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ThesisItem Open Access Assessment of agricultural vulnerability to climate change and enhancement of resilience through climate smart agricultural technologies in mid central table land zone of Odisha(Department of Soil Science and Agricultural Chemistry, OUAT, Bhubaneswar, 2022-12-27) Mohapatra, Kiran Kumar; Patra, Ranjan KumarOdisha, an agrarian state of India, is highly vulnerable to climate change. The present study attempts to develop an agricultural vulnerability index taking exposure, sensitivity, and adaptive capacity indicators for drought, flood, and climate change into account for 179 villages in the Tangi Choudwar block using the TOPSIS model. The village level agricultural vulnerability index for drought varied from 0.21-0.86, and twenty-five villages were categorized as "very high" to "highly vulnerable," 94 villages as "moderately vulnerable," 38 villages as low vulnerable," and 22 villages as very low vulnerable" to drought. Village level vulnerability mapping to flood showed that 14% of the villages were grouped under "low," 46% under "moderate," 21% under "high," and only 19% villages were under "very high" flood vulnerability. Sankarpur had the highest agricultural vulnerability to climate change (1.27), while Bandalo had the lowest (0.42). Village level vulnerability mapping to climate change showed that about 7% of the villages were grouped under "very low," 6% under "low," 27% under "moderate," 53% under "high," and only 7% of the villages were in the "very high" agricultural vulnerability index to climate change class. Further, it was attempted to develop a vulnerability reduction strategy by prioritization, implementation, and assessment of the impact of climate smart agriculture (CSA) technologies through resilience indexing. Of the 36 different CSA technologies, 18 technologies were highly preferred by expert judgments for Badakusunpur and Abhayapur villages. Among the CSA technologies, SRI-AWD (0.82) and DSR-AWD (0.68) methods of rice production had a higher climate smart index (CSI) than others. Global warming potential (GWP) was reduced by 25.5-27.5% in SRI-AWD and 19.9–22% in DSR-AWD as compared to farmer’s practices. Among the different rice-based cropping systems, the CSI was recorded the highest in the sunflower-rice (0.85) cropping system, followed by green gram/black gram-rice (0.80), maize-rice (0.76), and least in rice-rice (0.65). Intensification of rice crop with sunflower, black gram and green gram provided addition systemic yield of 2.24-2.95 Mg ha-1 calculated on the basis of REY. This also enhanced mean benefit cost ratio by 9.5 -12.3%, reduced system input energy consumption by 38.8 to 45.9%, and mitigated GHGs emission by 44.3 to 50.2% over rice-rice system. In sitespecific N management CSA practices, the customized LCC-based N management practices recorded the lowest greenhouse gas intensity (GHGI), which was 19.7–22.6% lower than the conventional method. Before implementation of CSA technologies, the agricultural resilience index was 0, which it increased to 0.41 and 0.36 during 2019–20, 0.46 and 0.40 during 2020–21, 1 and 0.44 during 2021–22 in Badakusunpur and Abhayapur villages after implementation of CSA technologies. The selected CSA technologies contributed to reduction of climate-induced vulnerability and increasing system resilience by strengthening the capabilities of various groups of farmers.ThesisItem Open Access Long-term effect of nutrient application on soil quality, resource use efficiency and crop productivity under rice-rice cropping system in Inceptisols of Odisha(Department of Soil Science and Agricultural Chemistry, OUAT, Bhubaneswar, 2022-09-26) Garnaik, Saheed; Samant, Prasanna KumarIn a 16-years long-term fertilizer experiment, an in-depth study was carried out to evaluate the changes in soil physical, chemical, and biological properties under long-term fertilizer application and to establish cause and effect relationship between soil properties and rice productivity using interpretable machine learning. There were 12 treatments involving control (without fertilizer application), 100% N (recommended dose of nitrogen), 100% NP (recommended dose of nitrogen