The drought monitor report as of Tuesday, Nov. 19 shows continued improvement across the state. Barton County has improved some with more land now up to abnormally dry. Stafford County is totally out of dry conditions. Almost 31% of the state is out of dry conditions. The six to ten-day outlook (Nov. 26 to 30) indicates a 40 to 60% chance of leaning below normal for temperatures and a 40 to 50% chance of leaning above normal for precipitation. The eight to 14-day outlook (Nov. 28 to Dec. 4) indicates a 50 to 60% chance of likely below normal for temperatures and near normal for precipitation.
The last two weeks we have experienced significant rainfall, especially for November which is one of our typically drier months. It has definitely improved our drought conditions, particularly soil moisture. Today, the importance of soil structure and soil water storage.
Simply put, the soil is made up of stuff and not stuff. The stuff consists of the mineral fraction (sand, silt, and clay) along with well broken-down organic material, humus. Particles larger than 2 mm are important but don’t define the soil texture. Less broken-down organic matter, you can still tell what it is, matters and will over time become humus. The “not stuff” portion of a soil is space – porosity. This pore space is where soil air and water move and are potentially stored. The “ideal” soil is 50 percent solids and 50 percent space. The 50 percent space should be about 45% mineral and 5% organic matter. The half that is space should ideally be filled with one-quarter air and one-quarter water. This is the ideal for most plants in general and crop plants specifically. So, how does soil structure factor into all this?
Soil structure is a function of several factors acting together, including human beings. We can either help promote or degrade soil structure through our cultural practices and cropping practices. Soil texture, the relative proportion of sand, silt, and clay, along with the type of clay determine the soil ability to aggregate, form structure. Soils with more clay tend to aggregate more strongly and form more small pores (micropores) due to their negative charge. These small pores are where soil water is held. Soils with more clay hold more water and more strongly. Humus, also plays an important role as it too has a net negative charge and can hold several times its weight in water. It also aids in promoting soil structure. Sand matters in that it promotes macroporosity. Macropores aid in water infiltrating into the soil and once in the soil percolating downward into the soil and subsoil. Long continuous pores greatly increase infiltration and water movement. We can destroy soil structure rapidly through excessive tillage or promote it reducing/eliminating tillage allowing for a well-developed pore structure.
It’s naturally much more complicated than this but the overall idea is that we are dealing with a changing climate with more extremes in precipitation. Drier dry periods with wetter wet periods. Effectively coping with these extremes through soil management is critical for continued, successful crop production here.
Dr. Victor L. Martin is the agriculture instructor/coordinator for Barton Community College. He can be reached at 620-792-9207, ext. 207, or martinv@bartonccc.edu.
