Alluvial Soil Of West Bengal Research Articles

Effect of Biological Products on Yield, Production Economics and Soil Nutrient Status of Transplanted kharif Rice (Oryza sativa L.) in Gangetic Alluvial Soil of West Bengal, India

Field experiment was conducted during kharif season of 2017 and 2018 at Instructional Farm under Bidhan Chandra Krishi Viswavidyalaya, West Bengal in sandy loam soil to study the growth and yield of transplanted kharif rice variety Satabdi (cv. IET 4786) as influenced by biological products. The experiment was laid down in randomized complete block design (RCBD) with seven treatment combinations replicated thrice. Results revealed that RDF + soil applied Bolt GR @ 10 kg/ha produced higher growth attributes and yield of tested rice cultivar. The same treatment registered significantly higher total N and K uptake in tested cultivar; while the highest P uptake was recorded with RDF + Seed treatment with JumpStart2.0 @ 0.83 ml/kg seed. The treatment RDF + soil applied Azospirillum @ 2 kg/ha brought about significant positive changes of available N content in post-harvest soil over control situation (only RDF). However, significantly higher available P content was estimated in plots with RDF + soil applied PSB @ 2 kg/ha. Application of bio-products failed to exert any significant influence on residual soil K. The crop receiving RDF + soil applied Bolt GR @ 10 kg/ha gave highest gross return, net return and B:C ratio. Hence, application of RDF (60-30-30 kg N, P2O5 and K2O/ha) along with Bolt GR @ 10 kg/ha or Azospirillum @ 2 kg/ha may be recommended to achieve higher grain yield of tested cultivar Satabdi (cv. IET 4786).

Effect of foliar application of micronutrients on summer mungbean varieties on alluvial soil of West Bengal

A field experiment was carried out during the summer seasons of 2020 and 2021 at Jaguli Instructional Farm, BCKV, Nadia (West Bengal), in the Gangetic alluvial soil, to assess the effect of varieties and micronutrient foliar spray on growth parameters, yield components, yield and economics of mungbean. Results revealed that different varieties significantly promoted growth parameters and variety Meha was found to be superior. Growth parameters was significantly higher under molybdenum foliar spray over other micronutrients foliar spray. The maximum number of pods per plant, pod length, seeds per pod and test weight were found in plants receiving sodium molybdenum foliar spray at 0.05%. Maximum seed yield and stover yield were also recorded in the same treatment where 0.05% sodium molybdenum spraying was done at pre flowering and pod development stage. Variety showed significant variation in pods per plant, pod length, seeds per pod and test weight and were maximum in variety Meha. Both seed and stover yield were highest in case of variety Meha over others. The gross returns, net returns and benefit: cost ratio were maximum in Meha variety with foliar application of sodium molybdenum. Hence, variety Meha with foliar spray of molybdenum could be more effective in augmenting mungbean growth, yield and economics in the Gangetic plains of West Bengal in the summer season.

Effect of integrated weed management on summer greengram under alluvial soil of West Bengal

Effect of integrated weed management on summer greengram under alluvial soil of West Bengal

Effect of Pretilachlor 50% EC on Weed Control of Transplanted Rice under Alluvial Soil of West Bengal, India

Field experiments were conducted at Regional Research Station of Bidhan Chandra Krishi Viswavidyalaya, Gayeshpur, West Bengal during winter season of 2014 and 2015 to evaluate the bio-efficacy against weeds & phytotoxicity of pretilachlor 50% EC on transplanted rice. The experiment was tested under randomized complete block design with three replicates. Among the herbicides, highest weed control index was recorded in pretilachlor 50% EC @ 2 kg a.i. ha-1 which imparted phytotoxic symptoms in rice plants resulting in yield reduction. However, the highest grain yield (3.59 t ha-1) was obtained with the application of pretilachlor 50% EC @ 1.2 kg a.i. ha-1 which was statistically at par with twice hand weeding. From these findings it can be concluded that the application of pretilachlor 50% EC @ 1.2 kg a.i. ha-1 can be recommended for effective weed management in transplanted rice in the study area.

