Effects of Land Use Change, Cultivation, and Landscape Position on Prairie Soil Organic Carbon Stocks

Ronald K. Salemme,Roman G. Kovach,Alexander N. Gennadiyev,Kenneth R. Olson

doi:10.4236/ojss.2018.87013

Abstract

Temperate grassland soils are typically a sink for carbon. However, it is estimated that up to 99% of tallgrass prairies in North America have been converted to another land use. These conversions can lead to increased soil erosion and soil organic carbon (SOC) mineralization rates, turning a large carbon sink into a source. The purpose of this study was to compare by land use the retention of SOC, TSN, and fly ash on sloping landscapes with an emphasis on measuring the subsoil in addition to the surface soil. Eight paired plots were established on adjacent, sloping landscape profiles in western Iowa; one site a cropland and the other a remnant tallgrass prairie. The prairie landscape had a baseline SOC stock of 232 Mg-C ha-1. After roughly 150 years of agriculture the cropland had 52% less SOC, 39% less TSN, and 22% less fly ash which equates to annual losses of 0.55 Mg-C ha-1 yr-1, 0.04 Mg-N ha-1 yr-1, and 0.0002 Mg-fly ash ha-1 yr-1.

Highlights

Temperate grasslands are one of the most converted and least-protected biomes worldwide and the tall-grass prairies of North America are no exception, with estimated loss of 82% - 99% since the time of settlement [1] [2]
The goal of this research is to measure the differences in surface and subsoil soil organic carbon (SOC), total soil nitrogen (TSN), and soil erosion between soil catena’s at a remnant-tallgrass prairie and an adjacent cropland
Within a land use type there were no significant differences seen between landscape positions the TS had marginally higher SOC and TSN (p-value = 0.0617 and 0.0961, respectively) than the other positions for both sites

Summary

Introduction

Temperate grasslands are one of the most converted and least-protected biomes worldwide and the tall-grass prairies of North America are no exception, with estimated loss of 82% - 99% since the time of settlement [1] [2]. When a prairie is converted to agricultural use the accompanying changes in vegetative cover and management practices can have severe negative impacts on soil organic carbon (SOC) stocks, largely through increases in soil erosion and SOC minera-. While the effects of land use conversion to agriculture have been widely studied, the results of such studies have been quite variable and far too often these studies soil sampling depth are limited to the upper 10 - 20 cm of the soil. As demand for arable land increases, the conversion of marginal lands becomes common place; this makes it critical that we continue to improve our understanding of the effects of cultivation on SOC stock in sloping landscapes

Objectives

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Conclusion