Nutrient Distribution Following Application of Swine Effluent Through a Subsurface Drip Irrigation System

Concerns' regarding utilization of animal waste in agriculture have led to the use of systems such as subsurface irrigation to minimize contact between above ground biomass and the waste. However little is known about the movement and distribution of nutrients applied via subsurface irrigation systems. The purpose of this study is to determine the distribution of nutrients found in swine effluent when applied through a subsurface drip irrigation system located on the Panhandle Research Station in Goodwell, Oklahoma. Suction lysimeters were used to collect solution samples at and between emitters on the inlet and distal ends of a single irrigation tape. Solution samples were obtained from fields with application rates of 2.38 L h-1 (0.63 gph) and 0.72 L h-1 (0.19 gph) respectively. Soil solution samples taken prior to swine effluent application were used to determine background levels of measured nutrients from previous effluent applications. Solution samples drawn within one day following each effluent application were used to determine the distribution and movement of nutrients. pH values, electric conductivity, orthophosphates, nitrate-N, ammonia-N, copper, zinc, and calcium was preformed on each sample. Calcium and copper concentrations increased over time regardless of application rate. Increased application rates (2.38 L h-1) resulted in increased NO3--N laterally with regards to the irrigation tape. Orthophosphate concentrations decreased with depth indicating no downward movement regardless of application rate. Emitter application rates of 0.72 L h-1 resulted in no significant correlation between lysimeter location and nutrient concentration, with the exception of orthophosphate. Based on the results of this study it appears that nutrients are not being lost. At the 2.38 L h-1 emitter application rates NO3--N and OP concentrations near the surface place these nutrients directly in the rooting zone for the plants.Department of Plant and Soil Science

Fabrication and characterization of net-shaped iron nitride-amine-epoxy soft magnetic composites

Soft magnetic composites (SMCs) offer a promising alternative to electrical steels and soft ferrites in high performance motors and power electronics. They are ideal for incorporation into passive electronic components such as inductors and transformers, which require a non-permanent magnetic core to rapidly switch magnetization. As a result, there is a need for materials with the right combination of low coercivity, low magnetic remanence, high relative permeability, and high saturation magnetization to achieve these goals. Iron nitride is an attractive soft magnetic material for incorporation into an amine/epoxy resin matrix. This permits the synthesis of net-shaped SMCs using a “bottom-up” approach for overcoming the limitations of current state-of-the-art SMCs made via conventional powder metal processing techniques. In this work we present the fabrication of various net-shaped, iron nitride-based SMCs using two different amine/epoxy resin systems and their magnetic characterization. The maximum volume loading of iron nitride reached was ∼77% via hot pressing, which produced SMCs with a saturation magnetic polarization (Js) of ∼0.9 T, roughly 2–3 times the Js of soft ferrites

Carbon-sensitive pedotransfer functions for plant available water

Currently accepted pedotransfer functions show negligible effect of management-induced changes to soil organic carbon (SOC) on plant available water holding capacity (θAWHC), while some studies show the ability to substantially increase θAWHC through management. The Soil Health Institute\u27s North America Project to Evaluate Soil Health Measurements measured water content at field capacity using intact soil cores across 124 long-term research sites that contained increases in SOC as a result of management treatments such as reduced tillage and cover cropping. Pedotransfer functions were created for volumetric water content at field capacity (θFC) and permanent wilting point (θPWP). New pedotransfer functions had predictions of θAWHC that were similarly accurate compared with Saxton and Rawls when tested on samples from the National Soil Characterization database. Further, the new pedotransfer functions showed substantial effects of soil calcareousness and SOC on θAWHC. For an increase in SOC of 10 g kg–1 (1%) in noncalcareous soils, an average increase in θAWHC of 3.0 mm 100 mm–1 soil (0.03 m3 m–3) on average across all soil texture classes was found. This SOC related increase in θAWHC is about double previous estimates. Calcareous soils had an increase in θAWHC of 1.2 mm 100 mm–1 soil associated with a 10 g kg–1 increase in SOC, across all soil texture classes. New equations can aid in quantifying benefits of soil management practices that increase SOC and can be used to model the effect of changes in management on drought resilience