Studies on Carrier and Liquid Based Bio-Fertilizer on Performance of Lentil (Lens esculenta) in Alluvial Soil of West Bengal

Lentil (Lens culinaris) is an important crop of sustainable agriculture system having good nutritional value. Liquid biofertiliser formulations are known to have better result at field level. A field experiment was conducted in the gangetic alluvial soil belt of West Bengal to study the performance of lentil cv WBL 77 (Moitree) at farmer’s field in Krishnaganj block, Nadia, WB in the rabi season 2020-21. The experiment was conducted in randomised block design having ten treatments replicated thrice. Carrier and liquid based formulations of rhizobium and phosphorus solubilising biofertilisers were used. The results revealed that growth and yield parameters responded positively when lentil were grown with different combinations of biofertilizer and inorganic fertilizers. Recommended dose of fertilizers (RDF) + liquid based rhizobium and PSB and was found to be better in respect to growth, nodulation and yield attributes. However, was statistically at par with treatment RDF + Carrier based Rhizobium & PSB. Plots where 75% RDF + liquid or carrier based biofertilisers were applied were observed to be at par with treatments where RDF and any one biofertilier were applied. Based on the study, we may infer that liquid biofertiliser formulations can have better effect on lentil growth, nodulation and yield.

Varietal Performances and Foliar Application of Nutrients on Yield and Economics of Utera Rapeseed-Mustard in Rice-Fallow of Alluvial Soils

A field experiment was conducted during winter seasons (November to February) of 2020–21 and 2021–22 to evaluate performances of different rapeseed-mustard varieties under foliar spray of nutrients on growth, yield components, yield and economics of utera (relay) rapeseed-mustard grown in rice–fallow. The experiment was laid out in a split plot design keeping rapeseed-mustard varieties, viz., Anushka, Binoy and PM-28 in main plots and eight different foliar spray of nutrients in sub-plots. Variety PM 28 registered significantly higher growth attributes, yield components, seed yield (1198.5 kg ha-1), stover yield (3300.4 kg ha-1) and biological yield (4498.8 kg ha-1) and also achieved significantly higher return per rupee invested (`Rs. 2.05) over other two varieties. Foliar spray of N:P:K (19:19:19) @2% twice at 30 DAS and 45 DAS+ZnSO4 @ 0.05% at 40 DAS+Boron (20%) @ 0.1% at 50 DAS was found significantly superior to all other foliar sprays with respect to yield components and seed yield (1233.2 kg ha-1), stover yield (3109.9 kg ha-1) and biological yield (4343.2 kg ha-1) irrespective of the varieties and also gave significantly higher return per rupee invested (Rs. 1`.93) over other foliar application. The study revealed that, cultivation of rapeseed-mustard along with foliar application of nutrients in rice fallow of alluvial soils of West Bengal was a better option to enhance growth, productivity and economics of utera rapeseed-mustard.

Evaluation of Productivity, Quality and Economics of Turmeric Under Different Moisture Regime and Integrated Nutrient Management at Eastern Indo-Gangetic Plains, India

An experiment was carried out during 2011 and 2012 at the Gangetic alluvial soils of West Bengal, India to assess the impact of four irrigation schedules and three nutrient sources on productivity, quality, water use efficiency (WUE) and economics of turmeric. The results showed that maximum yield was observed due to the main effects of irrigation schedule at 0.9 irrigation water (IW)/cumulative pan evaporation (CPE), nutrient schedule at 50% recommended dose of fertilizer (RDF) + 25% farmyard manure (FYM) + 25% vermicompost and their interactions at harvest stage during both years. The higher fresh (24.61 and 26.81 t ha−1) and cured (5.12 and 5.23 t ha−1) rhizome yield during both years, respectively, were registered under 0.9 IW/CPE with 50% RDF + 25% FYM + 25% vermicompost. The WUE was higher under 0.9 IW/CPE with 50% inorganic + 25% FYM + 25% vermicompost, resulting in a considerable increase in turmeric yield during both years. The irrigation and nutritional schedules (0.9 IW/CPE with 75% RDF + 25% FYM) had significantly higher return per rupee investment than other treatments. This study confirmed that application of irrigation at 0.9 IW/CPE and combine application organic and inorganic nutrient sources improved rhizome yield, WUE, quality and return per rupees investment, could be obtained more precisely from the knowledge of irrigation scheduling and integrated nutrient management.

