Environmental Analysis of Switchgrass on Soil

Gija Geme,Brittany Hagenhoff,Christina Dobson-Jones,Scott Mckay

doi:10.13189/ujc.2015.030302

Abstract

Conversion of biomass to fuel is quickly gaining popularity due to its carbon neutral status and the cost volatility of the traditional fossil fuel resources. Biomass feedstocks, such as switchgrass, require minimal fertilizers, labor, and land management. For sustainable switchgrass production to occur, we must understand environmental effects associated with switchgrass, such as any changes soil is undergoing during the growth of switchgrass. This particular study focuses on concentrations of potassium, phosphorus, and nitrogen in soil. Numerous soil samples were taken from four different species of switchgrass in areas with different amounts of nitrogen fertilization. This study found that there was not an overall trend amongst all the soil and switchgrass plots, however there were some similarities within the individual soils and grasses. The soil samples showed that there tends to be an overall decrease in phosphorus, potassium and nitrogen but some of the soil samples showed an increase in phosphorus, potassium and nitrogen content in 2009. Average nitrogen concentrations observed in soil ranged from 2.11-8.99 g N/kg soil and in switchgrass ranged from 3.38-7.67 g N/kg grass. The amounts of phosphorus in soil ranged from 30.7-179 mg P/kg soil and in switchgrass ranged from 14.5-52.7 g of P/kg grass. The amounts of potassium in soil ranged from 162-337 mg K/kg soil.

Highlights

There is a pretty high demand for creating renewable bioenergy crops due to the increase cost of transportation fuels and the risk environmentally dealing with nonrenewable energy
This study showed that the two-cut systems produces higher switchgrass yields but was depleting the soil potassium pool
Phosphorus, and potassium are the primary macronutrients for plants in soil

Summary

Introduction

There is a pretty high demand for creating renewable bioenergy crops due to the increase cost of transportation fuels and the risk environmentally dealing with nonrenewable energy. Switchgrass is a hopeful feedstock because of its increased biomass production under certain growing conditions and its sufficient forage and chemical makeup [1]. Switchgrass can produce high-quality forage with yields ranging from 2 to 5 tons per acre depending on variety, rainfall, soil type, as well as other environmental conditions. The nutrient content of this forage can be as high as 16 percent crude protein, if harvested correctly [2]. There is the possibility of having switchgrass as a “dual purpose” crop: biofuel and forage crop. While switchgrass is planted primarily for biofuels production, there is potential to harvest the early growth through haying or grazing, managing the remainder of the season’s growth for biofuels [2]

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Conclusion