The Regional Centre Jorhat, initially started in the year 1979 at the Assam Agricultural University campus is now running at Jamuguri Road, Jorhat – 785 004 with full fledged Institute infrastructure. The operational jurisdiction of the Centre is on 8 states of North-Eastern region comprising Arunachal Pradesh, Assam, Manipur, Meghalaya, Mizoram, Nagaland, Sikkim and Tripura. The Eastern Himalayan Regions, Meghalaya Plateau, Brahmaputra and Barak Valley Regions are treasure of natural resources including soils, vegetation, flora and fauna. This Regional Centre is entrusted for inventorization of soil resources of this region. Its activities are grouped into three categories viz. research, human resource development and capacity building of farmers through farmers-scientist interaction.
Following physical facilities are available at the Centre :
An office building with spacious residential and office campus
Well equipped soil analytical laboratory
Conference room for meeting and training
Well stocked library
GIS laboratory with advanced remote sensing and GIS soft wares
Spacious soil drying and sample store room
6 vehicles for field work (five Marshalls and one safari)
Well equipped Soil Analytical Laboratory
The Centre is equipped with excellent physical and chemical laboratory with sophisticated instruments like Atomic Absorption Spectrophotometer, microwave digester, pressure membrane apparatus, flame photometer, spectrophotometer, pH meter, advanced Nitrogen estimation system (Kjeldahl), mechanical shaker, distillation systems, reverse osmosis and heavy duty centrifuge.
The cartographic laboratory is well stocked with Survey of India topographic sheets of North Eastern Regions at various scales including aerial photographs and remotely sensed data products of LANDSAT and RESOURCESAT. In this laboratory base maps are prepared at various scales prior to digitization.
GIS laboratory is well furnished with updated desktop assemblage, laser and inkjet printers, A-zero size scanner, plotter and with latest software like Arc GIS ver.10.0, Geomatica ver. 10.1, TNT Mips ver. 7.7, Definiens Professional, Geomedia, etc. In this laboratory various soil and soil based thematic maps are finalized after being interpreted in Cartographic laboratory followed by digitization in GIS environment.
The Regional Centre has well furnished library including the latest stocks of national referred journals, books, manuals and popular magazines.
Soil Resource Inventory
The Centre has good infrastructure to take up soil resource inventory and land use planning related research in varied agro-ecological systems of North Eastern Regions.
Any other matter
Construction of a training hostel is in progress.
The Regional Centre, Jorhat is engaged in conducting research on soil survey and mapping, fertility mapping and land use planning in collaboration with relevant institutions and agencies.
Soil resource mapping of North Eastern Region at state level (1:250,000 scale)
The soils of the region including Arunachal Pradesh, Assam, Manipur, Meghalaya, Mizoram, Nagaland and Tripura states were surveyed and mapped on 1:250,000 scale following three tier approach viz. image processing; field surveys and laboratory analysis; cartography and printings. Soil physiographic models were used for mapping the soils of the region and maps are published state wise on 1:500, 000 scale. The soil mapping units are the association of soil family. Legend includes major landforms, soil depth class, drainage, particle size class, surface texture and erosion.
Soil resource mapping for district planning (1:50,000 scale)
For district level planning soil resource mapping was conducted on 1:50,000 scale with soil series association as mapping unit including Jorhat, Sibsagar, Marigaon and Kamrup districts of Assam, East Khasi Hills and Ri-Bhoi districts of Meghalaya and parts of Luit and Tirap districts of Arunachal Pradesh.
Soil nutrient status mapping for Assam and Tripura States
Site Specific Nutrient Management (SSNM) is the most logical solution to address nutrient use efficiency. Soil nutrient mapping based on geo-referenced soil sampling, laboratory analysis, structuring data base in a GIS platform and subsequent interpolation can give a clear indication of the impact of land use and management on changing soil fertility scenario on a real time scale. The geo-referenced soil nutrient maps will be helpful as fertilizer decision support tool for nutrient application in a site specific mode. Soil Nutrient Mapping of South, West, North and Dhalai districts of Tripura at 2.0 km interval grid spacing and for 13 priority districts of Assam (now 16) including Barpeta, Bangaigaon, Goalpara, Kokrajhar, Nalbari, Sonitpur, Darrang, Udalguri, Nagaon, Marigaon, Chirang, Bagcha, Lakhinpur, Dhemaji, Tinsukia and Karbi-Anglong districts at 1.0 km grid spacing have been accomplished.
