LAND RESOURCE INVENTORY FOR WATERSHED PLANNING AND DEVELOPMENT YADGIR RF-8 (4D5B1C1b) MICROWATERSHED Yadgir Taluk and District, Karnataka

Abstract

The land resource inventory of Yadgir Rf8 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 the 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 357 ha in Yadgir taluk & district, Karnataka. The climate is semiarid and categorized as drought-prone with an average annual rainfall of 866 mm, of which about 652 mm is received during south-west monsoon, 138 mm during north-east and the remaining 76 mm during the rest of the year. An area of 76 ha in the microwatershed is covered by soils and about 281 ha by rock outcrops. The salient findings from the land resource inventory are summarized briefly below.  The soils belong to 4 soil series and 4 soil phases (management units) and 3 land management units.  The length of crop growing period is about 120-150 days starting from 1st week of June to 4th week of October.  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 29 major agricultural and horticultural crops was assessed and maps showing the degree of suitability along with constraints were generated.  Entire cultivated area in the microwatershed is suitable for agriculture.  About 12 per cent area of the microwatershed has soils that are moderately deep (75 - 100 cm) and 10 per cent soils are very very shallow (<25 cm).  About 3 per cent area in the microwatershed has sandy soils, 1 per cent has loamy soils and 17 per cent clayey soils.  About of 17 per cent area of the microwatershed has non gravelly (<15%) soils and 4 per cent has gravelly (15-35%) soils.  About 11 per cent area of the microwatershed is medium (101-150 mm/m) and 11 per cent area very low (<50 mm/m) in available water capacity.  An area of 20 per cent has very gently sloping (1-3% slope) lands and 1 per cent has gently sloping (3-5% slope) lands in the microwatershed.  An area of about 6 per cent is severely (e3) eroded and 15 per cent area is moderately (e2) eroded.  An area of about 7 per cent soils are neutral (pH 6.5-7.3), 5 per cent are moderately acid (pH 6.0-6.5) and 10 per cent are slightly acid (pH 6.0-6.5) in soil reaction.  The Electrical Conductivity (EC) of the soils in the entire cultivated area of the microwatershed is <2 dsm-1indicating that the soils are non-saline.  An area of about 12 per cent of the microwatershed is high (>0.75%), 9 per cent is medium (0.50-0.75%) and 1 per cent is low (<0.50%) in organic carbon content.  Entire cultivated area of the microwatershed is medium (23-57 kg/ha) in available phosphorus.  An area of 17 per cent is low (<145 kg/ha) and 4 per cent is medium (145-337 kg/ha) in available potassium in the microwatershed.  Available sulphur is low (<10 ppm) in the entire cultivated area of the microwatershed.  Available boron is low (<0.5 ppm) in 16 per cent and medium (0.5-1.0 ppm) in 5 per cent area of the microwatershed.  Available iron is sufficient (>4.5 ppm) in the entire cultivated area of the microwatershed.  Available manganese and copper are sufficient in the entire cultivated area of the microwatershed.  Available zinc is deficient (<0.6 ppm) in the entire cultivated area of the microwatershed.  The land suitability for 29 major crops grown in the microwatershed were 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 38(11) 3(1) Guava - 41(12) Maize 38(11) 3(1) Sapota - 41(12) Bajra 38(11) 3(1) Pomegranate - 41(12) Groundnut - 41(12) Musambi - 41(12) Sunflower - 41(12) Lime - 41(12) Redgram - 41(12) Amla 38(11) 3(1) Bengal gram - - Cashew - - Cotton - 38(11) Jackfruit - 41(12) Chilli 38(11) - Jamun - - Tomato 38(11) - Custard apple - 41(12) Brinjal 38(11) - Tamarind - - Onion 38(11) - Mulberry - 41(12) Bhendi 38(11) - Marigold 38(11) - Drumstick - 41(12) Chrysanthemum 38(11) - Mango - -  Apart from the individual crop suitability, a proposed crop plan has been prepared for the identified LMUs by considering only the highly and moderately suitable lands for different crops and cropping systems with food, fodder, fibre and 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 to 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 sub marginal lands, field bunds and also in the hillocks, mounds and ridges. This would help in not only supplementing the farm income but also provide fodder and fuel and generate lot of biomass which would help in maintaining an ecological balance and also contribute to mitigating the climate change