Professor Ray R. Weil
| Agriculture and Tillage: |
| Cultivating to kill weeds in an Alabama soybean field. Note that the soybeans are wilting due to root pruning by the tillage sweep. |
| A Sri Lankan farmer with a traditional heavy tillage hoe |
| A farm tractor pulling a disk harrow and rolle for secondary tillage |
| Close-up of the disk on a disk harrow. The angle can be adjusted to cause a deeper "bit" and more soil turning. |
| Close-up of a sub-smiler or chisel plow in action (movement is to the left). |
| Close-up of a three bottom moldboard plow in action. Note that the plow slices thick layer of soil and inverts it, shattering it into aggregates in the process. |
| Man walking behind a horse drawn "walking plow" of the moldboard type. This type of plow was typical of the tillage implements used by American farmers between 1830 and 1930. Many farmers in developing countries still use animal draft power in this way. |
| Heavy sheeps foot roller used to compact soil prior to building a road bed or foundation |
| Outlet for a perforated pipe under-drainage system. The series of perforated pipes connected to this one under the farm field lowers the water table by hastening the lateral movement of water to the ditch. |
| Close-up of a partial clogged drainage pipe resulting from placement without a filter stock and with the perforations facing upward. |
| A grappler skidder harvesting logs near Edson, Alberta. Such equipment causes soil compaction that may reduce subsequent tree re-growth. |
| Foliar symptoms of salinity toxicity of soybean. The cultivar was very susceptible to salinity and the EC of the saturated paste was 6.0 dS/m. |
| A hydrangea plant treated with iron sulfate on the right side and limestone on the left. The year after treatment, the blossoms are blue in the acidified soil side and pink on the side with roots in limed soil. |
| Close-up of root nodules on soybean. Note the red interior color of the large nodule that has been sliced in half. This red color indicates active nitrogen fixation. |
| Shifting cultivation or Chena farming in the dry zone of Sri Lanka. Note the uneven distribution of ashes and scattered stumps allowed to remain. The ashes contain most of the cations that were in the vegetation, and a good part of the anions as well (much N and S goes up in smoke). |
| A rose showing foliar symptoms of iron deficiency. Note the intereveinal chlorosis, almost white leaves, and the fact that the symptoms are far worse on the younger leaves. |
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Direct questions and comments to Ellen Borkowski at ey9@umail.umd.edu Last modified Wednesday, March 1, 2000. |