GANGAVATHI

This centre was initially started at Dharwad in 1972 during Fourth Five year plan and later on it was shifted to Agricultural Research Station, University of Agricultural Sciences, Gangawati (Karnataka) w.e.f. April 01, 1989 to work in areas where large chunk of land affected by salinity problem occurred. It situated in Agro ecological region 6 (Deccan plateau, hot semi-arid region) and located at 15⁰ 00’ N Latitude and 76⁰00’ E Longitude.

• Characterization of underground water samples for irrigation in Bagalkot, Bellary, Bijapur, Davanagere, Koppal, Raichur, Gulbarga, Yadgir, Dharwad and Gadag districts of Karnataka.
• Tree species such as C. equisetifolia, D.sissoo, Glyricidia and A.auriculiformis have been found promising under saline waterlogged conditions of Tunga Bhadra Project (TBP) command area.
• Fruit species such as wood apple, jamun, pomegranate and sapota have been found promising under saline waterlogged conditions of TBP area.
• The threshold water table depth for cotton is found to be 95 cm in saline Vertisols of TBP. Yields are drastically reduced when water table is shallower than 95 cm. On saline soils having water table deeper than 95 cm, cotton should be irrigated once in 12-15 days for realizing higher yields.
• On saline soils, cotton and wheat can be successfully grown up to 5-7 dS/m and safflower 4-5 dS/m. Brinjal can be grown in saline (ECe: 4-6 dS/m) vertisols. Ridgeguard can be grown in saline (ECe: 4-6 dS/m) vertisols. Beet root can be successfully grown on saline soils with ECe up to 6-8 dS/m without any yield reduction.
• Tree species such as A.nilotica, D.sissoo and C.equisetifolia were found efficient in intercepting canal seepage when grown parallel to distributaries/canals. Such tree plantations control water logging and salinity in low-lying aera.
• Salt-tolerant crops such as cotton, wheat and sunflower can be grown successfully even in high saline soils (12-15 dS/m) by providing pre-sowing irrigation (of 6 cm depth). It is observed that salts in surface soil (0-30 cm) are leached out approximately at 60% leaching efficiency during pre-sowing irrigation.
• Interceptor drains of 10 cm dia. placed 1.7m deep, 500 m away from distributary intercepts the incoming canal seepage and prevents secondary soil salinization in the low-lying area Sindhanur near Gangavathi.
• To control salinity and water logging in undulating soils, a technology of multilayered interceptor drain was developed. Plants and grasses were identified for intercepting seepage. Bio drainage studies at ARS, Gangavathi revealed that planting of tree species such as Acacia nilotica, Delbergia sissoo and Casuarina equisetifolia in 2 to 4 row spacing 5 m away and parallel to canal were quite efficient in intercepting the canal seepage. Such plantations could intercept more than 80% of the seepage and relieve water logging problem along the canals.
• Subsurface drainage technology has been implemented. It has been established that reuse of drainage water is possible and hence it has become a source of irrigation water to many farmers located in the tail ends of the irrigation commands. Subsurface drainage lowered the water table, reduced soil ECe and increased the yield of crops. It has been shown that payback period of this technology is 2-3 years depending upon the initial status of soil and crops grown following land reclamation. Sub-surface drainage system coupled with nala cleaning is quite efficient in reclaiming salt affected soils in turn result in higher crop yields.
• The controlled drainage was developed by centre. It could save about 17.5% irrigation water (104 cm vs 126 cm) and 52.5% nitrogen (5.32 kg/ha 11.20 kg/ha) as compared to conventional drainage.
• In salt-affected soils, paddy can be successfully grown by adopting continuous ponding method of irrigation. Intermittent ponding badly affects paddy yields. The continuous ponding assures better leaching of salts compared to intermittent ponding.
• Due to continuous paddy cultivation, water table is raising at the rate of 10 cm per year in TBP command.
• In saline soils of TBP canal command, growing dhaincha in a paddy-paddy cropping sequence resulted in higher paddy yields apart from improvement in soil fertility.
• binana, a leguminous tree species has been identified as a promising genotype for saline/water logged soils.
• A salinity tolerant, high yielding mid early paddy genotype CSR-22 was released for cultivation in saline soils of TBP command area.
• Subsurface drainage system coupled with nala cleaning is quite efficient in reclaiming salt affected soils in turn result in higher crop yields.
• On saline soils (ECe 8-10 dS/m), irrigating cotton through drip at 2 to 3 days interval with saline water (<2.2 dS/m) resulted in higher kapas yield.
• In saline soils (ECe 6-7 dS/m) moving water table deeper than 1.2 m, drip irrigation at 2-3 days interval with saline water (<2.2 dS/m) or furrow irrigation once in 15-18 days resulted in higher brinjal yields.
• On saline soils (ECe 5 dS/m), sowing sunflower in ridges and furrows and application of 20 kg extra N resulted in higher yields.
• Under rainfed conditions, making tied and ridges in the beginning of the monsoon causes leaching of salts to below the root zone and thus help to obtain higher sunflower yield.
• Early sowing (June) of cotton with available saline (with 4 irrigations) and then switching over to canal (August) water realized the highest kapas yield (22.1 q/ha) compared to normal sowing with only good water during August (12.6 q/ha). Further, the salt balance remained favourable and did not cause any concern of using saline water.
• Application of pressmud @ 2.5 t/ha or poultry manure @ 2.5 t/ha or dhaincha @ 5 t/ha or FYM @ 10 t/ha to kharif paddy and 125% RDN to the kharif and rabi paddy resulted in higher yields and improved the soil properties.
• Threshold soil salinity levels (ECt) were worked out for Ashwagandha (4.87, 4.41 dS/m for seed and root respectively), Vetiver (6.0 dS/m), Palmarosa (5.02 dS/m), Khus grass (6.0 dS/m), Kamakasturi (4.8 dS/m), Tulsi  (5.1 dS/m), Citronella (7.2 dS/m), Shatavari (3.96 dS/m) etc.
• Citronella could be grown in saline Vertisols of ECe up to 7.2 dS/m.
• Rhodes, para and grazing guinea forage grasses could be grown in saline Vertisols of ECe up to 4-8 dS/m.
• Applying 20 % extra good quality irrigation water through drip with mulch for cotton crop under saline soils increases 3% of soil moisture improves leaching of salts in the root zone and also control weeds.
• Before puddling operation, land leveling by laser leveller under PTR method saves 11% of water compared to traditional method of leveling.
• Before sowing operation, land leveling by laser leveller under DSR method saves 6% of water compared to traditional method of leveling.