Browsing by Author "S. Sarkar"

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Calibration of a water uptake simulation model under varying soil moisture regime and nitrogen level for wheat crop
(1997) B.D. Sharma; S. Kar; S. Sarkar
Crop production is directly related to the time-depth status of soil water which is often predicted with the help of a simulation model avoiding time-consuming deterministic procedures. In the present study, the accuracy of a mathematical simulation model has been tested by comparing the simulated profile water content with its measured counterpart in a field experiment conducted with winter wheat on a sandy loam soil (Typic Ustipsamment). Wheat crop was grown under two soil water regimes, monitored by applying irrigation at 1.2 (wet, W) and 0.6 (dry, D) ratios of irrigation water to cumulative pan evaporation and at two levels of nitrogen: high, (120 kg ha-1, N) and low (60 kg ha-1, N). The calibration studies indicated high dependency of the simulation model on the depth of rooting used as an input parameter. The matching between simulated and measured profile water content was better when penetration depth of wheat roots was less than 0.6 m. Predictability of the model was found to be high under wet soil moisture regime and at low level of fertilizer nitrogen.
Comparison between simulated and measured profile water distribution
(1995) S. Sarkar; S. Kar
Physically based mathematical models are capable of portraying the process of soil water utilization by crop roots. However, there are few detailed studies comparing simulated profile water content with those observed experimentally in varying soil moisture status. The purpose of the present study was to test the accuracy of a diffusion based soil water simulation model under wet, moderately wet and dry soil water regimes in a coarse textured lateritic (Oxic Haplustalf) soil using peanut as a test crop. Simulated water content (SWC) usually matched well with the measured water content (MWC), the matching being very accurate when roots penetrated to the maximum depth (1.2 m). During the early part of the drying cycle simulated values were closer to observed values than they during the middle and later part of the drying cycle. Under wet regime simulated values were closer to observed values. © 1995.
Enhanced hydrogen photoproduction by non-heterocystous cyanobacterium Plectonema boryanum
(Elsevier Ltd, 1996) A.K. Kashyap; K.D. Pandey; S. Sarkar
Nitrogenase activity was derepressed in Plectonema boryanum following 18-24 h of microaerobic incubation. The cyanobacterium evolved hydrogen at a slow rate. Addition of reducing substances (sulfide, sulfite or dithionite) to the diazotrophic cultures resulted in an increase in nitrogenase activity or photoproduction of hydrogen. The reducing substances also restored phycocyanin degradation.
High-spin states in the odd-odd nucleus146Tb
(American Physical Society, 2004) Krishichayan; A. Chakraborty; S.S. Ghugre; R. Goswami; S. Mukhopadhyay; N.S. Pattabiraman; S. Ray; A.K. Sinha; S. Sarkar; P.V. Madhusudhana Rao; U. Garg; S.K. Basu; B.K. Yogi; L. Chaturvedi; A. Dhal; R.K. Sinha; M. Saha Sarkar; S. Saha; R. Singh; R.K. Bhowmik; A. Jhingan; N. Madhavan; S. Muralithar; S. Nath; R.P. Singh; P. Sugathan
The odd-odd 146Tb nucleus has been investigated using the 115In(34S,3n) reaction at 140 MeV incident energy using an array of eight Compton-suppressed Clover detectors. Based on the observed γ- γ coincidences, the level structure of 146Tb has been extended up to Ex∼ 10 MeV. Linear polarization measurements have been combined with angular correlations of the observed γ rays to assign the electromagnetic nature to the transitions. Probable origin of a cascade of M1 transitions observed around 8 MeV excitation energy has been discussed.
Impact of profile water status on nitrogen use pattern of dry land barley under varying nitrogen levels
(1998) S. Sarkar; S.K. Singh; A.P. Singh; S.R. Singh
A field trial was carried out during 1993–94 and 1994–95 winter seasons on Udic Ustochrept to evaluate the performance of dryland barley under varying profile moisture status and nitrogen levels. Three levels of initial moisture status of the root zone profile were: wet (100% field capacity), moderately wet (50% field capacity) and dry (rainfed) as the main treatment. The sub treatments were 0, 40, 60 and 80 kg N ha−1. During 15 to 60 days after sowing (DAS) availability of soil nitrogen and its uptake by the crop attained the highest values under wet regime. However, at 105 and 130 DAS dry moisture regime resulted in maximum values of both available soil nitrogen and plant nitrogen contents. In the same tune biomass production attained the higher values under wet regime as compared to the dry regime during 15 to 60 DAS and the trend was reverse at 105 DAS. Grain yield attained the highest value under dry regime followed by wet and moderately wet regimes. Irrespective of the profile moisture status both productivity and nitrogen use efficiency enhanced with the increase in nitrogen doses from 0 to 80 kg ha−1. Role of nitrogen was more pronounced under wet regime. © 1998, Taylor & Francis Group, LLC.