and phosphorus), 100% PK (recommended dose of phosphorus and potassium), 100% NPK (recommended dose of nitrogen, phosphorus, and potassium), 150% NPK (50% higher nitrogen, phosphorus, and potassium than recommended), 100% NPK + Zn (recommended nitrogen, phosphorus, and potassium along with Zinc), 100% NPK + FYM (recommended nitrogen, phosphorus, and potassium along with farm yard manure (FYM)), 100% NPK + FYM + LIME (recommended nitrogen, phosphorus, and potassium along with FYM and lime), 100% NPK + Zn + S (recommended nitrogen, phosphorus, and potassium along with Zinc and Sulphur), 100% NPK + Zn + B (recommended nitrogen, phosphorus, and potassium along with Zinc and Boron) and 100% NPK + Lime (recommended nitrogen, phosphorus, and potassium along with lime). The long-term integration of organic manure with inorganic NPK fertilizers substantially increased grain yield (190%, kharif; 212.7%, rabi) and provided economic advantage (85.1%, kharif; 105.1% rabi) compared to control in a rice-rice sequence. Manure addition increased energy use efficiency, net energy gain, and energy profitability in kharif and rabi (41.8% and 77.1%, 208.4% and 266.3%, 51.1% and 108%) over control. Apart from this, the higher quantity of methane emission was assisted by farmyard manure application. As a result, the global warming potential was highest in NPK+FYM; 49.4% (kharif) and 40.2% (rabi) in comparison to control plot. Conditional random forest model was built, based on important variables selected using permutation based variable importance approach. Further, the accumulated local effect plot was used to establish cause and effect relationship between important soil properties and rice yield. Although most of the soil properties varied across the treatments, total potassium, protease, urease, and permanganate oxidizable carbon are the most important soil properties, which individually accounted for up to 400 kg ha-1 variation in the rice productivity. The study demonstrated how interpretable machine learning techniques can be used in long-term fertilizer experiments to unravel the most meaningful information and these techniques can be used in other similar long-term experiments.ThesisItem Open Access Soil carbon and nitrogen dynamics in an intensive cropping system of coastal agro-ecosystem under integrated nutrient management practices(Department of Soil Science and Agricultural Chemistry, OUAT, Bhubaneswar, 2022-10-28) Sahoo, Sanjib Kumar; Mishra, Kshitendra NarayanSoil is the primary source and sink of all nutrients exhibiting significant influence on crop growth. Long-term experiments are pivotal for properly studying the inter-relations between the soil-plant-environment complex. Long-term consistent application of various organic, and inorganic nutrient sources, microbial inoculants, and crop residues to soil may significantly influence the carbon and nitrogen cycling in the agroecosystems. Thus, the present investigation was carried out in an intensive cereal-vegetable-pulse cropping system to study the soil carbon and nitrogen dynamics in coastal agroecosystem under long-term integrated nutrient management (INM) practices at the end of the 9th cropping cycle of sweetcorn-knolkhol-blackgram cropping sequence in a long-term fertility trial. The experiment was laid out in a randomized block design with ten treatments and three replications. The soil samples were collected from three different soil depths viz. 0-15 cm, 15-30 cm, and 30-45 cm. The different nutrient management treatments followed in the current experiment are control, Soil Test Dose of fertilizers (STD), STD+Farm yard manure (FYM), STD+Vermicompost (VC), STD+FYM+ Biofertilizers (BF), STD+VC+BF, STD+FYM+BF+Lime (L), STD+VC+BF+L, 50% STD+BF and uncultivated fallow. The labile C fractions, viz. water extractable organic C, microbial biomass C, particulate organic C, permanganate oxidizable C, were significantly increased with the integrated application different nutrient sources. The active pool of carbon was found to contain 40-45% of total organic carbon (TOC), mainly attributed to the addition of organics, biofertilizers, and crop residues to the cropping system. The lability index and carbon management index were also