Changes in soil test phosphorus from broiler litter additions

Nutrient surpluses on the Delmarva Peninsula have led to a continual accumulation of soil test phosphorus (STP), a potential source for transport of phosphorus (P) to surface waters. This article examines the effects of initial soil test P concentrations and broiler litter additions on STP accumulation. Broiler litter (BL) was applied at rates of 0, 2.5, 5, 7.5, and 10 g kg -1 (dry weight) to three soils: an Evesboro sandy loam (Mesic, coated Typic Quartzipsamments), a Pocomoke sandy loam (coarseloamy, siliceous, thermic typic Umbraquults), and a Matapeake silt loam (fine-silty, mixed, semiactive, mesic Typic Hapludults). Soils and BL were incubated for 16 weeks with subsamples analyzed after 4 and 16 weeks. There was a linear increase in STP (Mehlich-3), water-soluble P (WS-P), iron-oxide strip-extractable P (FeO-P), and Mehlich-3 phosphorus saturation ratio (M3-PSR) with broiler litter additions. Regression analysis indicated few significant differences in STP response to added BL between soils within the same soil group having different initial STP levels. Correlation analysis and stepwise regression indicated that increases in WS-P and FeO-P from added BL were more closely related to the degree of P saturation of the soil rather than traditional STP measurements. Therefore, decisions regarding manure placement within a watershed should be based on the potential P sorption capacity of the soil as well as potential P transport pathways when the goal is the reduction of P transfer to waterbodies

On-farm evaluation of a phosphorus site index for Delaware

The contribution of phosphorus (P) to non-point source (N PS) pollution of surface and groundwaters is a serious environmental problem in Delaware. In 1999, the Delaware Nutrient Management Act was passed limiting application of P on "high" P soils to a "three year crop removal" rate or to the amount recommended by a University of Delaware P site index. The Delaware P site index was developed and evaluated on seven farms in Delaware, through a joint effort between the universities of Delaware and Maryland. Results showed that 78% of fields evaluated were in the "low" risk category, with the remaining 22% falling into the "medium" (6%), "high" (7%), and "very high" (9%) risk categories. The components of the index found to have the greatest influence on P site index ratings were soil erosion, subsurface drainage, leaching potential, distance from field to surface water, soil test P and organic P application rates and methods. P site index ratings were found to vary by year, depending on manure applications, suggesting a need for yearly P site index evaluations or averages over a cropping rotation. The P site index worked well for identifying fields with differing relative potential risks of P loss; however, validation of these P loss assessments is needed to ensure that the risk categories assigned are sufficiently protective of water quality. Continual monitoring, analysis, and improvement of the P site index are needed to ensure that it remains a useful tool for P based nutrient management planning in the future

Determination of phosphorus source coefficients for organic phosphorus sources: Laboratory studies

Phosphorus losses in runoff from application of manures and biosolids to agricultural land are implicated in the degradation of water quality in the Chesapeake and Delaware Inland Bays. We conducted an incubation study to determine the relative P solubility and bioavailability, referred to as P source coefficients (PSCs), for organic P sources, which are typically land-applied in the Mid-Atlantic USA. Nine organic and one inorganic (ICH2PO4) P amendments were applied to an Evesboro loamy sand (mesic, coated Typic Quartzipsamments) at a rate of 60 mg P kri and incubated for 8 wk with subsamples analyzed at 2 and 8 wk. There was an increase in Mehlich-3 P (M3-P), water-soluble P (WS-P), iron-oxide strip extractable P (Fe0-P), and Mehlich-3 P saturation ratio (M3-PSR) with P additions, which varied by P source. The trend of relative extractable WS-P, Fe0-P, and M3-P generally followed the pattern: inorganic P > liquid and deep pit manures > manures and biosolids treated with metal salts or composted. We found significant differences in the availability of P from varying organic P sources. The use of PSCs may be beneficial when determining the risk of P losses from land application of manures and other organic P sources and could be used in risk assessments such as a P site index. These PSCs may also be useful for determining P application rates when organic P sources are applied to P deficient soils for use as a fertilizer source

Anion exchange membrane soil nitrate predicts turfgrass color and yield.

