Growing Rice Under Managed Water Table System:

Abstract

A lot of water is used in rice cultivation but under dwindling global water stocks, this issue of water use must be examined. Therefore rice (Oryza sativa L.) cultivar IR36 was grown in a controlled sand medium under nitrogen limiting conditions using a water table management system. The treatments used were water table at depths of 27.5cm, 15cm below the surface and saturated sand with the water table at the soil surface. Fifty four rice plants were grown for a period of 68 days. There were five harvests, with 9 plants harvested at each of the first four and 18 plants at the last harvest. Plant growth was determined by measuring rooting depth when harvesting, and the rest, shoot length, root dry mass and shoot dry mass after harvest. The saturated treatment was highest for all
parameters measured followed by the 15cm and finally the 27.5cm treatment. The water release characteristics indicated that there were no major differences between moisture contents when the water table was held at the depths used. For most of the parameters measured, significant differences emerged only after about 25 days after seeding indicating that there was the possibility of some water saving in the early days of rice production. Contrary to other findings, the rooting depth for the saturated treatment was higher than those for the 15cm and 27.5cm treatments, a factor, which could be attributed to the fact that rooting depth is greater when nitrogen is limiting.

Journal of the Ghana Science Association Vol. 10 (2) 2008: pp. 39-50