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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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20191
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Subject: Soil Sciences × End date: 2019 × Start date: 2019 × Thesis Type: M.Sc ×
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    ThesisItemOpen Access
    SOIL AVAILABLE PHOSPHORUS PEDOTRANSFER FUNCTION FOR ACIDIC SOILS OF CENTRAL BRAHMAPUTRA VALLEY ZONE OF ASSAM
    (AAU, Jorhat, 2019-07) Saikia, Bishnu Jyoti; Borkakati, Kabindra
    The study on “Soil available phosphorus pedotransfer function for acidic soils of Central Brahmaputra Valley Zone of Assam” was carried out with the objectives 1) to develop a soil available-P-pH pedotransfer function for acidic soils, 2) to verify the developed model with laboratory database and 3) to evaluate the relationship of available P with their various forms. In total 220 surface soil samples (0-15cm) were collected from the three districts of CBVZ of Assam viz. Nagaon (n=120), Morigaon (n=50) and Hojai (n=50). Physico-chemical properties for all the samples were determined by using standard methods. The pH, available P, OC and CEC of the collected soil samples were ranged from 3.45 to 6.50, 18.00 to 55.47 kg P2O5 ha-1, 0.32 to 1.34 per cent and 4.38 to 8.70 c mol (p+) kg -1, respectively. The average values of mechanical separates of the soils were found to be 35.82, 22.85 and 41.33 % for sand, silt and clay, respectively and the texture of these soils varied from sandy to clayey. Out of the 220 samples, 44 samples were selected on the basis of variation in soil texture for developing a pedotransfer function. The average values of mechanical separates of later consisted of 35.82 %, 22.85 % and 41.33 % sand, silt and clay, respectively. The range of pH, OC, CEC, Ald, Fed and available P ranged from 3.85 to 6.40, 0.32 to 1.34%, 4.90 to 9.40 [c mol (p+) kg -1], 0.34 to 1.62%, 0.61 to 1.84% and 20.11 to 55.47 P2O5 kg ha-1, respectively. A pedotransfer function (PTF) for predicting soil available P from soil pH data was developed and soil available P (AP) was estimated as a function of soil pH. The developed function is : Available P = -25.69+12.07*pH. The predicted P (i.e. soil available P predicted from the available P pedotransfer function) was compared with the soil available P estimated by laboratory test using the paired samples t-test and the Bland-Altman approach. The available P predicted by the soil available P pedotransfer function was found not to be significantly different from the soil available P determined by laboratory test (P >0.05). The mean difference between the soil available P-PTF and laboratory test was -0.004 kg ha-1 (95% confidence interval: -0.7699 and 0.7614 kg ha-1; P=1.00). The standard deviation of the soil available P differences was 2.518 kg P2O5 ha-1. More than 95% values of soil available phosphorus differences laid within the limits of agreement which in this case are -4.940 to 4.932 kg P2O5 ha-1. Thus, the pedotransfer function can be accepted as it also did not show any bias between the two methods calculated by Bland-Altman approach. Results revealed that the sequential occurrence of various inorganic P fractions followed the order: Fe-P > Al-P > organic-P > residual-P > Ca-P > saloid-P. The order of partial contribution of inorganic P fractions towards total inorganic P was Fe-P > Al-P > residual-P > Ca-P > saloid-P. Bray’s-I-P showed a significant positive correlation with OC (r= 0.742**), pH (r= 0.524**), CEC (r= 0.552**), clay (r= 0.508**), Ald (r= 0.464**), Fed (r= 0.519**) and significantly negative correlation with sand (r= - 0.407 **). Stepwise multiple regression analysis indicated that the highest contribution was impacted by Fe-P (38%) towards Bray’s-I-P whereas inclusion of res-P increased the variability to 48 per cent. All the P fractions jointly contributed 57 per cent towards the variability of available P. Step-wise multiple regression study showed the existence of dynamic equilibrium amongst different P fractions in the soils studied. Step wise multiple regression analysis indicated that the highest contribution was imparted by saloid-P (15%) towards predicted P while addition of Al-P contributed 22% towards predicted P. Inclusion of all the P fractions changed the variability to 37%. From the foregoing discussion, it can be concluded that the pedotransfer model can be accepted as because there was no bias between the two methods which is a pre-requisite according to Bland-Altman approach for both the methods to be in close agreement.