Changes in profile distribution and chemical properties of natural nanoparticles in paddy soils as affected by long-term rice cultivation

Systematic studies on the genesis, properties, and distribution of natural nanoparticles(NNPs) in soil remain scarce. This study examined a soil chronosequence of continuous paddy field land use for periods ranging from 0 to 1 000 years to determine how NNPs in soil changed at the early stages of soil genesis in eastern China. Soil samples were collected from coastal reclaimed paddy fields that were cultivated for 0, 50, 100, 300, 700, and 1 000 years.Natural nanoparticles were isolated and characterized along with bulk soil samples( 2-mm fraction) for selected physical and chemical properties. The NNP content increased with increasing soil cultivation age at 60 g m-2 year-1, which was related to decreasing soil electrical conductivity(172–1 297 μS cm-1) and NNP zeta potentials(from-22 to-36 m V) with increasing soil cultivation age. Changes in several NNP properties, such as pedogenic iron oxide and total organic carbon contents, were consistent with those of the bulk soils across the soil chronosequence. Notably, changes in NNP iron oxide content were obvious and illustrated active chemical weathering, pedogenesis, and potential impacts on the microbial community. Redundancy analysis demonstrated that the soil cultivation age was the most important factor affecting NNP properties, contributing 60.7% of the total variation. Cluster and principal component analysis(PCA) revealed splitting of NNP samples into age groups of 50–300 and 700–1 000 years, indicating rapid evolution of NNP properties, after an initial period of desalinization(approximately 50 years). Overall, this study provides new insights into NNP evolution in soil during pedogenesis and predicting their influences on agriculture and ecological risks over millennial-scale rice cultivation.     

Comparative utility of egg blastomere morphology and lipid biochemistry for prediction of hatching success in Atlantic cod, Gadus morhua L.

Six blastomere morphology parameters indicative of cell development abnormalities, egg diameter, dry weight, total lipid, lipid classes and fatty acids were determined for egg batches collected daily from three Atlantic cod (Gadus morhua) broodstock groups over the course of one spawning season. Egg batches were incubated to hatch and each morphological and biochemical parameter was tested as a predictor of hatching success. Five of the six blastomere morphology parameters were significantly positively correlated with each other. Correlation coefficients among several fatty acid parameters were also significant but correlation coefficients among the various lipid classes were mostly not significant. No significant correlations were found between blastomere morphology and lipid class or fatty acid parameters. Egg dry weight was negatively correlated with cell clarity, %docosahexanoic acid (DHA), DHA:eicosapentaenoic acid, and Σ polyunsaturated fatty acids. Fertilization success was not significantly correlated with any of the morphology or biochemistry parameters. Within‐population variability in several morphological and fatty acid parameters was related to elapsed time since onset of first spawning. However, the occurrence of such relationships with elapsed time was highly variable and inconsistent among the three broodstocks, typically being significant for only one or two broodstocks but not all three. Mean hatching success rates were high (>75%) in all three broodstocks but hatching success was not significantly related to any of the morphological or biochemical parameters nor to elapsed time from onset of first spawning. The implications of these results are discussed in terms of the utility of the various morphology and biochemistry parameters as measures of egg quality in marine finfish hatcheries.     

Dietary composition manipulation to enhance the performance of juvenile barramundi (Lates calcarifer Bloch) reared in cool water

Barramundi Lates calcarifer reared in cool water (20–22°C) grow slowly and feed is used poorly compared with fish in warm water (28–32°C). Two comparative slaughter growth assays were carried out with juvenile barramundi to see if increasing the digestible energy (DE) and/or the n‐3 highly unsaturated fatty acid (n‐3 HUFA) content of the feed would improve growth of fish raised in cool water. Increasing the DE content of the feed from 15 to 17 or 19 MJ kg⁻¹ while maintaining a constant protein to energy ratio in Experiment 1 brought about significant improvements in feed conversion ratio (FCR) (from 2.01 to 1.19) and daily growth coefficient (DGC; from 0.69 to 1.08%/day) for fish at 20°C. For fish at 29°C, improvements, while significant, were of a lesser magnitude: from 1.32 to 0.97 for FCR and from 3.24 to 3.65%/day for DGC. Increasing the absolute amount of dietary n‐3 HUFA, expressed as the sum of eicosapentaenoic and docosahexaenoic fatty acids, from 0.5% to 2.0% in Experiment 2 improved DGC linearly and FCR curvilinearly for fish at 29°C whereas at 20°C, DGC was not affected while FCR improved slightly (from 1.83 to 1.68). Feed conversion ratio was optimized with a dietary n‐3 HUFA of about 1.5%. Providing barramundi with a feed that is high in DE (viz 19 MJ kg⁻¹) and a digestible protein to DE ratio of 22.5 g MJ⁻¹ is a practical strategy for improving the productivity of barramundi cultured in cool water whereas increasing dietary n‐3 HUFA conferred very little additional benefit.     

