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Background: Defining the long-term effects of liquid dairy manure (LDM) applied by a recommended low emission method is important to ensure sustainable grass production and dairy operations. We used natural abundance δ15N and conventional measurements in a long term field experiment to better understand the long-term fate of N applied as LDM, mineral fertilizer (MIN) and both (ALT). Methods: We investigated the effects of long-term applications of LDM (with low-emission trailing shoe), MIN, and alternating LDM and MIN (ALT) on grass N uptake, soil N stocks, N losses and δ15N natural abundance in grass, soil and fine heavy fraction (silt + clay size heavy soil). Nominal annual rates of total N were 200 and 400 kg ha−1 for MIN and 400 and 800 kg ha−1 for LDM. Results: MIN and LDM (at 400 kg N ha−1) had similar NUE but LDM accumulated more total soil N (13% of applied) with less losses than MIN; ALT had high yields and losses. Herbage δ15N of MIN declined to near MIN levels after 10–15 years, indicating influence of pre trial management. Herbage δ15N of LDM was consistently lower than applied LDM, implying uptake of depleted urine N. High rates of enriched LDM had little effect on soil δ15N suggesting soil N was quite stable and enriched N was lost by non discriminating pathways like leaching. The physically protected fine heavy fraction contained most soil N. Conclusion: Clearer understanding of long-term N dynamics can improve sustainability of heavily fertilized perennial grasses on dairy farms. [ABSTRACT FROM AUTHOR]

Nitrate contamination of groundwater has been attributed to application of poultry litter to amend soil organic matter on raspberry farms in British Columbia, Canada. A field study assessed the risk of organic amendments that cause nitrate leaching and nutrient accumulation. The amendments, poultry litter, municipal compost, horse manure, and three types of dairy manure solids, were applied at 25 or 50 Mg dry matter ha-1 to match farm rates before new plantings. Plots were either unseeded or seeded with a grass mix to simulate berry establishment with grass alley crop. Soil was sampled at 0- to 15-, 15- to 30-, and 30- to 60-cm depths 15 times over 14 mo and analyzed for concentrations of NH4 + and NO3 -, and at 0 to 15 cm for total C, N, and P at 6 mo after application. Three grass harvests were analyzed for yield and N offtake. Poultry litter supplied more than twice the total mineral N and total P compared to the dairy solids and horse manure, while the compost was intermediate. At 25 Mg ha-1, poultry litter increased concentrations of soil (0-15 cm) NH4 + and NO3 - (>150 and >300 mg kg-1, respectively), compared with small short-term increases by compost (~70 and 100 mg kg-1, respectively). There was almost no increase from dairy and horse amendments. Grass N offtake reduced soil NO3 - concentrations but did not eliminate the risk of leaching from poultry litter. We conclude that dairy solids and horse manure present less risk of nitrate leaching and P loading than poultry litter or municipal compost. [ABSTRACT FROM AUTHOR]

Beef production plays a significant role in Canadian agriculture in terms of its contribution to total farm cash receipts and management of large tracts of land. The sustainability of the sector has been challenged on several fronts including greenhouse gas and ammonia emissions. An extensive survey of husbandry and agronomic practices in 2011 provided the unique opportunity to compute a detailed nitrogen (N) budget for 908 beef operations of different types from across Canada. The resulting overall-N and commercial-N budgets and overall commercial and beef nitrogen use efficiency (NUE) estimates varied markedly among the types of beef operations. Surprisingly, forage-based cow-calf operations with little importation of commercial N sources often had the largest overall surplus N (N remaining on farms), largely because of symbiotic N fixation of pasture and forage crops, a larger land-base and lower NH-N emissions compared to confinement housing. These operations had relatively low NUE estimates of about 0.33. In contrast, solely finisher operations had overall N budgets that were not different from zero and NUE of about 0.66. These operations purchase much of their feed and animal nutrition is carefully managed, so the NUE is distinctly higher than in forage-based systems. However, these operations also have high NH emissions. Observed regional differences in budgets were related to differences in deposition of atmospheric N and in legume content of forages. [ABSTRACT FROM AUTHOR]

