I conducted intercropping trials as key part of my PhD study, for the 2013 and 2014 seasons in the southern (Kpataribogu) and northern (Bundunia) Guinea savanna in northern Ghana. Cowpea, soyabean and groundnut were each intercropped with maize in different planting arrangements.

One of my major research activities was a set of trials that evaluated the role of inoculation, P-fertilizer and manure application on common bean and soyabean yield and yield components. As part of this work, I measured nitrogen fixation in both legumes using the ¹⁵N-natural abundance method. The proportion of nitrogen derived from atmosphere (%Ndfa) differed between the two legumes (Table 1 and 2).

Cowpea (Vigna unguiculata) is a major staple in Nigeria. Despite this, its yield has remained low at 450 kg ha^-1 (Omotosho, 2014). Soil infertility, particularly low levels of nitrogen (N), phosphorus and potassium, has been identified as one of the constraints to bridging the yield gap that exists in cowpea production (Mfillige et al., 2014). Grain legumes are normally able to meet part of their nitrogen need through biological nitrogen fixation (BNF).

Despite the importance of soyabean in Nigeria, yields on farmers’ fields have remained relatively low. The crop holds considerable potential for arresting soil fertility decline and enhancing household food nutrition. Therefore, this study aimed to exploit differences among soyabean genotypes, assess genotype environment effect on seed yield and rhizobia inoculation as a means of improving nitrogen fixation and productivity of soyabean across three locations in the savanna region of Nigeria.

Common bean seed multiplication

In order to examine the interaction between bean genotypes and rhizobium strains nodulating bean, seed of 29 different bean varieties that represent a great genetic diversity were obtained from CIAT, Colombia. They were multiplied in a screenhouse on soil samples collected from potential bean growing areas in Sidama, Ethiopia.

A lot has happened since last year: the first paper of my PhD, entitled Understanding variability in soyabean yield and response to P-fertilizer and rhizobium inoculants on farmers’ fields in northern Nigeria got published in Field Crops Research (Podcaster 34), I largely finished the data collection in Uganda and I have entered the final year of my PhD, so I will focus on writing up the results.

The aim of my study is to unravel the contributions of genetic, environmental and management related factors to common bean yield and nitrogen fixation. I am conducting a continuous cropping study, which involves rotations and intercropping of common bean with maize for six seasons and compare the performance of two bean varieties; namely improved Lyamungu 90 and local Mkanamna.

This study examined the impact of improved cowpea varieties on the income and the food security status of women farmers in southern part of Borno State, Nigeria. The study used data on farmers before the Promoting Sustainable Agriculture in Borno State (PROSAB) project started in 2004 and after the project folded up about ten years after in 2015.

The aim of my study is to explore the use of rhizobia inoculation in order to increase yield and biological nitrogen fixation of the selected groundnut genotypes in the Sudan and northern Guinea savannas of Nigeria. Last year, I have already started the field work with two experiments. The first experiment included the following treatments; six groundnut varieties and six different inoculants treatments (NC 92, SBG 234, MJR 518, WDL 129, +N (20 kg N ha ^-1), and -N (0 kg N ha^-1)).