Predicting the response of soil potassium to broccoli (Brassica oleracea var. italica) in a Gangetic Inceptisol of West Bengal, India through suitable chemical extractants

Finding a suitable method for estimating soil and crop specific potassium (K) bioavailability under variable range of soil fertility has been a mighty challenge. To undermine this, a field experiment was conducted under varying levels of fertilizer application on pre-established fertility gradient strips in the Indo-Gangetic plains of West Bengal, India for predicting crop response and to assess the K availability in winter growing broccoli by employing six acclaimed chemical extractants viz. ammonium bicarbonate-diethylenetriaminepentaacetic acid (AB-DTPA), calcium chloride (CaCl2), Kelowna, Mehlich-III, ammonium acetate (NH4OAc), and sodium tetraphenylborate (NaTPB4). The availability study of K followed the pattern as, CaCl2 < AB-DTPA < Kelowna < NH4OAc < Mehlich-III < sodium tetraphenylborate (NaTPB4). A higher extractability of K was envisaged under the conjoint application of higher doses of K fertilizers along with the organics. Among the extractants, NaTPB4 showed the highest correlation sum (3.98) and also yielded a significant relationship with plant tissue K concentration (0.858) and uptake (0.715). The NaTPB4, Mehlich-III, and NH4OAc extractants were found to be significantly related to most of plant indices. The Euclidean distance based cluster analysis and linear regression study further proved the relatively higher efficiency of NaTPB4 extractant followed by Mehlich-III and NH4OAc to estimate plant K response in broccoli under the Gangetic alluvial soils of West Bengal, India.

Integration of chemical fertilizer with biological products on growth and production of rice during wet season

The influence of different biological products (JumpStart, Bolt GR, Ratchat, Azospirillum and phosphate solubilizing bacteria/PSB) in conjunction with recommended dose of chemical fertilizer (RDF) were evaluated with one control (RDF only) on wet season rice cv. Satabdi (IET 4786) during wet season of 2017 and 2018 at Instructional Farm under Bidhan Chandra Krishi Viswavidyalaya, West Bengal. The experiment was laid down in randomized complete block design (RCBD) with seven treatment combinations replicated thrice. The results showed that tallest plants (103.5 cm) with maximum dry matter accumulation (889.8 g/m2) were observed in RDF +Bolt GR @ 10 kg/ha treated plots. The same treatment augmented panicle number/m2 (248.5), panicle weight (3.95g), filled grains/panicle (126.1), grain (4.22 t/ha) and straw yields (5.83 t/ha); being statistically at par with RDF + Azospirillum @ 2 kg/ha. Yield increase was to tune of 8.18 to 23.39 %. Significant and positive associations of grain yield with traits like plant height, dry matter accumulation, effective tillers/m2, panicle weight and filled grains/panicle were noticed. Bolt GR @ 10 kg/ha in conjunction with recommended dose of chemical fertilizer (RDF) recorded significantly higher N and K uptake in grain and straw. While greater P uptake in both grain and straw was noticed with Azospirillum @ 2 kg/ha and PSB @ 2 kg/ha. Combined application of JumpStart @ 0.83 ml/kg seed resulted in significantly greater fungal population in post-harvest soil. The actinomycetes and bacterial population were improved with soil applied Azospirillum @ 2 kg/ha and Bolt GR @ 10 kg/ha, respectively. Hence, we suggested a mixture of recommended dose of chemical fertilizer (RDF) with either Bolt GR @ 10 kg/ha or soil applied Azospirillum @ 2 kg/ha to exploit not only growth and yield of rice but also improvement of soil microbial populations for rice productivity in Gangetic alluvial soil of West Bengal.

Macronutrient Management Effects on Nutrient Accumulation, Partitioning, Remobilization, and Yield of Hybrid Maize Cultivars.

It is critical to understand nutrient dynamics within different plant parts to correctly fine-tune agronomic advices, and to update breeding programs for increasing nutrient use efficiencies and yields. Farmer’s field-based research was conducted to assess the effects of nitrogen (N), phosphorus (P), and potassium (K) levels on dry matter and nutrient accumulation, partitioning, and remobilization dynamics in three popular maize (Zea mays L.) hybrids (P3522, P3396, and Rajkumar) over two years in an alluvial soil of West Bengal, India. Experimental results revealed that NPK rates as well as different cultivars significantly (p ≤ 0.05) influenced the dry matter accumulation (DMA) in different plant parts of maize at both silking and physiological maturity. The post-silking dry matter accumulation (PSDMA) and post-silking N, P, and K accumulations (PSNA, PSPA, PSKA) were highest in cultivar P3396. However, cultivar P3522 recorded the highest nutrient remobilizations and contributions to grain nutrient content. Total P and K accumulation were highest with 125% of the recommended dose of fertilizer (RDF) while total N accumulation increased even after 150% RDF (100% RDF is 200 kg N, 60 kg P2O5, and 60 kg K2O ha–1 for the study region). Application of 125% RDF was optimum for PSDMA. The PSNA continued to increase up to 150% RDF while 125% RDF was optimum for PSPA. Cultivar differences significantly affected both remobilization efficiency (RE) and contribution to grain nutrient content for all tested macronutrients (N, P, and K). In general, RE as well as contribution to grain nutrient content was highest at 125% RDF for N and K, and at 100% RDF for P (either significantly or at par with other rates) for plots receiving nutrients. For all tested cultivars, nutrient remobilization and contribution to grain nutrient content was highest under nutrient-omission plots and absolute control plots. Both year and cultivar effects were non-significant for both grain and stover yields of maize. Application of 75% RDF was sufficient to achieve the attainable yield at the study location. The cultivar P3522 showed higher yield over both P3396 and Rajkumar, irrespective of fertilizer doses, although, the differences were not statistically significant (p ≥ 0.05). The study underscores the importance of maize adaptive responses in terms of nutrients accumulation and remobilization at different levels of nutrient availability for stabilizing yield.

