Influence of Bioslurry and Nitrogen Fertilizer on Soil Properties and Maize (Zea mays L.) Performance in Terraced Lixisols of medium and Acrisols of high altitudes in Rwanda

Abstract

Land terracing is promoted as a management practice for effective soil conservation in hilly areas. However, terraced lands are likely to  have low crop productivity where management practices, especially fertilizer application, do not consider changes in soil properties  following terracing. This study aimed to determine effects of integrated application of bioslurry and mineral nitrogen (N) rates on soil  biochemical properties and maize growth, N uptake and yields in terraced medium and high altitudes areas of Rwanda. A factorial  experiment in Randomized Complete Block Design with three replications was set up in two sites. Bioslurry rates of 0, 6, 12 and 18 t ha^-1  at medium altitude and 0, 5, 10 and 15 t ha^-1 at high altitude sites were combined with 0, 30, 60 and 90 kg N ha^-1. Results showed that  bioslurry rates of 12 - 18 t ha^-1 in medium altitude and 10 - 15 t ha^-1 in high altitude sites combined with 60 - 90 kg mineral N ha^-1 resulted  in significantly (P<0.05) higher plant heights, N uptake and grain yields of 7.8 - 8.0 t ha^-1 and 6.9 - 7.3 t ha^-1 in medium and high  altitudes sites, respectively. Their residual main effects resulted in higher bacteria and fungi populations. Bioslurry and N fertilizer  applications should be adjusted from current recommendations for increased maize yields in terraced Lixisols and Acrisols of medium  and high altitudes areas.