How do I Improve the Soil for Planting Cassava ?

If you do not select a good site for growing cassava you may have to spend a lot of time and materials to improve the soil. Cassava plants on good soils grow vigorously and are able to withstand some damage by pests and diseases. The following are examples of cultural practices you can use to improve soil properties.

Manure your farm: At land preparation, you can add organic manure to the soil to increase soil nutrients, improve soil structure, and improve the ability of the soil to hold water. Organic manure can be in the form of green manure or other dead plant or animal manure. In green manuring, plant foliage (fresh leaves and young green stems) is ploughed into the soil. Green manure improves soil properties as the foliage rots. Egusi melon and leguminous crops, for example, groundnuts and beans, make good green manure. Inorganic fertilizers can also be applied to increase soil fertility. For example, in southeast Nigeria, the recommended rate for NPK application is 400 kg. per hectare of land.

Prepare suitable seedbeds: Cassava fields on hilly sites with steep slopes are frequently eroded. The erosion will be severe if the leaf canopy of cassava plants is not thick enough to cover the ground against rain splashes. This happens in young cassava farms and if the varieties have a tall and less branching habit (Figure 5). If you cannot avoid growing cassava on steep slopes you can grow cassava varieties with early, low, and much branching habit (Figure 6) to cover the ground quickly and properly against rain erosion. You can also make ridges across the slopes and mulch the ridges to reduce erosion.

Mulch cassava seedbeds: Mulching involves covering the soil surface with plant materials. Mulching improves the fertility of the soil, increases the ability of the soil to hold sufficient water for plant growth, and reduces erosion and weed problems. Mulching cassava seedbeds is especially valuable when growing cassava in dry areas and on slopes.

 Mulching requires very large amounts of plant foliage. Dead plant foliage can be used as “dead mulch”. Sources of good dead mulch are foliage from alley crops, leguminous plants, rice husk, coffee hull and general crop and weed residues. Avoid using weed residues containing weed seeds, rhizomes, stolons, or tubers as mulch because these can increase weed problems on your farm. Straws of maize and guinea grass (Figure 7) are bad mulch materials because they take too long to rot and use up soil nitrogen as they do so.

You can grow plants as “live mulches”. For example, egusi melon (a food crop) planted at very close spacing on cassava seedbeds is a good live mulch. Nonfood crops can also be used as live mulches, but these are normally grown as improved fallow plants. For example, during fallow periods you can grow Mucuna pruriens var. utilis on land you have selected for growing cassava in the next season (Figure 8). Mucuna pruriens var. utilis is, however, a fire hazard in the dry season when its foliage dries.

Plant cassava in association with other crops: Appropriate intercrops improve soil properties in a manner similar to live mulches. Crops that are commonly intercropped with cassava are maize, rice, legumes, and vegetables. Legumes, for example, cowpea and groundnuts, are a particularly good intercrop because these plants make and release nutrients into the soil.