Effect of raised-sunken bed system on inter-plot water harvesting and productivity of rice (Oryza sativa) and French bean (Phaseolus vulgaris) in Meghalaya.

摘要

The effects of the raised-sunken bed system on the performance of rice and Phaseolus vulgaris were studied in Umiam, Meghalaya, India, during 2002 and 2003. The raised and sunken beds were established in a sequence for interplot water harvesting. The width of the sunken bed was 1.0, 1.5, 2.0, 2.5, 3.0 or 3.5 m, whereas the width of the raised bed was 1.0 m. Rice was grown in sunken beds, whereas P. vulgaris was grown in raised beds. The raised-sunken bed system significantly enhanced the grain yield of rice over the control (raised bed system for P. vulgaris and sunken bed system for rice) due to the prolonged submergence of rice seedlings. In 2002 and 2003, the highest grain (3.62 and 3.72 t/ha) and straw (6.62 and 7.02 t/ha) yields were obtained with a sunken bed width of 3.0 m. The green pod yield of P. vulgaris was lower under the raised-sunken bed system except at a sunken bed width of 3.0 or 3.5 m (on a par with the control) due to greater plant mortality as a result of excessive moisture and less aeration in plots. The raised-sunken bed system increased the depth and duration of submergence in sunken bed plots, which remained flooded up to 90-100 days after transplanting. The soil pH slightly decreased under the raised-sunken bed method. The organic C content, and available N, P2O5 and K2O also decreased in sunken beds over the control. The deterioration in fertility status was minimized as the width of the sunken bed increased..