Secondary Horticultural Cropping in a Paddy Field in the Mwea Irrigation Scheme, Kenya:

Different Drainage Techniques and Effect on Selected Crop Yields

Abstract

Perennial water shortage in the downstream area of the Mwea Irrigation Scheme (MIS) remains a major problem. Therefore, some farmers try to increase their cash income by cultivating horticultural crops after the main rice crop, but their cultivation technology has not yet been established. We conducted a field experiment to study the effectiveness of different surface drainage methods and how they affect the yield of selected crops because the vertisol that dominates the irrigated area is highly fertile but has extremely poor drainage. We compared a control area with surrounding ditches with a new drainage area consisting of additional ditches within the field. During the 2016 long rainy season (January–July), the period when soil water tension starts to rise in the new drainage area was earlier than that in the control area. The soil water content in the control area was slightly higher compared to the new drainage area. Therefore, it was found that the drainage capacity was enhanced by the new drainage method. There was no significant increase in the yield of soybean or green gram due to the drainage improvement. Meanwhile, disease occurrence was suppressed and the yield was increased in tomatoes by improving field drainage, and also by using “Rambo F1” and “Kilele F1”. Therefore, it was shown that bacterial wilt resistant cultivars are effective for secondary tomato cropping in MIS paddy fields.