Soil erosion assessment for monitoring soil degradation status
Following multi-criteria overlay, several critical parameter of soil erosion was integrated in GIS for Arunachal Pradesh, Assam, Manipur, Meghalaya, Nagaland, Sikkim and Tripura states. The assessment of soil loss revealed that in Assam state, severe (20-40 t/ ha/ yr) to very severely (>40t/ ha/ yr) eroded soils together occupies 43.13% of area, whereas, in Meghalaya and Nagaland, severe (20-40 t/ ha/ yr) to extremely severely (>80 t/ ha/ yr) eroded soils together occupied 52.91% and 79.38% of area of the states respectively.
Characterizing the soil resources in fluvial landforms of Majuli Island for land use using remote sensing and GIS.
A reconnaissance soil survey was carried out on 1:50,000 scale. The island has 43.2 per cent of area under sand bars, 13.6 percent of swamps 22.6 percent of flood plains (active and old), 11.8 percent of channel fills and 8.9 percent of natural levees. Thirteen soil series are identified and mapped into twenty five soil mapping units. Soils were evaluated for their suitability to twelve crops namely rice, wheat, mustard, potato, cabbage, peas, french bean, tomato, maize, alfalfa, cowpea and banana. The rice, mustard, cabbage, potato, french bean, tomato, maize, alfalfa, cowpea cropping system is mostly found suitable in channel fills (6.34 per cent) and active flood plains (7.8 percent). The rice-wheat, mustard, cabbage, pea, french bean, maize, alfalfa, cowpea system is suitable in Active flood plains (4.31 percent) and old flood plains (3.99 percent). The rice-potato, french bean, cabbage, peas, maize, alfalfa is suitable for active flood plains (4.42 per cent) whereas potato, cabbage, alfalfa, french bean, peas, cowpea, tomato system in natural levees during post rainy season only (9.3 percent).
Mapping and assessment of nutrient status of soils in River Island Majuli, Assam.
The status of available nitrogen, phosphorus and potassium of surface horizons of soil series were considered to derive five categories of fertility ratings viz., MLH, MLM, HLM, HLH, HMH. This rating scheme was followed for mapping unit groupings and in developing thematic map of nutrient status. The mapping units are grouped and estimated area under different categories. The six mapping units:- Adielengi - Bhakat –Chilkala, Bangaon-Bhakat-Garumara, Bharaki-Chilkala-Adielengi, Chilkala-Adielengi-Bhakat, Garumara-Bangaon and Kamalabari-Garumara-Bangaon have medium N, low P and medium to high K status. The other mapping units have high N, low P and high K status. The nutrient status shows distinct variation in soils on northern and southern banks of island. The soils in northern bank have high contents of NPK as compared to southern bank. Irrespective of soils in different land forms and textural variations, all soils are deficient in DTPA extractable Zn below the critical limit of 0.8 mgkg-1.
A sustainable cropping system for rice fallows of Brahmaputra valley of Jorhat district of Assam
In order to evolve a suitable cropping system for rice fallows two early maturing (120-130 days) varieties viz. Satya and Basundhara of rice were tested at different sites of Nagaon and Jamuguri village. Satya variety of rice performed better at both the sites than Basundhara registering an increase of 19.08% and 27.59% in seed yield over Basundhara at Nagaon and Jamuguri, respectively. The effect was more pronounced at Jamuguri than Nagaon soils. Combined use of SSP+MRP in 1:1 proportion resulted into a yield gain of 58.76 to 60% at Jamuguri pedon against 32.92-33.7% at Nagaon pedon over no P. Combined of SSP+MRP in 1:1 proportion proved advantageous than alone application of either sources. SSP proved better than MRP. Potato planted under residual P and moisture in rice fallows resulted in to a yield of 118.75 q/ha at Nagaon. Application of P to rice exerted considerable residual influence on potato. However, the yield of potato did not show considerable difference due various sources of P. The highest total productivity (110.90 q/ha) in terms of rice equivalent, production efficient (45.63 kg/ha/day) and land use efficiency (66.54%) was observed when potato was grown after Satya variety of rice under P and SSP + MRP (1:1 ratio) at Nagaon pedon. Experimental findings obviously indicated that rice fallows of Brahmaputra valley of Jorhat district, Assam can be successfully exploited by short season crops like black gram, green gram in spring/summer season and potato, rapeseed, french bean and peas during winter season with sizeable yield and monetary advantage.
Soil resource mapping of Kamrup district (1:50,000) of Assam for land use planning.
