Influence of soil managementa on some physical properties of a soil

1. In the 0 to 6 2/3 inch layer of the soils included in this study, plat 3 NW, the unfertilized continuous corn plat, has the lowest organic carbon content, the lowest moisture equivalent, the highest dispersion and erosion ratios, the lowest water-holding capacity, and, with one exception, the slowest rate of percolation. Plat 3 SW showed a slightly slower rate of percolation after the soil had been saturated with water for 1 1/2 hours. In this same layer of soil, plat 5 SW, the corn, oats, and clover plat on which fertilizer and lime have been used, has the highest organic carbon content, the lowest dispersion and erosion ratios, the highest water-holding capacity, the most rapid rate of percolation, and the highest moisture equivalent except the grass border, which has a slightly higher moisture equivalent. 2. In the 6 2/3 to 13 1/3 inch layer of soil, the results are quite different than in the surface layer. The unfertilized corn plat has a relatively low dispersion ratio and permits the most rapid percolation of water. The results presented in Fig. 1 and Table 2 indicate that the same is true for the unfertilized corn, oats, and clover plat in this same layer of soil. 3. In the 13 1/3 inch layer of soil, the unfertilized corn plat occupies the same position among the different samples as in the surface layer, except that it has a relatively high moisture equivalent. This may be accounted for by the fact that it contains a higher percentage of material of the size of clay and finer. The fertilized corn plat has a relatively low dispersion ratio in this layer of soil. No reason for this is apparent at this time. 4. Poor systems of cropping and soil treatment are not only accompanied by rapid declines in crop yields and a decrease in plant nutrients, but also by changes in the physical condition of the soil. In the surface soil especially these changes are undesirable. 5. It appears from the results reported here that soil on which poor cropping systems have been followed, and there are many such areas in Illinois, are much more subject to destruction by erosion than soils on which good systems have been followed. 6. The results also indicate that good physical condition of a soil, such as the one studied here, can be maintained if good systems of cropping and management are followed.