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ThesisItem Open Access ASSESSMENT OF POTASSIUM USE EFFICIENCY IN TRANSPLANTED RICE(2021) Seema Bhagowati; Das, Kulendra NathPotassium (K) the third major essential plant nutrient with diverse roles to play in plant metabolism is required in large amount by crops and is the seventh most abundant element in the earth crust. The total K reserves are generally large in most soils but large portion of soil potassium (90 – 98%) remains chemically bound in the crystal structure of minerals and thus unavailable or slowly available for plant uptake. Based on availability to plants, potassium is categorized into four groups viz., water soluble, exchangeable, non-exchangeable/fixed and lattice K. Potassium supply to crop is a complex phenomenon involving relationships among various K fractions, potassium fixation and release patterns in soil and quantity-intensity relationships. Moreover, the net negative balance for K in current agriculture scenario is 69% which is very high as compared N (19%) and P (12%). This vast difference is partly because of crop removal where 1.5 times more K is removed than N and the application of potassium through fertilizer is considerably lower than that of N or P. Keeping these points in view, a study was carried out on “Assessment of Potassium use efficiency in transplanted rice” in Nagaon district which is famously known as the 'Rice bowl of Assam'. A series of laboratory analysis along with field experiments was carried out to assess the potassium use efficiency in transplanted rice. The soil of the experimental plot was analysed for salient characteristics such as texture including mineralogy of sand, silt and clay, pH, EC, OC, CEC, available NPK contents and various forms of K. An incubation study was conducted upon imposition of ten different treatments for a period of 150 days to know the availability of various forms of potassium in the soils at 20, 40, 60 and 90 days after incubation. After completion of incubation period, soils from various treatments were taken for study the release pattern of step K, constant rate K and cumulative K and fixation of potassium in these soils. Along with the incubation study, a field study was also conducted consecutively for two years with the same ten treatments in rice crop (var. Ranjit) with three replications in RBD design. Post harvested soils were analyzed for various physico-chemical characteristics and different K forms. Crop related data were recorded to study the effect of potassium management on growth and yield of rice. The texture of the soil of the experimental plot was clay loam with very strongly acidic pH (= 4.92). Initial status of SOC (0.91%) was high in upper surface (0-15 cm) and medium (0.65%) in lower surface (15-30cm), available N and P medium and K was low in upper surface and low available N and K and medium P was found in lower surface. X-ray diffraction study clearly indicates that clay fraction of this soil contains minerals like clay mica, mixed-layer minerals, vermiculite, smectite and kaolinite. Sand fraction is dominated by resistant minerals like quartz, zircon and weatherable minerals like mica, feldspars and chlorite and silt fraction contains same minerals as that of sand along with kaolinite. Initial water soluble K (WS-K), exchangeable K (Exch. K), non exchangeable K (Non Exch. K), lattice K and total K were 9.20, 41.00, 1020.00 8856.00 and 9480.00 mg kg-1 respectively in the upper surface (0-15 cm) of the soil. In the lower surface the values were 5.40, 28.40, 1454.00, 10222.00 and 10885.00 mg kg-1 respectively for WS-K, Exch. K, Non Exch-K, Lattice K and total K. In incubation study, where biofertilizers (T2 and T4) and organic manures (T9 and T10) were applied increase in WS-K was found with progression of the incubation period and in field study, it was highest with 21.35 mg kg-1 in the plot receiving T10 = INM Package (50% NP + Full K + 5t/ha Vermicompost) and was the lowest 8.17 mg kg-1 in the control plot. A perceptibly significant increasing trend of Exch-K was found, irrespective of the nutrient source except control treatment in incubated soil. In field condition, Exch. K corresponded to the amount of chemical K fertilizer applied and also to the INM package including microbial consortia and highest amount was observed in INM Package (50% NP + Full K + 5t/ha Vermicompost). Exchangeable K was found to be highly and significantly correlated with available K (r= 0.993**), non-exchangeable K (r=0.602*), total K (r=0.826*) and lattice K (r=0. 769**). With the increase in incubation time the non exch. K decreased in the treatments T2 = Microbial consortia (Azospirillum + PSB + KSB) @ 4 kg/ha, T4 = 100% RDF + KSB @ 4 kg/ha and T6 = Potassium nano-fertilizer @ 100 ml/1.2 L. Lower values of non-exchangeable K were recorded in all the treatments with different levels of potassium as compared to initial (1.020 mg kg-1) in the field experiment maximum being found in 100% RDF application. The increase of non exchangeable K in the control treatment with concurrent decrease in exchangeable K indicates the existence of dynamic equilibrium among different forms of potassium. Lattice K content of the treatments varied differently with different treatments but the changes were statistically insignificant in all the treatments in 40 DAI (Days after incubation) to 60 DAI and the changes was statistically at par in 60 to 90 DAI. Maximum amount of lattice was recorded in plot receiving 100% K fertilizer along with N & P fertilizers and INM components while lowest was recorded in plots which did not receive any fertilizer in field condition. The lattice K was significantly and positively correlated with available K (r= 0.791*), water soluble K (r=0.801**), exchangeable K (r=0.769*), nonexchangeable K (r=0.697*) and total K (r=0.865**). Increased levels of fertilizers brought about significant increase in total K content i.e. in the treatments where application of full dose of recommended fertilizers were done the total K tended to increase. In field condition, treatments where 100% K fertilizers were applied alone or in combination with INM components for 2 years continuously observed an increase in total K, highest being observed in T10 = 100% NP + Full K + 5 ton/ha Vermicompost) (11015.50 mg kg-1). Highly significant positive correlation values among various forms of K implied the existence of dynamic equilibrium. The amount of K released in successive extraction with boiling 1N HNO3 decreased step wisely in all treatments and reached to a constant level at 8th number of extraction. Reverse was happened in cumulative K. K release was higher in INM packages than plots received either organic or inorganic fertilizer alone. Cumulative K release was significantly correlated to lattice K (r=0.881**) suggesting that 1.0 mol L−1 HNO3 chiefly extracted K from nonexchangeable K pool