Estimating SHmax azimuth with P sources and vertical geophones: Use P-P reflection amplitudes or use SV-P reflection times?

We compared two methods for extracting the azimuth of maximum horizontal stress (SHmax) from 3D land-based seismic data generated by a P source and recorded with vertical geophones. In the first method, we used the direct-SV mode that is produced by all land-based P sources. P sources generate SV illumination that radiates in all azimuth directions from a source station and creates SV-P reflections that are recorded by vertical geophones. Unless stratigraphy has steep dip, SV-P raypaths recorded by vertical geophones are the reverse of P-SV raypaths recorded by horizontal geophones. Thus, SV-P data provide the same S-wave sensitivity to stress fields as popular P-SV data do. In the second method, we retrieved P-P reflections and then performed an amplitude-versus-incident-angle (AVA) analysis of the amplitude-gradient behavior of P-P reflection wavelets. We did this analysis in narrow azimuth corridors to determine the gradient of reflection-wavelet amplitudes as a function of azimuth. This P-P AVA amplitude-gradient method has been of great interest in the reflection seismology community since it was introduced in the late 1990s. Each of these methods, AVA analysis of the gradient of P-P reflection amplitudes and azimuth-dependent arrival times of SV-P reflections can be used to determine the azimuth of SHmax stress. We compare the results of the two methods with ground truth measurements of SHmax azimuth at a CO2 sequestration site in the Michigan Basin. SHmax azimuths were determined from P-P and SV-P data at three major boundaries at depths of approximately 3500 ft (1067 m), 5500 ft (1676 m), and 7500 ft (2286 m). Two estimates of SHmax azimuth (one using SV-P data and one using P-P data) were made at each stacking bin inside a 24 mi2 (62 km2) image space. The result was approximately 98,000 estimates of SHmax azimuth across each of these three boundaries for each of these two prediction strategies. Histogram displays of PP AVA gradient estimates had peaks at correct azimuths of SHmax at all three depths, but the spread of the distributions widened with depth and split into two peaks at the deepest boundary. In contrast, each histogram of SHmax azimuth predicted by azimuth-dependent SV-P traveltimes had a single, definitive peak that was positioned at the correct SHmax azimuth at all three boundary depths.

Transcriptional responses of Trichodesmium to natural inverse gradients of Fe and P availability

The filamentous diazotrophic cyanobacterium Trichodesmium is responsible for a significant fraction of marine di-nitrogen (N2) fixation. Growth and distribution of Trichodesmium and other diazotrophs in the vast oligotrophic subtropical gyres is influenced by iron (Fe) and phosphorus (P) availability, while reciprocally influencing the biogeochemistry of these nutrients. Here we use observations across natural inverse gradients in Fe and P in the North Atlantic subtropical gyre (NASG) to demonstrate how Trichodesmium acclimates in situ to resource availability. Transcriptomic analysis identified progressive upregulation of known iron-stress biomarker genes with decreasing Fe availability, and progressive upregulation of genes involved in the acquisition of diverse P sources with decreasing P availability, while genes involved in N2 fixation were upregulated at the intersection under moderate Fe and P availability. Enhanced N2 fixation within the Fe and P co-stressed transition region was also associated with a distinct, consistent metabolic profile, including the expression of alternative photosynthetic pathways that potentially facilitate ATP generation required for N2 fixation with reduced net oxygen production. The observed response of Trichodesmium to availability of both Fe and P supports suggestions that these biogeochemically significant organisms employ unique molecular, and thus physiological responses as adaptations to specifically exploit the Fe and P co-limited niche they construct.

