Location: Natural Resource Management Research2013 Annual Report
1a. Objectives (from AD-416):
OBJECTIVE 1: Develop management strategies to decrease net greenhouse gas emissions from cold, semiarid agroecosystems, as a contributor to the ARS GRACEnet project. OBJECTIVE 2: Develop soil management guidelines to improve soil biophysical properties needed for sustainable production.
1b. Approach (from AD-416):
Concurrent trends of increased demand for agricultural products, increasingly scarce nonrenewable resources, and accelerating climate change have underscored the need for new and innovative agroecosystems that are resilient, highly productive, effectively utilize renewable resources, and minimize damage to the environment. Determining the relative sustainability of new and innovative agroecosystems requires a detailed understanding of management effects on emerging ecosystem services. Given this context, the goal of this project is to improve understanding of management impacts on greenhouse gas mitigation, carbon storage, and soil biological function. Over a time period of approximately five years, research activities will 1) develop management strategies to decrease net greenhouse gas emissions from cold, semiarid agroecosystems (Objective 1), and develop soil management guidelines to improve soil biophysical properties needed for sustainable production (Objective 2). Approaches to conduct these research activities will include field, laboratory, and greenhouse experiments. Anticipated products from this research include peer-reviewed publications, popular press articles, and web pages. Collectively, these products will serve a broad range of clientele (e.g., agricultural producers, personnel from public and private sector organizations, and scientists), and will contribute to an overall outcome of increased understanding of agroecosystem effects on emerging ecosystem services, with the intent of improving agricultural sustainability.
3. Progress Report:
Soil moisture status was monitored throughout the growing season for rotation and tillage treatments included in a long-term (19 yr) dryland cropping systems study. Measurements documented shifts in soil water use throughout the growing season as a result of changes made to two rotation treatments in 2012, where corn replaced millet, soybean replaced safflower, and a cover crop mixture replaced rye. Documenting soil water use in these new crops and crop mixtures will provide critical information regarding their adaptability regional growing conditions and capacity to respond to future climate change. Soil samples were collected from four long-term no-till cropping systems differing in rotation length and crop diversity at the Area IV Soil Conservation District (SCD) Cooperative Research Farm and analyzed for a suite of soil quality indicators. Collected data will provide critical information for understanding the value of crop rotations to affect soil functions throughout the northern Great Plains. This region is undergoing an unprecedented transition in agricultural land use involving the transition of grassland to annual crops, and recent documentation of cropping patterns in the region suggests an increased prevalence of monoculture cropping. Understanding crop rotation contributions to long-term soil functional capacity is essential to ascertain the relative sustainability of cropping practices throughout this important agricultural region. Soil samples from on-going biochar experiments throughout the U.S. were collected and analyzed for mycorrhizal root colonization, soil aggregation, total C and N, and glomalin. While biochar is speculated to improve nutrient retention, soil aggregation, and microbial activity, information is lacking regarding effects of biochar on soil properties and processes in temperate agroecosystems. Data gathered in this study will address this critical information need, and in turn, will provide science-based guidelines for the sustainable use of this soil amendment.
1. Plant tannins regulate soil fertility. Tannins are plant compounds present in leaves, bark, and roots. When plants decompose, tannins enter the soil and can change nutrient cycling dynamics. ARS scientists at Mandan, ND along with university collaborators added solutions of tannins and related non-tannin compounds to samples of surface soil gathered at multiple U.S. locations and measured how the compounds affected nutrient retention and soil fertility. In general, tannins resulted in net increases in soil fertility, whereas non-tannin compounds had little impact on soil fertility. Tannins and one non-tannin compound (i.e., gallic acid) reduced nitrogen solubility in soil, while meaningful amounts of both types of compounds were retained by soil, with the amount retained related to the soil carbon content. These ‘first-of-their-kind’ results suggest tannins play an important role in regulating soil fertility and have potential to reduce nutrient losses, increase use efficiency, and lower the risk of environmental losses.
Schmer, M.R., Liebig, M.A., Hendrickson, J.R., Tanaka, D.L., Phillips, B.L. 2012. Growing season greenhouse gas flux from switchgrass in the northern Great Plains. Biomass and Bioenergy. 45:315-319.