Soybean Grain Yield Responses to Soil Fertility Management in Northern Ghana.

Soybean (Glycine max) is an emerging cash crop in northern Ghana. Promising early maturing lines with potential to increase and sustain grain yields in dry areas have been identified, but data is limited on the effect of different soil fertility management options on their grain yield.The effect of five integrated soil fertility management options: 1) farmer’s practice (F, no fertilizer); 2) Rhizobium inoculant (R); 3) phosphorus and potassium (PK); 4) nitrogen, phosphorus and potassium (NPK) and R plus PK on grain yield of early-maturing (Anidaso,  TGX 1799-8F and TGX 1805-8F) and late-maturing (TGX 1834-5E (Afayak), TGX 1445-3E (Songda), TGX 1448-2E, TGX 1904-6F and Jenguma) soybean entries were evaluated in two separate experiments. In both experiments, the variety by ISFM interaction was not significant for any traits measured. For the early-maturing variety, Anidaso produce significantly more (15%) grain than the other entries, whilst for the medium-maturing varieties Jenguma produced more grain than Songada. For both soybean maturity types, application of NPK and RPK resulted in significantly higher grain yields than the control when averaged across sites and years.  For the early-maturing varieties, grain yield can be increased by a combination of either NPK or RPK and Anidaso for the early-maturing types, whilst the same ISFM options in combination with Jenguma or TGX-1904-F will results in higher yields for the medium-maturing varieties.