found to be better in fully integrated packages indicating better soil quality. In the current experiment, alterations in soil management practices have influenced MBN/STN ratio to a greater extent. Among different nitrogen forms, only 10% of soil total N was found to be inorganic-N fractions, while rest 90% was in the soil organic N forms. Among the different organic nitrogen fractions, hydrolysable ammonium (HAN), amino acid-N (AAN), amino sugar-N (ASN), and unidentified hydrolysableN (UHN) constituted 23%, 31%, 7%, and 39% of total hydrolysable N fractions, respectively. Non-hydrolysable N and hydrolysable N fractions constituted 28% and 72% of soil organic nitrogen, respectively, due to the adoption of INM practices. Addition of organics (VC or FYM) with inorganics increased the coarse-macroaggregate by 26-33%, respectively, over inorganicsonly treatments at surface soil layer. Integrated use of inorganic fertilizers and organic manures (FYM, VC) along with bio-fertilizers, lime, and crop residues enhanced the carbon mineralization (Cmin), nitrogen mineralization (Nmin), C0, N0, and the rate of mineralization in the soils indicating the availability of more active C and N pools as indicated by higher C mineralization quotient and active N fraction in soil. In contrast, the treatments involving no external fertilizer inputs have the lowest C and N mineralization potentials. Integrations of organic manures, inorganic fertilizers, biofertilizers, and lime were found to be effective in promoting C-N cycling and sequestration in acidic Inceptisols, particularly under intensive cereal-vegetable-pulse cropping systems.ThesisItem Open Access Isolation and characterization of cellulose degrading bacteria and evaluation of their potency in composting(Department of Soil Science and Agricultural Chemistry, OUAT, Bhubaneswar, 2022-12-27) Padhan, Kshitipati; Patra, Ranjan KumarThe rapid increase in human population and accelerated economic has caused an exponential increase in waste generation. There are enormous municipal solid wastes (MSW) and agricultural by-product produces which caused environmental risk due to its treatment like land filling and burning. Composting is a technique which valorises the waste with limited environmental risk but takes longer duration but the shortage of lands and large volume of organic waste require these waste to be treated quickly. However, inoculation with lignocellulolytic bacteria could potentially enhance the organic degradation and reduce the composting time of the waste. In this context, present study aimed at isolating cellulose degrading bacteria and evaluating their potential in composting of different wastes. Initially 42 cellulose degrading bacteria have been isolated from different places like composting site, Dump yard, residue incorporated field, forest soil, gut of caterpillar on the basis of their hydrolytic capacity. Then 14 bacterial isolates having hydrolytic capacity of >3 were selected for the secondary screening. The cellulose activity of all the bacteria have been performed and five isolates with enzyme activity >25 U/mL taken for biochemical and molecular study for their identification. The genetic sequence of 16s rRNA of five isolates were submitted to National Center for Biotechnology Information (NCBI) and assigned accession no ON150745, ON178665 ON725042, ON479186 and ON142173 for CBD4, CBG3, CBG2, CBC9 and CBG4 respectively. The optimum CMCase production conditions of the strains showed that three strains (CBC9, CBD4 and CBG2) having higher stability in different range of pH and temperature and have been selected for composting. Three potential wastes ie: paddy straw, maize stover and vegetable waste were inoculated with the selected strains and the composting process was studied. The changes in C:N ratio, nitrification index (NI), Chemical oxygen Demand (COD), Cation exchange capacity (CEC) and enzyme activity (cellulose, dehydrogenase and β-glucosidase) was studied. The degradation potential of the three test isolates as evident from the reduction in C:N ratio, Nitrification index, chemical oxygen demand and increase in cation exchange capacity of degrading waste were in the order of CBG2 > CBD4 > CBC9. The recovery