Vegetable Based Multitier Cropping System: A Model for Higher Income for the Farmers in Old Alluvial Soils of West Bengal

The weather condition prevailing during the crop season always plays very crucial role in crop production. Off and on crops face aberrant weather like flood that causes total crop failure in low line or flood prone areas. Vagaries of weather spoil the source of income which aggravates the farmer’s poverty. To overcome the problem of crop failure and financial loss in flood prone areas of Gangetic plain in Malda district, vegetable based multi-tier cropping system was propagated in farmers fields on upland situation. The study was conducted with five combinations of horticulture crops at upland situation of 15 farmers fields in Narayanpur village of Malda district of West Bengal for six years from 2014-15 to 2019-20.The farmers are usually growing single climber crop in upland on bower system and most of the land down under remains unutilized. In this situation, multi- tier cropping system is a resilient practice which opens a new door to the farmers for providing more production and income from succeeding crop. The study showed that practice enhanced production, farm income and subsequently increased the benefit cost ratio up to 3.13. Bitter gourd + elephant foot yam cropping system is economically viable and profitable because it provides highest land equivalent ratio and higher Monetary Advantage Index (MAI) value.

The Effects of Biofertilizers, Organic and Inorganic Nutrient Sources on Growth Parameters and Yield of Piper betle L. (Betlevine) under Gangetic Alluvial Soil of West Bengal

An experiment was carried out during two consecutive years of 2012-13 and 2013-14 at the experimental site of AICRP on MAP and Betelvine, Bidhan Chandra Krishi Viswavidyalaya, Kalyani, Nadia, West Bengal. The experiment was laid out in a randomized block design (RBD) replicated thrice with 9 treatments comprising of different combinations of organics (Azotobacter, Phosphobacter and mustard oil cake) and inorganic (urea and SSP) sources of nutrients. The maximum vine elongation, basal girth, leaf size, leaf yield and other yield attributing characters were found significantly better under application of Azotobacter @ 10 Kg + 140 kg N (MOC) + Phosphobacter @ 5 Kg + 50 Kg P +100 Kg K ha-1year-1. However, the treatment was statistically at par with Azotobacter @ 5 Kg + 170 Kg N (MOC) + Phosphobacter @ 5 Kg + 50 Kg P + 100 Kg K ha-1year-1 in respect of dry matter production. Hence, the treatment with Azotobacter @ 10 kg + 140 kg N (MOC) + Phosphobacter @ 5 Kg + 50 Kg P +100 Kg K ha-1year-1 application can be used as a best sustainable and eco friendly integrated nutrient management approach for better yield of betelvine under the gangetic alluvial zone of West Bengal.

Performance of Direct Seeded Rice under Integrated Nutrient Management Practices in Old Alluvial Soils of West Bengal

A field experiment was conducted during Kharif 2018-19 and 2019-20 at the farm of Regional Research station, Old Alluvial Zone, Uttar Banga Krishi Viswavidyalaya, Majhian, Dakshin Dinajpur, West Bengal to study the Performance of direct seeded rice (var. GB-1) under integrated nutrient practices. Highest number of effective tillers plant-1 (17.81), panicle length (29.56 cm) and number of filled grains panicle-1 (262.15) as well as seed yield (3051.89 kg ha-1) have been observed where direct seed rice crop received 75% of the recommended dose of fertilizers, FYM @ 5ton ha-1 and brown manuring with dhaincha. Highest number of effective tillers plant-1 (18.86), panicle length (28.89 cm) and number of filled grains panicle-1 (260.54) and seed yield (3079.92 kg ha-1) have also been observed with spraying of Vermiwash and N-P-K 19:19:19 at 35 DAS and 55 DAS respectively to the direct seeded rice crop. An increasing trend in residual fertility status has also been observed with this treatment compared to the initial fertility status of the soil. This treatment can be an acceptable option of integrated nutrient management practice for the direct seeded rice growers of the old alluvial zone.

