Rajendra Hegde

Role of Vesicular-Arbuscular Mycorrhizae in Mobilization of Soil Phosphorus

The microorganisms play a vital role in sustaining the crop production through improving the soil properties and plant nutrition. Among the microorganisms VAM (vesicular-arbuscular mycorrhizae) is a beneficial fungus that plays an important role in soil nutrient dynamics and improving soil physical, chemical and biological properties. Though phosphorus is the second macronutrient required in relatively large amounts by plants next to nitrogen, it is one of the most difficult nutrients for plants to acquire because of its low solubility, low mobility and fixation in soil. The mycorrhizal symbiotic association between fungi and plants plays an important role in the uptake of phosphorus. Many experiments have specified that VAM is able to alter mobilization of soil phosphorus of its host plants. The paper summarizes about mycorrhizal symbiosis of VAM involving multistep colonization process, soil phosphorus dynamics in the rhizosphere and mycorrhizal mechanism and pathways involved in phosphorus availability and uptake.

Land evaluation for groundnut (Arachis hypogaea L.) production in Pulivendula tehsil, Kadapa district, Andhra Pradesh, India

The land evaluation for enhancing ground nut (Arachis hypogaea L.) production in Pulivendula tehsil, Kadapa district was carried out as per FAO approach using soil map with 43 mapping units generated on 1:25000 scale and GIS technology to build thematic maps of suitable land units for peanut production with agroeconomic analysis. The land suitability analysis showed that 42.08 per cent of total cropped area is moderately suitable over current area of 14.8 per cent. with limitation of salinity, rooting depth, surface stoniness, gravelliness and soil texture. The economic evaluation for each soil mapping unit showed that only Pulivendula series has recorded benefit cost ratio more than 2 but in others this ratio is less 1.Results of landuse analysis suggested that participatory and bottom-up approaches are needed to understand the problems and opportunities in household agricultural production in order to develop appropriate landuse plans.

Characterization and Evaluation of Soils of Singanallur Watershed Using Remote Sensing and GIS

Watershed is an ideal unit calling for multidisciplinary approach to the resources management for ensuring continuous benefit on sustainable basis. Land Resource mapping plays a vital role in resource management. A detailed soil survey is planned for the Singanallur micro watershed, Kollegal taluk, Chamaraj nagar district, Karnataka by using cadastral map overlaid on Cartosat-1(ortho corrected)+LISS IV image as a base to characterize and classify the land resources. Based on elevation and slope, three physiographic units were identified namely gently sloping lands (3–5%) very gently sloping lands (1–3%) and nearly level lands (0–1%). Soil profile study was carried out to identify the problems and potentials of the land resources. Based on morphological and physiochemical properties, six soil series were identified and the study area was delineated into 25 management units. Taxonomically, these soil series were grouped under Alfisols (Typic Rhodoustalfs and Rhodic Paleustalfs) and Inceptisols (Typic Haplustepts). The site evaluation of the soils showed that nearly 50% of the watershed area is highly suitable for ragi, maize, onion, turmeric and banana. More than 70% area is moderately to marginally suitable for red gram and groundnut due texture limitation. Different land use options and suitable interventions were suggested based on the potentials and limitations of the watershed area. This baseline data helps to monitor the different development programmes for enhancing the agricultural production.

Economic Viability of Soil Resource Mapping and its Use in Enhancing Farm Income — A Case Study of Garakahalli Micro Watershed in Karnataka

The priority of government in enhancing farm income of historically low-yield areas in semiarid tracts of Karnataka is focused on increasing the efficiency in crop productivity and natural resource use. The land resource inventory is basically aimed at deriving comprehensive information on natural resources for designing micro-level land-use planning and for enhancing land productivity and farm income. In view of this, This paper has explored the economic viability of generating the soil survey information (1:12,500 scale) to minimize the cost of production thorough site-specific nutrient management in Garakahalli microwatershed, Karnataka. The study has shown that the per hectare cost of improved method of soil survey (using PAN+LISS III imagery) was higher at 264 over conventional method of soil survey costing 337. Improved method of soil survey can minimize the cost up to 22 per cent in field survey. The economic viability of soil map was assessed by estimating fertilizer requirement with and without soil information. The impact in change in fertilizer application of finger millet production on the basis of soil information can reduce application of nitrogen by 5265 kg and of phosphorus by 4661 kg with improvement of 1054 quintals of yield with economic benefits of 8.43 lakh in the watershed area of 527 ha. The study has found that the benefits of soil survey in site-specific fertilizer management in finger millet are reflected in the Benefit Cost Ratio 1:2.85 and the additional income due to soil management of 1600 per ha. The soil information is useful in minimizing fertilizer cost and enhancing farm income. The investment in soil survey and fertility management is economically viable at the watershed level.