Author : Dustin Nelson
Publisher :
ISBN 13 :
Total Pages : 160 pages
Book Rating : 4.:/5 (124 download)
Book Synopsis Phosphorus Security in Warm-Season Perennial Grasslands in NE Wisconsin by : Dustin Nelson
Download or read book Phosphorus Security in Warm-Season Perennial Grasslands in NE Wisconsin written by Dustin Nelson and published by . This book was released on 2020 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mitigation of water quality degradation from extensive, intensive agriculture is an ongoing global challenge. In many cases, remediation approaches must go beyond adjusting current practices, as previous management has led to a buildup of legacy soil phosphorus (P) in agricultural fields that is both difficult to remove and negatively impacts soil health and downslope water quality for decades. Perennial, warm-season grasslands have been suggested as one viable option to enhance P security in these fields. With deep, robust root systems, and significant aboveground biomass, warm-season grasslands have been shown to improve overall soil health, soil aggregate structure, soil porosity, and soil organic carbon (SOC) contents in previously cropped fields. These changes are expected to alter the location and nature of soil P, sequestering it within more stable biomass and soil organic matter pools, thereby increasing P security within the system. Surprisingly, few studies have directly evaluated changes in Bray-P concentration following conversion into warm-season grasslands, with a particular scarcity of information available on vertical changes within the soil profile during this transition. This project seeks to improve understanding of the effects warm-season grassland establishment on soil P security and mitigation efforts in high P agricultural soils in northeastern Wisconsin. These questions were evaluated in a warm-season grassland established on a formerly cropped field within the Oneida Nation, Brown County, WI by evaluating changes in vertically segregated and depth-cumulative soil properties measured both at the time of grassland establishment and six years later. At the time of grassland establishment, the field supported an average Bray-P concentration of 100.3 ppm in the top 30 cm of the soil profile; this level is considered excessive for Wisconsin. Both Bray-P concentrations and soil mass-adjusted Bray P decreased in the top 10 cm of the soil over the six-year study. Decreases appeared greater in soils with higher initial bulk densities and Bray P levels. Soil bulk density (BD) also decreased in the top 5 cm of the soil, and in the cumulative increment to a 30 cm depth. Additionally, total SOC and percent SOC accumulated in the top 10 cm of the soil, with greater increases observed in soils with lower initial C levels. A mass balance approach incorporating the findings of this study with previous work from the same site suggests that plant biomass held more P than was accounted for in decreases observed in the top 30 cm of the soil profile. These results suggest plant mining of soil P from deeper in the soil profile, and/or liberation of additional plant-available soil P from pools not measured, and a limited likelihood for significant P leaching from this system, despite very high soil Bray P levels. Overall, this research has shown, that even without harvest, in just 6 years, warmseason grasses increased P security and soil health in a high P agricultural soil in NE Wisconsin. Decreases in total Bray P, along with a decrease in soil BD and an increase in soil organic carbon have improved overall soil health, while converting reactive soil P into more secure organic pools. If combined with annual harvesting of aboveground biomass, this approach may be a particularly effective short and long-term option for managing soil P hotspots (i.e. excessive soil P) within agricultural watersheds. Our research shows that among candidate locations, those areas with highly compacted, organic C depleted, and P-enriched soils are likely to see the greatest improvements to overall soil health and P security when converted to grasslands.
