For more than four decades, researchers from the University of Nebraska-Lincoln and other institutions have been studying the long-term effects of tillage on the soil at research plots at the High Plains Ag Lab near Sidney.
More than 45 scientific journal articles, nine book chapters, a research bulletin and numerous scientific abstracts have been published from work conducted at these plots. Scientists with the USDA's Agricultural Research Service in Lincoln, Fort Collins, Colo., Akron, Colo., and Ames, Iowa, have worked on these plots, as have university scientists and graduate students from UNL, Colorado State University, Kansas State University and Michigan State University.
Now, a new chapter in long-term soil research is about to begin at the long-term tillage plots at the High Plains Ag Lab, according to Drew Lyon, UNL dryland cropping system specialist at the Panhandle Research and Extension Center in Scottsbluff. The plots are in a state of transition to an intermittent tillage study, which will study the effect of tillage every six years on soil quality changes.
All treatments will be managed as no-till in the years between plowing. In the year of plowing, half of each previous tillage treatment plot will be plowed and the other half of each plot will remain no-till.
Previously, the plots were cropped in alternate years to reflect the wheat-fallow rotation commonly used by farmers. The fallow plots received one of three treatments: plow, stubble-mulch, or no-till.
The new study will tell us about the long-term effects that occasional or intermittent tillage has on the soil, Lyon says.
Soil scientists with the USDA-ARS at Akron, Colo., are sampling the soil prior to initiating these changes. This will allow a summary of the effects of the last 40 years on soil quality and serve to establish initial soil conditions at the start of the new study.
The new study will likely need to run for 12 to 18 years before significant soil quality changes become evident. Long-term field studies, such as these, have provided valuable information on the long-term effects of agricultural practices on soil condition and function, as influenced by the ever-changing conditions of climate, weather, biological adaptation, and environmental, social, cultural, and technological considerations with time.
This information cannot be obtained from two- or three-year experiments, yet the majority of research reported today consists of these short-term experiments.
The new long-term research project will be conducted on land that now-retired dryland crops specialist Charlie Fenster and Gary Peterson, a soil scientist at UNL in Lincoln at the time, used to study what happened when a native grass site was converted to cultivated land in a wheat-fallow system with conventional tillage. They were interested in following changes in soil total N content from the introduction of tillage.
These plots were established in 1970, and a sod treatment was maintained in each of three replicates to serve as a control. The sod treatment was not hayed or grazed, but grass was burned occasionally to reduce residue accumulation and promote growth of warm-season species. No fertilizer has been applied to these plots. Native fertility is still sufficient to support winter wheat yields 40 years after the plots were initiated.
Funding long-term experiments has grown more difficult in recent years. This has resulted in the termination of many existing long-term field experiments and has prevented the establishment of new long-term experiments in the United States. The Long-Term Tillage plots at the High Plains Ag Lab are a valuable resource that is growing increasingly unique.