in the soil. The amounts of step K of the treated soils ranged within a limit of 1837.0 to 3529.0 mg kg-1, which is high and thereby expected to be nonresponsive to K fertilization for a longer duration to the growing crops. The absolute amount of K fixed in soil progressively increased while percent K fixation decreased with increase in level of added K in all the treatments. Least percent K fixation was observed in T10 and the maximum in control. As this soil contains minerals like mica, vermiculite and smectite in clay fraction so K fixation is also high in this soil. Grain and straw yield was significantly affected by various treatments with the highest yield (= 56.22 q ha-1) in T10 which received 100% NP + Full K + 5 ton /ha vermicompost and the lowest in control. Yield was always better in INM package plots. Grain yield exhibited significant positive correlation with NPK uptake (r = 0.891**, 0.946** and 0.970**), water soluble K (r = 0.785**) exchangeable K (r = 0.897**) and available K (0.867**), suggesting their availability to rice crop. The highest potassium use efficiency (PUE) of 51.96% was found in the plot receiving 50% NP + Full K + 5 t/ha Vermicompost (T10) while the lowest of 40.49% in the plot receiving Potassium nanofertilizer @ 100 ml/1.2 L of water (T6) treatment. The information generated in the present study related to the status and distribution of different forms of potassium and its availability, releasing behavior and fixation evaluated through plant utilizable non-exchangeable K i.e. step K and constant rate K gave a general idea about the availability of K under the influences of varying doses of applied K and INM packages. Finally it can be concluded that INM Packages were found to be better for maintaining available K status, K release from none available pools and low K fixation in the soil and the resultant crop yield compared to inorganic treatments.ThesisItem Open Access ASSESSMENT OF ZINC USE EFFICIENCY IN MAIZE-MAIZE CROPPING SEQUENCE(2022) Borah, Sanjib Ranjan; Basumatary, AnjaliA field experiment was conducted at Krishi Vigyan Kendra, Jorhat farm, Kaliapani, Teok, Assam Agricultural University during 2018-19 and 2019-20 to study the influence of zinc fertilization on zinc fractions in soil, its relationship with important soil properties, yield, nutrient uptake and zinc use efficiency in maize-maize cropping sequence. The experiment was laid down in a randomized block design (RBD) with twelve treatments consisted of zinc applied as soil with or without foliar application through zinc sulphate and zinc oxide nano particle (ZnO NPs). Distribution of different zinc fractions in soil were assessed after harvest of each crop in the sequence. Perusal of experimental findings revealed that zinc fertilization had a significant influence on different zinc fractions in soil during both the years under investigation. The study revealed that among the zinc treatments, soil application of Zn @ 3.75 kg ha-1 in combination with foliar application of 500 ppm ZnO NPs exhibited the highest water soluble plus exchangeable-Zn content of 1.10 mg kg-1 in soil. The highest concentration of complexed-Zn (2.95 mg kg-1), amorphous sesquioxide-bound- Zn (4.11 mg kg-1), crystalline sesquioxide-bound-Zn (3.76 mg kg-1), residual-Zn (125.65 mg kg-1) and total-Zn (137.33 mg kg-1) were recorded in the treatment receiving soil application of Zn @ 7.5 kg ha-1. Among the zinc fractions studied, the concentration and percent contribution of water soluble plus exchangeable-Zn to total-Zn was the lowest while residual-Zn fraction contributed the highest to the total soil zinc pool. Path coefficient analysis showed that the water soluble plus exchangeable-Zn had the highest contribution towards the DTPA extractable-Zn in soil. The distribution of different zinc fractions at post-harvest soil was found in the following order: water soluble plus exchangeable-Zn < complexed-Zn < crystalline sesquioxide bound-Zn < amorphous sesquioxide bound-Zn < residual-Zn. All the fractions of zinc were found to be significantly and positively correlation with each other indicating existence of dynamic equilibrium of zinc in soil. Zinc fertilization exerted a significant influence on available nutrient status of soil. The highest available nitrogen content of 182.50 kg ha-1 was found in the treatment receiving soil application of Zn @ 3.75 kg ha-1 in combination with foliar application of 500 ppm ZnO NPs. The available phosphorus content in soil was decreased with zinc fertilization and thus, soil application of Zn @ 7.5 kg ha-1 recorded the lowest available phosphorus content of 19.45 kg ha-1, while the highest phosphorus content of 23.74 kg ha-1 was recorded in the control. However, no significant influence of zinc fertilization on available potassium, exchangeable calcium and exchangeable magnesium content in the post-harvest soils were observed. The highest available sulphur content of 25.50 kg ha-1 was registered in the treatment receiving soil application of Zn @ 7.5 kg ha-1. In respect of content of available micronutrients in soil, the DTPA extractable Fe, Cu and Mn content in soil were decreased with Zn fertilization and the highest content of DTPA extractable Fe (37.38 mg kg-1), Cu (0.42 mg kg-1) and Mn (9.26 mg kg-1) in soil was recorded in the control treatment, whereas, the lowest content was found in the treatment receiving Zn @ 7.5 kg ha-1. Application of 500 ppm ZnO NPs as foliar with soil application of Zn @ 3.75 kg ha-1 recorded significantly the highest DTPA extractable Zn content of 1.33 mg kg-1 in the post harvest soil. The study also revealed that zinc fertilization significantly influenced the grain and stover yield of maize. Perusal of pooled data indicated that among the zinc treatments, combined application of 500 ppm ZnO NPs as foliar with soil application of Zn @ 1.25 kg ha-1 registered the highest grain yield (65.04 q ha-1), stover yield (80.39 q ha-1) and harvest index (46.95%) in maize- maize sequence. Zinc fertilization exhibited a significant influence on uptake of major as well as micronutrients by maize. The highest uptake of nitrogen, potassium, calcium and magnesium by maize crops were recorded in the treatment receiving soil application of Zn @ 1.25 kg ha-1 in combination with 500 ppm ZnO NPs as foliar. The highest uptake of phosphorus by grain (14.81 kg ha-1) and stover (18.22 kg ha-1) was recorded in the treatment receiving 500 ppm ZnO NPs as foliar whereas, the highest sulphur uptake by grain (9.95 kg ha-1) and stover (11.72 kg ha-1) was found in the treatment receiving combined application of 500 ppm ZnO NPs as foliar with soil application of Zn @ 3.75 kg ha-1. Among the micronutrients, the highest uptake of Fe (214.56 g ha-1), Cu (31.99 g ha-1), Mn (56.33 g ha-1) and Zn (156.36 g ha-1) by maize grain was found in the treatment receiving combined application of 500 ppm ZnO NPs as foliar with