Integrated nutrient management in relation to soil fertility and yield sustainability under dryland farming
(1997) S. Sarkar; S.R. Singh
[No abstract available]
Interactive effect of tillage depth and mulch on soil temperature, productivity and water use pattern of rainfed barley (Hordium vulgare L.)
(2007) S. Sarkar; S.R. Singh
Soil porosity and organic matter content influence the hydrology, thermal status and productivity of agricultural soils. Shape, size and continuity of soil pores are determined by tillage practices. Thus appropriate tillage and mulch management can conserve residual soil moisture during the post rainy season. This can play a key role in enhancing productivity under the rainfed ecosystem of subhumid region in eastern India. A field study was carried out on a fine loamy soil from 1993-1994 to 1995-1996. Two tillage treatments were conventional ploughing (150 mm depth) and shallow ploughing (90 mm) depth. Each tillage practice was tested with three mulch management viz., no mulch, soil dust mulch and rice (Oryza sativa L.) straw mulch. Soil organic carbon, bulk density, moisture retentivity, soil temperature with productivity and water use pattern of barley (Hordium vulgare L.) were measured. Reduction in ploughing depth resulted in nominal increase in profile (0.0-1.2 m) moisture status, yield, and soil thermal status at 14:00 and water use efficiency (WUE). However, it decreased the magnitude of soil temperature in the morning (07:00). Straw mulch conserved 19-21 mm of moisture in the profile (1.2 m) over the unmulched condition. Both soil dust and rice straw mulching elevated soil thermal status at 07:00 as compared to unmulched condition, but this trend was reversed at 14:00. Straw mulching significantly increased grain yield and WUE over soil dust mulch and unmulched condition. Impact of straw mulch was more pronounced under shallow ploughing depth. Shallow tillage with rice straw mulching is recommended to the farmers to obtain higher level of yield and water use efficiency. © 2006 Elsevier B.V. All rights reserved.
Lifetime measurements of microsecond isomers in the N=48 nuclei 88Zr and90Mo using recoil-isomer tagging
(American Physical Society, 2004) A. Chakraborty; Krishichayan; S.S. Ghugre; R. Goswami; S. Mukhopadhyay; N.S. Pattabiraman; S. Ray; A.K. Sinha; S. Sarkar; P.V. Madhusudhana Rao; U. Garg; S.K. Basu; L. Chaturvedi; A. Dhal; R.K. Sinha; I.M. Govil; M.B. Chatterjee; M. Saha Sarkar; R.K. Bhowmik; A. Jhingan; N. Madhavan; S. Muralithar; S. Nath; R.P. Singh; P. Sugathan
The recoil-isomer tagging technique has been used to study the isomeric states of nuclei in the vicinity of the N=50 shell closure. The nuclei of interest were separated from the projectilelike nuclei and other evaporation residues and transported to the focal plane of a recoil separator. The decay of the tagged isomer was studied at the focal plane using a high-purity Ge detector. The prompt transitions feeding the isomer were detected in an array of Clover Ge detectors placed around the target. The measured half-lives of the 8+ isomers in 88Zr and 90Mo are 1.41 (-0.09)(+0.12) μs and 1.17(-0.07) (+0.19), respectively. The corresponding transition probabilities are in reasonable agreement with the predictions of shell model calculations. The systematics of effective charges (ep and en) for N=48 nuclei are qualitatively understood in these calculations.
Simulation of evapotranspiration from groundnut under wet and dry conditions
(1995) S. Sarkar; S. Kar
A diffusion based simulation model was tested on groundnut (Arachis Hypogaea L) in a lateritic sandy loam soil (Oxic-Haplustalf) of eastern India. Two moisture regimes, wet and dry, were induced by recharging the soil profile (1.2 m depth) to field capacity storage, whenever soil water pressure reached -0.078 m at 0.225 m (wet) and 0.6 m (dry) soil depths, respectively. Moisture retention characteristics and hydraulic conductivity curves were measured for three distinct soil layers of the experimental soil profile. Readily available meteorological, soil and plant data were used as input parameters of the model. The simulated cumulative ET (ETS) closely corresponded with the field observed cumulative ET (ETf) in the early part of the drying cycle following irrigation. However at the later part of the drying cycle ET, deviated from the ETf, this being particularly true under wet regime. The closest match between ET, and ETf was observed under dry soil water regime 50-70 days after sowing (DAS). The model underestimated the field observed ET up to 50 DAS and there after overestimated it. © 1995.