Influence of air equilibration time,sampling techniques,and storage temperature on enzymatic starch availability of steam-flaked corn

Measuring enzymatic starch availability is commonly used as a quality control method to ensure steam-flaked corn manufacturing consistency in commercial cattle feeding operations. However, starch availability estimates can be variable. We conducted five experiments to evaluate factors influencing starch availability estimates of steam-flaked corn. In Exp. 1, sample handling methods were evaluated. Sifted flakes were immediately placed into a plastic bag, air equilibrated for 240 min, oven-dried, or freeze–dried. Directly oven-drying samples at 55°C decreased (P < 0.01) starch availability compared to other sample handling methods. In Exp. 2, sifted flakes were air equilibrated for 0, 15, 30, 60, 120, or 240 min. Air equilibration time did not influence (P ≥ 0.54) starch availability. In Exp. 3, samples were evaluated for effects of sifting through a 4-mm screen (flakes + fines vs. sifted flakes) and air equilibration time (0 vs. 240 min). Both sifting steam-flaked corn samples and air equilibration for 240 min increased starch availability (P < 0.01 and P = 0.02, respectively). In Exp. 4, we evaluated the effects of air equilibration time (0 vs. 240 min) on the two sifted portions (sifted flakes vs. sifted fines). There was an air equilibration time × sifted portion interaction for starch availability because air equilibration time increased (P < 0.01) starch availability of sifted fines but did not influence starch availability of sifted flakes. Concentrations of crude protein, soluble crude protein, neutral and acid detergent fiber, ether extract, and acid-hydrolyzed fat, Ca, P, K, Mg, S, Fe, Zn, Mg, and Cu were greater (P < 0.01) for sifted fines compared to sifted flakes. Starch availability and total starch concentration were greater (P < 0.01) for sifted flakes compared to sifted fines. In Exp. 5, effects of air equilibration time (0 vs. 240 min) and storage temperature (23°C vs. 55°ºC) on flakes + fines were evaluated. Storage of flakes + fines in heat-sealed foil bags at 55°C for 3-d decreased (P < 0.01) starch availability by 40.7%. Sifted flakes contained less moisture, greater total starch concentrations, and greater starch availability than sifted fines. Moisture, sifting, air equilibration time, and storage temperature influence starch availability of steam-flaked corn. Adoption of the strategies discussed in the current study will lead to more consistent estimates of starch availability.     

Factors influencing long-term street tree survival in Milwaukee,WI, USA

Street trees are exposed to a variety of site conditions, environmental factors, and physical disturbances which influence their survival in urban areas. This study draws on 25 years of urban forest monitoring data from the city of Milwaukee, WI (United States) to model the impacts of these factors on tree survival for a single cohort of trees. Tree condition, tree size, tree species, and site attributes were measured initially in 1979. These factors were measured again in 1989 and 2005 and compared to construction data for the same area during the study period. Multivariate logistic regression was used to identify factors associated with tree survival. Cross-validation show the final model could successfully predict tree survival nearly 85% of the time. Results indicate that tree survival varied by species. Additionally, trees were more likely to die as trunk diameter increased, planting space width decreased in the tree lawn, and tree condition decreased. Finally, trees adjacent to construction were nearly twice as likely to die as those not exposed to development and redevelopment activities.     

Evaluation of chemical amendments to control phosphorus losses from dairy slurry

Land application of dairy slurry can result in incidental losses of phosphorus (P) to runoff in addition to increased loss of P from soil as a result of a buildup in soil test P (STP). An agitator test was used to identify the most effective amendments to reduce dissolved reactive phosphorus (DRP) loss from the soil surface after land application of chemically amended dairy cattle slurry. This test involved adding slurry mixed with various amendments (mixed in a beaker using a jar test flocculator at 100 rpm), to intact soil samples at approximate field capacity. Slurry/amended slurry was applied with a spatula, submerged with overlying water and then mixed to simulate overland flow. In order of effectiveness, at optimum application rates, ferric chloride (FeCl₂) reduced the DRP in overlying water by 88%, aluminium chloride (AlCl₂) by 87%, alum (Al₂(SO₄)₃·nH₂O) by 83%, lime by 81%, aluminium water treatment residuals (Al‐WTR; sieved to <2 mm) by 77%, flyash by 72%, flue gas desulphurization by‐product by 72% and Al‐WTR sludge by 71%. Ferric chloride (€4.82/m³ treated slurry) was the most cost‐effective chemical amendment. However, Al compounds are preferred owing to stability of Al–P compared with Fe–P bonds. Alum is less expensive than AlCl₂ (€6.67/m³), but the risk of effervescence needs further investigation at field‐scale. Phosphorus sorbing materials (PSM) were not as efficient as chemicals in reducing DRP in overlying water. The amendments all reduced P loss from dairy slurry, but the feasibility of these amendments may be limited because of the cost of treatment.     

