Soil health indicator responses on Missouri claypan soils affected by landscape position, depth, and management practices

Abstract

Improved soil productivity will be vital to meet expected food and fiber demands of growing populations. Concepts of soil health assessments focus on specific soil properties and determination of a soil9s ability to maintain a range of ecological functions in its appropriate ecosystem, supporting long-term sustainability. Objectives of the investigation were to determine the influence of cover crop, soil depth, and landscape under varied management practices on biological soil health indictors. Four watersheds within the Chariton County Cover Crop Soil Health Farm, Missouri, United States, with Armstrong loam (fine, smectitic, mesic Aquertic Hapludalfs, 5% to 9% slopes eroded) were used for the study. Two watersheds were managed with cover crops, rotational planting, and no-till applications. Initial cover crop planting occurred during the fall of 2012. Two control watersheds received no cover crop management. It is important to note drought conditions persisted over the 2012 and 2013 growing seasons. Soils were sampled in 2012 and 2014 by landscape and depth (0 to 10, 10 to 20, and 20 to 30 cm) from the watersheds. Analyses included soil enzymatic activity, soil microbial diversity, and soil nutrients. Enzyme activities and nutrient levels significantly decreased with soil depth. For example, β-Glucosidase 0 to 10 cm depth values ranged from approximately 85 to 100 μg of para-nitrophenol (PNP) per gram oven dry soil (gds⁻¹), with 20 to 30 cm depth values ranging from approximately 35 to 40 μg PNP gds⁻¹. Nutrient levels, enzyme activities, and water stable aggregates displayed various levels of significance across landscape positions (<i>p</i> &lt; 0.01 and <i>p</i> &lt; 0.05). Carbon (C) and select enzyme indicator parameter measurements significantly (<i>p</i> &lt; 0.01 and <i>p</i> &lt; 0.10) differed between sampling events. We expected to detect significant relationships between soil biological activities and land management practices to identify practices that lead to improving soil health. However, identifying cover crop effect between watersheds proved challenging due to poor stand establishment and the duration of the monitoring period, emphasizing the importance of extended monitoring to determine the effects associated with long-term management conditions and health assessment practices.