Raised-Sunken bed system for increasing productivity of rice-based cropping system in high rainfall areas of Himachal Pradesh

Rice (Oryza sativa) and mash (Vigna mungo) are two important crops of high rainfall areas of Himachal Pradesh. Rice suffers from soil moisture stress, especially during later growth periods, while mash from excess soil moisture. A raised-sunken bed (RSB) system of cultivation was used to increase productivity of both the crops. Three raised-sunken bed width-ratios, viz. 0.5:1, 1:1 and 1.5:1, in 5 m long plots at 0.5–1% slope, were tested and compared with control plots with 0:1 width-ratio. The width of all sunken beds and control plots was the same, i.e. 3 m. Mash was cultivated on raised beds and rice in sunken beds. The RSB system increased depth and duration of submergence in sunken beds. The duration of submergence in sunken beds was increased by 19–25 days during 1999ws, and by 14–21 days during 2000ws over the control. The average submergence depth in sunken plots with 0.5:1, 1:1 and 1.5:1 width-ratio, respectively was 2.4, 3.0 and 6.6 times of that in control during 1999, and 2.1, 3.0 and 4.6 times during 2000. With receding of rains at 57 DAT, the matric potential in control plots at 15 cm soil depth decreased to −25.2 kPa by 80 DAT, while sunken beds were still saturated with rain water. The rice yield in sunken beds was higher than in control plots by 16–40% during 1999, and 11–34% during 2000. The 1.5:1 width-ratio gave statistically the highest rice yield during both the seasons. Adequate surface drainage improved root-zone aeration on raised beds, and as a consequence mash crop performed better on raised than in control plots. The average mash yield on raised beds was 61–78% higher than in control plots. These results demonstrate the potential of RSB system for increasing productivity of rice-based cropping system in high rainfall areas. The RSB system of 1.5:1 width-ratio and 30 cm elevation difference was the most effective land treatment for inter-plot water harvesting, and rice and mash productivity in a silty clay loam soil in high rainfall areas of Himachal Pradesh.