soil application of Zn @ 1.25 kg ha-1. The highest uptake of Fe (846.24 g ha-1), Cu (45.99 g ha-1), Mn (248.57 g ha-1) and Zn (279.58 g ha-1) by maize stover was also found in the same treatment. Analysis of pooled data indicated that method of zinc fertilization had significant influence on zinc use efficiency by maize. The highest agronomic efficiency (2382.51 kg kg-1), apparent recovery efficiency (36.88%), zinc utilization efficiency (4067.44 kg kg-1) and partial factor productivity (16913.19 kg kg-1) was recorded in the treatment receiving foliar application of 500 ppm ZnO NPs. The highest physiological efficiency (12816.13 kg kg-1), agro physiological efficiency (7567.77 kg kg-1) was recorded in the treatment receiving combined application of 500 ppm ZnO NPs as foliar with soil application of Zn @ 1.25 kg ha-1. Cost benefit analysis revealed that among different treatment combinations, the highest gross return (Rs. 1,17,072.00), net return (Rs. 82,773.00) and highest B-C ratio (2.41) was registered in the treatment receiving 500 ppm ZnO NPs as foliar in combination with soil application of Zn @ 1.25 kg ha-1. Considering improvement of crop yield and economic return, combined application of 500 ppm ZnO NPs as foliar with soil application of Zn @ 1.25 kg ha-1 was found to be superior over other treatmentsThesisItem Open Access ASSESSMENT OF SOIL ERODIBILITY AND PRODUCTIVITY POTENTIAL FOR WINTER RICE IN A TRANSECT OF JIYADHOL RIVER BASIN, ASSAM(2021) Saikia, Rituparna; Patgiri, D. K.Soil erosion is a major environmental problem in developing countries like India, where agriculture is the main economic activity of the people. The present investigation aims to assess the soil erodibility and productivity potential for winter rice in a transect of Jiyadhol river basin with respect to landform characteristics, morphometry, erosion hazard and potential for growing rice. The study area extends from 27.335 N to 27.574 N latitudes and 94.294 E to 94.540 E longitudes, covering an area of 47,389.13 ha. Based on topographical variation in satellite data, four distinct landform units were delineated which includes: piedmont plain (9,097.69 ha), upper alluvial plain (9,594.9 ha) lower alluvial plain (13,706.57 ha) and flood plain (14,977.0 ha). The drainage map identified the transect as fifth order drainage basin with higher no‘s of first order streams making it vulnerable to erosion hazard. There was significant variation of slope, physiographic structure and infiltration capacity across the basin. The mean bifurcation ratio (3.56) indicated that the basin is underlined by uniform materials and streams are branched systematically. Relatively lower value of ‗Rho‘ coefficient indicated meager capacity of hydrologic storage during the period of floods that could leads to higher runoff. The relatively higher drainage density (0.91 km km-2) could be the results of impermeable subsoil material, sparse vegetation and high relief. The drainage intensity (0.43) indicated that the basin area was highly susceptible to flooding and gully erosion. The elongation ratio, circulatory ratio, form factor ratio and shape factor indicated that the shape of the studied transect was nearly circular. Such basins are highly erosion prone as compared to elongated basins. A total of 170 no of geo-referenced surface (upto 30 cm) soil samples were collected for analyzing soil physico-chemical, hydro-physical and fertility related parameters. There was a decreasing trend in total sand and very fine sand content in soils from piedmont plain toward flood plain. Whereas, silt and clay content increases from piedmont plain towards flood plain. The textural properties of studied soils varied from loamy sand to clay loam; sandy loam was the dominant texture. The structural properties of studied soils varied from sub angular blocky to massive. Among the different landform units the highest bulk density was recorded in the piedmont plain soils (Mean 1.5 Mg m-3). The pH in the studied soils varied from very strongly acidic to slightly acidic (4.69 to 6.47). 69.4% of the total area was strongly acidic and 4.3% of the area was very strongly acidic. Cation exchange capacity, exchange capacity of clay, apparent cation exchange capacity and exchangeable cations were higher in flood plain soil which may be linked to corresponding higher clay and soil organic matter content. Likewise, the status of soil organic carbon, available nitrogen, available phosphorus and available potassium was high in soils of flood plain. Soils of flood plain exhibited higher macro-aggregation owing to higher clay and soil organic matter. However, piedmont plain soils exhibited higher microaggregate content. Soil erodibility indices viz., silt clay ratio, clay ratio, modified clay ratio, dispersion ratio, erosion ratio showed that piedmont plain soils are more susceptible to soil erosion. The geospatial assessment of their variability clearly prioritizes the areas with higher erosion susceptibility, where, suitable management practices may be undertaken to increase soil productivity. The findings from erodibility indices were further corroborated by soil loss assessment by universal soil loss equation, which revealed that 38.5 percent area was under severe soil loss. The areas in higher elevation were under higher soil loss and vice versa. The piedmont soils, affected by very severe erosion hazard (average soil loss of 34.80 t ha-1 yr-1) which might be due to dominating factors like higher relief, steep slope, lighter texture and weaker structure, hence need immediate adoption of conservation measures. The soil productivity and potentiality index was evaluated as per the procedure suggested by Riquir et al. (1970). Piedmont plain soils having productivity index values from 12.1 to 35.1 (Mean 23.0) were rated as poor to average classes. The acidic pH, low organic matter, low base saturation and coarse texture being the major limiting factors for crop production. The piedmont plain (Mean 2.01) and upper alluvial plain (Mean 1.79) soils had more coefficient of improvement as compared to lower alluvial plain (Mean 1.60) and flood plain (Mean 1.57) soils. Majority of the piedmont plain soils are found to be unsuitable for growing Sali, Ahu and Boro rice and the corresponding yield of Sali rice was also quite low. Therefore alternate crops may be grown with suitable irrigation facilities. The negative relationship of soil loss with rice yield, productivity, potentiality and suitability indicated that greater soil loss leads to decrease in productivity of soils. The potential productivity index value was higher for piedmont plain soils. Significant positive relationship was obtained between normalized difference vegetation index during peak vegetative stage with yield, soil organic matter, mean soil site suitability index for Sali rice and crop yield index in the first year of study Summarizing