|11-916NC Project Manager: E. M. Barnes|
SOIL WATER AVAILABILITY UNDER DIFFERENT TILLAGE PRACTICES IN COASTAL PLAIN SOILS
Alan Meijer, North Carolina State University
Drought conditions have been a challenge for NC cotton producers for the last four years. Many producers in the state do not have irrigation to mitigate drought risks; therefore, it becomes important to be aware of any factors within a producer's control to increase rainfall capture. Tillage systems can have a significant impact on the amount of rainfall that is lost to runoff, and cover crops can help create a mulch to minimize evaporation of water from the soil surface. Thus, understanding how soil moisture varies by tillage system could help producers when deciding what system best fits their operation.
Tests were located at the Upper Coastal Plain (Rocky Mt) and Peanut Belt (Lewiston) Research Stations. Tillage treatments (Disk, No-till, Strip-till 1, Strip-till 2) were applied and cotton was planted in a timely manner. Soil moisture monitoring equipment was installed and logged continuously in two treatments from each site.
Rainfall at Rocky Mount was fairly consistent in 2012, with multiple rain events in the 0.5 to 1" range from May through August. Precipitation at Lewiston was sparse through May and June. In both cases, potential evapotranspiration (PET) did not exceed precipitation. This is often not the case, and indicates that adequate moisture to supply the crop growth came via rainfall.
In both tillage methods and at both locations, water content was higher at 18-inch depth than at six inches, as we'd expect due to higher water holding capacity at that depth, and less draw down by roots or evaporation. Water content was greater for the most part in the conventional tillage (CT) plots at Rocky Mount at both depths, while at Lewiston, there was greater water content at six inches in the strip tillage (ST) versus the CT plots, while there was less soil water in the ST plots than the CT plots at 18-inches.
The greater water content in CT plots at both depths in Rocky Mount there was higher yield there for CT. However, the higher water content goes against traditional thinking that no-till (NT) will improve infiltration and protect from evaporation, etc. However, this field was not in long-term no-till, and as such, does not exhibit the benefits, possibly, of what we might expect out of true NT. Should significant rainfall occur after tillage (which did occur this year at Rocky Mount), the loosened soil can absorb a lot of water in a hurry, which might account for the higher water content throughout the profile at that location, and thus, the higher yields.
Due to the adequate rainfall in 2012, there were no other treatment yield responses and further conclusions based on this year's data are not possible.
|Project Year: 2012|
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