Desirable nitrogen (N) management practices for turfgrass supply sufficient N for high quality turf while limiting excess soil N. Previous studies suggested the potential of anion exchange membranes (AEMs) for predicting turfgrass color, quality, or yield. However, these studies suggested a wide range of critical soil nitrate-nitrogen (NO3-N) values across sample dates. A field experiment, in randomized complete block design with treatments consisting of nine N application rates, was conducted on a mixed species cool-season turfgrass lawn across two growing seasons. Every 2 wk from May to October, turfgrass color was assessed with three different reflectance meters, and soil NO3-N was measured with in situ AEMs. Cate-Nelson models were developed comparing relative reflectance value and yield to AEM desorbed soil NO3-N pooled across all sample dates. These models predicted critical AEM soil NO3-N values from 0. 45 to 1.4 micro g cm-2 d-1. Turf had a low probability of further positive response to AEM soil NO3-N greater than these critical values. These results suggest that soil NO3-N critical values from AEMs may be applicable across sample dates and years and may serve to guide N fertilization to limit excess soil NO3-N

Sociocultural Differences in Self- Construal and Subjective Well-Being: A Test of Four Cultural Models

In this study, the authors tested four cultural models—independence, interdependence, conflict, and integration—that describe the hypothesized relationships between dimensions of self-construal and components of subjective well-being among individualistic and collectivistic countries. Collectivistic countries that have undergone rapid socioeconomic changes (i.e., East Asian countries) and those with limited changes (i.e., African countries) were differentiated. Participants were 791 university students from four Western countries, 749 university students from three East Asian countries, and 443 university students from three African countries. Findings provided some support for the applicability of (a) the independence model to individuals from Western countries and (b) the integration model to individuals from East Asian countries. Mixed results were found among the African countries. The interdependence model is more applicable to African participants from the sub-Saharan region, but the integration model is more applicable to those from the North African region

γ -ray spectroscopy of astrophysically important states in Ca 39

Background: Nova explosions synthesize elements up to A≃40, and discrepancies exist between calculated and observed abundances of Ar and Ca created in the explosion. The K38(p,γ)Ca39 reaction rate has been shown to be influential on these isotopic abundances at the endpoint of nova nucleosynthesis. The energies of the three most important resonances, corresponding to Jπ=5/2+ excited states in the Ca39 nucleus above the proton separation threshold, are uncertain and one has been measured with conflicting values [Er=679(2) versus Er=701(2) keV] in previous experiments. Purpose: Reducing the uncertainties on the resonance energies would allow for a better understanding of the reaction rate. To improve these uncertainties, we searched for γ rays from the depopulation of the corresponding excited states in Ca39. Methods: We report a new measurement of these resonance energies via the observation of previously unobserved γ-ray transitions. These transitions were observed by studying the Ca40(3He,αγ)Ca39 reaction with Gammasphere ORRUBA Dual Detectors for Experimental Structure Studies (GODDESS). The updated resonance energies were then used to calculate the K38(p,γ)Ca39 reaction rate and assess its uncertainties. Results: In total, 23 new transitions were found, including three γ-ray transitions corresponding to the three Jπ=5/2+ states of astrophysical interest at energies of 6156.2(16), 6268.8(22), and 6470.8(19) keV. These correspond to resonance energies in the K38(p,γ)Ca39 reaction of 386(2), 498(2), and 701(2) keV. Conclusions: Updated K38(p,γ)Ca39 reaction rate calculations show a reduced upper limit at nova temperatures. However, the lower-than-previously-measured energy of the 498-keV resonance and uncertainty in its resonance strength increases the upper limit of the rate close to previous estimates at 0.4 GK

New γ -ray transitions observed in Ne 19 with implications for the O 15 (α,γ) Ne 19 reaction rate

The O15(α,γ)Ne19 reaction is responsible for breakout from the hot CNO cycle in type I x-ray bursts. Understanding the properties of resonances between Ex=4 and 5 MeV in Ne19 is crucial in the calculation of this reaction rate. The spins and parities of these states are well known, with the exception of the 4.14- and 4.20-MeV states, which have adopted spin-parities of 9/2- and 7/2-, respectively. γ-ray transitions from these states were studied using triton-γ-γ coincidences from the F19(He3,tγ)Ne19 reaction measured with the GODDESS (Gammasphere ORRUBA Dual Detectors for Experimental Structure Studies) at Argonne National Laboratory. The observed transitions from the 4.14- and 4.20-MeV states provide strong evidence that the Jπ values are actually 7/2- and 9/2-, respectively. These assignments are consistent with the values in the F19 mirror nucleus and in contrast to previously accepted assignments