above results it may be concluded that the Jiyadhol river basin transect is a fifth order watershed with high vulnerability to soil erosion. Majority of the soils of the study area have high soil erodibility owing to poor soil physical properties as well as topographical position. Geospatial assessment of soil loss has clearly delineated areas with severe soil loss, hence, based on this suitable conservation measures may be effectively adopted. Moreover, while formulating site specific crop management plan GIS based thematic maps of soil properties and erodibility may be taken as ready reckoner to augment productivity, profitability and sustainability of cropping systems in the area.ThesisItem Open Access SPATIAL ANALYSIS OF HEAVY METALS IN SOIL, PLANT AND GROUNDWATER IN NAGAON DISTRICT OF ASSAM USING GIS TECHNIQUE(2022) Hazarika, Prarthana Priyom; Medhi, Dr. B. K.Geospatial as well as geostatistical approaches using GIS tool to assess and characterize heavy metals namely Cd, Cr, Cu, Ni, Zn, Pb, Fe, As and Mn in soil, crop, and groundwater, their degree of pollution level, and phytoextraction behaviours of key metals were carried-out in Nagaon district of Assam during 2018 to 2021. To appraise the potential heavy metal sites, a random systematic method was used for sampling strategy by dividing the study area into a grid of 5 km× 5 km and collecting 160 composite soil samples from 0-15 cm depth for the total content of heavy metals using Atomic Absorption Spectrophotometer (Model: iCE 3500, Thermofisher). Geospatial analyses from different thematic maps of heavy metals revealed significant vulnerable points of elevated concentrations of Cd (> 0.31 mg/kg ), Pb (> 24.45 mg/kg ) and Ni (> 0.05 mg/kg ) in soils and Cd (>0.01 mg/L), Cr (>0.05 mg/L), Cu (>1.3 mg/L ), Fe (> 0.3 mg/L ), As (> 20 mg/L ) and Mn (> 0.1 mg/L ) in groundwater which is presumed to be due to anthropogenic factors. Geospatial interpolation pedagogies like Inverse Distance Weighted, Global Polynomial Index, Local Polynomial Index, Kriging, Kernel Smoothing and Diffusion Kernel were tested to estimate the metal concentrations at unsampled locations for assessment of their performance by comparing the Root Mean Square Error (RMSE) for cross-validation and all models provided more or less high prediction accuracy to mean value of the metals. Specific to the Kriging model, it was found to be best fitted with the lowest RMSE in all the metals except Mn and Ni in the soil where IDW and local Polynomial index was found to give the lowest RMSE. Other geospatial models that interpreted better groundwater heavy metals content with lowest RMSE were Inverse Distance Weighted Interpolation for Ni and Pb, Local Polynomial Index for Mn, Global Polynomial Index for Fe. The three-dimensional trend over the distribution of metals throughout the district best fitted the secondorder polynomial for Cd, Cu, Ni, Zn, Pb, Fe, As, and Mn in soils while both first and second-order polynomials according to XZ and YZ dimensions fitted well for Cd, Ni, Mn, Pb, Ni, and Cu in groundwater. Significant numbers of pairs of heavy metals to a certain extent were found to be spatially autocorrelated and all the pairs away from X-axis towards the extreme right corner and far above the axis reflected less influence of local characteristics of the heavy metal. Spatial autocorrelations were detected for 9 heavy metals and the autocorrelation distances were; Cd 60; Cr 60; Cu 60; Ni 55; Zn 57; Cu 55; Pb 65; Fe 68; As 62 and Mn 65 km for soil and Cd 60 Cr 57; Ni 65; Zn 57; Pb 60; Fe 65; As 57and Mn 60 km for groundwater. Co-variance cloud with search direction from North to South revealed the existence of spatial autocorrelation revealing a wider spatial shift of correlation towards the southern direction. The Pollution Indices (Single Pollution Index, Geo-accumulation Index, Ecological Risk Factor) showed the highest threat to the soil from Pb, Cd, and Ni respectively. Overall Multi Pollution Indices (Pollution Load Index, Average Single Pollution Index, Enrichment Factor, and Nemerow Pollution Index) encompassing all the metals showed that although there was considerable pollution in the soil, the soil was under the critical limit but towards the higher side. The Bio-concentration, Bio-accumulation, and Translocation Factor as was revealed from the pot culture experiment taking toria (variety TS-67) as test crop was found below 1 for all the graded levels of Pb envisaging the crop inefficient to hyperaccumulate, phyto-stabilize and phyto-extract Pb from the soil. A higher value of Bio-concentration Factor (>1) for Cd and Ni, revealed the crop efficiently hyper-accumulates Cd and Ni. BAF (>1) for Cd levels at 0.5 ppm, 1.0 ppm, and 1.5 ppm and Ni levels baring 60 ppm indicated the crop to be able to phytostabilises both Cd and Ni at lower concentrations. The Translocation Factor (< 1) for Cd and Ni was indicative of the inefficiency of toria to phytoextract Cd and Ni in its aerial parts. The study helped to find out the hotspots for certain heavy metals in the district which would certainly help in further decision making and take viable removal measures as well as suitable cropping systems. GIS maps validated through geostatistical approaches help in contributing contamination characteristics, degree of pollution of heavy metals in soils as well as groundwater based on which desired phytoremediation planning may be adopted.ThesisItem Open Access AGRO-PEDOLOGICAL ASSESSMENT OF THE TRADITIONAL AGARWOOD (Aquilaria malaccensis) GROWING AREAS OF UPPER BRAHMAPUTRA VALLEY ZONE, ASSAM(2022) Bordoloi, Anshuman; Dutta, SamironThe present investigation was carried out in some traditional Agarwood growing areas of the Upper Brahmaputra valley zone of Assam for pedogenic characterization of the soils and to evaluate the soil fertility status and microbial properties of soils around the Agarwood trees of high and low market values. The plant nutrient content and biochemical properties of the leaf of both types of trees were also determined and their relation with soil properties was assessed. An attempt was also made to evaluate the influence of different soil and plant properties on the quality of Agar trees of the area. To accomplish the objectives, ten locations were selected from three districts of the Zone. The highest number of locations (six) were selected in Golaghat district (Dhekial, Kakodunga, Naharani, Haanhpani, Podumoni, and Halowagaon) because of its largest area under Agarwood production. Out of the remaining four locations, two were selected in Jorhat (Alengi and Pirakota) and the other two were taken from Sivasagar district (Namti and Mathurapur). A soil profile was exposed in each location to characterize and classify the soils. Besides 120 numbers of composite surface (0-25 cm) and subsurface (25-50 cm) soil samples were collected from near the trunk of good and poor quality agar trees