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Assam Agricultural University, Jorhat

Assam Agricultural University is the first institution of its kind in the whole of North-Eastern Region of India. The main goal of this institution is to produce globally competitive human resources in farm sectorand to carry out research in both conventional and frontier areas for production optimization as well as to disseminate the generated technologies as public good for benefitting the food growers/produces and traders involved in the sector while emphasizing on sustainability, equity and overall food security at household level. Genesis of AAU - The embryo of the agricultural research in the state of Assam was formed as early as 1897 with the establishment of the Upper Shillong Experimental Farm (now in Meghalaya) just after about a decade of creation of the agricultural department in 1882. However, the seeds of agricultural research in today’s Assam were sown in the dawn of the twentieth century with the establishment of two Rice Experimental Stations, one at Karimganj in Barak valley in 1913 and the other at Titabor in Brahmaputra valley in 1923. Subsequent to these research stations, a number of research stations were established to conduct research on important crops, more specifically, jute, pulses, oilseeds etc. The Assam Agricultural University was established on April 1, 1969 under The Assam Agricultural University Act, 1968’ with the mandate of imparting farm education, conduct research in agriculture and allied sciences and to effectively disseminate technologies so generated. Before establishment of the University, there were altogether 17 research schemes/projects in the state under the Department of Agriculture. By July 1973, all the research projects and 10 experimental farms were transferred by the Government of Assam to the AAU which already inherited the College of Agriculture and its farm at Barbheta, Jorhat and College of Veterinary Sciences at Khanapara, Guwahati. Subsequently, College of Community Science at Jorhat (1969), College of Fisheries at Raha (1988), Biswanath College of Agriculture at Biswanath Chariali (1988) and Lakhimpur College of Veterinary Science at Joyhing, North Lakhimpur (1988) were established. Presently, the University has three more colleges under its jurisdiction, viz., Sarat Chandra Singha College of Agriculture, Chapar, College of Horticulture, Nalbari & College of Sericulture, Titabar. Similarly, few more regional research stations at Shillongani, Diphu, Gossaigaon, Lakhimpur; and commodity research stations at Kahikuchi, Buralikson, Tinsukia, Kharua, Burnihat and Mandira were added to generate location and crop specific agricultural production packages.

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2018 - 20193
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Subject: Soil Sciences × End date: 2019 × Start date: 2016 × Type: Thesis × Thesis Type: Ph.D ×
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    ThesisItemOpen 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, Rajen
    The 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.
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    ThesisItemOpen 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.
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    ThesisItemOpen Access
    DYNAMICS OF ZINC FRACTIONS AND AVAILABLE NUTRIENTS AS INFLUENCED BY ZINC FERTILIZATION ON RICE CULTIVARS
    (AAU, Jorhat, 2018-07) Baishya, Bhupen Kumar; Basumatary, A.
    A field experiment was carried out at the Instructional-cum-Research (ICR) farm, Assam Agricultural University, Jorhat during Kharif season, 2014 and 2015 to study the influence of zinc fertilization on the dynamics of zinc fractions, available nutrients status in the soil and crop yield and quality of rice grain of different cultivars. The treatments consisted of zinc applied through soil with or without foliar spray and five different rice cultivars. Total of twenty treatment combinations were laid out in factorial RBD with three replications. Distribution of different zinc fractions in soil were assessed during different stages of crop period of rice. Perusal of experimental findings showed that zinc fertilization exerted a significant positive effect on different zinc fractions in the soil during both the years of investigation. Among zinc treatments, concentration of all the zinc fractions were maximum with application of Zn @ 5 kg ha-1 + 0.5% foliar spray of Zn over other treatments. The study revealed that the concentration of the water soluble plus exchangeable Zn, complexed-Zn and crystalline sesquioxide bound-Zn fractions showed a decreasing trend from tillering stage to the harvest stage of the crop, while, availability of amorphous sesquioxide bound Zn, residual-Zn and total-Zn fractions followed an increasing trend with respect to concentration with the advancement of time. Among the zinc fractions, water soluble plus exchangeable form made the lowest contribution while residual fraction made the highest contribution to the total zinc pool than other fractions of Zn at all the growth stages of the crop. At harvest, zinc concentration in various fractions of Zn in soil varied in the following order: watersoluble plus exchangeable < complexed < crystalline sesquioxide bound < amorphous sesquioxide bound < residual fraction< total zinc. There was significant positive correlation among the Zn fraction in soil indicating existence of dynamic equilibrium of Zn in soil. The available fraction of all nutrients was initially higher and gradually decreased with advancement of crop growth. The maximum availability was obtained at tillering stage and thereafter as crop age advanced nutrient availability decreased. Analysis of pooled data revealed that application of Zn @ 5 kg ha-1 in soil + 0.5% foliar spray resulted in higher availability of nitrogen, potassium, sulphur and DTPAZn in soil at different stages of crop and recorded highly significant and positive correlation with different zinc fractions. Availability of phosphorus, DTPA-Fe, DTPAMn and DTPA-Cu were decreased with zinc application and the lowest content was found at treatment Zn @ 5 kg ha-1 in soil + 0.5% foliar spray and exhibited a significant but inverse correlation with different zinc fractions. Zinc fertilization influenced the crop yield and nutrient uptake. Highest grain yield was recorded in treatment receiving Zn @ 5 kg ha-1 + 0.5% foliar spray of Zn (53.40 q ha-1) and the lowest was in control (38.69 q ha-1). Among the cultivars, variety JKRH-401 recorded the highest grain yield (64.27 q ha-1) whereas variety Kolajoha recorded the lowest grain yield (30.50 q ha-1). Among different treatment combinations, application of Zn @ 5 kg ha-1 + 0.5% foliar spray of Zn in combination with cultivar JKRH-401 recorded the highest yield (71.82 q ha-1) . The highest straw yield was recorded in treatment receiving Zn @ 5 kg ha-1 + 0.5% foliar spray of Zn. Among the cultivars, the highest straw was recorded in JKRH-401(71.22q ha-1) while, the lowest was found in Aghunibora(49.27 q ha-1). Uptake of nitrogen, potassium, magnesium and sulphur by rice was significantly influenced by Zn-fertilization and the highest was found in treatment with treatment receiving Zn @ 5 kg ha-1 and 0.5% foliar sprays of Zn over other treatments. On the other hand, in respect of copper and manganese, application Zn @ 5 kg ha-1 and 0.5% foliar spray of Zn resulted the lowest uptake during all crop growth period. The cultivars, JKRH-401 recorded the highest uptake of all the nutrients at all stages of crop growth. In economic terms, combined application of Zn @ 5 kg per ha and 0.5% foliar spray of Zn in combination with cultivars, JKRH- 401 recorded the highest gross return, net return and B:C ratio (2.96 ). Zinc fertilization had significant impact on the nutrient content in both brown and polished rice grains. The treatment receiving Zn @ 5 kg ha-1 + 0.5% foliar spray of Zn recorded the highest concentration of nitrogen, potassium, sulphur and zinc for both brown and polished rice. Protein content was found to be the highest in treatment receiving Zn @ 5 kg ha-1 + 0.5% foliar spray of Zn and cultivar JKRH-401 exhibited the highest content of 10.71 % and 8.75 % in brown and polished rice, respectively. Highest amylase content (18.73 % and 20.42 %) was observed in same treatment and the cultivar Kolajoha recorded the highest amylase of 22.52 % and 24.16% in brown and polished rice, respectively.