Stable and Metastable vortex states and the first order transition across the peak effect region in weakly pinned 2H-NbSe_2

The peak effect in weakly pinned superconductors is accompanied by metastable vortex states. Each metastable vortex configuration is characterized by a different critical current density J_c, which mainly depends on the past thermomagnetic history of the superconductor. A recent model [G. Ravikumar, et al, Phys. Rev. B 61, R6479 (2000)] proposed to explain the history dependent J_c postulates a stable state of vortex lattice with a critical current density J_c^{st}, determined uniquely by the field and temperature. In this paper, we present evidence for the existence of the stable state of the vortex lattice in the peak effect region of 2H-NbSe_2. It is shown that this stable state can be reached from any metastable vortex state by cycling the applied field by a small amplitude. The minor magnetization loops obtained by repeated field cycling allow us to determine the pinning and "equilibrium" properties of the stable state of the vortex lattice at a given field and temperature unambiguously. The data imply the occurence of a first order phase transition from an ordered phase to a disordered vortex phase across the peak effect.Comment: 20 pages, 10 figures. Corresponding author: S. Ramakrishna

Effect of different phosphorus sources applied with phosphate solubilizing bacteria on bio-geochemical properties and phosphorus release pattern in vertisol

Various phosphorus (P) fertilizers are used for crop production in different types of soil. But there is a knowledge gap in choosing the right source and form of  P fertilizers to enhance the applied fertilizer use efficiency. An experiment was taken to identify the best phosphorus source and its effectiveness as a source of P in vertisol to unravel this problem of selecting suitable P fertilizer. With this background, an incubation experiment was conducted under laboratory condition to determine the phosphorus release pattern of different P sources [Single Super Phosphate (SSP), Rock Phosphate (RP), Diammonium Phosphate (DAP), Nano phosphate (Nano P), Phosphocompost (PC)] applied with phosphate solubilizing bacteria (PSB) and their influence on biogeochemical properties in vertisol.  Experimental results emphasized that P release from different sources was influenced by soil pH, electrical conductivity (EC), cation exchange capacity (CEC), soil organic carbon (SOC), and microbial population. Applied P sources significantly(p=0.05) influenced the CEC, SOC, and microbial population except for soil pH and Ec. The maximum release in available P was obtained at 30 and 60 days after incubation with SSP +PSB  (35.8 and 40.1 mg kg-1) and Nano P + PSB (33.9 and 38.6 mg kg-1) applied treatments, respectively.Whereas at 90 days after incubation Nano P + PSB (42.3 mg kg-1) and Phosphocompost + PSB (40.4 mg kg-1) treatments recorded the maximum P availability and minimum P (15.2, 13.9 and 11.8 mg kg -1) release was noticed in the control treatment throughout the period of incubation. It was evident that SSP or Nano P along with PSB application might be the best P source for Vertisol

Effect of sulphur, zinc and boron on the growth and yield enhancement of sunflower (Helianthus annuus L.)

Oilseed crops grown in different types of soil experience nutrient deficiency, especially sulphur, zinc and boron, which affect crop productivity. To tackle it, nutrient management practices must be streamlined to avoid improper fertilizations and deterioration of soil health. With this background, experimental trials were conducted to study the effect of sulphur, zinc and boron application on the growth, yield components and yield of hybrid sunflower at AyanAthur village, Ariyalur district (TN) during the summer seasons of 2016 and 2017. The experiments were laid out in Randomized Block Design (RBD) with three replications. The growth components of sunflower (plant height, leaf area index, dry matter production, leaf area duration (LAD) and growth analysis parameters such as crop growth rate (CGR), relative growth rate(RGR), net assimilation rate(NAR) and chlorophyll content, yield components and seed yield were significantly (level of significance P>0.05) influenced by foliar application of 0.5% Zn on bud initiation stage and seed formation stage and B @ 0.3% on bud initiation stage and ray floret formation stage along with S(sulphur) @ 40 kg ha-1 and RDF(recommended dose of fertilizers) as a soil application. Growth and yield parameters responded very little with the RDF alone. From both experimental results, we found that foliar application of Zn @ 0.5%and B @ 0.3% along with S @ 40 kg ha-1 and RDF recorded the highest percentage of dry matter production (44.4%), number of filled seeds (30.1%) and yield (32.4%) of hybrid sunflower

Residual effect of organics and direct effect of mineral nitrogen on rice (Oryza sativa L.) in two different textural soils

