Cassava agronomy research and adoption of improved practices in Thailand: Major achievements during the past 35 years

This paper reviews the results of past research conducted from 1965 to 2000 in two major cassava growing areas, the northeastern and eastern parts of Thailand. This research was carried out by the Field Crops Research Institute, Department of Agriculture (DOA), in collaboration with Kasetsart University and the Centro Internacional de Agricultura Tropical CIAT). The major achievements are described under the following three topics: Methods of cultivation, which tested and developed all the necessary components of cassava cultural practices, such as land preparation, planting time, age of harvest, spacing and plant population, planting method, stake size and storage, as well as weed control. Cassava-based cropping systems, which showed the feasibility of intercropping cassava with short-duration crops such as mungbean, peanut, soybean and sweet corn. Cassava soil conservation and fertility maintenance, which tested and developed appropriate production practices that both reduce soil loss by erosion and maintain high cassava yields. Long-term experiments on the effect of various fertilizer applications and soil management treatments showed the crop’s nutritional requirements, and indicate soil/crop management practices that will maintain high levels of cassava productivity as well as adequate soil fertility. INTRODUCTION In 1976 the cassava planted area in Thailand was only 692,320 ha. Ten years later in 1985 the area had increased to 1,476,800 ha (OAE, 1985), and in 1997 this had slightly decreased again to 1,265,120 ha (OAE, 1998). Cassava replaced some other crops like kenaf and its area expanded greatly due to its ease of cultivation and tolerance to drought and infertile soils. Research on technologies for enhancing cassava production until the early 1990s was limited to the local variety Rayong 1, with most emphasis placed on agronomic practices for increasing yields. Since then the cassava breeding program has released several new high-yielding cultivars, and agronomy research has focused mainly on developing appropriate technologies, which could produce a high level of productivity of these varieties and maintain soil fertility in cassava growing areas. This paper reviews the results of many experiments in cassava agronomy which have been conducted from 1965 to 2000. METHODS OF CULTIVATION Agronomy research initially concentrated on the testing and development of the necessary components in cassava cultural practices: 1. Planting Time In Thailand cassava can be planted all year round. A survey conducted in 1975 (Sinthuprama and Tiraporn, 1984) shows that 59% of cassava was planted in March to 1 Rayong Field Crops Research Center, Huai Pong, Rayong, Thailand. 2 Field Crops Research Institute, Dept. of Agriculture, Chatuchak, Bangkok, Thailand. 3 CIAT Regional Cassava Program for Asia, Dept. of Agriculture, Chatuchak, Thailand.