LAND RESOURCE INVENTORY FOR WATERSHED PLANNING AND DEVELOPMENT BHAGYANAGAR-1 (4D4A1X1g) MICROWATERSHED Koppal Taluk and District, Karnataka

Abstract

The land resource inventory of Bhagyanagar-1 microwatershed was conducted using village cadastral maps and IRS satellite imagery on 1:7920 scale. The false colour composites of IRS imagery were interpreted for physiography and these physiographic delineations were used as base for mapping soils. The soils were studied in several transects and a soil map was prepared with phases of soil series as mapping units. Random checks were made all over the area outside the transects to confirm and validate the soil map unit boundaries. The soil map shows the geographic distribution and extent, characteristics, classification, behavior and use potentials of the soils in the microwatershed. The present study covers an area of 473 ha in Koppal taluk and district, Karnataka. The climate is semiarid and categorized as drought - prone with an average annual rainfall of 662 mm, of which about 424 mm is received during south–west monsoon, 161 mm during north-east and the remaining 77 mm during the rest of the year. An area of 16 per cent is covered by soils, 1 per cent by railway, 23 per cent by rock outcrops and 61 per cent is by habitation and settlements. The salient findings from the land resource inventory are summarized briefly below.  The soils belong to 4 soil series and 5 soil phases (management units) and 2 Land Management Units.  The length of crop growing period is <90 days and starts from 2nd week of August to 2nd week of November.  From the master soil map, several interpretative and thematic maps like land capability, soil depth, surface soil texture, soil gravelliness, available water capacity, soil slope and soil erosion were generated.  Soil fertility status maps for macro and micronutrients were generated based on the surface soil samples collected at every 320 m grid interval.  Land suitability for growing 31 major agricultural and horticultural crops were assessed and maps showing the degree of suitability along with constraints were generated.  An area of about 16 per cent is suitable for agriculture.  About 2 per cent of the soils are shallow (25-50 cm), 3 per cent of the soils are moderately deep (75-100 cm) and 10 per cent soils are very deep (>150 cm).  Entire cultivated area of the microwatershed is falls under clayey soils at the surface.  About 13 per cent area has non-gravelly (<15% gravel) soils and 2 per cent has gravelly (15-35% gravel) soils.  About 2 per cent area is low (50-100 mm/m), 11 per cent area is medium to high (101-200 mm/m) and 2 per cent area is very high (>200 mm/m) in available water capacity.  About 6 per cent area of the microwatershed has nearly level (0-1% slope) lands and 10 per cent area of the microwatershed has very gently sloping (1-3% slope) lands.  An area of about 3 per cent area is moderately (e2) eroded and about 12 per cent area is slightly (e1) eroded.  An area of about 5 per cent soil are moderately alkaline to strongly alkaline (pH 7.8-9.0) and 10 per cent are very strongly alkaline (pH >9.0) in soil reaction.  The Electrical Conductivity (EC) of the soils in the entire cultivated area of the microwatershed is dominantly <2 dsm-1 indicating that the soils are non-saline.  Organic carbon is low (0.5%) in <1 per cent area, medium (0.5-0.75%) in 10 per cent area and high (>0.75%) in 6 per cent area.  Entire cultivated area of the microwatershed is medium (23-57 kg/ha) in available phosphorus.  An area of about 3 per cent is medium (145-337 kg/ha) and 13 per cent is high (>337 kg/ha) in available potassium.  Available sulphur is low (<10 ppm) in 13 per cent, medium (10 -20 ppm) in 1 per cent and high (>20 ppm) in 2 per cent area of the microwatershed.  An area of about 16 per cent is medium (0.5-1.0 ppm) and <1 per cent is high (>1.0 ppm) in available boron content.  Entire cultivated area of the microwatershed is deficient (<4.5 ppm) in available iron content.  Entire cultivated area of the microwatershed is sufficient (>1.0 ppm) in available manganese content.  Entire cultivated area of the microwatershed is sufficient (>0.2 ppm) in available copper content.  An area of about 15 per cent is deficient (<0.6 ppm) and <1 per cent is sufficient (>0.6 ppm) in available zinc content.  The land suitability for 31 major crops grown in the microwatershed was assessed and the areas that are highly suitable (S1) and moderately suitable (S2) are given below. It is however to be noted that a given soil may be suitable for various crops but what specific crop to be grown may be decided by the farmer looking to his capacity to invest on various inputs, marketing infrastructure, market price and finally the demand and supply position. Land suitability for various crops in the microwatershed Crop Suitability Area in ha (%) Crop Suitability Area in ha (%) Highly suitable (S1) Moderately suitable (S2) Highly suitable (S1) Moderately suitable (S2) Sorghum - 63(13) Sapota - - Maize - 63(13) Pomegranate - 63(13) Bajra - 63(13) Guava - - Groundnut - - Jackfruit - - Sunflower - 63(13) Jamun - 48(10) Cotton - 63(13) Musambi - 63(13) Red gram - 48(10) Lime - 63(13) Bengalgram - 63(13) Cashew - - Chilli - 12(2) Custard apple - 63(13) Tomato - - Amla - 63(13) Brinjal - 63(13) Tamarind - 48(10) Onion - - Marigold - 63(13) Bhendi - 63(13) Chrysanthemum - 63(13) Drumstick - 63(13) Jasmine - - Mulberry - 52(11) Crossandra - 15(3) Mango - -  Apart from the individual crop suitability, a proposed crop plan has been prepared for the 2 identified LMUs by considering only the highly and moderately suitable lands for different crops and cropping systems with food, fodder, fibre and other horticulture crops.  Maintaining soil-health is vital for crop production and conserve soil and land resource base for maintaining ecological balance and to mitigate climate change. For this, several ameliorative measures have been suggested for these problematic soils like saline/alkali, highly eroded, sandy soils etc.,  Soil and water conservation treatment plan has been prepared that would help in identifying the sites to be treated and also the type of structures required.  As part of the greening programme, several tree species have been suggested to be planted in marginal and submarginal lands, field bunds and also in the hillocks, mounds and ridges. That would help in supplementing the farm income, provide fodder and fuel, and generate lot of biomass which in turn would help in maintaining the ecological balance and contribute to mitigating the climate change.