Forty soil series have been identified and they have been mapped on 1:50,000 scale with 33 soil mapping units at association of soil series. About 41% area of Kamrup district was level to nearly level (0-1% slope). Steep to very steep sloping areas (>50%) cover an area of 19.38%. Nearly 19% of total geographical area of the district is under slight erosion, 30% area under moderate erosion and 13% under severe to very severe erosion class. The soils of the district belong to 4 soil orders, 7 sub-orders and 13 great groups and 20 sub-groups. Inceptisols were the dominant soil order (34.09% of TGA) followed by Entisols (29.89% of TGA), Ultisols (16.03% of TGA) and Alfisols (14.11% of TGA). The most extensive areas are very strongly acidic soils (pH 4.5-5.0) covering 52.13% of area. The organic carbon status of surface soil in the district has been grouped into 4 classes and 79.47% area of the district belongs to high category. The soil mapping units in the district have been grouped into 5 land capability subclasses based on the dominant soils in a unit. The most extensive class is IVsw (25.81%) occurring mostly in alluvial plain and flood plain. VIes class dominantly belongs to hilly region of the state.
Studies on infiltration, hydraulic conductivity and moisture storage of some soils of Jorhat district, Assam
Twenty sites from different physiographic units of Jorhat district have been selected for the study. The infiltration class for sandy/loam texture in forest soils is moderately rapid. The tea garden soils have four permeability classes viz. moderate (loam/sandy clay loam), rapid (sandy loam/loam), moderately rapid (sandy loam/loam/silty clay loam) and moderately slow (sandy loam). The rice soils have only three classes viz. moderately slow (clay loam, loam, sandy loam), moderate (sandy loam) and moderately rapid in silt loam textures. It is observed that rice soils have retained more water than tea garden and forest soils. In rice soils, clay loam soils retained more stored water than loamy and sandy loam soils. In case of Tea garden soil, silty clay loam retains more water than loam and sandy loam. Similarly in forest soils, silty clay loam/silt loam soils retain more water than sandy loam soil. It is apparent from the study that texture, bulk density have influence on infiltration rate. To confirm the results at regional level, this study may extend further to develop regional level prediction and integrating data base for post rainy crop management strategies in paddy fallows of Brahmaputra valley.
Detailed soil survey of Regional Rain- fed lowland rice research station farm, Gerua, Kamrup district, Assam
The farm is located at 26o11’N latitude and 94o47’E longitude comprising of an area of 12.5 ha. The soils of the farm have been developed on alluvium brought down by the river Brahmaputra. Depending upon the land situation the farm has been divided into 4 categories of landforms viz. medium land, moderately low land, low land and extremely low land. A high intensity detailed soil survey was carried on 1:5000 scale base map supplied by RRLRRS, Gerua and three soil series namely Gerua A, Gerua B and Gerua C have been identified and mapped. Soil pH ranges from 5.3 to 7.5. Organic carbon content in soils ranges from 0.27 to 1.87 gmkg-1. Available Nitrogen content of surface soils of the farm ranges from 150.86 to 678.89 kgha-1. The available phosphorus content in the soils of the farm ranges from 0.254 kgha-1 to 17.95 kgha-1 which have been rated as very low. Available potassium content in soils are dominantly low (<108 kgha-1) to high (>280 kgha-1) covering 93.52 percent and 0.26 percent area respectively.
Soils of Bhareli River Basin for Land Use Planning
The Bhareli river basin locating in between 26o02’45” to 27o09’55” N and 93o01’25” to 95o33’05” E covers an area of 1,53,737 ha. The upper part of the basin area comprising hilly terrain with moderately steep (15-30%) to very steep slope (>50%) belongs to Arunachal Pradesh and the lower part with nearly level (0-1%) to gently sloping (3-5%) land to Assam. River Bhareli drains the area to river Brahmaputra. The area has been divided into eight physiographic units viz. hilly terrain, piedmont zone, alluvial fan, flood plain, alluvial plain, aggraded valley, sand/gravel bar and inselberg. Reconnaissance soil survey has been carried out by using topobases on 1:50,000 generated through interpretation of satellite imagery and toposheet. 13 soil series have been identified and mapped in 10 soil mapping units at the level of association of soil series. Three orders viz. Entisols, Inceptisols and Alfisols have been identified covering 12570.74 ha, 77206.00 ha and 841.71 ha respectively. Five family classes viz. sandy, coarse-loamy, fine-loamy, fine and loamy-skeletal have been identified. Inceptisols further have been divided into 4 subgroups viz. Fluventic Dystrudepts, Typic Dystrudepts, Humic Dystrudepts and Pachic Dystrudepts.
