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Ammonia (NH 3 ) emissions from agriculture to the atmosphere, along with emissions of other pollutants from a variety of sources, are of concern to agriculture worldwide. National emissions from agricultural sources in Canada are linked to domestic consumption and export demand for agricultural products. The onus to limit emissions is often directed to the producers, but the marketplace and consumer are also responsible for the environmental impact of their choices. This objective of this study was to quantitatively link agricultural NH 3 emissions to per person consumption of food and protein and to agricultural exports from Canada. There are substantial differences in the NH 3 emissions per unit consumed protein among the various food types. As a result, shifts in the Canadian diet have had a large impact on relative per person NH 3 emissions. From 1981 to 2006, the total per person protein intake in the Canadian diet increased about 5%, but NH 3 emission related to that diet decreased 20%. This is largely related to consumption of less beef, which has a high emission per unit of meat or protein, and more poultry and cereals which have much lower emissions. Although these changes in diet were not because of environmental concerns by the consumers, they had substantial effects on national-level emissions. These consumer driven effects may well exceed the possible effects of best management practices intended to address NH 3 emissions at the producer level. Note that the Canadian population has increased 50% from 1981 to 2006 and meat and egg exports increased 570%, so that total emissions from food production in Canada have increased. Our results imply there will be further effects on national NH 3 emissions because of dietary and export drivers that are generally outside the scope of agro-environmental policy. [ABSTRACT FROM AUTHOR]

Highlights: [•] Estimates net organic and ammoniacal N content of manure in Canada. [•] Distinct differences among Ecoregions in the proportions of organic versus ammoniacal N. [•] Several best management practices (BMP) evaluated using recent costing information. [•] Relatively low-cost BMPs could save 1.6×107 kgNH3 for an estimated cost of $13M. [ABSTRACT FROM AUTHOR]

Abstract: National inventories of N emissions to the atmosphere from cattle depend on reliable information about husbandry practices, with appropriate spatial and temporal resolution. A survey of ∼1400 beef cattle farmers was used to quantify the prevalence of pasture and forage management practices that impact N intake and NH3 emissions, with implications for N2O emissions. These survey data were coupled to a mass balance model to inventory NH3 emissions by accounting for total ammoniacal (i.e., ammonia and ammonium) N (TAN) from excretion through to land spreading. As inputs, the model required excretion fractions, 2006 Canadian Census of Agriculture animal populations and detailed farm management practices from the survey. The N intake by grazing cattle was especially difficult to quantify. Early season grazing, when forages have elevated crude protein (>300gCP/kgdry matter), indicated potential for elevated emissions in May and June. Such exceptional CP concentrations during spring grazing may be important for N emissions, especially NH3. Additionally, beef cattle were reported by producers to spend 7–30%) of their time congregated, such as around water sources, feed or shade trees. This level of piosphere activity was attributed in the model to ∼20% increases in NH3 emissions relative to open pasture, and similar or higher effects would be expected for N2O emissions. This paper is part of the special issue entitled: Greenhouse Gases in Animal Agriculture–Finding a Balance between Food and Emissions, Guest Edited by T.A. McAllister, Section Guest Editors: K.A. Beauchemin, X. Hao, S. McGinn and Editor for Animal Feed Science and Technology, P.H. Robinson. [Copyright &y& Elsevier]

Abstract: Sleigh-foot application of slurry manure is the best method for applying slurry manure on many forage fields. This study was designed to assess agronomic effectiveness of multi-year surface banding of dairy slurry on a sward of tall fescue (Festuca arundinacea Schreb.). Our study showed that with this application technology, crop recovery of total-N from applied manure in the long-term is only about 77% that of mineral fertilizer. Despite relative inefficiency of N uptake from manure, yield response to manure equaled that to fertilizer at equivalent total-N rates although N-recovery was significantly lower. About 26–32% of applied manure-N was stored in soil organic matter and the buildup of soil-N was related to application rate of organic N. At moderate applications rates (approx. 400kgNha−1 a−1), soil N accumulated at about 120kgha−1 annually compared to 98kg ha−1 a−1 of unaccounted N, much of that probably volatilized and denitrified. Alternating between manure and fertilizer improved productivity per unit land area without increasing the rate of N non-recovery per unit of feed produced. [Copyright &y& Elsevier]

