Submitted to: Soil Science and Plant Nutrition (SSPN)
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/8/2008
Publication Date: 12/20/2008
Citation: Jung, W.K., Kitchen, N.R., Sudduth, K.A., Kremer, R.J. 2008. Contrasting grain crop and grassland management effects on soil quality properties for a North-Central Missouri claypan soil landscape. Soil Science and Plant Nutrition. 54(6):960-971. Interpretive Summary: Crop management has the potential to either enhance or degrade soil, which in turn impacts food production and the environment. Specific soil properties so affected are often referred to as “soil quality indicators”. Understanding management impact on soil quality indicators is vital for identifying sustainable cropping practices for the future. The 10 million acres of claypan soils in the U.S. Midwest have impaired soil quality from cultivation and accelerated erosion. The purpose of this investigation was to evaluate soil quality indicators on different landscape positions and from both grain and Conservation Reserve Program (CRP) management systems on claypan soils. We found that soil aggregates were 40% more stable at all landscape positions when managed with no-tillage that included a cover crop when compared to a tilled cropping system. This means the no-tilled soil was less prone to break into smaller textural pieces with rainfall and erosional forces. Other soil quality indicators were not different between the grain cropping systems. This is in contrast to similar studies on other soil types, where many soil quality properties are found to improve with no-till practices. Soil quality was improved with CRP. Soil aggregation under CRP management was more than double that of the grain cropping systems. Also, soil organic carbon and total nitrogen in the surface soil of CRP were about 30% higher than the grain crop systems. We conclude that the primary reason for this difference comes from the perennial plants in CRP that partition more carbon below ground than annual grain crops. We propose that claypan soils degraded as a result of tillage cropping will benefit most by converting to CRP or similar management, like hay cropping. Practices that enhance soil quality help farmers identify those production systems that improve soil health and in the long-run will be sustainable. Management systems showing improved soil quality will also help preserve water quality of streams, rivers, and lakes.
Technical Abstract: Crop management has the potential to either enhance or degrade soil quality, which in turn impacts crop production and the environment. Few studies have investigated how crop management affects soil quality over different landscape positions. The objective of this study was to investigate how 12 years of annual cropping system (ACS) and conservation reserve program (CRP) practices impacted soil quality indicators at summit, backslope, and footslope landscape positions of a claypan soil in north-central Missouri. Three replications of management systems were established in 1991 in a randomized complete block design, with landscape position as a split-block treatment. Four management systems were investigated: (1) annual cropping system 1 (ACS1) was a mulch tillage corn (Zea mays L.)-soybean [Glycine max (L.) Merr.] rotation system; (2) annual cropping system 2 (ACS2) was a no-till corn-soybean rotation system; (3) annual cropping system 3 (ACS3) was a no-till corn-soybean-wheat (Triticum aestivum L.) rotation system, with a cover crop following wheat; and (4) CRP was a continuous cool-season grass and legume system. In 2002 soil cores (0- to 7.5-, 7.5- to 15-, and 15- to 30-cm depths) were collected by landscape position and analyzed for physical, chemical, and biological soil quality properties. Soil organic carbon (SOC) was significantly increased with 12 years of CRP management, but not with other management systems. At the 0 to 7.5-cm soil depth of CRP, SOC increased over this period by 33% and soil total nitrogen sud storage by 34%. Soil aggregate stability was about 40% higher in no-till management systems (ACS2 and ACS3) than in the tilled system (ACS1). Soil aggregation under CRP management was more than double that of the three grain cropping systems. Soil bulk density at the shallow sampling depth was greater in ACS3 than for ACS1 and ACS2. In contrast to studies on other soil types, these results indicate only minor changes to claypan soil quality after 12 years of no-till management. We conclude that claypan soils degraded by historical cropping practices will benefit most by adoption of CRP or CRP-like management.