of compost was highest in case of paddy straw compost produced from CBG2 inoculation which was followed by vegetable waste and maize stover compost produced from same bacterial inoculation.ThesisItem Open Access Assessment of toxic elements in soil, water and crop grown in Narasinghpur block of Cuttack district, Odisha(Department of Soil Science and Agricultural Chemistry, OUAT, Bhubaneswar, 2022-12-31) Mohanty, Shraddha; Nayak, Rabindra KumarMetals are found naturally in the earth’s crust and their compositions vary among different localities, resulting in spatial variations of surrounding environment. The metal distribution in the biosphere is regulated by the properties of the given metal and by various environmental factors. Toxic elements and heavy metals contamination in soil, water and food crops are of serious concern due to their persistency in the environment and associated health hazard. It is difficult to destroy them biologically rather they transform from one oxidation state or complex to another form. Thus, toxic element contamination possess a potential threat to environment and human health. The present study investigated the toxic element content (Cd, Pb, Ni, Cr, Hg, As, F, Fe, Mn, Cu and Zn) in the soil, water and crop grown in Narasinghpur block of Cuttack district, Odisha. The pH of groundwater varied from 7.32 to 8.67. The content of fluoride ranged from 0.58 to 4.95 mg L-1 in groundwater of Narasinghpur block and 72% of ground water samples were beyond its permissible limit (1 mg L-1). Similarly, 59% and 36% of ground water samples were above its critical values for Cd (3µg L-1) and Pb (10 µg L-1) respectively. In the surface soil samples of Narasinghpur block total Cd and Pb content varied from 1.01 to 3.11 mg kg-1 and 34.39 to 62.23 mg kg-1 respectively. The findings of the study indicated significant enrichment of Cd and Pb in the surface soils over the local background values of the elements. The soils were categorized as slightly to moderately polluted based on different pollution indices with respect to Cd and Pb. As per the Risk assessment code (RAC), Cr, Ni, and Pb were of low to medium risk while Cd was at medium to high risk with Cd. The overall mean values of the heavy metals showed a decreasing order of Pb (48.62 mg kg-1) > Cr (4.28mg kg-1) >Ni (2.97 mg kg-1) > Cd (1.96 mg kg-1)>Hg (0.27 mg kg-1) >As (0.11 mg kg-1).The predominance of different fractions of Cd followed the order: residual > reducible (Fe-Mn oxide bound) > carbonate bound > exchangeable > oxidizable (organic matter bound). Multivariate analysis suggested the predominance of lithogenic influence on the content of Pb and Cd content in soils of Narasinghpur block. Risk assessment of heavy metals due to consumption of contaminated water and crops are reflected through several health risk indices, i.e. TF, HQ, HI, CR and TCR, which were found to be higher for children compared to adults. The build-up of Cd and Pb in the studied soils along with elevated fluoride content in the ground water is a matter of serious concern and needs proper monitoring and management strategies to avoid any potential detrimental effect on soil, crop and human health.ThesisItem Open Access Characterization, Taxonomic Classification and Fertility Status of Soils of Keonjhar District under North Central Plateau AgroClimatic Zone of Odisha(Department of Soil Science and Agricultural Chemistry, OUAT, Bhubaneswar, 2022-10-19) Dash, Prava Kiran; Mishra, AntaryamiSoaring food demand, population pressure, land degradation, shrinkage of agricultural lands, small size of agricultural land holdings, and diversified soil types in India warrant rapid soil assessments and digital soil mapping (DSM). In the present investigation, ‘Keonjhar’ district, which a topographically diversified tribal district of Odisha has been up taken as the study area for soil characterization, taxonomic classification, evaluation of soil fertility status, and preparation of digital soil maps using advanced geospatial technologies. For soil characterization and classification, 17 soil profiles of approximately 1m×1.5m×1.8m dimension were exposed, horizon wise peds were collected, processed, and analysed for morphological, physico-chemical, nutrient, and