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ARS Home » Midwest Area » Columbia, Missouri » Cropping Systems and Water Quality Research » Research » Publications at this Location » Publication #181696
Title: SITE-SPECIFIC SOIL QUALITY MANAGEMENT

Author
item JUNG, WONKYO - NIAST-RDA, KOREA
item Kitchen, Newell

Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 6/15/2005
Publication Date: 6/22/2005
Citation: Jung, W., Kitchen, N.R. 2005. Site-specific soil quality management. In: Eco-Friendly Precision Agriculture Research. Proceedings of the 2005 Meeting of the Korean Society of Precision Agriculture, June 22, 2005. Korean Society of Precision Agriculture, Suwon, Korea. p. 91-107.

Interpretive Summary: A healthy soil provides a link to plant, animal, and human health. History has repeatedly shown that mismanagement of soil resources can lead to poverty, malnutrition, and disasters. Yet, soil resources world-wide continue to be degraded through salinization, erosion, loss of tilth and biological activity, and build up of toxic compounds. Soil quality is a concept used to assess and monitor the ability of a soil to serve its functions. For this investigation, four specific aspects of soil quality are reviewed and then are highlighted with soil quality studies conducted on claypan soils in the U.S. Midwest. They are 1) improve soil quality through reduced erosion; 2) conserve soil organic carbon; 3) improve soil tilth with enhanced soil organic carbon; and 4) manage soil quality with site-specific practices and technologies. We found on claypan soils that soil quality for crop grain production was highly variable within fields. The soil quality indicator of choice for this function was depth of soil above the claypan soil horizon, sometimes referred to as topsoil depth. This indicator also provided a measure of soil erosion over the last 200 years as a result of modern agriculture. Field measurements with a sensor that measures soil electrical conductivity was the most rapid and cost-effective way to accurately estimate and then map topsoil depth. Over a 15-year period, soil organic carbon increased on these claypan soils when they were managed in grassland, such as with the USDA Conservation Reserve Program (CRP). Grain cropping over this same time period did not increase soil organic carbon, even when managed with no-tillage. Thus, cropping with no-tillage helped prevent further soil degradation from erosion, but did not improve soil quality from what it was 15 years ago. An increase in soil organic carbon with grassland management also helped improve other soil quality indicators. For example, soil aggregation measurements were more than 100% greater in grassland than in grain crop production. This soil quality information may help producers and their consultants as they consider various soil management options and their impact on long-term agricultural sustainability. Characterizing important soil quality parameters and how they change within fields will provide a basis for considering management practices that can help solve the challenge of developing profitable and environmentally friendly food and fiber production systems.

Technical Abstract: Soil quality is a concept used to assess and monitor the ability of a soil to serve its various functions. This investigation covers four aspects of soil quality with a literature review, and provides complimentary research findings recently conducted on U.S. Midwest claypan soils. The four aspects of soil quality addressed were 1) improve soil quality through reduced erosion; 2) conserve soil organic carbon; 3) improve soil tilth with enhanced soil organic carbon; and 4) manage soil quality with site-specific practices and technologies. The objectives of the field studies were to evaluate the effects of management practices and spatial variation on claypan soil quality properties, and to determine if apparent soil electrical conductivity (ECa) sensing could be used to assess soil quality properties. Claypan soil studies were conducted near Centralia, Missouri between 2001 and 2004. Soil cores (5.2 cm diameter by 0-7.5 cm, 7.5-15 cm, and 15-30 cm depths) and other in-field measurements were collected from three grain crop management systems, two Conservation Reserve Program (CRP) systems, and one hay crop system. Soil bulk density, clay content, depth to the claypan horizon, CEC, and Bray1-P were significantly correlated with ECa. The spatial characteristics of claypan soil properties varied greatly by landscape position and by soil depth. Claypan soil quality properties were not altered significantly by tillage management and crop rotation, but were greatly enhanced when managed with perennial grass for CRP systems. When grassland was more intensively managed as a hay crop, water infiltration was greatly improved when compared with other grain or CRP systems. Soil hydraulic conductivity estimated from infiltration measurements had a significant correlation with soil ECa. In conclusion, soil ECa provided a quick and economical way of estimating claypan soil quality properties. Perennial crop management systems, such as CRP, greatly improved claypan soil quality. We propose that characterizing the variation in the claypan horizon, especially the depth of topsoil above the claypan, is the most critical step in understanding soil quality of these soils.