of all the locations. In addition to soil samples, equal numbers of plant samples were also collected from these trees for the present study. The soils were dark yellowish-brown to brownish-yellow in colour and loam to clayey in texture. The sand, silt, and clay content of the soil profiles varied from 28.1- 54.5%, 19.6 -37.3%, and clay 22.7-42.8% respectively. Soil structure was mostly weak to medium sub-angular blocky. The bulk and particle density of the soils ranged from 1.19 -1.59 Mg m-3 and 2.48-2.61 Mg m-3 respectively. The average water holding capacity of the soils was found to be greater than 30%. The soils were very strongly acidic to slightly acidic with a pH range from 4.79 to 6.60 and found to increase with the depth of soils. The organic matter content of the soils was invariably high (>0.75%) in the surface horizons which decreased regularly with the depth of soils. The free Fe and Al oxides of the soils varied from 1.43-2.93% and 0.37-0.85% respectively. Among the exchangeable cations Ca was the most dominant cation followed by Mg, Na, and K. The CEC of the soils was quite low with a range from 7.8 to 10.5 cmol(p+)kg-1. The exchange acidity, Total acidity, and extractable Al of the soils varied from 1.38 -3.37, 2.22-4.28, and 2.04- 3.35 cmol(p+)kg-1respectively. The exchangeable Al contributed more than 80% of the exchange acidity of the soils. The average Al saturation was found to be more than 30% in all the soils. The morphological and physicochemical properties of soils indicated the development of a cambic horizon in the studied soils. Based on these properties, all the soils were classified as Typic Dystrudepts at the subgroup level except soils of Namti and Mathurapur of Sibasagar district which were classified as Ruptic Alfic Dystrudepts due to higher base saturation in lowermost horizons. The properties determined in composite soil samples showed significant variation among the different locations. The pH and organic carbon of the surface and subsurface soils ranged from 4.97 -5.80 and 1.08-1.37% respectively. The available N and P of the soils were medium on the surface while low to medium in subsurface soils. The status of available K was low to medium. The Ca and Mg content of the surface soils varied from 2.05-2.38 and 1.03-1.40 cmol(p+)kg-1 and in subsurface they ranged from 1.66-3.04 and 0.71-1.10 cmol(p+)kg-1 respectively. The content of S, Fe, Mn, Zn, and Cu of all the soils irrespective of depth was found to be sufficient barring a few irregularities. The B content however was deficient in all the soils (< 0.50 mg kg-1). The MBC and MPS of the surface soils varied from 455.44-827.31 and 6.09-7.43 and 327.36-668.37 and 5.54-7.69 in subsurface soils respectively. Most of these parameters showed significant variation between the soils under good and poor quality Agarwood trees except N, Ca, Mg, S, Fe, and Mn of soils. The nutrient content of leaf, bark, and wood showed significant variation among different locations. The range of nutrients for leaf N, P, K, Ca, Mg and S were 2.12 – 2.475 %, 0.176- 0.187 %, 0.558-0.629 %, 0.367- 0.475 %, 0.275-0.282 % and 0.034- 0.052 % respectively. The N, P, K, Ca, Mg and S of bark ranged from 1.152–1.477 %, 0.060-0081 %, 0.396-0.491 %, 0.329-0.446 %, 0.127-0.180 % and 0.019-0.028 % respectively. Similarly in wood these nutrients varied from 0.315- 0.516%, 0.062 - 0.081 %, 0.147 to 0.208 %, 0.231- 0.365 %, 0.120 – 0.226 % and 0.014-0.020% respectively. It was observed that the difference in concentration of the nutrients in soil under trees with good and poor health differ significantly and was found to be higher in soils under the tree with poor health. A similar observation was also made in the biochemical properties of the leaf. A significant relationship was observed between the plant nutrient concentration and nutrient content of soils. The biochemical properties also showed an identical relationship barring a few exceptions. An attempt was made to evaluate the influence of different soil properties, plant nutrient concentration, and biochemical properties on the quality of Agarwood trees through PCA. The PCA identified MBC, microbial population, the content of Zn, Cu, available P, available K, and organic carbon as the major soil factor that might have played crucial role in determining the quality of Agarwood trees. In addition to these soil factors, the nutrient concentration of bark and wood, concentration of secondary nutrients in leaf, and biochemical properties like total carbohydrate, chlorophyll-A, total chlorophyll, and residual sugar might be the other important plant factors determining the resinwood quality of Agarwood trees. Interestingly the content of all these properties identified through PCA was higher in the soils collected from near the trunk of trees with poor health and the plant samples collected from such plants. The pH and content of Zn in surface soils, MBC, and microbial populations were an exception.ThesisItem Open Access SOIL NUTRIENT ASSESSMENT AND GHG EMISSIONS OF PUDDLE RICE SOILS UNDER INTEGRATED NUTRIENT MANAGEMENT PRACTICES(AAU, Jorhat, 2020-05) Gogoi, Bhabesh; Borah, NilayThe present work was carried out during 2016-2018which forms a part of the long-term Permanent Plot Experiment on Integrated Nutrient Supply System in Cereal Based Cropping Sequence laid out during 1987-1988 under All India Coordinated Research Project on Integrated Farming System at Assam Agricultural University (AAU), Jorhat. The experiment was laid out in a randomized block design at Instructional-cum- Research Farm, Assam Agricultural University, Jorhat replicating 3 times with 8 treatment combinations viz.,T 1 : no fertilizer, no organic manure (control), T 2 : 100% RDF (chemical), T 3 : 50% RDF (chemical) + FYM @ 2.5 t/ha for winter rice and 100% RDF (chemical) for autumn rice, T4 : 75% RDF (chemical) + FYM @ 1.25 t/ha for winter rice and 75% RDF (chemical) for autumn rice, T 5 : 50% RDF (chemical) + rice stubble @3.0 t/ha for winter rice and 100% RDF (chemical) for autumn rice, T 6 : 75% RDF (chemical) + rice stubble @1.5 t/ha for winter rice and 75% RDF (chemical) for autumn rice, T 7 : 50% RDF (chemical) + Azolla @ 0.5 t/ha for winter rice and 100% RDF (chemical) for autumn rice, T 8 :75% RDF (chemical) + Azolla @ 0.25 t/ha for winter rice and 75% RDF (chemical) for autumn rice. Results revealed that the application of 50% RDF (chemical) + Azolla @ 0.5 t ha-1 in case of winter rice and 100% RDF (chemical) in case of autumn rice (i.e. T7) showed the highest NH4-N, NO3-N and available N content in soil followed by the application of 50% RDF (chemical) + FYM @ 2.5 t ha-1 in winter rice and 100% RDF (chemical) in autumn rice (i.e. T3) in case of the rice-rice sequence after 32 cycles of the cropping. On the other hand, different fractions of P (viz., available P, Occluded P, Saloid P, Ca-bonded P and total P) and K (viz., water soluble