2012 Annual Report
1a.Objectives (from AD-416):
The objective of this cooperative research project is to develop economically and environmentally sustainable uses for North Dakota’s natural resources by comparing the productivity of perennial warm and cool season potential bioenergy grasses at the western edge of the historic switchgrass range. Soil from plots testing 20 different treatments will be analyzed prior to planting and 5 and 10 years after establishment. This project will also educate producers and small communities concerning biomass crops and their economic and natural resource benefits including identifying the most appropriate perennial bioenergy crop(s) for each region and determining the requirements for and economics of establishment, maintenance and harvest and levels of soil carbon storage potential. Finally, data from this project will be used to evaluate the feasibility to provide enough consistent perennial biomass for 10% of the needs of a coal and biomass co-fired power plant.
1b.Approach (from AD-416):
Twenty treatments replicated four times will be established at five North Dakota State University (NDSU)Extension Service Experiment Stations (i.e. Hettinger, Williston, Minot, Streeter, and Carrington) in western and central North Dakota. Treatments include two harvests (annual and biennial) of three individual grass species and six mixes. The individual grass species are two switchgrass cultivars, tall wheatgrass, and intermediate wheatgrass. The mixes include: 1. a CRP mix with tall and intermediate wheatgrass; 2. a CRP mix with tall and intermediate wheatgrass plus alfalfa and sweetclover; 3. switchgrass and tall wheatgrass; 4. switchgrass and big bluestem; 5. switchgrasss and alti wildrye; and 6. alti and basin wildryes. Plots will be established and maintained for 10 years at each location by North Dakota Natural Resources Trust (NDNRT) and NDSU staff. Baseline soil samples were collected prior to grass planting and will be compared to soil samples collected 5 years after establishment and 10 years after establishment. Soil samples will be analyzed by USDA-ARS, Northern Great Plains Research Laboratory scientists for gravimetric water content, soil bulk density, electrical conductivity, soil pH, total carbon and nitrogen, soil inorganic carbon, particulate organic matter, extractable nitrate and phosphorus, glomalin, and water-stable aggregation.
The objective of this study was to quantify changes in soil bulk density, electrical conductivity, soil pH, and equivalent mass soil organic carbon (SOC), total nitrogen (TN), and available phosphorus (P), glomalin (BRSP), and water-stable soil aggregates (WSA) under perennial herbaceous biofeedstocks at five sites in North Dakota. Production of perennial herbaceous crops as biofeedstocks had subtle short-term effects on soil properties due to the inherently fertile soil conditions and high within-site variation in soil properties. Changes in soil properties were most prevalent at the Williston site, where the less fertile sandy soil and high biomass production contributed to increases in soil organic carbon, total nitrogen, and available phosphorus. Coarse-textured soils have the greatest potential to respond positively from perennial biofeedstocks in the short-term. Effects of harvest schedule and plant species on soil properties were infrequent and inconsistent across sites, and were unlikely to induce change in soil function. The data showed that over the five years of growth more soil was distributed into the largest ASC while it declined in the two smaller sizes. Larger aggregates increase pore space which improves air and water movement and reduces compaction, and aggregates act as microbial habitats for increased nutrient cycling. Despite inherent differences between sites and large within site variation in data, focus on these large aggregates may indicate differences between treatments within the total 10 years of this study.