Most ammonia ( NH3) emissions (85%) in Canada come from agricultural sources (400 kt/yr). There are international conventions that require countries to mitigate NH3 emissions but there are no federal or provincial guidelines in Canada stipulating emission targets or best practices for agriculture. This study examines the potential for mitigating atmospheric NH3 using a range of approaches. Taking current farm practices into account, employing proven low-cost measures (low-emission slurry application and slurry storage covers) would reduce annual emissions from livestock operations by 16 kt NH3-N, while using all available low-cost measures would reduce emissions by 79 kt NH3-N or 26% of livestock emissions. Another 36 kt/yr could be avoided by improving fertilizer practices, so that the total potential reduction would be about 29% of all agricultural emissions. Emissions from beef cattle and pig production could be reduced by 18% if consumption was cut by 50%, with greater mitigation if production for export was reduced, although the economic and social consequences need to be considered. Mitigation practices must be viewed in the context of possible pollution swapping especially in surplus nitrogen situations. Emissions must also be considered in terms of atmospheric NH3 transport to and from the USA, therefore bi-national agreements to jointly reduce emissions might be needed. It may be more cost-effective in Canada to strategically reduce emissions to minimize risks to health (from particulate matter) and the environment rather than to reduce annual national emission targets. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Animal Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Journal of Animal Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Orchardgrass (Dactylis glomerata L.) is a major component of many pastures in temperate North America. Early and profuse flowering in pastures is problematic, because livestock refuse to consume flowering stems, prompting many graziers to simply avoid using this species. The objective of this research was to determine the impact of reduced flowering on the quality of harvested forage under two harvest managements of orchardgrass. Six cultivars, three normal cultivars and three sparse-flowering cultivars (mean panicle density of 141 vs. 61 panicles m-2, respectively), were evaluated in field experiments at 21 locations in North America under a 3-cut harvest management. These cultivars were also evaluated at seven locations under a 5-cut harvest management. Sparseflowering cultivars averaged 9% greater crude protein (CP), 3% lower neutral detergent fiber (NDF), 2% greater NDF digestibility, and 2% greater in vitro dry matter digestibility (IVDMD) than normal cultivars. For the two digestibility measures, differential panicle density between the cultivar groups explained a significant portion of variability, indicating that the increase in forage quality was proportional to the decrease in panicle density below a threshold of about 50 panicles m-2. Lastly, differences in regrowth forage quality between cultivar groups were smaller, less consistent, and of lesser statistical significance than for first harvest. While selection for sparse flowering in orchardgrass resulted in significant cause-and-effect increases in firstharvest forage quality, these effects were too small to offset the reduced forage yield associated with the sparse-flowering trait. [ABSTRACT FROM AUTHOR]

Orchardgrass (Dactylis glomerata L.) is a major component of many pastures in temperate North America. Early and profuse flowering in pastures is problematic due to livestock refusal to consume flowering stems. The objective of this research was to determine the stability and agronomic impact of recently developed sparse-flowering orchardgrass populations across temperate North America. Six cultivars, three sparse flowering and three normal flowering, were grown at 21 locations in temperate North America and evaluated for panicle density, heading date, and forage yield. Sparse-flowering cultivars had 57% fewer panicles than normal-flowering cultivars, but this effect was highly dependent on mean winter temperature, with normal-flowering cultivars showing twice as much temperature sensitivity compared to sparse-flowering cultivars. Forage yield of sparse-flowering cultivars was reduced by approximately 24 to 32% for first harvest and 2 to 9% for regrowth harvests compared to normal-flowering cultivars and this reduction in forage yield was independent of mean winter temperature. The forage yield reduction associated with sparse flowering is most likely due to a combination of physiological load (loss of stems) and opportunity cost (lack of selection pressure for yield), suggesting an opportunity to improve forage yield potential of this sparseflowering germplasm pool. [ABSTRACT FROM AUTHOR]

The article discusses a study to evaluate the ammonia emissions which is associated with beef cattle production across Canada. It informs that data on farm practices that was obtained from a survey of 1380 beef farmers in 11 Ecoregions was used for the study. The study suggests that ammonia emissions per animal were relatively consistent across Ecoregions for confinement production and varies per animal as the proportion of animals on pasture varied with Ecoregion.

The article discusses a study on monthly modelling of Ammonia emissions from Canada's dairy farms in its 12 ecoregions. It mentions that the said chemical compound from livestock manure is expelled from barns, storages and manure land which affects farm operations as well as human health and ecology whenever it is emitted in the atmosphere. It also notes the application of models for estimating the intensity and spatial extent of the emission and its proportionality to the animal census.

