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1. Is Cover Crop Species Mixture and Diversity More Important at Building Soil Health than Shoot Biomass in a Semi-arid Region?Cover crop mixtures (CCMs) as partial fallow replacements have the potential to increase soil health, yet long-term studies on CCMs, especially in semi-arid environments are relatively rare. An eight-year study at two locations in semi-arid Montana sought to evaluate the effect of functional group (N fixer, tap roots, fibrous roots, brassicacae) and species richness (2, 6, and 8 species in a mix) on a range of biological, physical and chemical soil parameters. Although several soil health... P. Miller, C. Jones, C. Zabinski, K. D'agati, M. Housman, S. Tallman |
2. Soil Diversity and Agricultural Adaptation Across MicronesiaMicronesia, a sub-region of Oceania, comprises approximately 2,100 small islands belonging to five sovereign nations scattered across 2.9 million square miles of the Western Pacific. A majority of the islands are low-lying, sandy coralatolls, but high volcanic islands and raised limestone islands are major population centers in the region. Palau, in the west, was first settled by seafaring peoples as early as 4000-4500 BP and the colonization of Marshall Islands at the eastern edge... J. Deenik |
3. Preliminary Assessment of the Solvita-CO2 Test in Characterizing Management Effects on Soil Biological Activity in Some Soils of HawaiiThe health of agricultural soils depends to a great degree on management practices that promote soil organic matter accumulation. While total soil organic carbon (C) is the standard measure of soil organic matter, it changes slowly and does not provide a sensitive enough test to assess short term management effects on soil health. However, a key indicator of healthy soil is potential biological activity, which can be measured rapidly with soil testing via short-term carbon (C) mineralization following... J. Deenik, M. Loo |
4. Effects of Commercial Organic and Cyanobacterial Fertilizers on Instantaneous Water Use Efficiency in Drip Irrigated Organic Sweet CornWater and fertilizers are applied to maintain crop growth, yield, and quality. Nitrogen (N) fertilizer plays a crucial role in crop growth and yield development of sweet corn (Zea mays). Organic growers often use commercial organic animal- based fertilizers which vary in nutrient composition, forms of available N (NH4+- N and NO3--N), and have high transportation costs. Alternatively, cyanobacteria can be grown on-site as a source of N. Cyanobacteria haves unique dual properties because they... J. G. davis, A. Sukor, C. Ramsey |
5. Effects of Enhanced Mixing and Minimal Co2 Supplementation on Biomass and Nitrogen Concentration in a Nitrogen-fixing Anabaena Sp. Cyanobacteria Biofertilizer Production CultureNitrogen-fixing cyanobacteria are attractive as a nitrogen fertilizer because they are ubiquitous in nature and have minimal nutrient requirements. Our lab is scaling up production of a local strain of the nitrogen-fixing cyanobacterium Anabaena sp. in on-farm open raceways to determine its exonomic ppotential as a nitrogen fertilizer for horticultural crops. Our goal is to increase productivity in an organically certifiable growth medium above the current two week batch production levels... J. G. davis, J. Wenz, H. Storteboom |
6. Effect of Liquid Organic Fertilizers and Seaweed Extract on Daucus Carota Var. Sativus Growth CharacteristicsCommon N fertilizers used in organic production are often energy intensive to produce and expensive to transport. Cyanobacteria fertilizer produced on-farm could decrease impacts on the environment as well as production costs for organic farmers. In addition, cyanobacteria fertilizer could perform similarly to products marketed to increase production via plant growth hormones such as seaweed extract. The effects of common organic fertilizers as well as organic liquid cyanobacteria fertilizer on... J. G. davis, A. Wickham |
7. Nitrogen Transformations in Flooded Agroecosystems: a Case Study with Taro (Colocassia Esculenta)Wetland agriculture covers an estimated 170 million ha and contributes significantly to global food supply. Nitrogen fertilizers are subject to numerous potential transformation pathways in flooded systems. The present research was focused on improving our understanding of N transformations in a flooded agricultural system by addressing the following two broad objectives: 1) determine whether the presence of anammox bacteria and its activity contribute significantly to N losses, and 2) evaluate... J. Deenik, C. Penton, B. Popp, G. Bruland, P. Engstrom, J. Mueller, J. Tiedje |
