixation
Nitrogen Fixation, 2020
Nitrogen is a vital component of atmosphere and plays important roles in the biochemistry of all life forms on the earth. Various mechanisms of biological nitrogen fixation and recycling in the environment have been evolved in all known ecosystems. For example, symbiotic nitrogen fixation is the major N2-fixing mechanism in the agroecosystems. Symbiotic nitrogen fixation is dependent on the biotic factors, such as host plant genotypes and the microbial strains. However, the interaction of these biotic factors is influenced by abiotic factors, such as climate and environmental conditions. The effects of various environmental variables, such as pesticides, temperature, and light as well as acidity, alkalinity, salinity, phosphorus, and water content status of the soils on the nitrogen fixation have been discussed briefly in this chapter.
Indian Journal of Weed Science, 2017
Field study was carried out to determine the long term effect of herbicide application on soil microbial community in rice-rice cropping sequence in acid soil of NorthEast India. Treatment comprised of absolute control with one hand weeding, butachlor + 2,4-D with 100% NPK through chemical fertilizer, butachlor + 2,4-D with 75% NPK through chemical fertilizer and 25% through organic source, butachlor + 2,4-D rotated with pretilachlor with 100% NPK through chemical fertilizer and butachlor + 2,4-D rotated with pretilachlor with 75% NPK through chemical fertilizer 25% through organic source. Result revealed that, after 14 years of continuous use of herbicide and organic input along with recommended dose of fertilizer application demonstrated significant increase in the activity of acid phosphatase. The effect of herbicide application was more prominent with sole chemical fertilizer than with organic manure for 25% N fertilizer replacement. Dehydrogenase activity in soil was increased following herbicide application up to 14 days after that it again decreased more prominent with addition of organic manure than with chemical fertilizer. No characteristic trend of urease activity was observed after application of herbicide. Significant inhibition of respiration was observed after application of herbicide up to 14 days followed by gradual recovery afterwards. Microbial biomass carbon in soil was significantly enhanced by application of organic manure for 25% N fertilizer substitution. Under rice-rice cropping system, application of herbicide showed temporary decline in microbial population and enzyme activities up to 14 days. Application of organic manure for 25% N fertilizer substitution significantly enhanced the microbial population and enzyme activities as compared to sole application of chemical fertilizers. Further application of butachlor rotated with pretilachlor resulted in higher microbial population as well as enzyme activities.
Alachlor and Metribuzin Herbicide on N2-fixing Bacteria in a Sandy Loam soil
International Journal of Bio-resource and Stress Management, 2016
Herbicides interact with soil organisms and their metabolic activities and may alter the physiological and biochemical behavior of soil microbes. Some microbial groups are capable of using applied pesticide as a source of energy and nutrients to multiply, whereas the pesticide may be toxic to other organisms. Laboratory experiment was conducted to investigate the effect of two selective systemic herbicides viz., alachlor and metribuzin, at their recommended field rates (2.0 and 0.4 kg a.i. ha-1 , respectively) on the growth and activities of non symbiotic N 2-fixing bacteria in relation to mineralization and availability of nitrogen in a sandy loam soil of India. Both the herbicides, either singly or in a combination, stimulated the growth and activities of N 2-fixing bacteria resulting in higher mineralization and availability of nitrogen in soil. The single application of alachlor increased the proliferation of aerobic non-symbiotic N 2-fixing bacteria to the highest extent while that of metribuzin exerted maximum stimulation to their N 2-fixing capacity in soil. Both the herbicides, either alone or in a combination, did not have any significant difference in the stimulation of total nitrogen content and availability of exchangeable NH 4 + in soil while the solubility of NO 3 − was highly manifested when the herbicides were applied separately in soil. The effect of combined application of the herbicides was more or less at par with their single application.
Journal of Crop and Weed, 2017
A green house experiment was conducted to study the effect of different insecticides on population and activities of microorganisms in a typic ustiflavent soil. Results in general, revealed that insecticides BHC, Phosphomidon and Quinalphos exert beneficial effect on growth and activities of total bacteria, actimycetes, fungi, ammonifying and non-symbiotic nitrogen fixing bacteria as well as phosphate solubilizing organisms in the early stages whereas, Chlorpyriphos and Carbaryl showed positive influence at the later stages of the experiment. Nitrogen fixing and phosphate solubilizing power of soils are in accordance with the growth and activities of microorganisms in regard to different insecticides under study.
