South Asian Regional Network (SARNet)


Tropical Soil Biology and Fertility Programme


The SARNet, established in 1992, is a network of 60 scientists affiliated to universities, research institutes, and non-governmental organizations working on different aspects of soil biology and fertility in the four major ecological regions of the Indian subcontinent viz., the Indo-gangetic plains and the deserts, the Himalayan mountain system, and the Western Ghats mountain system. Any scientist conducting research and development activities within the framework of TSBF strategy is welcome to be a part of the network.

The research and development work is supported from grants to network individuals/institutions from national funding agencies viz., Ministry of Environment and Forests, Council of Scientific and Industrial Research, Indian Council of Agricultural Research, University Grants Commission and Department of Science and Technology, Government of India and international agencies viz., MacArthur Foundation, Winrock International, Asia-Pacific Network and Global Environmental Facility.


The SARNET-Coordination Unit at School of Environmental Sciences, Jawaharlal Nehru University, New Delhi 110067, in collaboration with the G.B. Pant Institute of Himalayan Environment and Development (an autonomous Institute of Ministry of Environment and Forests, Government of India), facilitates and supports:

(a)    interactions between individuals/institutions,

(b)   development of project proposals for funding from different agencies,

(c)    publication of research findings/development experiences,

(d)   training of young scientists and access to laboratory facilities/literature.

A synthesis of research and development activities of SARNET over the last 10 years (1992-2002) is being brought out in the form of an edited volume "Soil Biodiversity, Ecosystem Processes and Landscape Management".



For any further information contact us:





Current Research and Development Themes

(names of principal scientist(s) given in parentheses)

Indo-gangetic Plains

  • Nutrient cycling, carbon storage, and soil microbial processes in agroecosystems, agroforestry systems, and forest ecosystems in sodic soils of Indo-gangetic plains (Professor S.R. Gupta)
  • Management of organic manure and crop residues in rice-wheat system in the north-west India (Professor Bijoy Singh)
  • Productivity and nutrient cycling in agroforestry systems of Indo-gangetic plains in Haryana (Professor O.P. Toky)
  • Rhizobium inoculation in Indian soils (Dr R.K. Singh)
  • Density and distribution of earthworms and termites in agricultural landscapes in the Indo-gangetic plains (Dr T. Bhaduria).

Himalayan Mountain System

  • Ecological distribution and diversity of earthworms in natural and transformed ecosystems in central Himalaya (Dr B. Sinha and Dr T. Bhaduria)
  • Earthworm community structure, population dynamics, and feeding behavior in upland agricultural landscapes (Dr B.R. Kaushal)
  • Soil fertility and agricultural productivity in relation to land use intensity in mid-altitude Himalayan villages (Dr R.K. Maikhuri, and Dr K.S. Rao)
  • Patterns and impacts of land use-land cover change on soil fertility, ecosystem function, and local livelihood in the Himalaya (Dr K.S. Rao, and Dr R.K. Maikhuri)
  • Inventory and identification of growth promoting rhizobacteria for improving agricultural productivity in hill agroecosystems (Dr A. Pandey)
  • Management of organic residues for sustainable agricultural production in rainfed upland agroecosystems (Dr G.C.S. Negi)
  • Integrated nutrient management for agricultural improvement in settled agriculture in Himalaya (Dr R.D. Singh)
  • Studies on soil biology and ecology in shifting agricultural landscapes in the north-eastern India (Dr S.C. Tiwari)
  • Dynamics of microbial biomass and nitrogen mineralization in agricultural and forest ecosystems in the north-eastern India (Dr A. Arunachalam, and Dr K. Arunachalam)

Western Ghats

  • Litter production, decomposition, and nutrient cycling in agroforests (Professor B.M. Kumar)
  • Litter production, decomposition, and nutrient cycling in forest and agroforestry systems (Dr U.M. Chandrasekhara)
  • Diversity and ecological role of mycorrhiza (Professor D.J. Bagyaraj)
  • Diversity and ecological role of termites (Professor N.G. Kumar)
  • Diversity and ecological role of earthworms (Professor R.D. Kale)
  • Manipulating soil fauna for sustainable production in agricultural and plantation systems (Professor B.K. Senapati)
  • Manipulating soil fauna for sustainable production in traditional agriculture (Dr Partibha Basu)
  • Ecosystem structure and function in natural and managed ecosystems (Dr S. Sudhakar Swamy)
  • Dynamics of microbial biomass and nitrogen mineralization in different land use-land cover types in Indian desert (Dr S. Sundaramoorthy).

