**10. Crop establishment**

Proper establishment of the crops is critical for successful crop production. The aim is to get a fast and uniform sprouting of the planted vine cuttings and a vigorous early growth of the young sweet potato plants—all in order to develop an early and full canopy cover over the soil to suppress weeds, conserve soil moisture, minimize soil erosion, and to use all resources efficiently and evenly over the entire field. Once a uniform crop stand is established, further management of the crop becomes easier.

#### **10.1 Spacing and plant population**

Optimum planting density varies with soil type and other environmental conditions. The most commonly used spacing for sweet potato is 60 cm between rows or ridges and 20–30 cm between hills, giving a planting density of 83,333/ha for 20 cm spacing and 55,555/ha for 30 cm spacing [48]. The mounds are spaced at 70 cm x 70 cm and 3–6 vine cuttings are planted in each mound, giving a population density of 61,224–122,449 plants/ha. Increasing planting density beyond the optimum decreases plant vigour, increases the number of roots but decreases the root size, and increases the infestation of weevils [50]. The highest marketable root yields were obtained with a planting density per hectare of 66,666 in South Korea; 74,074 on alluvial soil with two plants per hill and 55,555 on flat bed in Bangladesh; 83,333 in Ethiopia [48]. Thus, a plant population range of 50,000–80,000 per hectare appears to be optimum for root production in most situations.