This study investigated the feasibility of altering the dietary cation-anion difference (DCAD) in grass by altering the grass variety and the amount and formulation of K fertilizer application. In experiment 1, treatments were combinations of 2 varieties (Barcel and HiMag) of tall fescue (Festuca arundinacea Schreb); 2 rates of K (0 and 250 kg/ha), supplied as KCl; and 2 rates of Mg (0 and 60 kg/ha), supplied as MgO. In experiment 2, K fertilizer was applied at 0 or 125 kg/ha as KCl or K2SO4. There was no difference between HiMag and Barcel tall fescue in the concentrations of Mg, S, and Cl. Application of K fertilizer decreased concentrations of Mg, but the magnitude of the decrease was not consistent across harvests. Conversely, application of Mg fertilizer increased Mg concentrations, but again, the magnitude of the increase was not consistent across harvests. The concentrations of Ca were higher in HiMag than in Barcel tall fescue, with the magnitude of the difference increasing from first to last harvest. Potassium fertilizer decreased Ca concentrations in the first, fourth, and fifth harvests only. Calcium concentration was decreased by a greater magnitude in HiMag tall fescue as a result of Mg fertilization. The HiMag tall fescue contained lower concentrations of K than did Barcel tall fescue in the first, second, and third harvests. Application of K fertilizer increased the K concentration in all 5 harvests but did not affect Na concentrations except in the last harvest. The HiMag tall fescue contained less Na than did Barcel, but the magnitude of the difference was affected by K and Mg fertilization. Application of K fertilizer decreased S concentrations in first-harvest grass, increased concentrations in second-and third-harvest grasses, and had no effect in fourth-or fifth-harvest grasses. Application of Mg fertilizer decreased S concentrations of tall fescue. Application of K fertilizer increased DCAD values for grass harvested from the second through fifth harvests. The increase in DCAD attributable to K fertilizer was less in HiMag than in Barcel tall fescue. Application of K fertilizer as K2SO4 increased dry matter yield and S concentrations of HiMag tall fescue, whereas K applied as KCl increased concentrations of K and Cl. There was no effect of fertilizer formulation on Na concentrations. The DCAD was lower in HiMag tall fescue fertilized with K2SO4 compared with that fertilized with KCl. This study showed that DCAD of grass can be manipulated by the choice of grass variety, fertilizer formulation, and fertilizer application rate. [ABSTRACT FROM AUTHOR]

Abstract: In order to improve understanding of how long-term use of manure affects nitrogen cycling processes, the effects of multiple years of manure applications on abundance of protozoa and nematode community structure were assessed. Plots of a grass sward in the Fraser Valley of British Columbia were either left untreated or were treated with dairy manure slurry or fertilizer, each at 50 or 100kg NH4–Nha−1, two to four times per year for six consecutive years. Nematode community structure and protozoan abundance were determined at 19 sample dates during the fourth (1997), fifth (1998) and sixth (1999) years of application. Protozoa, bacterivorous nematodes and fungivorous nematodes were consistently more abundant in soil treated with manure at both rates than in fertilized and untreated soil, indicating that microbial turnover and flux of nutrients through the soil food web was enhanced in manured soil relative to fertilized or untreated soil. The Maturity Index (MI) and the MI2-5 were both reduced by fertilization and manure, relative to the control. The MI for the manure treatment was lower than for the fertilizer treatment as a result of greater relative abundance of enrichment opportunist nematodes in manure-treated soil. Accordingly, the MI2-5 did not differ between the manure and fertilizer treatments, suggesting that with the exception of enrichment opportunists fertilizer and manure have similar effects on structural complexity of the soil food web. Populations of micro-fauna were also assessed through 1998 and 1999 in subplots that had been treated with manure or fertilizer for four years and stopped receiving manure or fertilizer in 1998, and in subplots given manure in 1998 that had previously either been fertilized or left untreated. Protozoa and bacterivorous and fungivorous nematodes remained more abundant through 1998 and 1999 in previously manure-treated plots than in previously fertilized plots, indicating that the cumulative effects of manure application on enhancement of microbial production can be detected through at least two growing seasons after applications cease. Application of manure for one year to previously non-treated or fertilized soil raised the abundance of protozoa and bacterivorous and fungivorous nematodes to levels comparable to continuously manured soil. [Copyright &y& Elsevier]

