Soil Compaction Effects on Soil Physical Properties and Soybean (Glycine max.) Yield in Ogbomoso, Southwestern Nigeria

Compaction is one of the major threats to soil sustainability as it can have negative effects on soil physical properties. Therefore, field experiments were conducted at Ladoke Akintola University of Technology Teaching and Research Farm, Ogbomoso, Southwestern Nigeria, in 2015 and 2016 to evaluate the influence of soil compaction on selected soil physical properties, growth, yield and nutrient uptake of soybean (Glycine max.). The experiment was arranged in a randomized complete block design and replicated three times. There were four treatments which consisted of 0 (no pass of tractor wheel), 4, 8, and 14 passes of tractor wheel totaling 16 treatments. Soil physical properties determined were; bulk density, total porosity, macroporosity and saturated hydraulic conductivity. While data recorded on soybean were plant height, stem girth, number of leaves, biomass and grain yield. Data collected were subjected to Analysis of Variance and significant means were compared using Least Significant Difference at 5% level of probability. Although not significant, soil physical quality decreased with increased levels of soil compaction in both years of study. Growth of soybean was significantly reduced by soil compaction with 14 passes producing the shortest plant (91.46, 29.10 cm) compared to the control (103.96, 30.27 cm), respectively, for 2015 and 2016. Grain yield of soybean significantly decreased by 12, 27, and 44% respectively, for 4, 8 and 18 passes of tractor wheel. The study indicates that soil compaction as a result of tractor wheel passes should be minimized on agricultural fields to reduce the adverse effects on soil physical properties, soybean growth and yield.