Response of Black Cumin (Nigella sativa L.) to Different Spacing and Nitrogen on Growth and Yield in New Alluvial Soil of West Bengal

Response of Black Cumin (Nigella sativa L.) to Different Spacing and Nitrogen on Growth and Yield in New Alluvial Soil of West Bengal

Genetic analysis of yield and yield attributing characters of blackgram (Vigna mungo (L.) Hepper) during summer season in gangetic alluvial soil of West Bengal

The experiment was laid out with twenty genotypes and three replications at Instructional Farm of Ramakrishna Mission Vivekananda Educational and Research Institute, Narendrapur, Kolkata, West Bengal. Among the genotypes RSU-03 showed significantly superior for number of branches per plant (9.07), number of pods per plant (26.27), 100 seed weight (5.15 g) and yield per plant (11.53 g). The phenotypic coefficients of variation (PCV) for all the traits were higher than the corresponding genotypic coefficient of variation (GCV). High heritability coupled with high genetic advance (% of mean) was recorded for no. of pods per plant, plant height, yield per plant which indicates the predominance of additive gene effects on the expression of these traits and these can be used for further breeding programmes for improvement of these traits. Some genotypes showed high percentage of protein and carbohydrate. Based on three ISSR primers, genetic diversity was analyzed. UBC-827 showed high polymorphism (88%) followed by UBC-856 (64%) and ISSR-33 (58%). Among the seven clusters, cluster VI stands out to be the largest.

Effect of integrated nutrient management on growth, productivity, quality and nutrient uptake of irrigated yellow sarson (Brassica campestris L var. yellow sarson) in older alluvial soil of West Bengal

A field experiment was conducted during rabi (winter) seasons of 2007-08 and 2008-09 to study the effect of integrated nutrient management on growth, yield, oil content and nutrient uptake of yellow sarson (Brassica cam-pestris L var. yellow sarson) in older alluvial soil of West Bengal. Significantly higher leaf area index (1.75 at 40 days after sowing; DAS), dry matter accumulation (1366.9 g/m2 at 80 DAS) and highest number of siliquae/plant (118.3), number of seeds/siliqua (21.8), seed yield (1.90 t/ha), stover yield (3.86 t/ha) were recorded significantly (at 5% lev-el) higher with poultry manure (PM) @2.5t/ha +50%RDF (Recommended Dose of Fertilizer i.e. 80-40-40 of N-P2O5-K2O kg/ha) + PSB (phosphate solubilising bacteria) + AZ (Azotobacter) during both the years and on pooled basis. An average of 30.5% and 233% increase in seed yield by this treatment was recorded over sole application of RDF and control respectively. Integrated application of PM (2.5 t/ha) + 50% RDF + PSB + AZ recorded highest oil content (43.16%) and positive effect on soil fertility status. The highest benefit: cost ratios (2.26 and 2.4 in 2007-'08 and 2008-'09 respectively) were achieved from the use of 50% RDF + PM (2.5 t/ha) +PSB+AZ.

Effect of nitrogen and foliar spray of potassium nitrate and calcium nitrate on growth and productivity of yellow sarson (Brassica campestris L. var yellow sarson) crop under irrigated condition

A field experiment was conducted during rabi season of 2007-’08 and 2008-’09 to study the effect of calcium nitrate {Ca (NO3)2} and potassium nitrate {KNO3} at 50 % flowering stage and soil applied nitrogen {N: (0, 40 and 80kg N/ha)} on growth, productivity and economics ofyellow sarson at farmers field under irrigated old alluvial soil of West Bengal. Highest leaf area index (LAI) values at 40 days of crop age (1.748 and 1.592), dry matter accumulation (1404.3 and 1288.8 gm-2) at 80 days and crop growth rate (C.G.R) (27.87 and 25.68 g m-2 day-1) in between 40 to 60 days were obtained at Nitrogen application at the rate of 80 kg / ha and mixed spray of 0.203 % Ca (NO3)2 + 0.25 % KNO3 respectively. Soil application of 80 kg N/ ha along with foliar spray of 0.203 % Ca (NO3)2 + 0.25 % KNO3 resulted increase in seed yield (1.68 t ha-1) by 12 % over 80 kg N/ ha with only water spray (1.5 t ha-1). Foliar spray of 0.203 % Ca (NO3)2 + 0.25 % KNO3 improved the yield components and seed yield over their sole application. Application of 80 kg N/ha along with 0.203 % Ca (NO3)2 + 0.25 % KNO3 at 50 % flowering stage was found to be the most effective in increasing yellow sarson production in old alluvial soil.

