Soil Of Assam Research Articles

Evaluation of extractants and critical limits of Sulphur for rapeseed in acid soils of Assam

Evaluation of extractants and critical limits of Sulphur for rapeseed in acid soils of Assam

Influence of chemical and biological properties of field grown pea and lentil rhizospheres on nodulation status and resident rhizobial population in acidic soils of Assam, India

The influence of rhizospheric properties on nodulation status and resident rhizobial population of pea and lentil grown at twenty three sites of Assam were assessed. Besides the plant infectivity of rhizobia isolated from pea and lentil nodules were tested for symbiotic effectiveness. The survey established significant variation of nodule number ((35.-223.plant)), nodule dry weight (6.6 to 271. mgplant) and most probable number count ( to 147g soil) across the twenty three diverse sites. Rhizospheric properties <italic>viz</italic> pH, organic carbon, available P<sub>2</sub>O<sub>5</sub> and K<sub>2</sub>O could establish significant correlation with nodule number (r=0.892*, 0.771*, 0.753* and 0.669*) and most probable number(r=0.784*, 0.580*, 0.615* and 0.649*) counts, correspondingly. Microbial biomass carbon showed significant correlation with nodule number(r=0.672*). Dehydrogenase and phosphomonoesterase activities too showed significant correlation with nodule number(r=0.695* and 0.634*) and most probable number (r=.575* and 0.534*) count, respectively. The symbiotic effectiveness of isolated rhizobia demonstrated significant variation of nodule score (1.33-3.67). Only 6 isolates could attain nodule score of ≥3.0, irrespective of resident rhizobial population.

Complete genome sequence analysis of Pseudomonas aeruginosa N002 reveals its genetic adaptation for crude oil degradation

The present research work reports the whole genome sequence analysis of Pseudomonas aeruginosa strain N002 isolated from crude oil contaminated soil of Assam, India having high crude oil degradation ability. The whole genome of the strain N002 was sequenced by shotgun sequencing using Ion Torrent method and complete genome sequence analysis was done. It was found that the strain N002 revealed versatility for degradation, emulsification and metabolizing of crude oil. Analysis of cluster of orthologous group (COG) revealed that N002 has significantly higher gene abundance for cell motility, lipid transport and metabolism, intracellular trafficking, secretion and vesicular transport, secondary metabolite biosynthesis, transport and catabolism, signal transduction mechanism and transcription than average levels found in other genome sequences of the same bacterial species. However, lower gene abundance for carbohydrate transport and metabolism, replication, recombination and repair, translation, ribosomal structure, biogenesis was observed in N002 than average levels of other bacterial species.

Fungal Degradation of Cellulosic Materials in Assam I Studies on Soil Aspergilliei

Nineteen species of Aspergillus were isolated from the soil of Assam, during a systematic investigation of soil mycoflora in 1972-74. The paper describes the presence of these species in different regions of Assam with special consideration to cellulose destroying capacity of these species, and the results indicate that these isolates play a very important role in degradation of cellulosic materials in stores under user conditions.

Carbon fixation, partitioning and storage in field planted with wheat (Triticum aestivum) at different moisture regimes

Impacts of agricultural management on soil organic carbon and soil carbon storage in fields planted with wheat at North East India are not well documented. Experiments were conducted to investigate the impact of water regimes on soil organic carbon and carbon storage in wheat grown alluvial soil of Assam. Continuous input of plant organic matter to soil through root exudation during the growth period of wheat variety ‘Sonalika’ was monitored in a twoyears field study. Carbon fixation and partitioning by the plants were estimated in terms of photosynthesis and biomass accumulation, respectively. Results demonstrate that there was increase in organic carbon at upper and lower depth of soil due to addition of crop root biomass. An average increment of 15.71% and 11.18% soil organic carbon at irrigated and rainfed conditions, respectively was recorded over the initial value during two years. Increment in net photosynthetic rate and higher dry matter accumulation was considered as the primary cause for higher grain productivity at irrigated condition.

Physiological Disorder of Rice Associated with High Levels of Iron in Growth Medium

ABSTRACT Three rice (Oryza sativa L.) varieties viz. ‘CR 683‘, ‘Budumoni’ “Budumoni”, and ‘Akisali’ were grown in sand culture in a greenhouse with three levels of iron (Fe) in nutrient solutions viz., 0.045 (control), 5.34, and 7.12 mM Fe to study the effects of iron on physiology of rice seedling growth. Shoot length, root, and shoot dry weights were reduced significantly by higher levels of Fe in the medium. Results of leaf bronzing have revealed higher bronzing score in the seedlings grown at 7.12 mM Fe in the growth medium. Occurrence of bronzing was severe in varieties ‘CR683’ and ‘Akisali’. Variety ‘Budumoni'maintained higher leaf chlorophyll content, nitrate reductase activity and total soluble protein in the leaves at 5.34 and 7.12 mM Fe. Higher concentration of iron in the nutrient medium exerted an inhibiting effect on the concentration and content of almost all the macro and micronutrients in the root and shoot. Higher Fe and nitrogen (N) contents and lower phosphorus (P), potassium (K), manganese (Mn), copper (Cu), and zinc (Zn) were determined in roots and shoots in plants grown in medium supplied with 7.12 mM Fe. The variety ‘Budumoni’ “Budumoni” performed relatively better in comparison to other tested varieties at 7.12 mM Fe in the growth medium. ‘Budumoni’ “Budumoni” can be considered a suitable rice variety to use in the rice-breeding programme for Fe toxicity tolerance in acid soils of Assam.