National/Regional Activities

  • Conservation and Sustainable Management of belowground biodiversity in selected areas of the Himalaya and the Western Ghats (TSBF/UNEP/GEF project involving several scientists: K.G. Saxena, National coordinator)
  • Biodiversity-ecosystem function-sustainable livelihood linkages in the Himalaya (Professor P.S. Ramakrishnan, and Professor K.G. Saxena in collaboration with other scientists)
  • Adaptability and vulnerability dimensions of climate change in mountain ecosystems of India (Professor P.S. Ramakrishnan and Professor K.G. Saxena in collaboration with other scientists).

Research Highlights

Diagnostic features of farming systems and farm-environment-economy linkages

  • Land use changes accompanying reduction in fuelwood and fodder production from private farmland and thereby more pressure on forests: improvement in economy at the cost of loss of ecosystem services and biodiversity, invasion by exotic weeds, and increased losses due to wild animals
  • The best fodder species showed the highest concentration of polyphenols and the highest C/N ratio
  • Most of the traditionally valued tree fodder species do not fix nitrogen and have lower degree of water and nutrient stress tolerance
  • Peak litter fall in most polyphenol rich species occurred just before rainy season and of polyphenol poor species long before rainy season. In all species, the highest rate of decompositon occurred during rainy season
  • Significant species x soil moisture stress interaction observed in laboratory based mineralization studies
  • Ammonium availability more critical than allelopathic effects in determining nitrification rates
  • Microbial biomass negatively correlated with N mineralization rates. Agroforestry tree species differ in respect of temporal patterns of microbial biomass and nitrogen mineralization
  • Positive impact of N fixing trees on perennial cash crops but not on annual food crops
  • Phaseolus radiatus, Flemingia vesitata, and Glycine max quite profitable in poor quality soil and low level of organic manure inputs
  • Soil erosion is a problem only on terraces with slopes >6 degree under potato cultivation, more so during high rainfall years
  • No crop yield losses if 25 percent branches of farm trees are retained
  • Farmers apply lower quantities of manure to rainy season crops because of their perception of more severe crop-weed interaction under water stress/abnormal rainfall
  • Traditional manure preparation and storage processes are such that significant amount of nutrients are lost
  • Earthworm abundance and soil organic carbon and available nutrient status in 9-year old tree-crop mixed farming system on abandoned land were significantly higher than those of forests and traditional rainfed/irrigated agroecosystems. Termites occurred only in mature forests. Among microarthropods, mites constituted the most dominant group in all sites. Collembola constituted the second-most dominant group in agricultural and agroforestry land use and diplura in forest land use
  • Better tree survival and growth with lesser cost can be achieved by transplanting saplings from private farm lands and applying traditional manure in degraded lands
  • Cultivation of medicinal plants could improve local economy together with improvement in conservation of forest and wild biodiversity: lower labour and forest biomass needs
  • Desmodium and Lathyrus could be grown during fallow phase
  • Integration of traditional informal and conventional institutions could reduce the cost and risks of conservation programs.

Interventions for socio-economic development coupled with environmental conservation

  • Moisture conservation by using Lantana camara shoot as mulch at the recession of monsoon rains: increase in crop yields and earthworm activity—impact on other soil organisms and ecosystem processes?
  • Oak based traditional manure (forest litter+livestock excreta) provides better quality of manure and synchrony than pine based manure: increase in crop yields together with improvement in forest biodiversity and ecosystem function.
  • Life saving irrigation (run-off harvesting and recycling) enables two times higher yield—amelioration of water stress and faster mineralization.
  • Mixed plantation based agroforestry system including rain water harvesting technology could be a viable option for rehabilitation of degraded community lands. In early phases of rehabilitation, carbon sequestration in soil higher than that in tree bole component—configuration of species in mixed plantations, belowground-aboveground interactions,  appropriate water technology for private farm land
  • Manipulation of soil biota could enhance yields of tea—applicability in other ecoregions and agricultural systems
  • Vermiculture technologies—farmers’ acceptability and policy support
  • A local isolate of Glomus mosseae was effective in promoting vigour of Leucaena; Glomus fasciculatum and G. macrocarpum improved growth of citrus. Mycorrhizal plants have greater tolerance to soil stresses and pathogens—lab to farm?
  • Inoculation with Azotobacter chroococcum and Azospirillum brasilense could enhance productivity of maize in a subtropical site but not in a temperate climate site—impact of inoculant on other soil organisms?
  • Strains of Pseudomonas corrugata with a potential of producing antifungal compounds, P solubilization isolated.




SARNet –