Subsurface drainage (SSD) improves crop productivity in canal command areas suffering from waterlogging and salinity problems. However, excessive drainage of paddy fields under conventional SSD is known to cause irrigation water shortage during critical growth stages of rice and also results in excessive leaching of nitrogenous fertilizers particularly at the tail end of the irrigation command. To overcome these problems farmers of the Tungabhadra Project (TBP) irrigation command used to block the outlets of lateral drains of the SSD system. In order to provide a lasting solution to this problem through a controlled drainage approach, a comparative field study was conducted on clay loam soil at the Agricultural Research Station (ARS), Gangavathi, over four seasons. In general, there was a reduction in drain discharge depth of 64% in the case of controlled drainage over conventional SSD, with an average irrigation water saving of about 17%. Average nitrogen loss was also reduced by 50.4% compared to conventional drainage. Paddy grain yield improvement was slightly higher (from 3.84 to 5.14 t ha−1) for conventional compared to controlled conditions (3.76–4.83 t ha−1). © 2019 John Wiley & Sons, Ltd. © 2019 John Wiley & Sons, Ltd.

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The Tungabhadra irrigation command area (TBP) in Karnataka, India, has three scenarios: the head, mid and tail reach command areas. The head reach has ample good quality canal water availability, and the mid reach area has limited canal water availability. In recent decades, rice–rice monocropping in vertisols, especially by these head and mid reach farmers, has led to not only water shortages but also the development of waterlogging and secondary soil salinization in the tail (lower) reach of the command due to seepage. As the soil salinity in the head reach was less severe, a slightly wider drain spacing of 60 m was adopted over 15 ha. In the case of the mid reach, salinity was slightly higher than the head reach but slightly less than the tail reach, hence 50 m drain spacing was laid out over 24 ha. Due to the slightly higher soil salinity at the tail end of the command, a closer drain spacing of 40 m was adopted over 11 ha. In all these scenarios, the drain depth was 1.0 m. Despite differences in irrigation water availability and different soil salinity conditions, the study clearly indicated over six seasons that the SSD system is a viable solution for the reclamation of waterlogged saline soils and enhancing rice productivity in all three scenarios of the TBP command.

A field experiment was carried out at Agricultural Research Station, Gangavathi, Karnataka during 2012-13 to 2014-15 A comparison of Laser guided leveler technology with zero tillage along with crop residue treatment and Farmers practice were carried out and it was found that Significantly higher yield and straw was recorded in the former practice (2450 and 2756 kg ha -1 ) as compared to later (1850 and 1950 kg ha -1 ). Similarly, number of plants per sq. meter area and plant height was significantly higher in laser leveling with zero tillage and 100% previous crop residue retained treatment and lowest in normal leveled land in farmers practice. Among eight treatment, the quantum of irrigation water applied was less in case of laser leveling with zero tillage with 100% previous crop residue retained treatment followed by laser leveling with zero tillage with 50% previous crop residue retained treatment and was more in case of farmers practice (control). The total water saving was to the extent of 27% in case of laser leveling with zero tillage with 100% crop residue retained treatment over control treatment. After harvest, the pH and ECe of the blocks varied between 7.9-8.66 and 4.04-9.04 dS/m at 0-15 cm and 7. 87-8.68 and 3.76-8.25 dS/m at 15-30 cm depths respectively. After harvest of third year crop, slightly higher soil organic carbon content was recorded at surface depth (0-15 cm) in T 7 treatment as compared to before sowing. It was concluded that, higher yield of wheat and water saving can be achieved in laser leveled land by using 100% previous crop residue retained in zero till land under saline soils.

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