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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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20181
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Subject: Soil Science × Author: Choudhury, Muqsitur Rahman × End date: 2019 × Type: Thesis × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    SOIL FERTILITY EVALUATION IN KARIMGANJ DISTRICT OF ASSAM UNDER DIFFERENT LAND USE SYSTEMS
    (AAU, Jorhat, 2018-03) Choudhury, Muqsitur Rahman; Dutta, Samiron
    The present investigation was carried out to evaluate soil fertility status of Karimganj district of Assam under various land use systems. A total of one hundred twenty geo-referenced composite soil samples were collected from twelve different land use systems of the district. The results revealed a wide textural variation ranging from silt loam to clayey in the studied soils. The sand, silt and clay content of the soils varied from 6.3-64.5%, 7.0-59.7% and 11.2-41.3%, respectively. The clay was found significantly higher in rice based land use systems and lower in plantation based land use systems. The mean values of bulk density varied from 1.22 to 1.32 Mg m-3 in rice based LUS, 1.28 to 1.48 Mg m-3 in arable LUS and 1.20 to 1.36 Mg m-3 in plantation based LUS. Bulk density was significantly higher (1.48 Mg m-3) in uncultivated land use system and lowest (1.20 Mg m-3) recorded in forest. The mean values of particle density of the soils under all the land use systems ranged from a minimum value of 2.22 (± 0.06) Mg m-3 in forest land use to a maximum of 2.67 (± 0.07) Mg m-3 in arecanut land use system. Porosity was greater than 50% in soils under Tea and Rubber plantation and the mean value ranges from 45-50 % except in abandoned jhum land. Soil pH was found to be very strongly to moderately acidic (4.81-5.78). Barring the soils under Tea, abandoned jhum and forest, most of the soils have mean pH values more than 5.0. Organic carbon content of soils under all the land use systems was medium to high. It was highest in forest followed by abandoned jhum, tea, rubber and rice-vegetable LUS. Similar trend was also noticed in total organic carbon content of the soils. The EC of the soils was recorded as normal (< 1 dS m-1) and the variation was minimum for all the soils of twelve land use systems. The mean values of total exchangeable cations (TEC) under all the land use systems ranged from 1.22 (± 0.15) cmol(p+)kg-1 in tea land use system to 4.44 (± 0.47) cmol(p+)kg-1 in forest land use system. TEC was mostly influenced by clay content and pH of the soils. CEC of the soils ranged from 7.8 to 10.8 cmol(p+)kg-1and found to be mostly regulated by clay fraction of the soils. It was significantly highest in Forest LUS which was at par with rice-vegetable [10.6 cmol(p+)kg-1] and rice-fallow [10.3 cmol(p+)kg-1] systems. The percent base saturation of the soils in most of the LUS varied from 30 to 40%. Soils under Tea and Rubber plantation showed exceptionally lower values (< 20%). The available nitrogen content of the soils varied significantly from 183.1 to 477.7 kg ha-1. It was found medium only in four LUS (forest, abandoned jhum, arecanut and rice-vegetable) and rest were recorded for low status. The available phosphorus content was distinctly highest (23.1 kg ha-1) in forest land use system and lowest (7.9 kg ha-1) in tea LUS. Barring Tea and rubber, all the LUS exhibited medium status of available P. Available potassium content is medium in all the tree based LUS except Rubber. Soils under rice-based and arable LUS showed low status of this nutrient. Calcium and micronutrients was found sufficient but Mg and B status was low in all the LUS. Highest (23.08 mg kg-1) content of Av. S was observed on the forest land and lowest (9.65 mg kg-1) in the rubber land use system. Higher levels of carbon stock were recorded in plantation crop based land use systems particularly in forest, abandoned jhum and tea where more than 50 Mg ha-1 carbon stock was observed. Barring rice-fallow and rice-oilseed LUS, all the other LUS showed a carbon stock range of 30-40 Mg ha-1. The dominance of NH4+-N over NO3--N was observed irrespective of land use systems in the studied soils. The NH4+-N content of the soils was found greater than 50 mg kg-1 in almost all the LUS except in tea (49.05 mg kg-1) and arecanut (15.30 mg kg-1) LUS. The content of NO3--N was more than 5.0 mg kg-1 in all the LUS. It was particularly high in plantation crop based LUS (6.43 – 8.85 mg kg-1). Total N content decreased significantly from forest (0.165%) land use to rice-oilseed (0.044%) LUS. Similar to NO3--N, tree based LUS recorded higher Total N than other land use systems. Among the different P fractions, Fe-P was found to be the most dominant fraction followed by occluded P, Al- P and Ca-P. The highest amounts of Fe-P, Al-P & Occl-P were recorded in tea plantation and forest land use exhibited highest amounts of Ca-P and Total P. The different fractions of soil potassium were found high in plantation crop based LUS except the soils under rubber plantation. Mean values of water soluble, exchangeable and non exchangeable potassium of the soils were varied from 6.44 to 9.73 mg kg-1, 28.65 to 63.38 mg kg-1 and 550 to 791 mg kg-1 respectively. Abandoned jhum land recorded for the highest exchangeable and available potassium whereas forest land showed highest reserves of non-exchangeable and mineral potassium contents. Nutrient Index Values (NIV) in respect of organic carbon was high in tree based LUS like forest, abandoned jhum, rubber, tea LUS including rice-vegetable and pulse-oilseed LUS and lowest was observed in rice-fallow system whereas the NIV of organic carbon for the district was high. NIV for available N was low for the district with only three LUS (forest, abandoned jhum and arecanut) having the medium value. The NIV for available P was found medium for the district and in all the LUS except vegetable-vegetable, tea and rubber where it was low. In case of available K, only four LUS (forest, abandoned jhum, arecanut and tea) was recorded for medium NIV for potassium and others were low as similar to the low NIV value recorded for the whole district. There was a gradual decrease in SFI from forest land to other land uses. The forest maintains greater fertility, followed by uncultivated, abandoned jhum, arecanut plantation and lowest fertility was recorded in tea land use system. SEF was highest in forest, followed by abandoned jhum, arecanut plantation and least for tea. Highly significant correlations of SFI and SEF with soil physico-chemical and fertility properties indicated that these two indices can successfully be used as indicators of soil quality. Various thematic maps on different soil parameters showed that most of the soils of Karimganj district are sandy clay loam in texture (55.49%), strongly acidic in reaction (67.33%), high in organic carbon (85.07%), low in Av. N content (76.88%), medium in Av. P content (78.40%), medium in Av. K status (78.56%), high in DTPA-Zn (99.98%) and low in HWS-B (100%). A total of 250 numbers of Soil Health Cards were distributed to farmers of the district.