Evaluating Nutrient And Sediment Losses From Agricultural Lands

Author : Melissa Danielle Miller
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (18 download)

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Download or read book The Importance of Intra-management Practice Variability in Phosphorus and Total Solids Losses from Agricultural Fields written by Melissa Danielle Miller and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Eutrophication and sedimentation are persistent issues in the Chesapeake Bay Watershed. Best management practices (BMPs), such as no-till and shallow-disk manure injection, are promising solutions to reduce nutrient and sediment losses to water bodies. However, field studies seeking to quantify the effectiveness of shallow-disk injection as a P mitigation strategy are often constrained by hydrologic variability across spatial and temporal scales. There is an increased need to understand how BMP effectiveness is affected by site-specific conditions in order to better target BMP implementation to areas where they will be most effective. This thesis focuses on characterizing and explaining variability in total solids (TS) and phosphorus (P) losses from twelve experimental plots in central Pennsylvania (PA). The overall objective was to understand the underlying causes of variability in P and TS losses from these plots to provide greater context for understating the effectiveness of shallow-disk injection versus broadcasting. The first chapter assesses variability in the transport dynamics of dissolved P (DP), total P (TP), particulate P (PP), and TS losses from these agricultural plots. It employs load-discharge (L-Q) analyses and CVC/CVQ ratios to examine differences in transport characteristics among manure application methods and among plots of the same manure application method. Shallow-disk injection was found to be more effective than broadcasting in promoting dilution of DP, and to a lesser extent, TP. In contrast, PP showed stronger dilution patterns in broadcast plots than injection plots. There was no difference between application methods for TS. Variability among plots within each manure application practice was largely dependent on relative contributions of overland and subsurface flow. Overall, shallow-disk injection appears to be an effective practice to reduce DP and TP losses while maintaining the erosion-reducing benefits of no-till.The second chapter is focused on understanding which soil, landscape, and hydrologic characteristics play more dominant roles in driving P loss from these plots. Multiple linear regression was used to describe how manure application practices interact with soil and landscape characteristics and predict overland and subsurface P exports. On average, injection plots exported 65% less DP and 48% less TP in overland flow and 81% less DP and 51% less TP in subsurface flow, with almost no differences in PP exports. The multiplicative effects of flow and Mehlich-3 P were the most effective predictors of P losses via both overland and subsurface flow, and unstratified (0-15 cm) measures of Mehlich-3 P concentrations were more or as effective as stratified (0-5 cm and 5-15 cm) concentrations in predicting losses in overland flow. While, soil and landscape characteristics, like soil texture and curvature, often provided additional predictive power. The results of this analysis revealed that shallow-disk injection is effective in reducing P losses and may be effective in preventing P build-up in soils without prior history of manure application.These two studies highlight the importance of understanding site hydrology and management practices as primary drivers of P losses from agricultural fields. Extensively monitored plots such as these provide a unique opportunity to study the effects of BMPs, such as shallow-disk injection, on a small scale, allowing for the assessment of variability among individual units. This work suggests that shallow-disk injection is an effective practice to reduce DP losses by reducing P source availability on the soil surface but does not exacerbate PP losses.