K, available K, exchangeable K, non-exchangeable K, lattice K and total K) were found maximum in case of T3 followed by T5. Different fractions of C in rice soil were increased and varied significantly due to INM practices over unfertilized control (T1). The total organic carbon (TOC), total inorganic carbon (TIC) and total C was found to be highest in case of T3; whereas, the highest content of Walkley & Black C, less labile C and non-labile C in soils were recorded in case of T5. Yet again, T7 [50% RDF (chemical) + Azolla @0.5 t ha-1 in winter rice and 100% RDF (chemical) in autumn rice] was registered with the maximum content of water soluble C, microbial biomass C, very labile C and labile C in the soils underricerice system. In this study, all the fractions of NPK and C were found to be lowest in T1 (unfertilized control) treatment. The sensitivity index revealed that the microbial biomass C and water soluble C fractions were the most sensitive ones for different nutrient management practices as compared to other C fractions under study; whereas, the lowest sensitive fractions included non-labile C, less labile C, total inorganic C, total organic C andtotal C. Data on SOC stock due to INM practices varied significantly from 39.11 Mg ha-1 under T1 (unfertilized control) to 67.14 Mg ha-1 under T3(receiving FYM @2.5 t ha-1 + chemical fertilizers).The soil C sequestration ranged between (-)2.77 Mg ha-1 under T1 and 24.07 Mg ha-1 under T3. Over the control treatment (T1), 41.81 to 71.67% build up of C in the soils were recorded due to various INM treatments after 32 years of rice-rice cropping sequence. In this study, the highest bacterial population was recorded in case of T7(receiving Azolla @0.5 t ha-1 + chemical fertilizers); whereas, fungal population was found maximum in case of T3 (receiving FYM @2.5 t ha-1 + chemical fertilizers). Various 6 soil enzymes viz. dehydrogenase (DHD), phosphomonoeaterase (PMEase), fluorescein diacetate (FDA) and urease, involved in energy flow and nutrient cycling showed significantly higher activities under INM treatments. Significantly highest activity of DHD and urease was found in T7, while PMEase and FDA hydrolysis activities were found to be maximum in T3.There was a decrease in all the enzymatic activities over initial in the unfertilized control treatment (T1) after 32 years of rice-rice cropping. The pattern of CO2, CH4 and N2O emissions under rice-rice cropping system varied significantly with the stages of rice growth as well as by the different INM treatments under study. The CO2 and CH4 emissions peaked at 60 days after transplanting (DAT) of winter rice (cv. Ranjit) and 45 DAT of autumn rice (cv. Disang). On the other hand, N2O emission peaked first at 30 DAT and secondly at 60 DAT of winter rice (cv. Ranjit) in case of all the treatments except unfertilized control. However, only one N2O emission peak was observed at 45 DAT in case of autumn rice (cv. Disang) under study. The highest emissions of CO2 and CH4 during winter crop (cv. Ranjit) were observed in case of T5 receiving rice stubbles @3.0 t ha-1 + chemical fertilizers. In contrast, N2O emission during winter crop cv. Ranjit initially (up to 45 DAT) was found to be highest in case of the T2 (100% RDF, chemical); and afterwards, highest N2O emission was observed in case of T7 receiving Azolla @ 0.5 t ha-1 + chemical fertilizers. In case of autumn rice (cv. Disang), the maximum emissions of CO2, CH4 and N2O were recorded in T5(receiving rice stubbles@3.0 t ha-1 + chemical fertilizers). The lowest CO2, CH4 and N2O emissions were recorded in T1. It was evident in this study that the GHG emissions for the control (T1) and for Azolla cover + chemical fertilizer treatments (i.e. T7 and T8) were relatively low and similar during the initial stages of winter rice cv. Ranjit (up to 60 DAT) and autumn rice cv. Disang (up to 30 DAT). Among all the organic sources, supplementation of Azolla along chemical fertilizers resulted maximum reductionin GHG emissions from rice-rice system over FYM and ricestubbles. Pearson correlation matrix between the GHGs indicated that the emission of CO2 had a positive and significant correlation with CH4 (r=0.874**)and N2O (r=0.748*)emissions from the rice-rice cropping system. However, the correlation between the CH4 and N2O emission was positive and non-significant (r=0.623NS)in this study. Significant and positive correlation of CO2 and CH4 emissions from rice-rice cropping system were recorded with different fractions of C viz., WSC, WBC, MBC, VLC, LLC, LC, NLC, TOC and TC. The correlations of N2O emission with NH4-N, NO3-N and available N were found to be significant and positive; whereas, it was positive but nonsignificant with total N in soil. Likewise, microbial activities, enzymatic activities in soil and yield and yield attributing characteristic of rice crop were positively correlated with the emissions of CO2, CH4 and N2O from the rice-rice system of cropping. Yet again, in this study, GHGs were found to have not significant correlation with the plant height of rice crop. Overall, the findings of the present study lead to the conclusion that application of 50% RDF (chemical) + rice stubbles @ 3.0 t ha-1 in winter rice (cv. Ranjit) followed by 100% RDF (chemical) in autumn rice (cv. Disang) i.e. T5 could be considered as the best nutrient management practice for the rice-rice sequence in terms of highest yield (7.27 Mg ha-1), gross return (67.72 ×103 Rs. ha-1) andnet return(39.79 ×103 Rs. ha-1)with a B:C ratio of 2.42 in one way, enhancing the soil health under long run condition, in other. However, so far as the issue of GHG emission and global warming is concerned, application of 50% RDF (chemical) + FYM @ 2.5 t ha-1 in winter rice and 100% RDF (chemical) in autumn rice (2nd best treatment in terms of soil properties and yield with the B:C ratio 2.41) may be considered as better option for rice-rice cropping system under the prevailing climatic condition of Assam.ThesisItem Open Access MORPHOMETRY, SOIL ERODIBILITY AND PRODUCTIVITY POTENTIAL OF A TRANSECT OF MORIDHAL RIVER BASIN IN DHEMAJI DISTRICT OF ASSAM(AAU, Jorhat, 2020-08) Bharteey, Prem Kumar; Deka, BipulThe present investigation was carried out to study the morphometry, soil erodibility and productivity potential of Moridhal river basin in Dhemaji district of Assam. The Moridhal watershed, encompassing 30,730 ha geographical area, is situated between 94052 E to 94069 E longitude and 27038 N to 27064 N latitude. Based on total variation in satellite data (Resourcesat-2, LISS-4), four distinct physiographic units of the Moridhal watershed were delineated which includes: upper piedmont plain (1,844 ha), lower piedmont plain (2,391 ha), alluvial plain (9,888 ha) and flood plain (16,607 ha). The stream order map of the Moridhal river basin was prepared by on screen digitization using Q GIS software and the morphometric parameters