Rice can grow well in standing water; but it does not require standing water as a rule. In the traditional cultivation water level of 2-3 inches is always maintained. This is because of the farmers belief that rice requires more water for better growth and good yields. The other reason is not to allow emergence of weeds. But in SRI, the field is irrigated just enough to saturate the soil with moisture. Subsequent irrigation is suggested after soil forming fine cracks. The irrigation interval depends on the soil type and weather condition. This kind of water management avoids root degeneration in rice plant, increases microbial activity in the soil making the nutrients easily available to plants. It helps in healthy and better growth of roots. The roots also spread wider. However, due to intermittent wetting and drying allows the weeds to grow more rapidly and abundantly.
Research studies have amply demonstrated that there is positive correlation between weeder use and crop yields. In the experiments conducted during 2001-2002, the yield was compared with the use of rotary weeder ( five times with ten days interval from 20 days after transplanting till booting stage) with the conventional hand weeding ( 3 times) for wet season and chemical weeding and two times hand weeding for dry season. In both the seasons, mechanical weed control significantly increased grain yields. Weeder use alone increased the plant height and enhanced the grain yield by 10.9% as compared to manual weeding. An engine operated weeder is the product of latest technology & it accelerates the weeding process. We at SAEPL have a patented product and this product has got wide acceptance in all government & private sectors.