Dietary calcium to phosphorus ratio affects postprandial phosphorus concentrations in feline plasma

The impact of dietary phosphorus on chronic renal disease in cats, humans and other species is receiving increasing attention. As calcium (Ca) and phosphorus (P) metabolism are linked, the ratio of Ca:P is an important factor for consideration when formulating diets for cats and other animals. Here, we describe a fully randomized crossover study including 24 healthy, neutered adult cats, investigating post-prandial responses in plasma P, ionised Ca (iCa) and parathyroid hormone (PTH) following one meal (50% of individual metabolic energy requirement) of each of six experimental diets. Diets were formulated to provide P at either 0.75 or 1.5 g/1000kcal (4184kJ) from the soluble phosphorus salt sodium tripolyphosphate (STPP, Na5P3O10), variable levels of organic Ca and P sources, and an intended total Ca:P of ∼1.0, 1.5 or 2.0. For each experimental diet, baseline fasted blood samples were collected prior to the meal, and serial blood samples collected hourly for 6 hours thereafter. For all diets, a significant increase from baseline was observed at 120mins in plasma PTH (p<0.001). The diet containing the highest STPP inclusion level and lowest Ca:P induced the highest peaks in post-prandial plasma P and PTH levels (1.8mmol/l and 27.2pg/ml, respectively) and the longest duration of concentrations raised above baseline were observed at 3 hours for P and 6 hours for PTH. Data indicate that Ca:P modulates postprandial plasma P and PTH. Therefore, when formulating diets containing soluble P salts for cats, increasing the Ca:P ratio should be considered.

The possible use of scarce soluble materials as a source of phosphorus in Vicia faba L. grown in calcareous soils

<p><span lang="EN-US">Phosphorus (P) is affected by many factors that minimize its solubility especially in calcareous soils. The aim of this work was to conduct laboratory and greenhouse experiments to study the effect of using P solubilizing substances, </span><em><span lang="EN-US">i.e., </span></em><span lang="EN-US">compost, humic acid (HA), citric acid and ethylene di-amine tetra acetic acid (EDTA), and rhizobacteria, </span><em><span lang="EN-US">Bacillus megaterium</span></em><span lang="EN-US"> var. </span><em><span lang="EN-US">phosphaticum</span></em><span lang="EN-US"> on solubilizing P from different sources, ordinary superphosphate (OSP), rock phosphate (RP) and basic slag (BS). The effect of these treatments on the P- availability in El-Nubaria calcareous soil and P- uptake by faba bean (</span><em><span lang="EN-US">Vicia faba </span></em><span lang="EN-US">‘</span><span lang="EN-US">Giza 843</span><span lang="EN-US">’</span><span lang="EN-US">) were studied. Obtained results showed that the solubility of P sources differs in their ability to release soluble P in the following order: OSP &gt; RP &gt; BS. The following descending order was appeared of available P in soil with addition of solubilizing agents: citric acid &gt; EDTA &gt; HA &gt; compost for these sources of P, for both experiments. Regarding the interaction between solubilizing agents, the treatments of HA combined with EDTA or citric acid were superior in giving high concentrations in soil, and vigor plant growth. In addition, the solubility of P increased by about 5-6 times for all sources in the presence of P- dissolving bacteria. It seemed that the presence of appreciable amounts of Mg, S, Fe, Mn, B and other elements in BS played a role in enhancing plant growth and increasing yield, especially in the presence of added bacteria. BS could be used in calcareous soils and for soils characterized by low nutrient supply as sandy.</span></p>

The distribution of phosphorus from recycled fertilizers to different soil fractions determines the phosphorus availability in soil