Nitrogen through organics and inorganics application is an alternate to maintain soil health and crop productivity in the rice cropping system. With this background, field experiments were conducted in farmer’s field at Kuttalam during 2012-2013, 2013-14 to evaluate residual organics and mineral nitrogen (100%N) on growth parameters and yield of rice (Oryza sativa) in sandy clay loam and clay loam soil. The treatments consisted of residual organics viz., composted coir pith (CCP), green manures (GM), sugarcane trash compost (STC), vermicompost (VC), poultry manure (PM) and FYM applied(100%N) and a combination of above residual organics with urea@50%N besides 100% recommended dose of nitrogen (RDN) and control. The results revealed that residual organics and urea recorded higher growth parameters like plant height, chlorophyll content, leaf area index(LAI), crop growth rate (CGR), relative growth rate(RGR), net assimilation rate(NAR), No. of tillers/hill compared to their individual addition. The growth parameters were more under residual PM in combination with mineral nitrogen in both the soils. Residual PM + fertilizer nitrogen (100% N) recorded highest grain (4485, 4693 kg ha-1) and straw yield (6984, 5897 kg ha-1) in clay loam and sandy clay loam soils, respectively. The lowest grain(3292, 2993 kg ha-1) and straw yield(4998, 4003 kg ha-1) were recorded in residual GM + fertilizer (100% N) in both soils. Among organics alone, residual PM(100% N) registered highest grain yield (4025, 4048 kg ha-1) in both soils. It can be concluded that the application of poultry manure alone or in combination with N fertilizers enhanced the growth and improved soil health.

Physiological response and productivity of aerobic rice (Oryza sativa L.) to iron fertilization in typic Ustifluvents soil

Aerobic rice is projected as a sustainable rice production technology for the immediate future to address water scarcity and environmental safety. Micronutrient deficiency, particularly iron is one of the main factors responsible for low productivity in aerobic rice. With this perspective, a field experiment was conducted at farmer’s field in 2022 at  Kuttalam,  Mayladuthurai district,  Tamilnadu, in sandy clay loam (Padugai Series – Typic Ustifluvents) to predict the response of aerobic rice (Oryza sativa) to iron nutrition. The experiment was laid out in randomised block design with eleven treatments (Recommended dose of fertilizers (RDF) NPK only (control)(T1),  (RDF) + FeSO4  @ 25 kg ha-1 (SA) (T2),  RDF + FeSO4  37.5 kg ha-1 (SA)(T3),RDF+ FeSO4  @ 50 kg ha-1 (SA)(T4),  RDF+ FeSO4  @ 25 kg ha-1 (SA) + FeSO4 @ 1% (FS)(T5), RDF+ FeSO4  37.5 kg ha-1 (SA) + FeSO4 @ 1% (FS)(T6) , RDF+ FeSO4 @ 50 kg ha-1 (SA) + FeSO4 @ 1% (FS)(T7), RDF+ FeSO4 @ 25 kg ha-1(SA) + Fe-EDTA @ 0.5% (FS)(T8), RDF+ FeSO4 37.5 kg  ha-1 (SA) + Fe-EDTA @ 0.5% (FS)(T9), RDF+ FeSO4 @ 50 kg ha-1 (SA) + Fe-EDTA @ 0.5% (FS) (T10) and RDF + Seed priming 0.05M Fe-EDTA(T11)) and replicated thrice.  The results revealed that application of  FeSO4 @ 50 kg ha-1 (SA) + Fe-EDTA @ 0.5% (FS) with RDF recorded the highest growth and yield parameters and the highest grain (3438 kg ha-1) and straw yield (5078 kg ha-1) compared to other treatments including control. This study concluded that iron fertilization through the soil and foliar application could enhance aerobic rice productivity

Integrated nutrient management - promising way to reduce carbon dioxide and methane emission in flooded rice ecosystem: A review

Climate change is an inevitable ruling issue caused by the increasing concentration of greenhouse gases (GHG’s) in the atmosphere worldwide. It will have a considerable impact on agriculture and its related fields like live stocks and fisheries. In India, the main sectors contributing to these emissions are industry, agriculture and waste, with a total emission of 334 MT CO2 eq. Besides, the major sources in agriculture are enteric fermentation (63.4%), rice cultivation (20.9%), agricultural soils (13.0%), manure management (2.4%) and on-field burning is the crop residue (2.0%). Thus, the crop productivity sector (rice cultivation, soil and field burning of crop residues) contributes 35.9% to the total emission from agriculture. Therefore, reducing GHG emissions and enhancing the C sequestration in soil and biomass has become challenging. However, the total GHG’s emission from all sectors of the country has decreased from 33% in 1970 to 18% in 2010. Cutting off GHGs emission from agriculture can be achieved by sequestering C and reducing methane emissions(CH4) and carbon dioxide(CO2) through various soil and crop management strategies. Integrated nutrient management (INM) practice ensures the Soil –plant –atmospheric continuum (SPAC) in a  promising way, reducing the GHGs emission by sequestering more carbon to soil than emissions. A studious prominent INM solution can be identified to develop a mitigation strategy that helps in climate change adaptation and sustains soil health through soil carbon sequestration