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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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Subject: Agricultural Meteorology × Author: Kakoti, Mriganko × End date: 2023 × Start date: 2023 × Type: Thesis ×
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    ThesisItemOpen Access
    AGRO-CLIMATIC CHARACTERIZATION FOR PLANNING SMART AGRICULTURAL PRACTICES IN ASSAM
    (2023) Kakoti, Mriganko; Deka, Rajib Lochan
    The present study was undertaken with the objective to characterize the agroclimatic environment for improved planning of agricultural practices in Assam by calculating assured weekly rainfall at different probability levels along with occurrence of dry and wet spell and estimation of moisture availability index which will help in accessing the crop growing duration as well as planning suitable agricultural practices in the region. Long- term rainfall data for a span of 31 years (1991-2021) across 33 designated stations located at six agro-climatic zones of Assam were gathered from IMD, Pune. However, the daily temperature data (maximum and minimum) for the same period were not available in the IMD dataset for all the selected stations. To compensate for this missing information, daily temperature data was obtained from the NASA POWER (Prediction of Worldwide Energy Resources) data portal. The amount of weekly rainfall at different probability levels (90%, 75% and 50%) were calculated using incomplete gamma distribution model and Markov chain model was used to find out the probabilities of occurrences of 2 and 3 consecutive wet weeks or dry weeks by taking threshold limit of 20 mm of rainfall per week. Characterization of rainfall revealed that annual mean rainfall was highest at Karimganj (3397 mm) followed by Lilabari (3182 mm), Kokrajhar (3170 mm), Silchar (3104 mm), Gharmura (3095 mm) and lowest was observed at Lumding (1305 mm) followed by Bokajan (1341 mm). The coefficient of variation (CV %) of annual rainfall varied from 12.4 % to 24.9 % in Lower Brahmaputra valley zone (LBVZ), 13.1 % to 18.1 % in North Bank plains zone (NBPZ), 15.1 % to 18.9 % in Central Brahmaputra valley zone (CBVZ),11.4 % to 18.3 % in Upper Brahmaputra valley zone (UBVZ), 13.2 % to 26.8 % in Hills zone (HZ) and 17.3 % to 27.4 % in Barak valley zone (BVZ) during 1991-2021 indicating rainfall was highly dependable and less erratic in LBVZ, NBPZ, CBVZ and UBVZ as compared to HZ and BVZ which showed high CV. Seasonal rainfall analysis revealed that contribution of monsoon season rainfall to the total annual rainfall was highest (66 %) followed by premonsoon season rainfall (26%), post-monsoon (7%) and winter (2%). Rainfall during postmonsoon and winter were highly variable as CV (%) was more than 45% and 50%. The weekly rainfall data indicated that rainfall was mainly concentrated between 16th to 38th SMW and more than 20 mm of assured rainfall was received during this period at 75% probability level. However, in some stations under Kamrup (R), Kamrup (M) and Sonitpur district this period was between 16th to 35th SMW while the stations under rain shadow belt like Lumding, Golaghat and stations of eastern Karbi Anglong district the period was between 19th to 36th SMW. From 42nd SMW onwards less than 10 mm of weekly rainfall was received at 75% probability level across all the designated stations. The probable occurrence of two consecutive wet weeks increased from 15th, 16th to 38th SMW across all the stations except this period was less for stations under Kamrup (R), Kamrup (M) and Sonitpur district (NBPZ) and for stations located under the rain shadow belt (18th to 38th SMW). Occurrence of dry weeks probability was more than 50% from 43rd SMW across all the stations which corresponds with the growing season of rabi crops in the region. The weekly Moisture Adequacy Index (MAI) values were determined by computing the ratio of AET to PET. PET values were estimated using Thornthwaite's (1948) method, while AET values were derived from Thornthwaite and Mather's (1955) water balance model. This calculation allowed us to assess the availability of moisture in the study area on a weekly basis. Assam comprises of a mixture of different types of soil types. For crop planning and suggesting suitable practices, major two types viz., sandy loam soil having 100 mm water holding capacity and silt clay loam soil with 200 water holding capacity were considered and accordingly MAI was calculated. MAI value increased from 0.4 in rabi season and reaches maximum value of 1 during kharif season indicating enough moisture to support water demanding crops. Almost in most of the stations there was greater chance for water surplus during monsoon season thus offer opportunity for water harvesting and supplemented irrigation to mitigate moisture stress conditions. It can prove beneficial for successive rabi crops also. Soil with high water holding capacity i.e., 200 mm WHC had higher MAI value in all the seasons as compared to soils with l00 mm WHC. The weekly MAI suggests the possibility of sowing kharif crops without affecting the later rabi crops. The length of growing period (LGP) calculated over the period 1991-2021 revealed that the lowest average LGP of 239 days was found in stations of Hills zone and the highest average LGP of 303 days was found in stations of BV zone. When averaged over 31 years, it was observed that the mean LGP accounts for 277 ± 31 days with RF/PET ratio greater than 0.5 and MAI value ranging more than 0.75. The weeks in which the RF/PET ratio was greater than 0.25 with MAI value ranging from 0.4 to 0.75 indicated the presence of residual soil profile moisture. Based on these approaches, pre sowing cultivation, seed bed preparation, sowing and transplanting window was suggested for different agroclimatic zones of Assam.