Gaseous nitrogen emissions and forage nitrogen uptake on soils fertilized with raw and treated swine manure

Treatments to reduce solids content in liquid manure have been developed, but little information is available on gaseous N emissions and plant N uptake after application of treated liquid swine manure (LSM). We measured crop yield, N uptake, and NH3 and N2O losses after the application of mineral fertilizer (NH4 NO3), raw LSM, and LSM that was decanted, filtered, anaerobically digested, or chemically flocculated. The experiment was conducted from 2001 to 2003 on a loam and a sandy loam cropped to timothy (Phleum pratense L.) with annual applications equivalent to 80 kg N ha(-1) in spring and 60 kg N ha(-1) after the first harvest. Raw LSM resulted in NH3 emissions three to six times larger (P < 0.05) than mineral fertilizer. The LSM treatments reduced NH3 emissions by an average of 25% compared with raw LSM (P < 0.05). The N2O emissions tended to be higher with raw LSM than with mineral fertilizer. The LSM treatments had little effect on N2O emissions, except for anaerobic digestion, which reduced emissions by >50% compared with raw LSM (P < 0.05). Forage yield with raw LSM was >90% of that with mineral fertilizer. The LSM treatments tended to increase forage yield and N uptake relative to raw LSM. We conclude that treated or untreated LSM offers an alternative to mineral fertilizers for forage grass production but care must be taken to minimize NH3 volatilization. Removing solids from LSM by mechanical, chemical, and biological means reduced NH3 losses from LSM applied to perennial grass.     

Precipitation of liquid swine manure phosphates using magnesium smelting by-products

Swine manure contains considerable amounts of total (P) and soluble phosphorus (PO(4)-P) which may increase the soil P content when applied in excess to crop requirements and, consequently, risk water eutrophication. The feasibility of using magnesium (Mg) from the by-product of electrolysis and foundries (BPEF) for the removal of P from liquid swine manure was studied by adding up to 3 g of Mg as BPEF per liter of nursery (NU) and grower-finisher (GF) swine manure in 25-L plastic buckets. Changes in P and other elements were monitored for up to 360 h. Small amounts of Mg as BPEF (0.5 and 1.0 g Mg L(-1) manure) reduced the total P concentration of the liquid fraction by 70 to 95% of both manure types with respect to the control treatment of mixed raw manure. A settling period of 8 h or more was necessary to significantly reduce the liquid fraction's total P concentration for both manure types. Reduction of PO(4)-P varied from 96 to 100% in the liquid fractions for both manure types, which along with natural settling, explains most of the total P reduction in that fraction. The addition of BPEF did not influence the N content of manure. The low P liquid fraction can be safely applied to saturated P soils whereas the high P solid fraction offers the opportunity of transporting manure to agricultural soils deficient in P. Since N is conserved, both liquid and solid fractions could be valuable fertilizer manure by-products.     

Residual soil nitrate after potato harvest

Nitrogen loss by leaching is a major problem, particularly with crops requiring large amounts of N fertilizer. We evaluated the effect of N fertilization and irrigation on residual soil nitrate following potato (Solanum tuberosum L.) harvests in the upper St-John River valley of New Brunswick, Canada. Soil nitrate contents were measured to a 0.90-m depth in three treatments of N fertilization (0, 100, and 250 kg N ha(-1)) at two on-farm sites in 1995, and in four treatments of N fertilization (0, 50, 100, and 250 kg N ha(-1)) at four sites for each of two years (1996 and 1997) with and without supplemental irrigation. Residual soil NO3-N content increased from 33 kg NO3-N ha(-1) in the unfertilized check plots to 160 kg NO3-N ha(-1) when 250 kg N ha(-1) was applied. Across N treatments, residual soil NO3-N contents ranged from 30 to 105 kg NO3-N ha(-1) with irrigation and from 30 to 202 kg NO3-N ha(-1) without irrigation. Residual soil NO3-N content within the surface 0.30 m was related (R2 = 0.94) to the NO3-N content to a 0.90-m depth. Estimates of residual soil NO3-N content at the economically optimum nitrogen fertilizer application (Nop) ranged from 46 to 99 kg NO3-N ha(-1) under irrigated conditions and from 62 to 260 kg NO3-N ha(-1) under nonirrigated conditions, and were lower than the soil NO3-N content measured with 250 kg N ha(-1). We conclude that residual soil NO3-N after harvest can be maintained at a reasonable level (<70 kg NO3-N ha(-1)) when N fertilization is based on the economically optimum N application.     