Linking soil microbial community structure to potential carbon mineralization: A continental scale assessment of reduced tillage

Potential carbon mineralization (Cmin) is a commonly used indicator of soil health, with greater Cmin values interpreted as healthier soil. While Cmin values are typically greater in agricultural soils managed with minimal physical disturbance, the mechanisms driving the increases remain poorly understood. This study assessed bacterial and archaeal community structure and potential microbial drivers of Cmin in soils maintained under various degrees of physical disturbance. Potential carbon mineralization, 16S rRNA sequences, and soil characterization data were collected as part of the North American Project to Evaluate Soil Health Measurements (NAPESHM). Results showed that type of cropping system, intensity of physical disturbance, and soil pH influenced microbial sensitivity to physical disturbance. Furthermore, 28% of amplicon sequence variants (ASVs), which were important in modeling Cmin, were enriched under soils managed with minimal physical disturbance. Sequences identified as enriched under minimal disturbance and important for modeling Cmin, were linked to organisms which could produce extracellular polymeric substances and contained metabolic strategies suited for tolerating environmental stressors. Understanding how physical disturbance shapes microbial communities across climates and inherent soil properties and drives changes in Cmin provides the context necessary to evaluate management impacts on standardized measures of soil microbial activity

Recombinant Vesicular Stomatitis Virus Vaccine Vectors Expressing Filovirus Glycoproteins Lack Neurovirulence in Nonhuman Primates

The filoviruses, Marburg virus and Ebola virus, cause severe hemorrhagic fever with high mortality in humans and nonhuman primates. Among the most promising filovirus vaccines under development is a system based on recombinant vesicular stomatitis virus (rVSV) that expresses an individual filovirus glycoprotein (GP) in place of the VSV glycoprotein (G). The main concern with all replication-competent vaccines, including the rVSV filovirus GP vectors, is their safety. To address this concern, we performed a neurovirulence study using 21 cynomolgus macaques where the vaccines were administered intrathalamically. Seven animals received a rVSV vector expressing the Zaire ebolavirus (ZEBOV) GP; seven animals received a rVSV vector expressing the Lake Victoria marburgvirus (MARV) GP; three animals received rVSV-wild type (wt) vector, and four animals received vehicle control. Two of three animals given rVSV-wt showed severe neurological symptoms whereas animals receiving vehicle control, rVSV-ZEBOV-GP, or rVSV-MARV-GP did not develop these symptoms. Histological analysis revealed major lesions in neural tissues of all three rVSV-wt animals; however, no significant lesions were observed in any animals from the filovirus vaccine or vehicle control groups. These data strongly suggest that rVSV filovirus GP vaccine vectors lack the neurovirulence properties associated with the rVSV-wt parent vector and support their further development as a vaccine platform for human use

Carbon-sensitive pedotransfer functions for plant available water

Currently accepted pedotransfer functions show negligible effect of management-induced changes to soil organic carbon (SOC) on plant available water holding capacity (θAWHC), while some studies show the ability to substantially increase θAWHC through management. The Soil Health Institute\u27s North America Project to Evaluate Soil Health Measurements measured water content at field capacity using intact soil cores across 124 long-term research sites that contained increases in SOC as a result of management treatments such as reduced tillage and cover cropping. Pedotransfer functions were created for volumetric water content at field capacity (θFC) and permanent wilting point (θPWP). New pedotransfer functions had predictions of θAWHC that were similarly accurate compared with Saxton and Rawls when tested on samples from the National Soil Characterization database. Further, the new pedotransfer functions showed substantial effects of soil calcareousness and SOC on θAWHC. For an increase in SOC of 10 g kg–1 (1%) in noncalcareous soils, an average increase in θAWHC of 3.0 mm 100 mm–1 soil (0.03 m3 m–3) on average across all soil texture classes was found. This SOC related increase in θAWHC is about double previous estimates. Calcareous soils had an increase in θAWHC of 1.2 mm 100 mm–1 soil associated with a 10 g kg–1 increase in SOC, across all soil texture classes. New equations can aid in quantifying benefits of soil management practices that increase SOC and can be used to model the effect of changes in management on drought resilience

