Effects of riparian grazing on distinct phosphorus sources

Riparian areas play an important role in maintaining water quality in agricultural watersheds by buffering sediment, nutrients, and other pollutants. Recent studies have shown that in some cases riparian areas are a net source of phosphorus (P) in cold climates. This study assessed the impact of cattle grazing or harvesting of riparian areas on the spatial and vertical distribution of water-extractable phosphorus (WEP). This study measured the WEP in four distinctive sources: biomass, litter, organic layer, and Ah horizon in three riparian locations extending from the edge of the waterbody to the field edge. In addition to a control, three treatments were examined: 1) grazing; 2) high-density grazing; and 3) mowing. Prior to implementing the treatments, the Ah (0-10cm) soil was the largest pool of WEP (42.5 mg m-2, ~44%); however, the biomass (i.e., standing vegetation) was a considerable proportion of the total (26.3 mg m-2, ~25%) WEP pool. The litter and organic layer had median WEP a..., A randomized complete block experimental design was used to assess the sources of riparian WEP and investigate how it changes following cattle grazing or mowing treatments. In addition to a control, the three treatments included grazing, high-density grazing, and mowing. Each treatment, including a control, was replicated in riparian areas surrounding four prairie potholes (wetlands). Samples of biomass, litter, organic layer, and Ah horizon, were collected in three locations both pre- and post-treatment.
Four types of samples were collected: 1) biomass, 2) litter, 3) organic layer, and 4) Ah horizon. Using a 0.25 m2 quadrate, biomass was collected by cutting the standing live vegetation and litter by raking the surface and picking up the previous year’s growth. Both the biomass and litter were dried at 40 deg C, weighed, and homogenized using a blade grinder (<1cm). A composite of five soil samples was collected within the same quadrat as the biomass/litter using a 19 mm diameter so..., , ## Effects of riparian grazing on distinct phosphorus sources

Alexander J Koiter*1 and Tamaragh Y Malone2

*corresponding author

1Brandon University, Department of Geography & Environment
270 18th St, Brandon, MB Canada, R7A 6A9
email: [[e-mail]](mailto:[e-mail])
ORCID: 0000-0002-9355-9561

2Brandon University, Department of Biology, 270 18th St, Brandon, MB Canada, R7A 6A9
ORCID: 0009-0002-5887-5574

This manuscript has been accepted for publication at the Journal of Environmental Quality. A preview of the manuscript, including notebooks for analysis, can be found at [https://alexkoiter.ca/riparian-grazing-manuscript](https://alexkoiter.ca/riparian-grazing-manuscript/)

## Data Overview

The data sets and accompanying Quarto (.qmd) files used in this publication can be found in the [notebooks](https://github.com/alex-koiter/riparian-grazing-manuscript/tree/main/notebooks).

1. **P_concentration.csv** contains the Water Extractable P concentration for each sample...,