The potential for the 2012 drought in South Dakota to persist into 2013 is a real concern according to Dennis Todey, SDSU State Climatologist (See High Risk of Drough Issues Continuing into 2013).
As an agronomist, my first response to his report was, “How can we increase or maintain soil moisture through management?” My first thought was to skip fall tillage which would:
- Maintain residue cover on the soil surface to minimize evaporation
- Leave stalks or stubble standing to increase snow capture
Since harvest is over, we cannot increase crop stalk or stubble height, but growers can avoid what fall tillage they are still thinking of conducting.
A 3-year study in Morris, Minnesota, showed that leaving corn stalks taller and standing significantly increases snow depth in the field (Figure 1). Assuming an estimated snow to liquid ratio of 10:1, the 14 inches of extra snow captured in the Minnesota study equates to 1.4 inches of rain.
Figure 1. The depth of snow affected by corn stalk height (Adapted from Sharrat, 2002).
Depending on snowfall totals and weather conditions, skipping fall tillage and capturing more snow could help increase soil profile moisture and yield potential in the 2013 growing season.
In a different study comparing no-till versus conventional-tilled wheat, demonstrated leaving standing stubble enhances snow retention, increases snow water infiltration, and reduces the variability in soil moisture across the field (Qui et al., 2011). These researchers determined that the extra stored soil moisture (2.3 inches) could increase winter wheat yield potential by 13 bu/ac on ridge tops.
Another study showed that significantly more soil moisture recharge had occurred when sunflower stalks were left 18 to 28 inches tall versus being laid flat from an increase in snow capture (Nielson, 1998).
We do not know how much snow we will get this winter or how much of that extra captured snow will contribute towards additional soil moisture. However, all previous research suggests that leaving crop residues standing versus lying flat can increase the amount and uniformity of snow cover. This will in turn improve our chances at increasing soil moisture available for the 2013 crop. The relationship between crop water use and crop yield in the High Plains are shown in Table 1.
Table 1. The estimated yield response with each additional inch of crop water use (CWU) above the threshold CWU*
*Adapted from Crop Water Use in Limited-Irrigation Environments by Loyd Stone.
Using the data from Table 1, and assuming we store just one additional inch of available soil water through additional snow capture, we could easily increase profit by more than $50/ac by skipping fall tillage.
- Sharrat, B.S. 2002. Corn stubble height and residue placement in the northern US Corn Belt; Part 1. Soil physical environment during winter. Soil and Tillage Research 65:243-252.
- Qiu, H., D.R. Huggins, J.Q. Wu, M.E. Barber, D.K. McCool and S. Dun. 2011. Residue mangagment impacts on field-scale snow distribution and soil water storage. Transaction of the ASABE 54(5):1639-1647.
- Nielson, D.C. 1998. Snow catch and soil water recharge in standing sunflower residuce. J. Prod. Ag. 11:476-480.