Potential of Cultivating Dry Season Maize along a Hydrological Gradient of an Inland Valley in Uganda

Alibu Alibu,Becker Becker,Senthilkumar Senthilkumar,Köpke Köpke,Neuhoff Neuhoff

doi:10.3390/agronomy9100606

Abstract

Inland valley wetlands with higher soil moisture than surrounding uplands offer a yet unexplored opportunity for increasing maize production in East Africa. For three consecutive years, we conducted field experiments to assess the potential of an inland valley in Central Uganda for producing dry season maize. A randomized complete block design was used with six treatments including farmer’s practice, unfertilized control, organic and inorganic fertilizer applications at high and low rates. These were repeated four times at each of the three hydrological positions of the inland valley (fringe, middle, and center). The maize grain yield of 3.4 t ha−1 (mean across treatments and years) exceeded the national yield average by 42%. High and sustained soil moisture in the center position of the inland valley was associated with the highest grain yields irrespective of the year. Due to soil moisture deficit in the fringe and middle hydrological positions, grain yields were not only lower but also highly variable. Intensive manuring with a combination of green and poultry manure produced high yields that were comparable to those with mineral fertilizers (both at 120 kg N ha−1). Lower amounts of either mineral or organic fertilizer (60 kg N ha−1) provided no yield gain over the unfertilized control. Inland valley wetlands, thus, offer promise for farmers to harvest an additional maize crop during the dry season, thus contributing to farm income and regional food security.

Highlights

Maize (Zea mays) is the most important staple crop grown in East Africa [1]
We investigated the suitability of the different hydrological positions of an inland valley wetland in Central Uganda for producing dry season maize and tested its response to different crop management options including mineral and organic fertilizers
We found in this study that the agronomic N-use efficiency of applied fertilizer increased toward the center of the inland valley (Table 3), which might explain in-part the higher yields at the center as compared to the other hydrological positions

Summary

Introduction

Maize (Zea mays) is the most important staple crop grown in East Africa [1]. The grains form an important part of the food and feed system of the region providing more than 19% of the dietary calorie supply for the population [2] and contributing 30%−50% of the household income of smallholder farmers, who produce about 90% of the maize. The per capita annual consumption of maize grain in Kenya, Tanzania, and Uganda amounts to 103, 73, and 31 kg, respectively [3]. Tanzania alone uses up to 800,000 MT of maize as animal feeds, while Kenya and Uganda use only about 350,000 [5] and. Maize in East Africa is predominantly grown in smallholder farms under rainfed conditions with low fertilizer input. The dependence on rainfall increases the vulnerability of these farming systems to Agronomy 2019, 9, 606; doi:10.3390/agronomy9100606 www.mdpi.com/journal/agronomy

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