mineralogical parameters. Results revealed that soils were in general AC, A-Bt-C, and A-Bw-C profiles, sandy loam in soil texture, sub-angular blocky in soil structure, rich in ferruginous mottles, acidic, non-saline, low in mineralizable nitrogen (N), Bray’s phosphorus (P), available sulphur (S), medium to high in NH4OAc potassium (K), and sufficient in micronutrients. Quartz, orthoclase (K bearing feldspar), and Fe bearing minerals including hematite and goethite dominated the mineralogical composition of the soils. As per USDA Soil Taxonomy, soils have been classified under 13 subgroups (including five new subgroups for Odisha) and under 3 soil orders i.e., Entisols, Inceptisols, and Alfisols. Soils have been classified under the land capability sub-classes of IIs, IIIes, IIIsw, and IVes with soil limitations related to soil acidity, poor soil fertility status, soil erosion, and poor drainage conditions. For soil fertility status evaluation and DSM, 1,024 surface (0.30m depth) soil samples were analyzed for 14 soil properties viz., soil organic carbon (SOC), pH, electrical conductivity (EC), available N, P, K, S, exchangeable calcium (Ca), magnesium (Mg), available iron (Fe), manganese (Mn), copper (Cu), zinc (Zn), and boron (B). Soil fertility evaluation of the surface soils revealed that low SOC status, soil acidity, low available N, P, S, and deficiencies of Zn and B are the major soil related constraints of the surface soils. Therefore, application of suitable liming materials and balanced application of nutrients are recommended.Accuracy and economics of DSM are often influenced by sample size or sampling density. In this context, the present investigation has evaluated the impact of sampling density on prediction accuracy of DSM using two different mapping approaches viz., spatial interpolation and machine learning (ML). For this experiment, out of the 1,024 surface sample points, 800 were used for model calibration experiments and the remaining 224 were reserved for independent validation. The original calibration dataset (sampling density of 96 samples per 1,000 km2) was further subdivided into six subset sampling densities viz., 96, 48, 24, 12, 6, and 3 samples per 1,000 km2 by sequential removal of sample points from the original calibration dataset. Spatial interpolation was performed for each of the sampling density using ordinary kriging. Simultaneously, five ML algorithms viz., multi-perceptron regressor (MLP), random forest (RF), extra trees regressor (ETR), gradient boosting (GB), and CatBoost were tested using 574 covariates (remote sensing and digital terrain attributes) on the same set of six sampling densities. The results revealed that R2 for semi-variogram model fit improved with the increasing sampling density. Independent validation of the resultant maps revealed that Lin’s concordance correlation coefficients (CCCs) increased, and root mean square errors (RMSEs) decreased by increasing the sampling density. However, the rate of gain in each of the quality metrics decreased with each sequential improvement in the sampling density.ThesisItem Open Access Direct and residual effect of sulphur on rice-toria cropping system in rice fallow Alfisols of Odisha(Department of Soil Science and Agricultural Chemistry, OUAT, Bhubaneswar, 2022-07-16) Mishra, Ambika Prasad; Dash, A.K.A field experiment on “Direct and residual effect of sulphur on rice-toria cropping system in rice fallow Alfisols of Odisha” was conducted consecutively for two years (2018-19 and 2019-20) to address the state problem in rice-fallow areas constituting of 5.76 lakh hectare (10.8 % TCA) by accommodating rice-toria cropping system in farmer’s field located at Goindia block of Dhenkanal district. A cropping window of 25 days was created for the residual oilseed crop toria by replacing 170 days duration prevailing rice variety with 145 days, to utilise both the residual moisture as well as nutrients in the soil. The limiting nutrient sulphur (S) was low in status and was supplemented through four sources (Gypsum, Elemental Sulphur, SSP and Navaratna) and two methods of their application viz: basal and spilt method applied @ 30 kg ha-1 yr-1 through ten treatments. A mixture