IMPACTS OF VEGETATIVE BUFFERS AND WINTER CROPS ON WATER QUALITY AND PROFITABILITY OF SMALL TO MIDSIZE FARMS IN PENNSYLVANIA

Open Access
Author:
Sciaudone, Kyra Tatiana
Graduate Program:
Biorenewable Systems
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
March 16, 2018
Committee Members:
  • Thomas Lehman Richard, Thesis Advisor
  • Armen R. Kemanian, Committee Member
  • Cibin Raj, Committee Member
  • Katherine Yoder Zipp, Committee Member
Keywords:
  • Energy Crops
  • Profitability
  • Crop Budgets
  • Water Quality
  • Switchgrass
  • Willow
  • Agroecosystem Model
  • Mahantango Creek
  • Pennsylvania
  • Flood Frequency
Abstract:
Substantial production of advanced and cellulosic biofuels is needed to achieve the biofuel blending mandates set by the U.S. Renewable Fuel Standard. The success of increasing production of these fuels is hindered by many technological and logistical challenges including feedstock selection, availability and affordability. This research provides an analysis of the environmental and economic impacts of alternative feedstocks including winter rye, switchgrass, and willow on farms within the Mahantango Creek Watershed in Pennsylvania. This analysis can help develop a more complete picture of the tradeoffs between water quality and farm income. The agroecosystem model Cycles was used to establish the environmental impact of incorporating winter rye and perennial energy crops into the landscape, as well as the expected yields. This information, integrated into crop budgets, was used to determine the average profit of different row crop rotations and energy crops. Adding winter double crops to baseline summer-only crop rotations increased profits by $404 ha-1 year-1 due to an increase in corn grain and soybean grain yields, as well as the addition of winter rye biomass. Environmental metrics showed improvement when these crops were integrated in rotations, decreasing soil carbon loss without increasing nitrate leaching for most soils. From a financial perspective, annual crops were typically more profitable than perennial crops unless they were on land that frequently floods or has other high risks of annual crop failure. When risks of annual crop failure reduce the differential per hectare profit, perennial strips or streamside multi-functional buffers that produce biomass crops as well as ecosystem services can be the most profitable option. However, there can still be a minimum buffer width of harvested energy crop required to overcome the total loss of income from the 10.7-meter (35-foot) unharvested forest buffer typically required to provide shade and leaf litter for aquatic life including cold-water fisheries. These minimum widths are a function of feedstock selling price and flood frequency, and those variables had a large impact on the profitability of various width buffers. Considering environmental benefits, all buffer widths and vegetation composition would be more beneficial than annual crops in terms of water quality due to reduction in nitrate leaching. From a soil health perspective, simulations of soil characteristics found that the introduction of perennials or winter crops improved the net soil carbon accumulation for most soil types, with a positive correlation between both soil depth and soil organic matter content on increased crop yield. These results establish the costs associated with integrating energy crops as either perennial buffers or double crops within agricultural landscapes, and also estimate the supply of these crops that could be available as a feedstock for biofuels or other purposes. Overall, the results show that incorporating winter double crops on landscapes has the potential to increase farm income and decrease soil carbon loss for this watershed. For vegetative buffer strips, it was found that an ideal width for this watershed based on economic and environmental considerations varied based on flood frequency and feedstock selling price. For average floodplain sites in the Mahantango watershed, flood frequencies of 3 years or greater lose money with conventional corn-soybean annual crop rotations, and farmers would cut their losses by planting perennial buffers even without harvesting for biomass markets. For perennial crop prices of $90 Mg-1 the breakeven flood frequency was about 5 years. For sites without flood risk, perennial crop prices had to be on the order of $135 Mg-1 to be more profitable than conventional annual crop rotations. Integrating this information with detailed flood zones and hydrologic mapping could fine-tune these recommendations for specific fields and farms in this watershed. This information will be important for local land-owner decisions, researchers interested in performing field-trials of vegetative buffer strips, and companies that are interested in establishing next generation biomass conversion facilities.