A field study on the effects of dietary monensin on milk production and milk composition in dairy cows

The objectives of this study were to quantify the effect of 16 ppm of dietary monensin on milk production and composition of dairy cows, and to investigate factors having a potential impact on this effect. Data were generated from a total of 3577 Holstein dairy cows (47 herds) in Quebec enrolled in a herd-level, randomized clinical trial investigating the effects of monensin supplementation. Milk production and composition data were collected from monthly dairy herd improvement (DHI) testing. Monensin increased milk production by 0.9 kg/cow/d in cows under 150 days in milk (DIM) (P < 0.05). Monensin decreased milk fat percentage by 0.18 percentage points during the whole lactation (P < 0.05). This decreasing effect was larger for component-fed cows (P < 0.05) and for cows being fed low levels of dietary physically effective particles (P < 0.05) when compared respectively to cows fed total mixed ration and cows fed high levels of dietary physically effective particles. The results of this study suggest that monensin influences milk production and milk composition of dairy cows, and that diet composition and feeding system influence those effects.     

Metabolic interactions of agrochemicals in humans

Agrochemicals and other xenobiotics are metabolized by xenobiotic-metabolizing enzymes (XMEs) to products that may be more or less toxic than the parent chemical. In this regard, phase-I XMEs such as cytochrome P450s (CYPs) are of primary importance. Interactions at the level of metabolism may take place via either inhibition or induction of XMEs. Such interactions have often been investigated, in vitro, in experimental animals, using subcellular fractions such as liver microsomes, but seldom in humans or at the level of individual XME isoforms. The authors have been investigating the metabolism of a number of agrochemicals by human liver microsomes and recombinant CYP isoforms and have recently embarked on studies of the induction of XMEs in human hepatocytes. The insecticides chlorpyrifos, carbaryl, carbofuran and fipronil, as well as the repellant DEET, are all extensively metabolized by human liver microsomes and, although a number of CYP isoforms may be involved, CYP2B6 and CYP3A4 are usually the most important. Permethrin is hydrolyzed by esterase(s) present in both human liver microsomes and cytosol. A number of metabolic interactions have been observed. Chlorpyrifos and other phosphorothioates are potent inhibitors of the CYP-dependent metabolism of both endogenous substrates, such as testosterone and estradiol, and exogenous substrates, such as carbaryl, presumably as a result of the interaction of highly reactive sulfur, released during the oxidative desulfuration reaction, with the heme iron of CYP. The hydrolysis of permethrin in human liver can be inhibited by chlorpyrifos oxon and by carbaryl. Fipronil can inhibit testosterone metabolism by CYP3A4 and is an effective inducer of CYP isoforms in human hepatocytes.     

The effect of row spacing and seeding rate on biomass production and plant stand characteristics of non-irrigated photoperiod-sensitive sorghum (Sorghum bicolor (L.) Moench)

To evaluate row spacing and seeding rate effects on yield and plant stand characteristics of high-biomass sorghum, a photoperiod-sensitive cultivar was sown at three different row spacings (76, 38, and 19 cm) and seeding rates (218,000, 306,000, and 393,000 seeds ha⁻¹ for one site-year and 116,000, 204,000, and 291,000 seeds ha⁻¹ for three site-years) from 2009 to 2010 in Alabama and Arkansas, USA. Measurements included above-ground dry matter production, plant height, stem density, and stem diameter. Narrower row spacing (i.e. 19 cm) produced the highest biomass for all site-years. Increasing seeding rate did not affect yield for three of the site-years, and decreased yield for one. The 19 cm row spacing produced the highest stem densities. Plant height increased with increasing seeding rates at one site and decreased with higher seeding rates at another site. At one location, stem diameter declined as seeding rates and stem density increased. It was concluded that narrower row spacing (19 cm) provides the maximum yield benefit by significantly increasing stem density, and low seeding rates (116,000 seeds ha⁻¹) are preferable because higher seeding rates do not positively affect yield and may cause morphological changes (i.e. taller plants with thinner stems) conducive to lodging.