Abstract: Plots of a tall fescue (Festuca arundinacea) sward in the south coastal region of BC, Canada, were treated with dairy manure slurry or fertilizer at 50 or 100kgNH4-Nha−1 up to four times per year for six consecutive years; control plots received no manure or fertilizer. The length of fungal hyphae and abundance of bacterial cells were determined by direct counting at 19 sample dates during the fourth (1997), fifth (1998) and sixth (1999) application years. Bacterial abundance was significantly greater in manured soil than in fertilized and untreated soils. In contrast, hyphal length was significantly greater in untreated soil than in manured and fertilized soils. In subplots that ceased to receive manure in 1998, bacterial abundance remained greater through 1998 and 1999 than in previously fertilized plots, indicating that the 4 year cumulative effect of manure was detectable for at least two growing seasons after applications cease. The apparently negative effect of manure and fertilizer on fungal hyphae also appeared to persist through 2 years after applications ceased. Bacterial abundance increased after an initial application of manure for 1 year to previously untreated plots, but not to levels comparable to plots treated with manure continuously from 1994 to 1998. Increases in bacterial abundance, during the one to three week intervals immediately following individual applications of manure, were inconsistent and other factors, such as soil moisture, temperature and perhaps crop phenology appear to have had strong effects on the timing of these microbial responses. Annual means for bacterial abundance and total microbial biomass in the continuous manure treatment were similar for all 3 years. This suggested that the manure-induced increase in microbial biomass probably reached a plateau between one and 3 years after applications commenced. The large bacterial populations along with abundant carbon substrates in manured soil, relative to fertilized soil, were probably capable of immobilizing influxes of mineral N, explaining the observations that less leaching occured from manured than from fertilized soils. [Copyright &y& Elsevier]

• Historical slurry applications to grassland improve corn response to applied N and P. • Historical applications of separated slurry had less corn response than whole slurry. • Historical treatments have impact on corn even with current fertilizer application. • Corn performance responded linearly to historical application rates of organic-N. Removing solids from dairy slurry improves grass N response and reduces soil loading of P and organic N which makes this practice useful for sustainable farming. Therefore, it is important to understand the effects of long-term applications on grass of separated dairy slurry on the growth and N response of a subsequent corn crop. This two-year field study investigated the residual effects after 11 years with applications on a perennial grass (Festuca arundinacea Schreb.) of whole (WS), separated dairy slurry (LF) obtained from the second stage of a two stage lagoon system, mineral fertilizer (Fert), WS plus Fert (WS/Fert), and Control (no fertilizer), on two subsequent crops of silage corn (Zea mays L.). In addition to the legacy nutrients, the corn received commercial fertilizer at rates 0, 100, 200 kg N ha–1 or 200 kg N ha–1 plus starter P (40 kg ha–1) at time of planting. Whole-crop yield and N uptake were determined at harvest stage. Over two years, corn yielded more with greater N and P uptake after long-term applications of WS than LF, Fert and WS/Fert, regardless of current fertilizer applications. Additional mineral fertilizer N and P did not substitute for the historical effects. There was a significant linear relationship of corn N uptake with historical applications of organic-N but not with mineral-N or total-N across current fertilizer treatments. These results support farmer practice of supplementing first-year corn, after long-term manure application on grassland, with modest N and P as starter application only and then increasing N rates thereafter. [ABSTRACT FROM AUTHOR]

Recent developments in composting technology enable dairy farms to produce their own bedding from composted manure. This management practice alters the fate of carbon and nitrogen; however, there is little data available documenting how gaseous emissions are impacted. This study measured in-situ emissions of methane (CH 4 ), carbon dioxide (CO 2 ), nitrous oxide (N 2 O), and ammonia (NH 3 ) from an on-farm solid-liquid separation system followed by continuously-turned plug-flow composting over three seasons. Emissions were measured separately from the continuously-turned compost phase, and the compost-storage phase prior to the compost being used for cattle bedding. Active composting had low emissions of N 2 O and CH 4 with most carbon being emitted as CO 2 -C and most N emitted as NH 3 -N. Compost storage had higher CH 4 and N 2 O emissions than the active phase, while NH 3 was emitted at a lower rate, and CO 2 was similar. Overall, combining both the active composting and storage phases, the mean total emissions were 3.9 × 10 −2 g CH 4 kg −1 raw manure (RM), 11.3 g CO 2 kg −1 RM, 2.5 × 10 −4 g N 2 O kg −1 RM, and 0.13 g NH 3 kg −1 RM. Emissions with solid-separation and composting were compared to calculated emissions for a traditional (unseparated) liquid manure storage tank. The total greenhouse gas emissions (CH 4 + N 2 O) from solid separation, composting, compost storage, and separated liquid storage were reduced substantially on a CO 2 -equivalent basis compared to traditional liquid storage. Solid-liquid separation and well-managed composting could mitigate overall greenhouse gas emissions; however, an environmental trade off was that NH 3 was emitted at higher rates from the continuously turned composter than reported values for traditional storage. [ABSTRACT FROM AUTHOR]