source of sulphur was prepared combining Gypsum and SSP in 1:1 ratio and was applied as basal. The soil test dose for N, P2O5 and K2O was common to all treatments (80-50-40) for rice and (40-20-20) for toria crop. The limiting nutrient S was only applied to the rice crop for both the years and its carry over effect was realised with the second crop toria. Deletion of S from fertiliser schedule resulted in 18.0 and 23.3 per cent decrease in total biomass and system productivity respectively. Sulphur application irrespective of sources increased the system productivity by 35 per cent compared to no -S application. The highest system productivity was recorded in the practice receiving ES0 (8.5 t ha-1) applied in spilt method. Spilt method of application of different sources of S proved superior to basal method of application. Based on the system productivity performance, the S sources followed the order: ES0 > Mixture source = SSP > Gypsum > Navaratna.The uptake of different nutrients (N, P, K and S) increased by 38, 48, 37 and 42 percent respectively as compared to no-S use under the influence of S supplementation. The use of mixture source influenced the uptake of these nutrients by 44, 57, 49 and 54 percent respectively as compared to no-S use. The partial factor productivity (PFP) under the influence of sulphur nutrition had increased the NPK uptake ranging from 24 to 60, 26.2 to 33 and 27 to 61 per cent respectively, depending upon the sources. Spilt application of different S sources increased the agronomic efficiency (AE), ranging from 32 to 47 kg from a level of 20 to 40 kg due to their basal application with an increase ranging from 27 to 50 per cent. The sulphur uptake efficiency (SUE) had increased to an extent of 15.1 percent irrespective of sulphur supplementation. The oil content (%) of toria due to residual S application was raised to a level of 39.2 per cent from 33.1 per cent in control practice. The grain quality of the rice crop viz: protein, cysteine and methionine irrespective of S application increased by 8.2 per cent, 15 percent and 16.8 per cent respectively. Among the different fractions of S in soil, the organic fraction (82.9 %) dominated over inorganic (10.4 %) and un-extractable one (6.7 %). There was depletion of S from the un-extractable fraction which was recovered more through inorganic fraction followed by the organic fraction. Among the inorganic fractions the, WS-S contributed maximum to system productivity (r=0.73**) and S uptake (0.88**). There was build of N, P, K and S nutrients status during the two years of cropping; however, the status of N and S remained still low but P and K high. The rupee earned per rupee investment was remunerative and positive under the influence of S application compared to the negative value of (0.98) for no-S use practice. In general there was increase of 57 per cent of the return over no -S use practice. The highest B: C was recorded with S source applied as ES0 (1.64) or mixture source (1.64) which followed the order as: ES0 = Mixture source > SSP > Gypsum > Navaratna. Thus, the rice fallow situation in the state of Odisha could be improved by accommodating two crops by adjusting the cropping window in rice crop and supplementing deficient nutrient like sulphur either by spilt application of sulphur sources or by customised source of Gypsum and SSP prepared in 1:1 ratio applied as basal @ 30kg ha-1 yr-1 to the main crop as sequence.ThesisItem Open Access Phosphorus dynamics in rice-rice system under long term manurial practice in Inceptisols(Department of Soil Science and Agricultural Chemistry, OUAT, Bhubaneswar, 2022-11-04) Shivhare, Sugyata; Rout, K.K.Investigation has been made for knowing the effect of long term manurial treatments on change in various phosphate fractions in different layers of soil, their contribution to P uptake under intensively rice producing system in an acidic Inceptisol. The work also included study on P supply parameter under the same situation. Phosphorus (P) is a limiting nutrient in many rice production areas, particularly in highly weathered soils in low latitude regions. Most arable soils cannot supply sufficient amount of the element to the crops. Although the total P