Recycling of agricultural wastes to reduce mineral fertilizer input, in particular phosphorous (P), plays crucial role in sustainable agriculture production. Understanding the transformation of phosphorous (P) fractions and their bioavailability following soil application of different renewable P-contained fertilizers is very important for improving P use efficiency and reducing environmental risks. In this study, the effects of mineral P-fertilizer superphosphate and recycled P-fertilizers, i.e., poultry manure, cattle manure, maize straw and cattle bone meal, on their distribution to different soil P fractions, their transformation and the availability of soil P were determined by soil P sequential fractionation and 31P solution nuclear magnetic resonance (NMR). The results showed that addition of mineral P fertilizer, poultry manure and cattle manure increased P fixation in a red soil more than that in a fluvo-aquic soil. In both fluvo-aquic and red soils, cattle manure out-performed all other recycled P sources used in improving soil P availability. The concentration of Olsen-P in fluvo-aquic and red soils supplemented with cattle manure were increased by 41 %–380 % and 16 %–70 % than the other recycled P sources. A structural equation model (SEM) explained 95 % and 91 % of Olsen-P variation in fluvo-aquic and red soils, respectively. Labile P fractions had positive effects on Olsen-P of fluvo-aquic and red soils. 31P-NMR study showed that amount of orthophosphate was the main factor affecting the availability of P from different P sources. In summary, cattle manure was found to be a superior renewable source of P in improving bioavailable P in soil, and its use thus has considerable practical significance in P recycling.

An evaluation of soil phosphorus storage capacity (SPSC) at proposed wetland restoration locations in the western Lake Erie Basin

Historical loss of wetlands coupled with excess phosphorus (P) loading at watershed scales have degraded water quality in portions of the western Lake Erie Basin (WLEB). In response, efforts are underway to restore wetlands and decrease P loading to surface waters. Because wetlands have a finite capacity to retain P, researchers have developed techniques to determine whether wetlands function as P sources or sinks. The following technical report evaluates the soil P storage capacity (SPSC) at locations under consideration for wetland restoration in collaboration with the Great Lakes Restoration Initiative (GLRI) and the H2Ohio initiative. Results indicate that the examined soils display a range of P retention capacities, reflecting historic land-use patterns and management regimes. However, the majority of study locations exhibited some capacity to sequester additional P. The analysis supports development of rankings and comparative analyses of areas within a specific land parcel, informing management through design, avoidance, removal, or remediation of potential legacy P sources. Additionally, the approaches described herein support relative comparisons between multiple potential wetland development properties. These results, in conjunction with other data sources, can be used to target, prioritize, justify, and improve decision-making for wetland management activities in the WLEB.

Designing Calcium Phosphate Nanoparticles with the Co-Precipitation Technique to Improve Phosphorous Availability in Broiler Chicks

Dicalcium phosphate (DP) is a mineral involved in the metabolism and development and is used as a dietary source of phosphorus (PT) for poultry. Our study objective is to design nano-dicalcium phosphate (NDP) by co-precipitation. The methodological procedure was divided into two phases: (1) NDP synthesis, and (2) bird performance, digestibility, and Ca-P in chick’s tissues. The sizes of the NDP were 20–80 nm. NDP had the Ca: P ratio of 1:1.12. The birds were divided into control diet (available P (Pa) = 0.13%) and three supplementary P sources [Commercial (Calcium phosphate), analytical grade (DP) and nanoparticles (NDP)] with three Pa levels (0.24, 0.35, 0.46%). Supplementary P sources compared to the control treatment had the highest body weight gain (698.56 vs. 228; p < 0.05) and feed intake (FI) (965.18 vs. 345.82), respectively. The digestibility of PT (67%) improved with 0.35% NDP. The highest contents of PT -breast were with the levels of 0.35 and 0.46% NDP. The PT, ash, and diameters were higher (p < 0.05) with supplementary P compared to the control treatment. As conclusion, the use of 0.35% NDP was the ideal dose in the chicks for the digestibility, absorption values, and the amount of PT in the breast.

Watershed Response to Legacy Phosphorus and Best Management Practices in an Impacted Agricultural Watershed in Florida, U.S.A.

