The influence of some management systems on the growth and yield of two soyabean varieties (Glycine Max, (L), Merrill)

A factorial experiment with a Split plot design with four replications was conducted to study the effect of variable soil management systems on the growth, and yield of two soyabean cultivate in Kumasi (6o 43’N, 1° 36’W) located in the Forest zone of Ghana. The coil management systems consisted of three seedbed configurations (flat, ridged and furrowed) which were either mulched with 6t/ha dried grass or unmulched. The two soyabean varieties – TGX 888 – 49C, an early maturing variety and TGX 536-02D, a medium maturing variety - were grown at a standard population density of 8.9 plants/m2 in the major and minor seasons of 1987. Another experiment was conducted in the major season of 1966, using the above population density in a randomized complete block design with four replications. Only one soyabean variety, TGX 888-49C was grown on two seedbed configurations (flat and ridged) with three mulching rates, 0, 6 and 12t/ha. Seasonal variations in soil temperature were evident with values being generally higher in the major season and on the ridged plots. The diurnal rage in soil temperature was greatest on the ridged plots, followed by the flat plots, with the furrowed plots giving the least range. Mulching significantly reduced coil temperature, and the magnitude of reduction increased as mulching rate and coil temperature increased. Soil moisture content in the 0-30cm soil depth was considerably influenced by seedbed configuration, with the values determined being in the order of flat > furrowed ridged plots, and ridged > flat > furrowed in the 1987 major and minor season respectively. Mean percentage emergence in the major season of 1987 was highest on the flat seedbed, followed by the furrowed and then the ridged plots, In the minor season, the corresponding order was ridged, flat and furrowed seedbeds. Emergence in the major season of 1988 was better on the ridged than on the flat plots. Seasonal variation in rainfall and coil moisture influenced vegetative growth and final seed yield. These parameters wore greater in the major season than in the minor season, and were significantly influenced by seedbed type. In the major and minor seasons, the respective increases were in the order of ridged < furrowed < flat plots, and furrowed < flat ridged plots. Mulching increased most of the plant characters studied. However, increasing the mulch rate from 6 to 12t/ha did not have any significant effects Mulching significantly increased C, L and E in the early vegetative stage in the major and minor seasons. Crop growth rate and components were influenced by seasonal changes in soil moisture and temperature. C, L and E were significantly higher on the flat seedbed, with the least values recorded on the ridged plots during the vegetative stage in the major season of 1987. In the minor season, the highest and lowest C and E were obtained on the ridged and flat plots respectively. Ridged plots gave a significantly higher L at flowering in the minor season of 1987. Premature, loss of leaf resulting in a reduced leaf area and thus photosynthate supply was found to have limited seed yield by reducing seed sink size and mean weight of seed.

Source: KNUST