Response of Potato Crop to Integrated Nutrient Management in the Indo-Gangetic Alluvial Soils of West Bengal, India

Response of Potato Crop to Integrated Nutrient Management in the Indo-Gangetic Alluvial Soils of West Bengal, India

Integrated Use of Inorganic, Biological and Organic Manures on Rice Productivity, Nitrogen Uptake and Soil Health in Gangetic Alluvial Soils of West Bengal

Integrated use of bio-organic and inorganic fertilizers can improve crop productivity and sustain soil health and fertility. The present research was conducted for two years at Block Seed Farm, Nabagram, Murshidabad, West Bengal to study the effects of green manuring (GM) with dhaincha (Sesbania spp.), farmyard manure (FYM, 5 t ha−1), azophos containing Azotobacter and phosphate solubilizing bacteria (PSB) @ 15 kg ha−1 and zinc sulphate (ZnSO4) @ 25 kg ha−1 on soil fertility, microbial population i.e. Azotobacter and phosphate solubilizing microorganisms (PSM), N uptake and productivity of kharif rice (variety IET 4786) in gangetic alluvial soils of West Bengal. Rice crop was grown in two successive years (2009 and 2010) during rainy seasons with NPK fertilizers as per state recommendation at varying level in different combination with FYM, GM, biofertilizers, ZnSO4 at recommended dose under irrigated conditions. It is evidenced from the experiment that application of ZnSO4 had a significant positive influence on rice yield as well as on Azotobacter and PSM population when applied in combination with FYM/GM and azophos. The results showed that NP fertilizers at 25% reduced rate compliment 100% NP level in a more or less similar fashion when applied along with 100% K fertilizer, green manuring with dhaincha/FYM, ZnSO4 and azophos for successive years. Maximum grain and straw yield of rice was obtained by application of 100% NPK fertilizer, green manuring with dhaincha, ZnSO4, azophos (4.56 and 5.13 t ha−1 of grain and straw yield, respectively) followed by its 75% NP counterpart (4.47 and 5.02 t ha−1 of grain and straw yield, respectively) and both the treatment effects was found statistically equivalent. Integrated use of green manure at 75% recommended NP dose along with azophos and ZnSO4 enhanced the grain and straw yield by 20.8 and 10.8 per cent, respectively and grain and straw N uptake by 31.7 and 12.4 per cent respectively over 100% NPK alone. Irrespective of treatments, soil health status with respect to soil OC, N, P, K and microbial population has been improved in organic, inorganic and biologically treated combined applications as compared to sole inorganic sources. Application of bio-organic amendment increased plant recovery as well as soil available N in rice crops for subsequent years compared to fertilizer alone. Maximum available N of 226 and 246 kg ha−1 during 1st and 2nd year, respectively was recorded in green manured plot supplemented with ZnSO4, Azotobacter, PSB at 25% reduced level of NP fertilizers.

Phosphate-solubility and phosphatase activity in Gangetic alluvial soil as influenced by organophosphate insecticide residues

An experiment was conducted under laboratory conditions to investigate the effect of four organophosphate insecticides, viz. monocrotophos, profenophos, quinalphos and triazophos at their field application rates (0.75, 1.0, 0.5 and 0.6kga.i.ha−1, respectively), on the growth and activities of phosphate solubilizing microorganisms in relation to availability of insoluble phosphates in the Gangetic alluvial soil of West Bengal, India. The proliferation of phosphate solubilizing microorganisms was highly induced with profenophos (38.3%), while monocrotophos exerted maximum stimulation (20.8%) towards the solubility of insoluble phosphates in soil. The phosphatase activities of the soil (both acid phosphatase and alkaline phosphatase) were significantly increased due to the incorporation of the insecticides in general, and the augmentation was more pronounced with quinalphos (43.1%) followed by profenophos (27.6%) for acid phosphatase, and with monocrotophos (25.2%) followed by profenophos (16.1%) for alkaline phosphatase activity in soil. The total phosphorus was highly retained by triazophos (19.9%) followed by monocrotophos (16.5%), while incorporation of triazophos and quinalphos manifested greater availability of water soluble phosphorus in soil.