This proposal seeks funding for the Center for Advanced Forestry Systems (CAFS) studies conducted by the Virginia Polytechnic Institute and State University site. Funding Requests for Fundamental Research are authorized by an NSF approved solicitation, NSF 10-507. The solicitation invites I/UCRCs to submit proposals for support of industry-defined fundamental research.
The proposal covers the use of fertilizer labeled with stable isotopes to determine the uptake and ecosystem fate of fertilizer nitrogen (N) in three of the most important plantation tree species in the US (loblolly pine, Douglas-fir, and black walnut). The project will compare N dynamics following N fertilization with conventional and enhanced efficiency fertilizers in forest ecosystems. The conventional fertilizer and newly developed enhanced efficiency fertilizers will be labeled with the isotope and evaluated in forest ecosystems in the South, Midwest and Pacific Northwest. The fundamental knowledge gained in this project will improve the efficiency of fertilizer use in forests. This will enable forest managers to use the least amount of fertilizer to optimize growth and minimize potential environmental impacts from excessive fertilizer use.
Results from this effort are likely to benefit industrial members to make them more economically competitive. Waste of fertilizer will also be minimized. The forestry community at large will benefit from the results. The investigators will actively recruit students from underrepresented groups in forestry, including women and minorities. Infrastructure enhancement is mainly in terms of conceptual basis for N fertilization.
Fertilization with nitrogen can be used to increase the growth and productivity of forest ecosystems that commonly grow on relatively infertile soils. Urea is the most frequently used nitrogen fertilizer. However, recent advances in fertilizer technology have produced enhanced efficiency nitrogen fertilizers that may be more effective and have less environmental impacts that urea. In this research we compared three different types of enhanced efficiency fertilizers with urea to determine how effective they are in when used in forestry. We studied this in three of the major types of forests in the United States: loblolly pine in the South, Douglas-fir in the Pacific Northwest, and walnut in the Midwest. There were 18 study sites in the South from Virginia to Florida to Texas, 8 study sites the Midwest in Indiana, and 10 study sites in the Pacific Northwest in Washington and Oregon. At each site we applied the four different types of fertilizer and also included an unfertilized control to compare their environmental fate and uptake efficiency. Each of the fertilizers was labeled with stable isotopes of nitrogen that enabled us to very accurately follow and track the fertilizer nitrogen through the ecosystem. Using this approach we were able to determine how much of the nitrogen was lost through volatilization to the atmosphere, how much was leached and how much was retained in the ecosystem. We could also determine how much of the fertilizer nitrogen was taken up by the trees and the understory vegetation as well as how much was retained in the forest floor and the soil at each site. We sampled the vegetation and soils at each site for a two-year period. This enabled us to calculate uptake efficiency of each of the fertilizers and determine if the enhanced efficiency fertilizers were more effective than urea at providing the needed nutrients to the trees. Our study found that in the South between 25 and 50% of the nitrogen added in urea was lost through volatilization to the atmosphere over the first 15 days following fertilization. Losses were greater when the urea was applied during the summer compared to the spring. The volatilization losses from the enhanced efficiency fertilizers were much less, ranging from 5 to 25% during the first 15 days. We found very little leaching losses below 30cm for any of the fertilizers. This result indicates that enhanced efficiency fertilizers are effective at reducing volatilization losses The study also found that between 50 and 100% of the added nitrogen fertilizer was retained in the forest ecosystem following application. Between 15 and 45 % of the added nitrogen was recovered in the trees, with most of that in the foliage. The majority of the nitrogen was in the mineral soil. The differences in ecosystem nitrogen retention following fertilization were not consistently higher in the enhanced efficiency fertilizers compared to urea. This research project has increased our knowledge of the fate of applied nitrogen and the fundamental processes controlling nitrogen transformations in forest ecosystems. This information will be of great value to forest industry because it will lead to improved forest productivity and more efficient use of high cost nitrogen fertilizer. It will also be valuable to the broader scientific community interested in developing an improved understanding of fundamental ecosystem processes affecting nitrogen dynamics in forests. These results will enable foresters and land managers to apply nitrogen fertilizers more efficiently in forests. This will decrease the amount of fertilizer needed to achieve a given level of growth, which will increase financial returns and help increase the competiveness of the US forest industry. It will also reduce negative environmental impacts of forest fertilization because the precise amount of fertilizer needed can be applied to forests. The fundamental knowledge gained in this project will improve the efficiency of fertilizer use in forests. This will enable forest managers to use the least amount of fertilizer to optimize growth and minimize potential environmental impacts from excessive fertilizer use. Society will benefit from increased productivity of plantation forests (more wood from less land) with less environmental impacts.