Abstract: Controlled release urea (CRU) has been shown to improve nitrogen fertilizer use efficiency in a number of production systems. However, the effectiveness of CRU will be strongly affected by the environmental conditions of the region. Research trials were conducted at five locations across four major ecoregions spanning 1600km across the Northern Great Plains and Pacific Maritimes of North America from 2004 to 2006 to evaluate the effects of a single application of polymer-coated urea (CRU) or split applications of urea fertilizer as compared with non-coated urea for their effects on crop growth, crop N concentration, and crop N accumulation of wheat (Triticum aestivum L.), barley (Hordeum vulagre L.) canola (Brassica napus L.) and corn (Zea mays L.) across a wide range of environmental conditions. Urea applied as an in-soil band at the time of seeding was generally as or more effective than similarly placed CRU, split application of urea or blended urea and CRU in the semi-arid Mixed Grassland, moist Aspen Parkland or wet Boreal Transition ecoregions in increasing early season dry matter yield and seed or grain yield of canola, wheat or barley. Similarly, broadcast urea was as or more effective than broadcast CRU, split applications or blended applications in increasing corn dry matter yield under the wet conditions in the Lower Mainland ecoregion. There were some situations where use of split applications or use of the CRU in a blend with the non-coated urea resulted in increases in grain yield as compared to the non-coated urea, primarily under moist conditions in the Boreal Transition or Aspen Parkland ecoregions. Some yield losses occurred from use of the CRU as compared with the non-coated urea and were attributed to delays in release of N from the granule that limited early season N availability and crop growth, especially in corn with a high N demand. Effects on grain N concentration and accumulation of N in the crop at harvest were mixed, with the CRU, blended applications of CRU and urea or split applications occasionally producing higher grain N concentration and N accumulation in the crop than the non-coated urea. Benefits of CRU on grain N concentration were more frequent than benefits on grain yield, but were not large or consistent. Response of crop growth and N uptake to N management was generally similar under CT and RT, with occasional differences occurring due to changes in yield potential or N deficit associated with the differences in tillage management. Therefore, under growing conditions across a wide range of ecoregions in the Northern Great Plains and the Pacific Maritimes, the use of CRU or split applications do not appear to provide a consistent improvement in crop yield, N concentration in the grain, total N accumulation at harvest, or nitrogen use efficiency as compared to standard regional timing and placement of non-coated urea. [Copyright &y& Elsevier]

• Above-ground biomass and soil temperature were well simulated using DNDC across sites. • DNDC showed reasonable performances in estimating soil water and inorganic N contents. • DNDC captured the manure application timing and rate impacts on total N 2 O emissions. • Daily N 2 O simulations may be improved by integrating N 2 O diffusivity and consumption. It is uncertain whether process-based models are currently capable of simulating the complex soil, plant, climate, manure management interactions that influence soil nitrous oxide (N 2 O) emissions from perennial cropping systems. The objectives of this study were (1) to calibrate and evaluate the DeNitrification DeComposition (DNDC) model using multi-year datasets of measured nitrous oxide (N 2 O) fluxes, soil moisture, soil inorganic nitrogen, biomass and soil temperature from managed grasslands applied with manure slurry in contrasting climates of Canada, and (2) to simulate the impact of different manure management practices on N 2 O emissions including slurry application i) rates (for both single vs. split); and ii) timing (e.g., early vs. late spring). DNDC showed "fair" to "excellent" performance in simulating biomass (4.7% ≤ normalized root mean square error (NRMSE) ≤ 29.8%; −9.5% ≤ normalized average relative error (NARE) ≤ 16.1%) and "good" performance in simulating soil temperature (13.2% ≤ NRMSE ≤ 18.1%; −0.7% ≤ NARE ≤ 10.8%) across all treatments and sites. However, the model only showed "acceptable" performances in estimating soil water and inorganic N contents which was partially attributed to the limitation of a cascade water sub-model and inaccuracies in simulating root development/uptake. Although, the DNDC model only demonstrated "fair" performance in simulating daily N 2 O fluxes, it generally captured the impact of the timing and rate of slurry application and soil texture (loam vs. sandy loam) on total N 2 O emissions. The DNDC model simulated N 2 O emissions from spring better than split manure application (fall and spring) at the Manitoba site partially due to the overestimation of available substrates for microbial denitrification from fall application during the wet spring periods. Although DNDC performed adequately for simulating most of the manure management impacts considered in this study we recommend improvements in the simulation of soil freeze-thaw cycles, manure decomposition dynamics, soil water storage, rainfall canopy interception, and microbial denitrification and nitrification activities in grasslands. [ABSTRACT FROM AUTHOR]