Methane emission characteristics and its relations with plant and soil parameters under irrigated rice ecosystem of northeast India

Methane flux from rice varieties grown under two identical soils of Assam were monitored. In the first experiment, variety Jaya and GRT was grown in sandy loam soil of Lower Brahmaputra Valley Zone of Assam and the second experiment was conducted with variety Jyotiprasad and Bishnuprasad in sandy to sandy loam soils of Upper Brahmaputra Valley Zones of Assam. Methane flux recorded from variety Jyotiprasad and GRT was higher compared to variety Bishnuprasad and Jaya. The seasonal integrated flux recorded was 10.76 g m −2, 9.98 g m −2, 9.74 g m −2 and 11.31 g m −2 for variety GRT, Jaya, Bishnuprasad and Jyotiprasad, respectively. All the varieties exhibited two methane peaks one at maximum tillering stage and other at panicle initiation stage of the crop. Crop growth parameters such as leaf number, number of tillers and leaf area index (LAI) showed strong positive relationship with total methane flux. In both the experiments it was calculated that CH 4 emission was substantially influenced by crop phenology and growth. This study emphasise the relationship of different growth parameters with methane emission.

Comparative assessment of organic, inorganic and integrated management practices in rice (Oryza sativa)-based cropping system in acid soil of Assam

A field experiment was conducted from 2008-09 to 2014-15 under All India Coordinated Research Project on Integrated Farming System at Assam Agricultural University, Jorhat, Assam, to evaluate the effect of organic (alone), inorganic (alone) and integrated nutrient management on soil properties and productivity of rainfed winter rice (Oryza sativa L.)toria [Brassica rapa subsp. Dichotoma (Roxb.) Honalt]blackgram [Vigna mungo (L.) Hepper] system. The highest rice-equivalent yield (8.91 t/ha) was recorded with the application of 100% NPK through organic sources plus intercropping with wheat (Triticum aestivum L.) during the winter (rabi) season and okra [Abelmoschus esculentus (L.) Moench] during the summer. Application of 100% recommended dose of fertil- izer (RDF) through FYM, vermicompost and mustard seed-cake in the rice during the rainy (kharif) season, fol- lowed by toria + wheat during rabi and blackgram + okra during the summer season resulted in the maximum av- erage uptake of N, P and K (95.5, 20.1 and 84.9 kg/ha respectively). Bacteria, fungi and Actinomycetes counts as well as microbial biomass carbon in soil were the highest (253 104, 137 104, 195 104 and 163.95 ?g/g re- spectively) in the organic management having 100% supply of nutrients through 1/ FYM + 1/ vermicompost + 1/ 3 3 3 mustard seed cake (MSC) along with 3.5 kg/ha each of Azospirillum/Azotobacter and phosphate-solubilizing bac- teria. The highest dehydrogenase, phosphatase and urease activity in soil was also observed in the same treat- ment. Full dose of NPK through organic sources to ricetoriablackgram sequence intercropping with wheat dur- ing the winter (rabi) and okra during the summer registered the highest earthworm count (25 numbers per m3).

Maximizing system productivity and profitability through crop intensification and diversification with rice (Oryza sativa)-based cropping systems in acid soils of Assam

A field experiment was conducted for 6 consecutive years during 200809 to 201314, at Jorhat, Assam, to study the soil fertility, system productivity and profitability through crop intensification and diversification with rice (Oryza sativa L.)-based cropping system under irrigated medium land acid soil situation of Assam. From the pool analysis of data, it was observed that rice-equivalent yield, system productivity and nutrient-use productivity were found to be the highest in winter ricecabbage [Brassica oleracea (L.) greengram [Vigna radiata (L.) Wilczek] (REY 17.72 t/ha) sequence, followed by winter ricechilli (Capsicum annuum L.)blackgram [Vigna mungo (L.) Hepper] sequence (REY 14.37 t/ha) among the 8 cropping sequences under study. There were improvements in post harvest physico-chemical properties of soil in different rice-based cropping systems. Significant variation with 34.0, 36.9 and 65.5% increase in available N, P O and K O, respectively, were recorded in winter riceradish 2 5 2 (Raphanus sativus L.)French beangreengram sequences over initial status of soil. Total uptake of nutrients were also the highest of winter riceradishFrench beangreengram sequence followed by winter riceknolkhol [Brassica oleracea L. convar. acephala (L.) Alef. Var. gongylodes L.]French beancowpea [Vigna unguiculata (L.) Walp.] (fodder) sequence. Economic analysis of the systems revealed that the highest gross returns (210.8 103 /ha), net returns (145.1 103 /ha) and benefit: cost ratio (2.21) were recorded in winter ricecabbage greengram sequence under irrigated medium land situation of Assam.