were evaluated through measurement of linear, areal and relief aspects. The drainage streams were delineated up to 4th order with stream numbers of 36, 14, 5 and 1, for I, II, III and IV order, respectively. The mean bifurcation ratio and Rho coefficient for the Moridhal watershed was computed to be 2.22 and 0.41, respectively. The computed value of aerial aspects like elongation ratio, circulatory ratio, form factor ratio and shape factor revealed elongated shape of the watershed area. The studied relief aspects include parameters like basin relief, relief ratio, ruggedness number, and relative relief. The calculated value of ruggedness number (0.03) and relative relief (0.055 per cent) indicated higher infiltration and lower runoff in the studied area. GPS based surface and core soil samples representing different physiographic units were collected and analyzed for various physico-chemical properties. The texture of the studied soils varied from loamy sand to clay, sandy loam being dominant. There was an increasing trend of very fine sand and silt content from upper piedmont plain to floodplain. The bulk density and particle density of studied soils varied from 1.10 to 1.67 Mg m-3 and 2.16 to 2.74 Mg m-3, respectively. The value of porosity, water holding capacity and hydraulic conductivity of the studied soils ranged from 24.99 to 54.68 per cent, 19.88 to 63.12 per cent, and 0.11 to 6.54 cm hr-1respectively. Field capacity and available water content showed significant positive correlation with clay content and porosity, while permanent wilting point exhibited significant positive correlation with sand content. The pH of the soils was extremely acidic (4.2) to slightly acidic (6.3). The electrical conductivity in the studied soils varied from 0.01 to 0.16 dS m-1 which was almost negligible. The cation exchange capacity of the studied soils varied from 3.88 to 19.40 cmol (p+) kg-1 with a mean value of 9.69 cmol (p+) kg-1. Amongst the exchangeable cations, Ca++ was found to be the dominant in the studied soils followed by exchangeable Mg++, K+ and Na+. The exchange capacity of clay and apparent CEC showed wide variation in the studied area. The base saturation varied from 33 to 83 per cent and the organic matter content was medium to high (range 5.50 to 29.60 g kg-1). The available N, available P2O5 and available K2O content varied from low to high with a range between 137.98 to 570.75 kg ha-1, 18.47 to 67.20 kg ha-1 and 37.23 to 549.16 kg ha-1, respectively. The nutrient index for available N, P2O5 and K2O were found to be 1.88 (Medium), 2.15 (Medium) and 1.32 (Low). The principal factor analysis, which was carried out using 35 characters, could explain 71.20 per cent of the total variance with the seven number of extracted eigen values. There was an increasing trend of macroaggregate from upper piedmont plain (mean 24.9 per cent) to flood plain soils (mean 47.4 per cent). The microaggregate in the studied soils varied from 17.8 to 89.8 per cent and the mean weight diameter ranged between 1.00 to 2.74 mm. The erodibility of the studied soils was assessed by computing various erodibility indices like clay ratio, silt clay ratio, modified clay ratio, dispersion ratio, erosion ratio and erosion index. The mean value of clay ratio, silt/clay ratio and modified clay ratio were found to be 4.02, 1.35 and 3.63, respectively. The dispersion ratio of the soils varied from 0.06 to 1.18 with a mean value of 0.19. It was observed that 48.82 per cent of the total studied soil samples had dispersion ratio values above 0.15 which may be considered as erodible. The erosion ratio and erosion index of studied soils varied from varied from 0.01 to 0.55 and 0.03 to 0.71, respectively. It was observed that almost all the studied physico-chemical properties influenced the erodibility indices to a great extent. The soil loss varied from very slight to very severe (range 0.87-67.77 t ha-1 yr-1) with a mean value of 16.19 t ha-1 yr-1. A significant positive correlation of soil loss was noticed with very fine sand (r = 0.229**), silt (r = 0.212**), microaggregate (r = 0.351**) and relief (r = 0.711**). The studied soils exhibited a decreasing trend of soil loss from upper piedmont plain towards flood plain. The productivity indexes of the studied soils varied from 12.13 to 62.14 with a mean value of 35.22. The potentiality index and coefficient of improvement values of studied soils varied from 41.04 to 90.25 and 1.11 to 4.69, respectively. Soil site suitability criteria for crops viz., Sali rice, Ahu rice, Boro rice, wheat, mustard/rapeseed, sesame, pea, potato, onion and coconut were evaluated. The study revealed that the soils were permanently unsuitable (N1) to moderately suitable (S2) for Sali rice, Ahu rice, Boro rice, wheat, pea, mustard/rapeseed, sesame, potato, onion and coconut. Major constraints identified in the watershed lies in acidity, organic carbon, texture, flooding, drainage and low precipitation in early growth stage during rabi season. GIS based maps for various themes like pH, organic matter, available N, available P2O5, available K2O along with soil loss, productivity, potentiality, and soil-site suitability for studied crops were also prepared to depict the spatial distribution under different classes.ThesisItem Open Access CHANGES IN SOIL BIOLOGICAL PARAMETERS AS EFFECTED BY THE APPLICATION OF ORGANIC INPUTS IN RICE-TORIA SEQUENCE(AAU, Jorhat, 2019-07) Chauhan, Manoj Kumar; Baruah, RajenThe field trials were conducted to assess the changes in soil chemical and biological parameters along with yield and yield attributing characters of rice and toria crops in sequence during 2015-17. The treatment combinations were as Control (T1), 50% recommended dose of fertilizer (RDF)+50% biofertilzer (BF) (T2), 50% RDF+50% Enriched Compost (EC) (T3), 100% RDF (T4), 100% BF (T5) and 100% EC (T6). The data were recorded at various stages of crop growth and soil samples were analysed for different characters at different stages of rice and toria crops. The results showed that the treatment T3 consisting of 50% EC and 50% RDF recorded the highest accumulation of N (265.49 and 258.01 kg/ha), P (23.14 and 23.00 kg/ha), and K (152.94 and 148.38 kg/ha) at maximum tillering stage of rice and flowering stage of toria, respectively but remained at par with 100% RDF treatment in both the crops during the period of investigations. The accumulation of organic carbon (12.49 g/kg soil in rice and 12.14 g/kg soil in toria) was recorded significantly higher than 100% RDF treatment (11.01 g/kg soil in rice and 10.60 g/kg soil in toria) at similar stages of both the crops which remained at par with 100% EC (T6) treatment. Soil accumulation of Organic carbon (OC), N, P and K was found higher in T6 treatment over T5 treatment. However, soil accumulation of OC, N, P and K gradually declined from maximum tillering stages of rice and flowering stage