Subsurface (tile) drainage has increased dramatically in eastern South Dakota in the last several years driven by increases in precipitation and commodity and land prices. With this increase in drainage, there has also been increased public concern about the environmental impacts of drainage.

The objective of a subsurface (tile) drainage system is to control a high water table to create favorable soil water conditions for crop growth and field operations. This article discusses drain spacing requirements for patterned tile systems or for parallel laterals within the targeted areas of a targeted drainage system. Although the information here is focused on areas with parallel laterals, the same information can be used to give an idea of the area that will be effectively drained by a single drain line.

Soon after the soybean plant develops its first true leaves, we often see yellow areas or “spots” in the fields as we cruise by on the highway. Upon closer inspection we note the leaf veins are green while the tissue between is yellow or chlorotic. In later growth stages the soybean plant can be stunted compared to areas not affected. These symptoms are characteristic of Iron Deficiency Chlorosis or IDC.

“My soybean yields haven’t kept up with my corn yields.” How many times have we heard that statement? In fact it is true. Corn yields have climbed by about 40% over the last 25 years whereas soybean has climbed only about 30% over the same time period.  In some cases, the difference is even greater. Inadequate production practices – including soil fertility - get the blame as soybean is often treated as a second partner after corn.