In this paper soil compaction is described in relation to soil physical factors, root growth, and nutrient uptake by crop plants; rice growth and yield.
In compaction, soil solids are rearranged with compression of liquid and gaseous phases accompanied by volume change. Soil compaction affects water retention characteristics, water intake rates, and gaseous exchange. In compacted soil, bulk density, microvoids, thermal conductivity, and nutrient mobility increase and macrovoids, hydraulic conductivity, and water intake rates decreases. Medium textured soils are most susceptible to compaction. Plants response in relation to root growth and nutrient uptake varies depending on particular stage of development under a particular environment.
Soil compaction, which cuts down percolation losses and reduces the water requirements of rice, appears to be a more practical and economical tillage practice than puddling for increasing rice growth and yield and water use efficiency. Compaction as a tillage practice is simpler, consumes less energy, is easily designed, and shows possibility of mechanization of wetland rice cultivation by replacing messy and difficult operation of puddling, especially on medium textured soils.
________________________________________________________________________________ 1 Scientific Officer, SRDI, Dhaka and PhD Fellow, Dept. of Agronomy, BSMRAU, Gazipur
The compaction of soil can be defined as an increase in its dry density,and closer packing of solid particles or reduction in porosity (McKyes,1985).In other words, soil compaction is a dynamic soil behavior by which the state of compaction is increased (Gill and Vanden Berg, 1967). Soehne (1958 ) determined that for arable soils compaction could be described by the following relationships: n = - A ln P + C Where, n = porosity, C = porosity obtained by compacting loose soil at a pressure of 10 psi, A = slope of the respective plotted...