Adsorption–desorption behaviour of flufenacet in five different soils of India

Adsorption–desorption of the herbicide flufenacet (FOE 5043) has been studied in five soils from different locations in India (Delhi, Ranchi, Nagpur, Kerala and Assam) varying in their physico-chemical properties. The organic matter (OM) content varied from 0.072 to 0.864%, clay content from 2.5 to 43.7% and pH from 4.45 to 8.35. The adsorption studies were carried out using a batch equilibration technique. Ten grams of soil were equilibrated with 20 ml of aqueous 0.01 M CaCl2 solution containing different concentrations (0–30 mg litre−1) of flufenacet. After equilibration, an aliquot of supernatant was taken out for analysis. During desorption, the amount withdrawn for analysis was replenished with fresh 0.01 M CaCl2 solution and further equilibrated. Desorption studies were carried out with the 30 mg litre−1 concentration of flufenacet only. The adsorption studies revealed that there was moderate to high adsorption of flufenacet considering the comparatively low organic carbon content in the five test soils. Average Kd values ranged from 0.77 to 4.52 and Freundlich KF values from 0.76 to 4.39. The highest adsorption was observed in Kerala soil (OM 0.786%; clay 25%; pH 4.45) followed by Ranchi, Nagpur and Delhi soils, and the lowest in Assam soil (OM 0.553%; clay 2.5%; pH 6.87). The trend in adsorption could be attributed to the chemical nature of flufenacet and the physico-chemical properties of the soil such as pH, OM and clay contents. OM and clay contents were positively correlated whereas pH was negatively correlated. Soils having low pH, high OM and high clay contents showed higher adsorption. Desorption studies revealed that there was a hysteresis effect in all the soils. Hysteresis coefficient values (ratio of nad and ndes) varied from 0.09 to 0.45. The study implies that, because of its moderate to high adsorption, flufenacet is likely to persist in soil for some time. However, the possibility of its movement by leaching or surface run off is less. © 2001 Society of Chemical Industry

Adsorption-desorption behaviour of flufenacet in five different soils of India.

Adsorption-desorption of the herbicide flufenacet (FOE 5043) has been studied in five soils from different locations in India (Delhi, Ranchi, Nagpur, Kerala and Assam) varying in their physicochemical properties. The organic matter (OM) content varied from 0.072 to 0.864%, clay content from 2.5 to 43.7% and pH from 4.45 to 8.35. The adsorption studies were carried out using a batch equilibration technique. Ten grams of soil were equilibrated with 20 ml of aqueous 0.01 M CaCl2 solution containing different concentrations (0-30 mg litre-1) of flufenacet. After equilibration, an aliquot of supernatant was taken out for analysis. During desorption, the amount withdrawn for analysis was replenished with fresh 0.01 M CaCl2 solution and further equilibrated. Desorption studies were carried out with the 30 mg litre-1 concentration of flufenacet only. The adsorption studies revealed that there was moderate to high adsorption of flufenacet considering the comparatively low organic carbon content in the five test soils. Average Kd values ranged from 0.77 to 4.52 and Freundlich KF values from 0.76 to 4.39. The highest adsorption was observed in Kerala soil (OM 0.786%; clay 25%; pH 4.45) followed by Ranchi, Nagpur and Delhi soils, and the lowest in Assam soil (OM 0.553%; clay 2.5%; pH 6.87). The trend in adsorption could be attributed to the chemical nature of flufenacet and the physicochemical properties of the soil such as pH, OM and clay contents. OM and clay contents were positively correlated whereas pH was negatively correlated. Soils having low pH, high OM and high clay contents showed higher adsorption. Desorption studies revealed that there was a hysteresis effect in all the soils. Hysteresis coefficient values (ratio of n(ad) and n(des)) varied from 0.09 to 0.45. The study implies that, because of its moderate to high adsorption, flufenacet is likely to persist in soil for some time. However, the possibility of its movement by leaching or surface run off is less.

Influence of Continuous Submergence on the Kinetics of pH, Eh, and Ec in Some Acid Soils of Assam

Influence of Continuous Submergence on the Kinetics of pH, Eh, and Ec in Some Acid Soils of Assam

Effect of Phosphorus Fertilization on `Priming' of Native Phosphorus By Rice in Acid Soils of Assam

Effect of Phosphorus Fertilization on `Priming' of Native Phosphorus By Rice in Acid Soils of Assam