Simultaneous photoproduction of hydrogen and ammonia by a non-heterocystous cyanobacterium Plectonema boryanum
(1992) S. Sarkar; K.D. Pandey; A.K. Kashyap
[No abstract available]
Spectroscopy of Nb90 at high spin
(2005) A. Chakraborty; Krishichayan; S.S. Ghugre; R. Goswami; S. Mukhopadhyay; N.S. Pattabiraman; S. Ray; A.K. Sinha; S. Sarkar; P. V. Madhusudhana Rao; U. Garg; S.K. Basu; M.B. Chaterjee; M. Saha Sarkar; L. Chaturvedi; A. Dhal; R.K. Sinha; I.M. Govil; R.K. Bhowmik; A. Jhingan; N. Madhavan; S. Muralithar; S. Nath; R.P. Singh; P. Sugathan
Excited states of Nb90 were investigated via prompt and delayed γ decays and the recoil-isomer tagging technique. The level scheme of Nb90 has been extended up to J=19 and Ex=8.4 MeV. Half-lives of the 11- and 17/2- isomeric levels in Nb90,91 were measured to be 0.47±0.01 and 3.3±0.4 μs, respectively. The results are compared with the predictions of large-basis shell model calculations. The effects of truncation of the valence model space on the calculated results are discussed. © 2005 The American Physical Society.
Spin-parity measurements in the neutron-rich N ∼ 20 34P and 36S nuclei
(2006) Krishichayan; A. Chakraborty; S. Mukhopadhyay; S. Ray; N.S. Pattabiraman; S.S. Ghugre; R. Goswami; A.K. Sinha; S. Sarkar; U. Garg; P.V. Madhusudhana Rao; S.K. Basu; B.K. Yogi; L. Chaturvedi; A. Dhal; R.K. Sinha; M. Saha Sarkar; S. Saha; R. Singh; R.K. Bhowmik; A. Jhingan; N. Madhavan; S. Muralithar; S. Nath; R.P. Singh; P. Sugathan
Yrast and near-yrast energy levels in the neutron-rich N ∼ 20 nuclei 34P, 36S were populated using transfer/deep-inelastic processes following the 34S + 115In reaction at an incident energy of 140MeV. The use of a multi-clover array has facilitated polarization measurements of the observed γ-rays and necessitated some changes in the previously known level scheme. The observation of the negative-parity levels in these nuclei on the periphery of the "island of inversion" is indicative of the influence of the intruder orbitals on the level structure at low spins. Shell-model calculations indicate that the inclusion of the orbitals from the upper pf shell is important even for the low-lying positive-parity states.
The effect of organic and inorganic fertilizers on soil physical condition and the productivity of a rice-lentil cropping sequence in India
(2003) S. Sarkar; S.R. Singh; R.P. Singh
A field experiment lasting 9 years was initiated in 1987 to study the effect of integrated nutrient management involving incorporation of wheat straw (WS) or farmyard manure (FYM) alone or in combination with inorganic fertilizer on a fine loamy mixed hyperthermic udic Ustochrept. Soil physical properties and the productivity of a rice-lentil cropping sequence were examined in a dry land farming system. At the end of the ninth cropping season, addition of organic materials had increased organic carbon, aggregate stability, moisture retention capacity and infiltration rate of the surface soil while reducing the bulk density. Application of inorganic fertilizer alone decreased the stability of macro aggregates and moisture retention capacity but increased the bulk density values. Treatment effects on moisture retentivity were more pronounced in the higher (0.3-1.5 MPa) suction range. During the first six experimental years, sole application of inorganic fertilizers produced 10-17% higher grain yield of rice, compared to sole application of organic sources or combined organic and inorganic sources. Annual applications of wheat straw and farmyard manure gave higher grain yields of rice from the seventh year onwards. Grain yields of lentil were higher with organic sources either alone or combined with inorganic nutrients.
Water use pattern and productivity of rainfed yellow sarson (Brassica rapa L. var glauca) in relation to tillage and mulching
(Elsevier B.V., 1996) R. Moitra; D.C. Ghosh; S. Sarkar
Field experiments were conducted during 1983-1989 to 1990-1991 on a sandy loam (Typical ochraqualf) soil of eastern India, to determine the effects of four mulch types: (no mulch; soil dust mulch; green mulch at 20 mg ha-1; and rice straw mulch 5 mg ha-1); and three tillage treatments (two, four and six ploughings to 100 mm depth) on profile water conservation, grain yield and water use efficiency (W(ue)) of rainfed yellow sarson (Brassica rapa L. var glauca). Green and dry straw mulches conserved 15% and 13.7% more water than the no mulch treatment in the top 500 mm of the soil profile. As compared with the no mulch condition, grain yield was increased by 47%, 43% and 16% respectively under green, straw and soil dust mulching. Besides vegetative mulches, soil dust mulch also increased the W of the crop. Grain yield and W(ue) were not significantly changed by an increase in the number of ploughings from two to six.