Linking soil microbial community structure to potential carbon mineralization: A continental scale assessment of reduced tillage

Potential carbon mineralization (Cmin) is a commonly used indicator of soil health, with greater Cmin values interpreted as healthier soil. While Cmin values are typically greater in agricultural soils managed with minimal physical disturbance, the mechanisms driving the increases remain poorly understood. This study assessed bacterial and archaeal community structure and potential microbial drivers of Cmin in soils maintained under various degrees of physical disturbance. Potential carbon mineralization, 16S rRNA sequences, and soil characterization data were collected as part of the North American Project to Evaluate Soil Health Measurements (NAPESHM). Results showed that type of cropping system, intensity of physical disturbance, and soil pH influenced microbial sensitivity to physical disturbance. Furthermore, 28% of amplicon sequence variants (ASVs), which were important in modeling Cmin, were enriched under soils managed with minimal physical disturbance. Sequences identified as enriched under minimal disturbance and important for modeling Cmin, were linked to organisms which could produce extracellular polymeric substances and contained metabolic strategies suited for tolerating environmental stressors. Understanding how physical disturbance shapes microbial communities across climates and inherent soil properties and drives changes in Cmin provides the context necessary to evaluate management impacts on standardized measures of soil microbial activity

Organic carbon dynamics and soil stability in five semiarid agroecosystems

Interest in integrated crop-livestock agroecosystems (ICL) has increased due to their versatility in management options, potential to offset increasing levels of atmospheric C and enhanced agronomic and ecosystem sustainability. Identifying agroecosystems that have the greatest potential for C sequestration requires an understanding of soil organic C distribution within aggregate fractions. Six soil aggregate C pools were physically isolated to evaluate the C sequestration potential of three ICLs and two continuous cotton (CTN) agroecosystems in the Texas High Plains. The proportions of the water stable aggregate fractions were used to calculate mean weight diameter, an indicator of soil stability. The first ICL (FRG CTN) included paddocks of dry land perennial native grasses, a foxtail millet-cotton (Setariaitalica [L.] P. Beauv. And FiberMax 9058F, respectively) rotation, and WW B-Dahl – Old World Bluestem [bluestem; Bothriochloa bladhii (Retz) S.T. Blake] under deficit irrigation (replacement of approximately30% evapotranspiration). The second ICL (OWB BER) included paddocks of deficit irrigated bermudagrass [bermuda; Cynodon dactylon (L.) Pers.] and bluestem and the third ICL (FRG RC) included paddocks of irrigated bluestem and row crop production. Soil samples (0–5 and 5–20 cm) were collected in July 2010. In general, ICLs increased water stable macroaggregates providing a physical protective shell for SOC and increasing C sequestration potential. A strong correlation between SOC and mean weight diameter identified a critical SOC level of 5.5 Mg ha−¹ for the greatest increases in mean weight diameter. Of the five agroecosystems evaluated, FRG RC and OWB BER ranked the highest in terms of mean weight diameter (130% larger), whole SOC (up to 45% more), and intra-aggregate microaggregate SOC (157% greater) relative to CTN production. Increased stability and reduced exposure of intra-aggregate fractions resulted in relatively greater intra-aggregate microaggregate SOC under perennial vegetation. The potential to serve as significant SOC accumulators may aid in offsetting increasing atmospheric C levels, and while specific to these semiarid soils, the identified critical SOC level can act as a target for producers to minimize and ultimately reverse soil degradation