Soil phosphorus (P) built up due to past management practices, legacy P, in the Lake Okeechobee Watershed (LOW) in south-central Florida, U.S.A., is often discussed as the root cause of lake eutrophication. Improvement of the lake’s water quality requires the identification of critical P sources and quantifying their contributions. We performed a global sensitivity analysis of the Watershed Assessment Model (WAM), a common evaluation tool in LOW environmental planning, using the Morris method. A pre-calibrated WAM setup (Baseline) of the LOW sub-watershed, Taylor Creek Nubbin Slough (TCNS), was used as a test case. Eight scenarios were formulated to estimate the contributions of various P sources. The Morris analysis indicated that total phosphorus (TP) loads were highly sensitive to legacy P in improved pastures, the major land use covering 46.2% of TCNS. The scenario modeling revealed that legacy P, inorganic fertilizers, and other sources contribute 63%, 10%, and 32%, respectively, to the Baseline TP load of 111.3 metric tons/y to the lake. Improved pastures, dairies, citrus, and field crops are the top TP load contributors. Our results have important implications for water quality improvement plans in the LOW and highlighted the need for accurate spatial mapping of legacy P and incorporation of such information in modeling efforts for watersheds demonstrating legacy P problems.

Soil Phosphorus and Corn Development Under Application of Phosphate Sources

Knowledge of the solubility of phosphate fertilizers is fundamental for phosphorus (P) recommendation management and for choosing the laboratory evaluation method of nutrient availability in the soil according to the history of fertilization. The aim was to evaluate the initial development of corn plants as a function of the application of triple superphosphate (TSP) and natural phosphate of Arraias (NPA) with and without liming and incubation time, as well as to evaluate the available P in the soil with the use the extractors Mehlich-1 and Mehlich-3. An experiment was installed in an 8 &times; 3 &times; 2 factorial scheme, being 8 fertilizer incubation times (180, 140, 100, 80, 60, 40, 20, 0 day(s) before planting), 3 P sources (control&mdash;without P, TSP and NPA) and 2 refers to the application of limestone (with and without limestone). Were evaluated the shoot and root dry matter, analysis of P, Ca, Mg, and Zn in shoot and P in roots. In the soil, P levels were determined by Mehlich-1 and Mehlich-3 extractors. There was a greater accumulation of P with the application of TSP with limestone in all incubation times. The application of the NPA allowed a greater accumulation of P in the plants without the application of lime. The previous incubation of the NPA did not favor the efficiency of this source, neither in the soil with corrected acidity nor in the soil with its original acidity. Mehlich-3 proved to be adequate to determine the phosphorus content in soil fertilized by NPA.

Effect of different phosphorus sources applied with phosphate solubilizing bacteria on bio-geochemical properties and phosphorus release pattern in vertisol

Various phosphorus (P) fertilizers are used for crop production in different types of soil. But there is a knowledge gap in choosing the right source and form of P fertilizers to enhance the applied fertilizer use efficiency. An experiment was taken to identify the best phosphorus source and its effectiveness as a source of P in vertisol to unravel this problem of selecting suitable P fertilizer. With this background, an incubation experiment was conducted under laboratory condition to determine the phosphorus release pattern of different P sources [Single Super Phosphate (SSP), Rock Phosphate (RP), Diammonium Phosphate (DAP), Nano phosphate (Nano P), Phosphocompost (PC)] applied with phosphate solubilizing bacteria (PSB) and their influence on biogeochemical properties in vertisol. Experimental results emphasized that P release from different sources was influenced by soil pH, electrical conductivity (EC), cation exchange capacity (CEC), soil organic carbon (SOC), and microbial population. Applied P sources significantly(p=0.05) influenced the CEC, SOC, and microbial population except for soil pH and Ec. The maximum release in available P was obtained at 30 and 60 days after incubation with SSP +PSB (35.8 and 40.1 mg kg-1) and Nano P + PSB (33.9 and 38.6 mg kg-1) applied treatments, respectively.Whereas at 90 days after incubation Nano P + PSB (42.3 mg kg-1) and Phosphocompost + PSB (40.4 mg kg-1) treatments recorded the maximum P availability and minimum P (15.2, 13.9 and 11.8 mg kg -1) release was noticed in the control treatment throughout the period of incubation. It was evident that SSP or Nano P along with PSB application might be the best P source for Vertisol.