Effect of Homogeneous and Heterogeneous Soil Compaction on Shoot and Root Growth of Field Bean and Soybean
The study was done to observe the effects of soil compaction on field bean and soybean growth in greenhouse. Plastic cylindrical tubes of 58 cm height and 12 cm diameter were filled with silty loam soil with three bulk densities i.e., low (1.25 g/cm3), medium (1.45 g/cm3) and high (1.65 g/cm3) either separately or in combination of low/medium (level 1), low/high (level 2) and medium/high (level 3) as top and sub-soil densities. 
 
General effect of compaction was a reduction in shoot and root growth and in yield of both the legumes; probable reason seemed to be mechanical impedance. At homogeneous compaction throughout the soil profile high bulk density decreased the root dry matter from 6 to 32 % and total root length from 30 to 57% but total root volume was not much affected due to thickening of the roots. From 4 to 31% reductions were also observed in shoot dry matter. Increase in only subsoil density from medium to high (level 2) decreased shoot and root dry matters (8 to 36% and 16 to 39%, respectively) but not the total root length. Plant growth was more hampered when both top and subsoil densities were increased (level 3) but the total root length was not highly affected in the upper (0 to 20 cm) and middle (20 to 40 cm) layer.