A Comparison of Tractor Wheel But Ditch and Traditional Ditch Methods of Field Drainage in Wet Seeding Rice Culture

Abstract

As a method of improving field drainage in wet direct seeding rice culture, surface water drainage by tractor wheel rut ditch is compared with traditional drainage methods. It is shown that this method of drainage leads to an improvement in the conditions of both ponding spots and vacant spots. The relationship between seedling establishment density and the ponding period is analyzed through field experiments. The experiments were carried out in the experimental field in the Muda Irrigation area in Peninsular Malaysia in the second cropping seasons of 1989 and 1990. Two types of ditches-tractor wheel rut ditches and the traditional type of ditch made by pulling soil-filled rice sacks across the field-were tested and compared with a control Plot where no ditches were constructed. All three plots had earlier been levelled. The progress of the drainage after puddling was analyzed along with that of the ponding spot areas, vacant spot areas, the ponding period, and seedling establishment density. These experiments showed that the drainage effect, seedling establishment density and vacant spot conditions were most favorable in the plot with tractor wheel rut ditches and the worst in the control plot, which had no ditches. Vacant spots were shown to occupy 3% of the area in the tractor ditch plot, 6.6% in the traditional ditch plot, and 8.5% in the control plot. A close correlation between the existence of the ponding spots and vacant spots was noted in each area. That is, in a plot with small ponding spots, the vacant spots were also small. Furthermore, it was observed that the longer the ponding period was, the lower was the seedling establishment density. When ponding days were longer than three days, seedling establishment density was less than 100/m2, whereas if ponding was longer than five days it was less than 50/m2.