Abstract
The adoption of ISFM technologies such as maize-soybean intercropping system is being promoted as one of the options to address low soil fertility and crop productivity among the farmers of the central highland of Kenya. The purpose of this study was therefore to determine the effects of maize-soybean intercropping patterns on soil inorganic N, N uptake and soil chemical properties. The experiment conducted during 2012 LR and 2012 SR and it was arranged in a randomized complete block design (RCBD) with four replications. The treatments were four maize (M) – soybean (S) intercropping patterns (conventional=1M:1S; MBILI-MBILI=2M:2S; 2M:4S; 2M:6S) and two sole crops of maize and soybean, respectively. The results showed that at Embu during 2012 LR, at harvest the MBILI and 2M:4S treatments observed significantly (p=0.0525) the lowest N03- - N content (8.24 mg kg-1 and 9.15 mg kg-1, respectively); and at Kamujine during the same 2012 LR, at harvest the sole soybean treatment recorded statistically (p = 0.0301) the highest N03- - N content (8.24 mg kg-1). At Kamujine the sole soybean treatment recorded statistically (p=0.0131) the highest (12.84 mg kg-1) soil mineral N. The N uptake by maize and soybean was significantly affected by the intercropping patterns and it was positively correlated with soil mineral N, at both sites during the sampling period. During 2012 SR at Embu site, the MBILI treatment observed significantly the highest soil total N value of 0.05% (p=0.0530). The soil SOC was not significantly affected by the intercropping patterns at this location. The SOC was significantly affected by the intercropping and the conventional treatment recorded the highest value of 2.46%, p=0.0020.
Key words: Maize-soybean, intercropping patterns, soil mineral-N, N-uptake, chemical soil properties, central highlands, Kenya.