8. The Use of Biochar As a Fertility Amendment in Tropical SoilsBiochars made from modern pyrolysis methods have attracted widespread attention as potential soil amendments to improve plant productivity in the infertile soils of the tropics. Feedstock and pyrolysis conditions affect the physico-chemical properties of biochar with important implications for soil fertility and plant growth. Specifically, biochar volatile matter (VM) significantly affect soil inorganic nitrogen (N) status and ash content impacts soil elemental composition and pH. This paper highlights... J. Deenik, T. Mcclellan |
9. Biochar Volatile Matter Content Effects on Plant Growth and Nitrogen Transformations in a Tropical SoilBiochars made from modern pyrolysis methods have attracted widespread attention as potential soil amendments with agronomic value. A series of greenhouse experiments and laboratory incubations were conducted to assess the effects of biochar volatile matter (VM) content on plant growth, nitrogen (N) transformations, and microbial activities in an acid tropical soil. High VM biochar inhibited plant growth and reduced N uptake with and without the addition of fertilizers. Low VM charcoal supplemented... J. Deenik, A. Mcclellan, G. Uehara |
10. Variability of Manure Nutrient Content and Implications for Manure Sampling ProtocolThe variability of manure nutrient levels within and across farms makes manure sampling and development of reliable tabular values challenging. The chemical characteristics of beef, dairy, horse, sheep, and chicken solid manures in Colorado were evaluated by sampling six to ten different livestock operations for each manure type and comparing the results to values found in the literature. Due to the semi-arid climate of Colorado, manure tends to be drier and have lower ammonium (NH4-N) levels... J. G. davis, K. Iversen, M. Vigil |
11. Soil Testing to Improve Phosphorus Management on Intensive Vegetable Farms in HawaiiAccording to a recent survey of soil samples sent to the Agricultural Diagnostic Service Center (ADSC) at the University of Hawaii between October 2002 and September 2003, a majority of the samples showed soil test P (STP) levels in the high or excessive categories. Despite high soil test P, many farmers in Hawaii continue to apply P fertilizers. We began a project to evaluate soil P status on a range of vegetable farms throughout the state, to determine crop response to P fertilizers on soils... J. Deenik, S. Fukuda, R. Hamasaki, R. Shimabuku, R. Uchida |
12. Determining Plant Available Nitrogen from Manure and Compost Topdressed on an Irrigated PastureComposting manure is a practice that is gaining acceptance as an environmentally sound manure management practice at large animal production operations. Composting produces a value-added product that enhances the fertility and physical properties of soil. During the composting process, nitrogen and phosphorus in the original feedstocks are converted through microbial activity into predominantly stable organic compounds, lessening the risk of loss of these nutrients into the environment. Compost... J. G. davis, T. Bauder, K. Corwin doesken, A. Elliott |
13. Best Management Practices (Bmps) for Ammonia Emissions Reduction from Animal Feeding Operations: a Colorado Case StudyAmmonia emissions from agriculture are a growing concern, in particular, in Colorado where nitrogen deposition in Rocky Mountain National Park has highlighted public concerns. Due to the high level of political pressure on agriculture to reduce its emissions, the agricultural community in Colorado has recently developed a Rocky Mountain National Park Ag Strategy for decreasing ammonia emissions from agriculture and nitrogen deposition in the park. The strategy includes the completion of a thorough... J. G. davis, A. Elliott, N. Marcillac, J. Pritchett, C. Stewart, A. Mink |
14. Reducing Dairy Effluent Phosphorus Content Through Struvite ProductionForced precipitation of struvite (magnesium ammonium phosphate hexahydrate, MgNH4PO46H2O) in wastewater treatment has recently received increased attention as a method of phosphorus (P) recycling. Dairy lagoon P concentrations can be lowered, and the recovered struvite has the potential to be marketed and used as a fertilizer. Struvite may even be useful in organic production on calcareous soils, where rock P (PR) is not an option. A new organic treatment method, based on an existing... J. G. davis, J. Ippolito, M. Massey, R. Sheffield |
15. Predicting Phosphorus Runoff from Calcareous SoilsStudies have shown that as extractable soil P levels increase, runoff P levels also increase. This relationship has been found on many different soils, but tends to be unique for each soil series. Very little research exists evaluating this relationship in calcareous soils. The objectives of this study were to determine soil series specific relationships between soil test phosphorus (STP) and runoff P for three calcareous soils, to compare the use of different soil extractants for runoff P prediction... J. G. davis, R. Schierer, J. Zumbrunnen |