Title: Understanding Productivity Variation on Un-Irrigated Claypan Soils Authors
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: April 27, 2006
Publication Date: April 27, 2006
Citation: Jung, W., Kitchen, N.R., Sudduth, K.A. 2006. Understanding productivity variation on un-irrigated claypan soils [abstract]. Korean Crop Science Society annual meeting, April 27-28, 2006, Choenan, Korea. Technical Abstract: A high clay-content argillic horizon occurring 10 to 100 cm below the surface restricts soil water movement and reduces nutrient efficiency of claypan soils, which affect soil quality related to production and environmental buffering. The objective of this study was to determine the impacts of long-term (12 yr) annual cropping systems (ACS) and conservation reserve program (CRP) practices on the soil quality of a claypan soil in north central Missouri. In 2002, soil cores were collected (0- to 7.5-, 7.5- to 15-, and 15- to 30-cm depths) from summit, backslope, and footslope landscape positions (LP). Management systems included: (i) annual cropping system 1 (ACS1), a mulch tillage corn-soybean rotation system; (ii) annual cropping system 2 (ACS2), a no-till corn-soybean rotation system; (iii) annual cropping system 3 (ACS3), a no-till corn-soybean-wheat rotation system with red clover as a cover crop; and (iv) CRP, a continuous cool-season grass and legume system. Soil cores were analyzed for soil particle size distribution, bulk density, cation exchange capacity, soil organic carbon (SOC), total N (TN), microbial respiration, and water-stable soil aggregation. No interactions were observed between cropping system and LP. At the 0- to 7.5-cm soil depth, CRP increased SOC storage by 33% and TN storage by 34%. Soil aggregation under CRP management was more than double that of the ACS. On the backslope, soil aggregation was significantly higher than on the footslope. SOC and TN were significantly higher on the footslope than on the backslope at the 7.5- to 15-cm soil depth. These results show that soil quality of claypan soil landscapes was not significantly different among ACS management practices. Compared to ACS, CRP enhanced soil quality. Understanding relationships between sensor-based measurements and soil properties related to soil quality may help in developing site-specific management options. The objective of this research was to examine whether sensor-based apparent soil electrical conductivity (ECa) could be used to predict soil quality indicators for claypan soil fields in the U.S. Midwest. Soil samples were obtained in 2002 at three depths (0 - 7.5 cm, 7.5 - 15 cm, and 15 - 30 cm) and at 65 locations within a 4-ha area of an agricultural field located in north central Missouri. Samples were analyzed for numerous physical, chemical, and microbiological properties that serve as soil quality indicators. ECa measurements were also collected with an electromagnetic induction-based sensor in different orientations and at different heights above the soil. Yield, obtained using a combine equipped with a yield-sensing system, was available for corn (Zea mays L.)(4 years) and soybean (Glycine max (L.) Merr) (5 years) crops. At the deepest sampling depth, soil bulk density (BD), clay, silt, cation exchange capacity (CEC), and Bray-1 P were the most significantly correlated (r>0.55) with ECa. Soil properties were regressed against ECa, and R2 values were often improved by including a quadratic term of ECa, especially at the 0- to 7.5-cm depth. Some soil properties (e.g., clay and CEC) and ECa that were positively correlated to yield in years with average or greater than average cumulative July to August precipitation (>15 cm), were negatively correlated to yield for years with less than average precipitation (<15 cm). We found that our best results were when we used the EC sensor near the soil surface, as opposed to lifting the sensor above the ground. Our results suggest that sensor-based ECa can be an efficient way of estimating some claypan soil quality measurements.