Nitrogen- vs. phosphorus-based dairy manure applications to field crops: nitrate and phosphorus leaching and soil phosphorus accumulation

Management of animal manures to provide nutrients for crop growth has generally been based on crop N needs. However, because manures have a lower N/P ratio than most harvested crops, N-based manure management often oversupplies the crop-soil system with P, which can be lost into the environment and contribute to eutrophication of water bodies. We examined the effects of N- vs. P-based manure applications on N and P uptake by alfalfa (Medicago sativa L.), corn (Zea mays L.) for silage, and orchardgrass (Dactylis glomerata L.), leaching below the root zone, and accumulation of P in soil. Treatments included N- and P-based manure rates, with no nutrient input controls and inorganically fertilized plots for comparison. Nitrate concentrations in leachate from inorganic fertilizer or manure treatments averaged 14 mg NO(3)-N L(-1), and did not differ by nutrient treatment. Average annual total P losses in leachate did not exceed 1 kg ha(-1). In the top 5 cm of soil in plots receiving the N-based manure treatment, soil test P increased by 47%, from 85 to 125 mg kg(-1). Nitrogen- and P-based manure applications did not differ in ability to supply nutrients for crop growth, or in losses of nitrate and total P in leachate. However, the N-based manure led to significantly greater accumulation of soil test P in the surface 5 cm of soil. Surface soil P accumulation has implications for increased risk of off-field P movement.     

Metabolism of aceclofenac in cattle to vulture‐killing diclofenac

The nonsteroidal anti‐inflammatory drug (NSAID) diclofenac is highly toxic to Gyps vultures, and its recent widespread use in South Asia caused catastrophic declines in at least 3 scavenging raptors. The manufacture of veterinary formulations of diclofenac has since been banned across the region with mixed success. However, at least 12 other NSAIDs are available for veterinary use in South Asia. Aceclofenac is one of these compounds, and it is known to metabolize into diclofenac in some mammal species. The metabolic pathway of aceclofenac in cattle, the primary food of vultures in South Asia, is unknown. We gave 6 cattle the recommended dose of aceclofenac (2 mg/kg), collected blood thereafter at intervals for up to 12 h, and used liquid chromatography with mass spectrometry in a pharmacokinetic analysis of aceclofenac and diclofenac in the plasma. Nearly all the aceclofenac administered to the cattle was very rapidly metabolized into diclofenac. At 2 h, half the aceclofenac had been converted into diclofenac, and at 12 h four‐fifths of the aceclofenac had been converted into diclofenac. Therefore, administering aceclofenac to livestock poses the same risk to vultures as administering diclofenac to livestock. This, coupled with the risk that aceclofenac may replace diclofenac in the veterinary market, points to the need for an immediate ban on all aceclofenac formulations that can be used to treat livestock. Without such a ban, the recovery of vultures across South Asia will not be successful.     

Drivers and constraints of waste-to-energy incineration for sustainable municipal solid waste management in developing countries

Journal of Material Cycles and Waste Management - Implementation of waste-to-energy (WtE) incineration has recently surged in developing countries, but the drivers of this growth and the...     

Manure sampling for nutrient analysis: variability and sampling efficacy

Reliable estimation of nutrient concentrations is required to manage animal manure for protecting waters while sustaining crop production. This study was conducted to investigate sample variability and reliable nutrient analysis for several manure types and handling systems. Serial samples were collected from dairy, swine, and broiler poultry operations while manure was being loaded onto hauler tanks or spreaders for field application. Samples were analyzed for total solids (TS), total nitrogen (N), ammoniacal nitrogen (NH4-N), total phosphorus (P), and potassium (K). The least number of samples needed for reliable testing of total N and P, defined as +/- 10% of the experimental means with 99% probability, was obtained for each farm using a computer-intensive random resampling technique. Sample variability within farms, expressed as the coefficient of variation (CV), was mostly 6 to 8% for farms that used agitation of manure storages but several times higher (20-30%) on farms where no agitation was applied during the sampling period. Results from the random resampling procedure indicated that for farms that used agitation, three to five samples were adequate for a representative composite for reliable testing of total N and P; whereas for farms without agitation, at least 40 samples would be required. Data also suggest that using book values for manure nutrient estimations could be problematic because the discrepancies between book standards and measured farm data varied widely from a small amount to several fold.