Soils of Research Farm of ICAR Complex for NEH Region, Jharnapani and NRC on Mithun, Medziphema, Nagaland for optimizing land use
Soils of two research farms of ICAR Complex for NEHR, Jharnapani and NRC Mithun, Medziphema have been surveyed for their characterization, mapping and identifying their problems and potentials. The soils have been mapped at phases level of soil series through a high intensively detailed survey on 1: 2000 scale. The area qualifies for hot moist sub-humid hyperthermic agro-ecological zones (17J) with LGP 270-300 days. Six soil series, viz., JhA, JhB, JhC, JhD, JhE and JhF have been identified and mapped in ICAR Complex covering 33.50 acre of area. Eight soil series have been identified in Research Farm of NRC on Mithun, Medziphema, viz., MdG, MdH, MdDI, MdJ, MdK, MdL, MdM and MdN covering an area of 135.15 acre. Soils of ICAR Complex Farm have been grouped into four land capability classes, viz., IIs, IIIe, IIIs and IVs. Class IVs covers the maximum area of 29.47% of the farm. Seven classes have been identified in NRC on Mithun Farm namely, IVs, Vies, Vis, VIIes, VIIe, VIIIes with two types of limitations, viz., reflecting unfavourable soil condition and soil erosion.
Detailed Soil Survey of Research Farms of Paren and Jaluki village under Mbiu Reu Micro-watershed in Nagaland for Land Use Planning.
Detailed soil survey on 1:1000 scale of two research farms of Paren and Jaluki village, Nagaland covering 7.5 ha and 2.4 ha respectively has been carried out. The area belongs to hot moist sub humid hyperthermic agro-ecological zone with LGP 270-300. Soils of Jaluki farm have been developed on table land with level (0-1%) to very gently slope (1-3%). Four series has been identified and mapped in the farm of Jaluki village and five soil series have been identified in the farm of Paren village. Grid points collected at an interval of 5m have been for generation of thematic maps of soil reaction, available nitrogen and available copper of Paren farm. Two classes viz. slight acidic (4.5-6.5) and neutral (6.5-7.5) have been identified which cover 5.8 ha and 1.70 ha respectively. 77.3 percent area of the farm has been rates as slightly acidic. The farm belongs to 3 categories of available nitrogen viz. high, medium and low which cover 4.69 ha, 2.61 ha and 0.20 ha, respectively. Copper content of soils have been rated as marginal (1.0-1.5 mgkg-1), in 2.79 ha, adequate (1.5-2.0 mgkg-1) covering 37.2 percent, 32.67 percent and 30.13 percent respectively.
Assessment and mapping of important soil parameters including macro and micro nutrients for the state of Tripura towards land use planning.
The results showed that 49.2 percent area of the state belongs to strongly acidic (5.1-5.5) category followed by 24.46 percent under very strongly acidic (4.5-5.0). 70.78 percent of the state belongs to medium category of organic carbon (0.75-1.5%). Soils of majority area (about 36.32 percent of the state) have medium status of available nitrogen (280-450 kgha-1). Soils of 73.0 percent area are very low (< 25 kgha-1) in available phosphorus content. Soils of 51.0 percent of the state have medium level of (150-340 kgha-1) available potassium. All soils are sufficient in available Iron and Manganese and Copper content. However, soils of 16.40 percent area are deficient (<0.5 mgkg-1) in available Zinc. The study showed that soil acidity together with the low range P, moderate N & K status as well as deficient zones of zinc certainly indicate in general the low fertility status of the state and therefore requires attention regarding soil management practices for optimum agricultural production viz. liming of rain fed/ irrigated uplands and medium lands (pH <5.5) with limestone/dolomite, paper mill sludge, marketable lime as available locally in ground form (80 mesh size), in order to neutralize soil acidity. Adequate phosphorus fertilization depending upon crop and cropping sequence along with recommended dose of micronutrient application particularly zinc @25 kg ZnSO4 ha-1 every three years.
Assessment and mapping of important soil parameters including macro and micro nutrients for the state of Assam towards land use planning.
The results showed wide range of spatial variability in various soil parameters among the 13 (now (16) priority districts of Assam. In Dhemaji district, extremely acidic soils were predominant followed by strongly acidic and very strongly acidic and moderately acidic soil covering 34.4%, 31.8%, 17.1% and 12.2% of area, respectively. High soil organic carbon was predominant in Nagaon and Lakhimpur district covering 90.4% and 74.3% of area respectively. It was observed that available nitrogen was low in 69.2% area of Udalguri district. In Sonitpur district, 28.9% of area is deficient in available zinc content.