of toria to harvesting stage of both the crops. Although no significant changes in soil pH was recorded, but the lowest pH was recorded in T4 treatment in both the crops ranging from pH 5.19 to pH 5.22, even lower than the initial soil pH value of 5.24. The results revealed that the bacterial, fungal and actinomycetes population varied with the treatments and with the stage of the crops. The treatments comprising of 50% EC and 50% RDF (T3) recorded the highest bacterial population of 19.63 cfu x105/g and 19.25 cfu x105/g soil at flowering stages of rice and toria, respectively. The fungal population was 9.12 cfu x105/g soil in rice and 8.88 cfu x105/g soil in toria, respectively. The actinomycetes population was 45.75 cfu x104/g soil in rice and 45.12 cfu x104/g soil in toria at flowering stages of rice and toria crops and declined thereafter at harvesting stages of both the crops. The microbial diversity in T3 and other organic treatments found significantly higher than 100% RDF and control treatment. Soil respiration, microbial biomass carbon, and soil enzymes (fluorescein di-acetate activity, dehydrogenase activity, acid phosphatase activity and urease activity) behaved differently with different treatment whereas T3 (50% EC + 50% RDF) exhibited the best performance over other treatments at all the stages of rice and toria crops during both the years. All the biological parameters were found at their peak at flowering stages and declined thereafter at harvesting stages of both the crops. All the bio-chemical properties in treated plots in rice-toria sequence were found significantly higher than the untreated control and even over the initial values of each parameters. Unlike soil bio-chemical properties, agronomic parameters of rice (no. of tillers/hill, plant height, panicle length, grain and straw yield) and toria (plant height, no. of siliqua/plant, grain and stover yield) crops recorded higher values in 100% RDF (T4) treatment which remained at par with, 50% EC + 50% RDF treatment (T3). The grain yield of rice (45.09 q/ha) and toria (893.38 kg/ha) in the 100% fertilized plots (T4) were found at par with T3 treatment (43.72 q/ha in rice 885.63 kg/ha in toria) receiving 50% EC and 50% RDF, but both recorded significantly higher yield over sole application of biofertilizer, enriched compost and control treatment. The beneficial effect of INM treatment (T3) that facilitated favourable soil conditions were reflected in grain yield of both rice and toria crops which was equivalent even with 100% RDF treatments. Rice yield was more closely and positively correlated (at p<0.05) with OC (r=0.587*), N (r=0.932*), P (r=0.746*) and K (r=0.972*) as compared to soil enzymes such as acid phosphatase (r=0.637*), urease (r=0.512*). Similarly, a strong relationship was also recorded among toria yield with OC, N, P and K and other soil biochemical properties. Furthermore, soil respiration and MBC exhibited strong relationship both in rice (r=0.961*) and toria (r=0.966*) crop. All the soil biological properties registered positive correlation with chemical properties of soil.ThesisItem Open Access ASSESSMENT OF CARBON FOOTPRINT IN RICE-RICE CROPPING SYSTEM AS AFFECTED BY FERTILIZER MANAGEMENT(AAU, Jorhat, 2019-07) Borah, Rupjyoti; Das, K.N.The present study aimed at assessing the carbon footprint in rice-rice cropping system as affected by various fertilizer management combinations and source of nitrogen was carried out in the ICR Farm, AAU (26°71'N, 94°18' E) 91.0 m above MSL during the years 2016-17 and 2017-18. The initial pH, organic carbon, available N, P2O5 and K2O of the experimental plot were 5.84, 0.61%, 132.561 kg ha-1, 214.48 kg ha-1 and 33.734 kg ha-1, respectively. There were no significant differences in soil pH amongst the variety while significant differences were observed within various fertilizer combinations and source of N. Soil organic carbon values ranged between 0.62 to 0.85% and significant difference was observed amongst the fertilizer treatments and source of N. The various fertilizer combinations in case of available nitrogen also showed a similar trend with the highest mean value of 169.84 kg Nha-1 in the treatment with full recommended dose of fertilizer (RDF). Available P2O5 in the system also followed a similar trend (36.07 kg ha-1) while available K2O significantly varied within the varieties and fertilizer combinations with higher values in Mahsuri-Banglami system (49.94 kg K2O ha-1). Significant differences in methane emissions were observed amongst the varieties and also in between the fertilizer combination treatments.The methane emission was 388.33 mg m-2hr-1 in Ranjit-Lachit system and 285.61 mgm-2hr-1 in the Mahsuri-Banglami cropping system. High methane emission was observed in RDF followed by 50% RDF+Vermicompost and INM. During the entire crop growing season, the largest variation in methane emission was observed in the early growth period. Methane emission indicated two distinct peaks during the entire crop growth period, irrespective of the treatments. Peaks of nitrous oxide emissions were obtained after topdressing of nitrogenous fertilizers. Significant variations were also observed in between the fertilizer combination treatments may be due to varying organic carbon in the various treatments. Ranjit-Lachit system recorded higher mean cumulative N2O emissions (10.72 gm-2) than Mahsuri-Banglami system (4.92 gm-2). The RDF treatments recorded highest mean cumulative N2O emissions amongst the fertilizer combinations. Temporal pattern of flux irrespective of treatments showed a trend of gradual increase with the growth of the crop, thereafter a slow decline in fluxes. The highest mean cumulative CO2 emissions (2953.43 mg m-2) was recorded in the Ranjit-Lachit system and within the fertilizer combinations, the highest mean value of 3125.20 mg m-2 was recorded under RDF treatment. Mapping of the three different tiers of carbon footprint showed that the tier-1 was the dominant contributor of carbon footprint. The Total System Spatial Carbon Footprint (SCF) under different treatments recorded higher values in case of INM treatments involving 50%NP + Full K + 5t/ha enriched compost and vermicompost treatments in both the cropping systems. Within the INM treatments, higher SCF of 62.00 t CE ha-1 was obtained in Ranjit-Lachit system while in case of Mahsuri-Banglami system, the highest SCF was obtained in INM treatment with NCU and UCU (48.91 t CE ha-1). Yield scaled carbon footprint (YCF) indicated highest value of 13.23 kg CE kg-1 grain in case of Mahsuri-Banglami system while 50% RDF supplemented with 5 t ha-1vermicompost and uncoated urea recorded the highest YCF with 15.96 kg CE kg-1 of grain in Ranjit-Lachit cropping system. Considering the yield compensation and sustainability of the soil resources, the INM with slow release N source proved to be the better in rice-rice cropping system.