Evaluation of maize yield in flood recession farming in the Okavango Delta, Botswana

摘要

Flood recession farming locally known as molapo farming in the Okavango Delta is practiced along the edges of the river channels or seasonally flooded depressions on its fringes. It relies on residual moisture and natural fertilization of the floodplains, and is promoted as being more productive than dry-land farming. However, the productivity of this low-input farming system has not been extensively investigated. The objective of this study was to evaluate the yield potential of maize (Zea mays L.) in molapo farming. Two molapo field experiments and one dry-land experiment were conducted at Matsaudi and Lake Ngami, and Shorobe, respectively, in a randomized complete block design with four replications. Maize grain yield and plant height were measured from six consecutive plants from the centre row. The results showed that maize grain yield and plant height were significantly (P < 0.05) higher at Lake Ngami than at either Matsaudi or Shorobe. Late planting at Lake Ngami coincided with rainfall in November providing even and abundant soil moisture which contributed to better productivity of maize. Similarly, soil fertility was also better at Lake Ngami. Maize grain yield although lower (2.41 t ha-1) at Matsaudi and Shorobe (2.58 t ha-1) than at Lake Ngami (3.4 t ha-1), it is much higher than yields normally obtained by small-holder farmers in semi-arid zones in sub-Saharan Africa, where yields are often less than half of the potential yields. Similarly, plant height was significantly (P < 0.05) higher at Lake Ngami (235 cm) than either Matsaudi (194 cm) or Shorobe (192 cm). It could be concluded that timely planting of maize in molapo fields supplemented by rainfall is capable of producing better yields in semi-arid regions where water is the most limited resource to crop production.