The article presents a study regarding the activity of dairy farmers in Canada in 2005 related to the use of nitrogn (N) and especially practices that led to loss of ammonia (NH3). The study examines the ecoregion and differences in terms of farm size in dairy feed and manure nitrogen management. It reveals the significance of ecoregion and farm size differences in representing the nation's dairy farm management.

Two experiments were conducted to evaluate the potential to use leaf chlorophyll index (LCI), measured using a Minolta SPAD-502 meter, for making fertilizer nitrogen (N) recommendations for silage corn in a high N fertility environment. In Experiment 1, treatments were 0, 40, 80, 120, 160, and 200 kg N ha[sup -1] as NH[sub 4]NO[sub 3] broadcast at corn emergence. At the six-leaf stage, soil inorganic N to 90cm depth, total Kjeldahl N concentration of the fifth leaf, sixth leaf, and the above-ground portion of the plant, and LCI of the fifth and sixth leaves, were determined. In Experiment 2, LCI and LCIR (ratio of LCI to LCI from a reference plot receiving 200 kg N ha[sup -1] at corn emergence) were measured at approximately the six-leaf stage in 87 trials 1994-1996. Treatments consisted of different fertilizer N rates applied at sidedress, and corn yield and pre-sidedress soil nitrate test (PSNT) values were determined. In Experiment 1, nitrogen concentration of the above-ground plant increased with increasing soil inorganic N content up to about 350kg Nha[sup -1], and LCI generally increased linearly with leaf total N concentration. However, the relationship between LCI and leaf N concentration varied among years, and the relationship between leaf total N concentration and above-ground plant total N concentration was inconsistent. In Experiment 2, above-ground plant total N concentration was a poor predictor of soil inorganic N supply and corn relative yield when measured over a number of trials. Leaf chlorophyll index at the six-leaf stage therefore has significant limitations as an indicator of corn N status or soil inorganic N supply. Despite these limitations, LCI had a 68% success rate in identifying fields which were responsive and unresponsive to sidedress N using a critical LCI value of 43.7 SPAD units. This success rate is similar to that obtained with the PSNT. However, LCI cannot be used to recommend rates of fertilizer N for LCI values below the... [ABSTRACT FROM AUTHOR]

The purpose of this study was to measure corn response to nitrogen (N), to evaluate the feasibility of using the pre-sidedress soil nitrate test (PSNT) for making fertilizer N recommendations for silage corn, and to evaluate the environmental and economic implications of adopting fertilizer N recommendations based on the PSNT in south coastal British Columbia, Canada, a region of high soil N fertility. Eighty-seven trials were conducted from 1994-1996 with corn or forage grass as a preceding crop on fields having a history of manure application. Non-manured trials received no spring manure application whereas manured trials received a spring application typical of that farm field. In 1994, treatments included sidedress N rates of 0, 30, 60, 90, 120, and 150kg N ha-[SUP1] replicated twice. In 1995 and 1996, trials with less than 30mg NO[SUB3]-N kg[SUB-1] soil to 30cm depth prior to sidedress received the same treatments as in 1994, whereas trials with concentrations above this value received two treatments, 0 and 150kgNha[SUP-1] replicated four times. Trials received less than 50kgN ha[SUP-1] at planting. Yield response to sidedress N was limited, with 71, 87, and 55% of trials with 90% or higher relative yield (yield at 0kgNha[SUP-1] divided by yield at 150kgNha[SUP-1]) in 1994, 1995 and 1996, respectively. The limited yield response was attributed to high soil N mineralization, which averaged 166 and 146kgNha[SUP-1] for non-manured trials in 1995 and 1996, respectively. The critical PSNT value (above which no yield response to sidedress N is expected) was predicted to be 19 and 23 mg NO[SUB3]-Nkg[SUP-1] soil using the Cate-Nelson procedure and a linear-plateau regression procedure, respectively. A critical PSNT test value of 32 mg NO[SUB3]-N kg[SUP-1] soil was predicted using a linear-plateau regression of the estimated N rate which would maximize economic return (N[SUBMER]) against PSNT test value. In addition, a model designed to minimize the risk of yield... [ABSTRACT FROM AUTHOR]