Changes in the physico-chemical properties of soil and harvested soybean seeds in response to soil solarization and bradyrhizobial inoculation

Abstract

Field experiments were carried out in 2005 to assess the effect of solarization on the physico-chemical properties of soil at various depths, and nutrient content of two harvested seeds from soybean-bradyrhizobia symbiosis. Experiments were organized in a Randomized Block Design with two levels of inoculation and three durations of solarization. Results indicate that at 5 cm depth, solarization increased the soil temperature by 14.5°C, 18°C and 16°C, respectively after four, eight and 12 weeks, whereas at 25 cm depth, it was enhanced by 14°C and 9.5°C, respectively, after 1–2 months and three months over the control. The soil conductivity and pH increased with the solarization period. The sand grain fractionation in soil gradually decreased while the clay-size fractions increased continually with the duration of solarization. The nutrient concentrations in soil were consistently increased with the duration of solarization. The nutrients accumulation in seeds was also improved by solarization and inoculation. The oil concentration of seeds was not affected by these treatments. Two months' solarization significantly enhanced the seed yield more than other treatments. Under the experimental conditions, the present study suggests that soybean-bradyrhizobia symbiosis can be increased under solarization practices through improved nutrients nutrition.

Keywords:

• bradyrhizobial inoculation
• solarization
• physico-chemical properties
• soybean

Acknowledgements

The authors thank the University of Ngaoundéré-Cameroon for providing the research plots and the Society MAISCAM-Cameroon for the two soybean cultivars gratuitously provided. They are also grateful to Dr Messine O. from The Institute of Research and Agricultural Development (IRAD-Wakwa, Ngaoundéré) for his assistance in data analysis.