EFFECT OF METHODS OF LAND PREPARATION ON THE YIELDS OF FOUR CASSAVA CULTIVARS IN THAILAND

Abstract

Cassava has been grown in Thailand for many years. Land is usually prepared by plowing with a 3-disk plow followed by a 7-disk harrow and ridging. This method of land preparation results in a very loose soil, which is free of weeds and easy to plant. However, it has also led to the formation of a compacted subsoil or hardpan. A trial on alternative methods of land preparation was conducted at three sites from 2001 to 2004 to determine the effect of land preparation on the yields of four cassava cultivars. The results indicate that on average for three years in a farmer's field near Rayong Field Crops Research Center, tillage treatments had a significant effect on the fresh root yield of the four cassava cultivars. Using a subsoiler followed by 3-disk plow produced the highest fresh root yield of 24.60 t/ha, while the no-tillage treatment produced the lowest yield of 19.26 t/ha. At the Thai Tapioca Development Institute site, there were significant differences among tillage treatments for fresh root yield of the four cassava cultivars. Using the subsoiler followed by a chisel plow produced the highest fresh root yield of 21.59 t/ha and the second highest net income; this was followed by the no-tillage treatment (which brought in the highest net income). At Khaw Hin Sorn Research Station of Kasetsart University, tillage treatments also had a significant effect on fresh root yields. Using a 3-disk plow followed by 7-disk harrow and ridging up-and-down the slope produced the highest fresh root yield of 32.21 t/ha, but using a 3-disk plow followed by a 7-disk harrow, with or without subsoiling, brought in the highest net incomes. Among the four cultivars, there was no significant difference in fresh root yield; however, they differed in starch content.