Effect of Soil Compaction and Bulk Density on the Growth and Yield of Soybean (Glycine max) on Sandy Clay Loam Soil of the Semi-arid Region of Northern Nigeria as Influenced by Tractor Wheel Traffic

Soil compaction from farm machinery is an environmental problem. The effect of compaction on plant growth and yield depends on the crop grown and the environmental conditions that crop encounters. The effect of compaction from tractor traffic on soybean (Glycine max), variety TGX1448-2E, on a sandy clay loam soil in the semi-arid region of northern Nigeria was investigated for two growing seasons, 2015 and 2016. A randomized complete block design of the field of plots with treatments of 0,5,10, 15 and 20 passes of a tractor MF 390 was used. Each treatment was replicated three times. The soil bulk density, penetration resistance and soil moisture content for each applied load were measured and the yield from each treatment was determined. Agronomic treatments were kept the same for all plots in both 2015 and 2016. Results showed increased soil bulk density, penetration resistance and soil moisture content with increased tractor passes. Highest grain yield was obtained at 5 tractor passes with a mean bulk density of 1.76 Mgm,-3 penetration resistance 1.70 MPa and moisture content 13.37% with a mean yield of 2568 kgha-1 and lowest was obtained from 20 tractor passes were 340 kgha-1. Statistical models were used to predict yield as a function of bulk density, penetration resistance, moisture content, contact pressure, and a number of tractor traffic passes. Grain yield with respect to moisture content gave the best yield prediction (r2 = 0.94).