Interdisciplinary Toxicology, 2014
Effects of chemical fertilizers (urea, super phosphate and potash) on toxicities of two carbamate insecticides, carbaryl and carbofuran, individually to the N2-fixing cyanobacterium, Cylindrospermum sp. were studied in vitro at partially lethal levels (below highest permissive concentrations) of each insecticide. The average number of vegetative cells between two polar heterocysts was 16.3 in control cultures, while the mean value of filament length increased in the presence of chemical fertilizers, individually. Urea at the 10 ppm level was growth stimulatory and at the 50 ppm level it was growth inhibitory in control cultures, while at 100 ppm it was antagonistic, i.e. toxicity-enhancing along with carbaryl, individually to the cyanobacterium, antagonism was recorded. Urea at 50 ppm had toxicity reducing effect with carbaryl or carbofuran. At 100 and 250 ppm carbofuran levels, 50 ppm urea only had a progressive growth enhancing effect, which was marked well at 250 ppm carbofuran l...
Herbicides and Environment, 2011
Besides weeds, herbicides can act upon other species, causing serious side effects on non-target rice field inhabiting organisms. Moreover, herbicide residues contaminate soils and water, remain in the rice crop, enter the food chain, and finally are ingested by humans with rice foodstuffs and water (Liebman, 2001). Traditionally, paddy fields are home-ecosystems to many species. In early 1991 Kenmore (as cited in Clay, 2004) wrote that "Rice ecosystems often have more than 700 animal species per hectare in highly intensified fields in the Philippines and over 1000 so far described in Asian species of higher trophic level predators and parasitoids." Besides the application of ever-increasing quantities of synthetic fertilizers, the increasing application of pesticides, mainly herbicides, has led to the disappearance of much of this biodiversity. In addition, non-target survivors have been continuously threatened by these xenobiotics. 3.1 Effects on non-photosynthetic microorganisms Frequently, non-photosynthetic microorganisms undergo stress conditions caused by herbicide application. For instance, the metabolism of the Gram-negative bacteria Stenotrophomonas maltophilia, sometimes present in rice field irrigation channels (Reche & Fiuza, 2005), could be negativelly affected by some rice field herbicides (Lü et al., 2009). These authors showed that a mixture of quinclorac and bensulfuron-methyl (BSM) induced the activity of the antioxidant enzymes superoxide dismutase and catalase of a S. maltophilia strain (WZ2), thus demonstrating the induced oxidative stress caused by the herbicides. The effect of BSM on a soil microbial community in a model paddy microcosm was studied by Saeki & Toyota (2004). BSM did not affect bacterial numbers remarkably, either in the overlying water or in the surface paddy soil, but the nitrification potential was significantly suppressed was significantly suppressed. The composition of culture-independent microbial communities and the change of nitrogenase activities under butachlor application to paddy soil were investigated by Chen et al. (2009). The results of their work showed that the nitrogen-fixing ability was suppressed shortly after butachlor application but was augmented after 37 days both in upper and lower soil layers. A significant variation on microbial community shift was also demonstrated, favouring the diazotrophic microorganisms within the general bacterial communities imposed by butachlor, which may be a reason for the boosting nitrogen-fixation ability in paddy soils. Other effects of butachlor applied at 5.5 μg.g-1 to 22.0 μg.g-1 to microbial populations inhabiting dried paddy soil resulted in a decline of actinomycetes number and and an increase of bacteria and fungi, but fungi were easily affected by butachlor compared to bacteria, particularly at higher butachlor concentrations (Min et al., 2001). 3.2 Effects on photosynthetic microorganisms 3.2.1 Effects on microalgae Besides nonphotosynthetic organisms, on the first level of rice field trophic chain we can find the phytoplankton, microscopic algae which are the food for the next steps in trophic chain.