Impacts of soybean monoculture on soil physical and chemical properties

Abstract

Monoculture is a common farming practice in most farming households that causes undesirable effects on the quality of soil. Legumes as a crop species are being used for soil productivity improvement, given the fact that they fix nitrogen into the soils and nitrogen being one of the essential crop nutrients. Analysis of the impacts of these legumes, in this case soybean crop, will provide a better understanding of the net effect of the repeated cultivation of this crop on the soil physical and chemical properties, hence how the fertility and productivity of the soils maybe affected. This study was done with the aim of establishing the effects of the practice of soybean monoculture on soil physical and chemical properties subsequently the productivity of the soils. The study was carried out on a farmer’s field of about six acres of land in Gulu district. The experiment was carried out in two planting seasons with a look at the previous soil conditions before cultivation. Data was collected on Nitrogen, available P, Organic Matter, exchangeable bases (Na+, Ca2+ and K+) and soil structure and analyzed using the IBM SPSS Statistical Data Editor. There were significant differences showing reductions in the levels of soil physical and chemical properties between the seasons with the exception of Na which remained constant throughout the experiment. For the soil structure, there was a positive correlation with the stated hypothesis, where there was a significant reduction in the soil structure quality between the pre-planting and the first and second seasons, the first and the second seasons were rather constant. N, P, K and OM together had similar variations in between the seasons where the differences between the pre-planting and the first seasons of cultivation were not significant. Soil pH was contrary to the values of the other properties, in that the difference between the pre-planting season is significant with the first season of soybean cultivation, and in turn not significant with the second season of planting. Na throughout the experiment remains constant without any significant change. Ca follows a similar trend as the results of soil structure. According to the results, soybean monoculture is shown to be detrimental to the soil properties hence soil beneficial practices such as intercropping, fertilisation etc. are recommended.