content of soils may be large, only a small part of it is available for plant uptake Therefore P fertilizer is applied every season to overcome the deficiency. When fertilizer is applied to soil, only a small amount (10-30%) is taken up by the crop and a major part is not available to the present crop. Considering very low use efficiency of these fertilizers, more amount of the element than the actual requirement is very often applied through fertilizers every season. For this study a 13 year old ICAR funded long term fertilizer experiment with rice-rice production system at Bhubaneswar in an acidic (pH 5.8 ) Inceptisols was used. The experiment consisted of 12 treatments (Control, 100%N, 100%PK, 100%NP, 100%NPK,150%NPK, 100%NPK+FYM, 100%NPK+FYM+Lime,100%NPK+Zn,100%NPK+S+Zn, 100%NPK+B+Zn and 100%NPK+Lime) in 4 replications. The study was conducted during 4 seasons i.e., Rabi 2016-17, Kharif 2017, Rabi 2017-18 and Kharif 2018. Crop yield and post-harvest soil properties were measured for surface and subsurface soils. The crop yield, P uptake and relevant soil properties were determined by standard procedures. The P fractions were analysed by modified Kuo method of sequential extraction and adsorption-desorption study on soils of post-harvest, Rabi 2017-18 and Kharif, 2018 was done by using Langmuir adsorption isotherm, and supply parameter by Khasawneh and Copeland method. The relative contribution of P fractions to plant uptake was determined by Hierarchical partitioning method in R software. There was an accumulation of P on surface soil in all P fertilized treatments and depletion in P minus treatments. Depending on the P balance, the treatments differed significantly with respect to P accumulation. Highest P accumulation (841.92 kg ha-1 ) in surface soil was observed due to application of 150%NPK. The treatments viz. 100% NPK + FYM and 100% NPK + FYM + Lime had relatively less P built up than 100% NPK. The results revealed that after 13 years, the total P varied from 409.47 kg ha-1 to 719.24 kg ha-1 in Rabi and 447.95 kg ha-1 to 790.93 kg ha-1 in Kharif, as compared to initial status of 632kg ha-1 during 2005.The inorganic P fractions constituted 75.91 to 90.06% in Rabi and 69.56 to 89.77% in Kharif of total P and organic P, 9.94-24.03% in Rabi and 10.23%-30.25% in Kharif season. Among the inorganic fractions, Fe-P was the predominant fraction that varied from 143.52 kg ha-1 to 236.22 kg ha-1 in Rabi and 142.41kg ha-1 to 264.28kg ha-1 in Kharif, Sal-P was the lowest measuring 20.49 kg ha-1 to 57.57 kg ha-1 during Rabi and 21.61 kg ha-1 to 60.72 kg ha-1 during Kharif. The fractions in respect of their content were: Sal-P < Occl-P < Al-P < Ca-P < Red-P < Fe-P in surface and Sal-P < Occl-P < Al-P < Ca-P < Fe-P < Red-P in subsurface soils. With depth all the fractions of P followed a decreasing trend except Ca-P and Occl-P and there was no substantial seasonal variation among the fractions. The uptake and crop yield were found to be strongly correlated (0.979 *** in Rabi and 0.972*** in Kharif) with each other. Among the inorganic P fractions the relative contribution of Ca-P was highest in both the seasons. The contribution of different fractions was in the order: Ca-P (65.13%) > Sal-P(25.66%) > Occl-P (13.61%) > Al-P (8.74%) > Red-P (6.36%)> Fe-P (4.13%) in Rabi, and Ca-P (48.45%) > Occl-P (36.37%) > Sal-P ( 25.91%) > Al-P ( 11.78 %) > Red-P (2.59%) > Fe-P (2.19%) in Kharif. The total inorganic P contribution to P uptake was 80.85% in Rabi and 78.52% in Kharif season.Phosphorus balance study revealed that both apparent P-balance and true P-balance were positive in all the fertilized treatments and negative in control and 100% N treatment that received no P. A moderate P balance was maintained in the treatments (NPK + FYM or NPK + FYM + Lime ) as compared to optimal or super optimal doses of NPK, because of more removal through higher biomass production. Addition of 50% more phosphorus in 150% NPK treatment caused 36.57% more P accumulation than 100% NPK treatment. Season wise grain yield and P uptake poorly correlated with apparent P balance (r= 0.337 to 0.438), true P balance(r= 0.457 to 0.521) and total stock of P (r=0.457 to 0.521). Whereas the system sustainability strongly