**8. Rainfed production**

Cassava is nearly entirely a rainfed crop in most parts of the world. Rainfed cassava cultivation involves careful attention to planting dates, the use of planting methods and planting sites that make use of available soil moisture, and waterconserving soil management procedures. Cassava may be grown all year if rainfall is evenly distributed, but it cannot be planted during seasons of excessive rains or drought [15]. Farmers in locations where there is only one rainy season per year plant as soon as the rains begin, which is normally in April–May in the northern tropics and October–November in the southern tropics. As the topsoil begins to dry out with the coming of the dry season, new plants will grow deeper roots once established. Before the start of the 5-month rainy season in Andhra Pradesh, India, farmers plant cassava in well-watered nursery beds to induce sprouting and root development. The rooted stakes are relocated to the field as the rains begin. If the early rains fail to hold off and any of the transplanted stakes perish, they are replaced with newly sprouted stakes from the nursery beds. Farmers can make the most of the short wet season by using this method, which eliminates the need for irrigation. In lowland paddy fields, however, some farmers plant short-duration cassava in February, after the rice has been harvested and the soil is still wet.

In lowland paddy fields, however, some farmers plant short-duration cassava in February, after the rice has been harvested and the soil is still wet. During the dry months that follow, the crop benefits from the leftover soil moisture, and it is harvested after 8 months before the area is utilized again for rice. Because the plants receive adequate soil moisture throughout the most essential stage of their growth cycle, planting early in the rainy season will normally generate the largest yields. However, outputs depend on the cultivar of the crop planted. Also, the edaphic nature of the soil coupled with the maturity of the crop as well as the rainfall intensity reinforced to determine the harvest achieved by a farmer in a given year. Planting during the month of June for instance, resulted in yield of about

#### *Cassava Production Enterprise in the Tropics DOI: http://dx.doi.org/10.5772/intechopen.104677*

38 tonnes/hectare as against 26 tonnes/hectare at the beginning of dry season in October [15]. Later research at the same location in Thailand found that planting from August to November produced the highest average yield. A more recent experiment, this one conducted over 3 years, yielded a different outcome. Cassava root yields were highest when it was planted in December, early in the dry season, and harvested 11 months later, in November [16].

Under rainfed agriculture, planting practices must be adapted to the soil moisture levels. Plant stakes on the tops of ridges or mounds to keep the roots above the standing water when the soil is poorly drained and overly wet due to heavy rainfall. This will also help to prevent root rot. When cassava is planted on the flat land in Thailand during dry periods, the rates of stake sprouting and plant survival are much higher, owing to the somewhat increased soil moisture content in the top 30 cm of soil [17]. In heavy and wet soils, stakes should be planted at a shallow depth of 5–10 cm, but slightly deeper in light-textured and dry soils.

With minimal tillage, which enhances internal drainage, the risk of waterlogging is reduced. When tillage is employed, farmland is better worked during the time when the internal drainage of the soil is optimum. The advantage of this is that it gives room for the practice of zero tillage which further enhances the soil condition. Planting 2 months towards the end of rainy season is beneficial as it reduces weed menace.