Protein kinase C and ion transport in the posterior gills of the Chinese crabEriocheir sinensis

The possible involvement of protein kinase C in control of ion transport was investigated on a preparation of isolated, perfused posterior gills of the Chinese crabsEriocheir sinensis (collected in 1989 from lakes near Emden, northern Germany) acclimated to fresh water. 1-oleyl-2-acetyl-sn-glycerol (OAG) and phorbol 12-myristate 13-acetate (PMA), two activators of protein kinase C, when added to the perfusion saline, induced depolarisation of the transepithelial potential difference (PD) and an increase in transepithelial Na⁺ influx. The observed increase was proportional to OAG concentration up to 250µM, with a 2.5× accelerated Na⁺ influx. OAG and PMA remained without effect on Cl^– fluxes. The observed effects were in agreement with an activation, via protein kinase C, of the Na⁺/K⁺ ATPase located on the serosal side of the epithelium.     

Determination of metal and organometal trophic bioaccumulation in the benthic macrofauna of the Adour estuary coastal zone (SW France, Bay of Biscay)

A multidisciplinary approach has been adopted in order to investigate the bioaccumulation of metals and organometals in macrobenthic populations. A complete method coupling a sampling strategy and classification of benthic organisms with a performant analytical procedure for the analysis of both metals and organometals has been developed. A single sample preparation method using a TMAH extraction and species specific isotope dilution makes it possible to analyse metals and organometals in the same extract, which is especially interesting for situations where only a limited amount of sample is available. Low detection limits have been obtained in the range of 12-250 pg g(-1) for mercury and butyltin compounds and 0.4-50 ng g(-1) for metals with good precision (1-10% RSD) even for a very low mass of sample (0.02 g). This method has been applied for monitoring contamination and bioaccumulation of metals and organometals as well as the biodiversity and trophic structure of the macrobenthic population of the Adour Estuary (South-West, France). The benthic macrofauna diversity indicates that inner estuarine stations are moderately polluted whereas outer estuarine stations are less impacted. However, metals concentrations in both sediment and benthic biomass do not change drastically between stations. Moreover, the bioaccumulation has been determined in relation to the feeding guild of benthic organisms. The results demonstrate that higher bioaccumulation is generally observed for deposit feeders directly impacted by sediment contamination compared to suspensive feeders and predators. Biomagnification along the trophic levels was highlighted for MMHg but no significant trend was observed for the other metallic compounds.     

Suspended particulate matter determines physical speciation of Fe,Mn, and trace metals in surface waters of Loire watershed

This study investigates the spatiotemporal variability of major and trace elements, dissolved organic carbon (DOC), total dissolved solids (TDS), and suspended particulate matter (SPM) in surface waters of several hydrosystems of the Loire River watershed in France. In particular, this study aims to delineate the impact of the abovementioned water physicochemical parameters on natural iron and manganese physical speciation (homoaggregation/heteroaggregation) among fine colloidal and dissolved (<?10 nm), colloidal (10–450 nm) and particulate (>?450 nm) phases in Loire River watershed. Results show that the chemistry of the Loire River watershed is controlled by two end members: magmatic and metamorphic petrographic context on the upper part of the watershed; and sedimentary rocks for the middle and low part of the Loire. The percentage of particulate Fe and Mn increased downstream concurrent with the increase in SPM and major cations concentration, whereas the percentage of colloidal Fe and Mn decreased downstream. Transmission electron microscopy analyses of the colloidal and particulate fractions (from the non-filtered water sample) revealed that heteroaggregation of Fe and Mn rich natural nanoparticles and natural organic matter to the particulate phase is the dominant mechanism. The heteroaggregation controls the partitioning of Fe and Mn in the different fractions, potentially due to the increase in the ionic strength, and divalent cations concentration downstream, and SPM concentration. These findings imply that SPM concentration plays an important role in controlling the fate and behavior of Fe and Mn in various sized fractions.

Physical speciation by heteroaggregation of (Fe-Mn) compounds: high [SPM]?→?[Fe-Mn] particulate faction; low {SPM]?→?[Fe-Mn] colloid-dissolved fraction.