correlated with apparent P balance (r=0.694**, 0.583* and 0.609*), true P balance (r=0.724**, 0.628* and 0.660*) and total stock of P (r=0.724**, 0.628* and 0.650*). Thus true P balance and total stock of P in surface soil are better indicators of yield sustainability of each season and system as a whole. Study on adsorption-desorption of P in laboratory revealed that the adsorption maxima varied from 112.36 µg g-1 to 140.84 µg g-1 in Rabi and 84.74 µg g-1 to 129.87 µg g-1 in Kharif , intensity varied from 1.158 µg ml-1 to 1.68 µg ml-1 in Rabi and 0.98 µg ml-1 to 1.47 µg ml-1 in Kharif. The treatments with higher pH and higher SOC (100%NPK+FYM, 100%NPK+FYM+Lime) had lower adsorption maxima and higher concentration of P in soil solution (Intensity) because of presence of more negatively charged ions that compete with phosphate ions for adsorption. Supply parameter for P was found to be more in two high yielding treatments, 100%NPK+FYM and 100%NPK+FYM+Lime.The study demonstrates that integration of FYM @5t ha-1 with NPK is very important for enhancing Phosphorus availability to rice-rice system in acid Inceptisols. But further research is also necessary for optimising correct dose of P for recommendation where required P stock will be maintained without extra accumulation for optimum plant nutrition and sustainable crop production. In this study more emphasis has also been given to inorganic P fractions ,future research should aim at studying release of P from organic fractions of soil and subsoil.ThesisItem Open Access Optimization of Phosphorus management practices and duration of rice in rice-green gram cropping system for rainfed medium land rice fallow(Department of Soil Science and Agricultural Chemistry, OUAT, Bhubaneswar, 2023-02-22) Prusty, Meenakhi; Dash, A.K.In India, the most kharif rice growing areas (around 11.7 mha) remain fallow during rabi due to many biotic, abiotic and socio-economic constraints (Gummaet.al.,2016).Odisha also accounts 10% (12.2 lakh ha) of the rice fallow area of India. So efficient utilisation of the fallow land is the main concern for sustainable crop production. In this context pulses are considered to be an efficient crop for management of rice fallow area along with mitigation of pulse shortage and soil health management. Keeping this in view, the present study entitled “Optimization of Phosphorus management practices and duration of rice in rice-green gram cropping system for rainfed medium land rice fallow” was conducted at farmer’s field of Gajamara village, Dhenkanal during 2018-19 and 2019-20.The statistical design of the experiment was Split Plot with 4 main plot treatments viz., P1-100% of STD for P as basal to rice, P2- 100% of STD for P to both the crops,P3-50 % of STD for P to rice & 100% of STD for P to green gram, P4 -100% of STD for P of both the crops applied to rice with 3 subplots comprised of different rice varieties viz., V1-Mandakini, V2-Lalat and V3- Pratikhya.Significantly highest pooled system yield of 6.87 t ha-1 was recorded in P2 among the P management practices whereas highest system yield of 6.51 tha-1was observed with the treatment where green gram was sown after harvest of rice variety Mandakini. Similarly highest system N, P & K uptake of 122.17, 46.59 & 141.69 kg/ha respectively were recorded in the same treatment P2 whereas highest uptake of 115.79, 40.24 & 125.69 kg/ha respectively was recorded in the treatment where green gram was sown after harvest of rice variety Pratikshya.Duration of rice varieties have no significant effect on various nutrient harvest index factors. Among P management practices highest system Pi of 555.6 kg ha -1 was recorded in P2 whereas highest Pi value of 520.4 kg ha -1 was observed in treatment where gram sown after rice variety Pratikshya. Maximum net return of Rs.50, 058/- & Rs.58,220/- and B: C ratio of 1.66 &1.75 was obtained during 2018-19 and 2019-20 respectively in treatment where 37.5 kg P2O5/ha in rice & 50 kg P2O5 /ha in green gram was applied along with the soil test dose of N & K2O. Among duration of rice varieties highest B: C ratio of 1.74 & 1.78 was recorded in the treatment where green gram sown after Mandakini, during the year 2018-19 and 2019-20 respectively.
