Maize-sweetpotato intercropping influences on agronomic characteristics and soil chemical properties in Swaziland

Abstract

Intercropping is a common cropping system in the humid tropics, and involves growing two or more crops simultaneously on the same farm. The aims of the study were to assess the effects of intercropping maize (Zea mays L.) and sweetpotato [Ipomoea batatas (L.) Lam.] on agronomic characteristics and soil chemical properties in Swaziland. Five plant population treatments [T|, maize alone at 40,000 plants/ha; Ti, sweetpotato alone at 33,333 plants/ha; Tj, maize at 40,000 plants/ha, intercropped with sweetpotato at 33,333 plants/ha; T4, maize at 40,000 plants/ha, intercropped with sweetpotato at 16,666 plants/ha; and T5, sweetpotato alone at 16,666 plants/ha were arranged in a randomized complete block design that was replicated four times. Data were analyzed using the MSTAT-C statistical package. Results showed no significant differences in leaf area, and number of leaves/plant in both maize and sweetpotato. Sole maize yielded significantly (p < 0.05) higher (mean cob yield, 4,287.5 kg/ha) than intercropped maize (mean, 1,780.2 kg/ha). Sweetpotato tuber diameter was significantly greater (14.3 cm) under monocropping al 16,667 plants/ha at 16 weeks after planting (WAP), than intercropped sweetpotato (mean, 5.9 cm). Soil pH was significantly improved from 5.3 to 6.3 under maize­ sweetpotato, when 50% of the recommended sweetpotato population was used. It is recommended that sweetpotato farmers sow sweetpotato as a monocrop, but should they wish to intercrop with maize, they should plant maize at 40,000 plants/ha and mix-crop it with sweetpotato at 33,333 plants/ha.