, J. 2000. Soil aeration for dairy manure spreading on forage: Effects on ammonia volatilisation and yield. Can. J. Soil Sci. 80: 319-326. Experiments were conducted to evaluate the effects of performing soil aeration either before or after spreading liquid manure in forage production systems. The experiments included eight trials performed in 1996 using a non-interfering diffusion method to determine ammonia (NH 3 ) flux emissions from both aerated and control plots. For all eight trials, the manure application rate was 75 355 L ha -1 . The average NH 3 loss for the aerated treatment was 67.3 kg ha -1 while the loss for the control plots was 63.0 kg ha -1 . Although differences in the NH 3 loss between treatments were low, substantial variations were observed between individual trials depending on the prevailing meteorological conditions.To further evaluate the effects of soil aeration, 11 trials were carried out on Nova Scotia dairy farms in 1996 and 1997 to identify yield effects. Manure application rates ranged from 18 000 to 64 000 L ha -1 . The average forage yield on aerated treatments was 9.4% below control treatments (i.e., manure without aeration). Of the 11 trials, 9 resulted in significantly (P < 0.05) reduced yield with soil aeration. Les déperditions moyennes de NH 3 à partir des parcelles aérées se montaient à 67,3 kg ha -1 contre 63,0 kg pour les parcelles témoins. Bien que ces différences soient faibles, des variations importantes étaient observées d'un essai à l'autre selon les conditions météorologiques. Pour pousser plus avant l'évaluation des effets de l'aération du sol, 11 essais étaient implantés en 1996 et en 1997 dans des exploitations laitières de la Nouvelle-Écosse pour dégager les effets sur les rendements fourragers. Les doses d'épandage utilisées allaient de 18 000 à 64 000 L ha -1 . Le rendement moyen obtenu dans les parcelles aérées était de 9,4 % inférieur à celui des parcelles témoins (c.-à-d. fertilisées mais non aérées). Sur les 11 essais, 9 démontraient des baisses significatives (P < 0,05) du rendement lorsque le sol avait été aéré.

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Her Majesty the Queen in Right of Canada as represented by the Minister of Agriculture and Agri-Food Canada. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. aBstractStrategies to improve sustainability are important in intensively managed potato (Solanum tuberosum L.) systems. Th is study has assessed rotation systems and N sources to mitigate potato yield and soil organic matter decline in Prince Edward Island (PEI), Canada. Th ree-year potato rotation systems were initiated in 2006: continuous potato (CP); potato-barley (Hordeum vulgare L.) underseeded with red clover (Trifolium pratense L.)-red clover (PBR); and potato-barley-sorghum sudan grass ([Sorghum bicolor L.) used as green manure])/winter rape (Brassica napus subsp. rapifera) (PBSW); and potato-barley-canola ([Brassica napus susbsp. napus] used as green manure)/winter rape (PBCW). Th ree diff erent N sources (mineral N fertilizer, liquid hog manure, and lobster fl ake) were applied in a split-plot fashion during the potato phase. Potatoes were grown in 2006, 2009, 2012, and again in 2013 to evaluate residual eff ects. In 2012, total N or total C in the whole soil, in particulate organic matter or in the slurry fractions were not aff ected by N sources or rotation systems. Th e PBSW and PBCW rotations generated signifi cantly higher potato yields in 2009 and 2013, whereas the CP rotation produced signifi cantly lower potato yields in 2 of 4 yr. Th e addition of lobster fl ake suppressed yield compared with other N sources in 3 of 4 yr. Th e PBR rotation, which is common in PEI can increase nitrate losses over winter. Alternatively, the PBSW and PBCW rotations may represent a good substitute to the PBR rotation as they can increase potato yield while minimizing nitrate losses.Agriculture and Agri-Food Canada, Crops and Livestock Research Centre,

Livestock manure is an important source of N for forage grass production. The long‐term effects of semisolid beef manure application to forage grass on potentially mineralizable N (N0), mineralizable N pools, and field estimates of soil N supply were evaluated in dike‐land (heavy textured, poorly drained) and upland (medium‐textured) soils in Nova Scotia, Canada. Treatments included an unfertilized control, annual spring application of 100 kg N ha−1 mineral fertilizer or annual applications of 75, 150, or 300 kg total Kjeldhal N ha−1 as manure (M75, M150, and M300, respectively) from 1995 to 2004. Soil samples collected in fall 2004 were used to estimate N0 using a 44‐wk aerobic incubation at 25°C. The N0 values were 62 and 49% higher in the M300 treatment (324 and 480 kg N ha−l) than the other manure treatments (199 and 323 kg N ha−1) for the upland and dike‐land soils, respectively. The mineralization rate coefficient ranged from 0.045 to 0.082 wk−1 Manure application increased the readily mineralizable N pool (Pool I); higher rates of application resulted in higher values in both soils. The intermediate and stable mineralizable N pools were increased only by the M300 treatment in the upland soil but not in the dike‐land soil. Long‐term manure application of the M300 treatment resulted in high N0 with no yield benefits, which can increase the risk of N losses to the environment in both soils, whereas Pool I was responsive to all manure application rates.

, T. 2001. Effects of surface manure application timing on ammonia volatilization. Can. J. Soil Sci. 81: 525-533. The purpose of this study was to evaluate the influence of timing of application on ammonia (NH 3 ) volatilization from surface-applied dairy manure. Field trials were conducted over a 2-yr period (1994 and 1995) at the Agriculture and Agri-Food Canada Research Farm in Nappan, Nova Scotia. A total of eight trials were performed in an attempt to characterize what effect the timing of application (morning vs. late afternoon/early evening) has on NH 3 volatilization losses. Ammonia losses were also related to several meteorological parameters. The total percentage of NH 3 volatilized in the 10 h following field spreading ranged from as low as < 2% to approximately 66%. Late-day spreading typically resulted in at least a 30% reduction in overall NH 3 flux densities, primarily due to substantial reductions in NH 3 losses occurring within the first 10 h after manure application. The positive benefits of late-day manure spreading were more pronounced during warm, dry weather conditions. Significant (P < 0.05) positive linear correlations were observed between NH 3 volatilization in the 10 h following spreading and solar radiation (r 2 = 0.56), wind speed (r 2 = 0.53), temperature (r 2 = 0.34) and vapour pressure deficit (r 2 = 0.53).Results from this study have indicated that late day manure spreading practices can substantially reduce NH 3 volatilization.Key words: Slurry, ammonia volatilization, dairy, manure application, timing Gordon, R., Jamieson, R., Rodd, V., Patterson, G. et Harz, T. 2001. Incidence du moment de l'épandage du fumier sur la vaporisation de l'ammoniac. Can. J. Soil Sci. 81: 525-533. L'étude devait établir si la vaporisation de l'ammoniac (NH 3 ) dépend du moment où l'on épand le fumier de bovins laitiers à la surface du sol. Les auteurs ont effectué des essais au champ pendant deux ans (1994 et 1995), à la ferme expérimentale d'Agriculture et Agroalimentaire Canada à Nappan, en Nouvelle-Écosse. En tout, huit essais ont servi à déterminer quels effets le moment de l'application (matin ou fin de l'après-midi/début de la soirée) pouvait avoir sur les pertes de NH 3 attribuables à la vaporisation. On a aussi associé ces pertes à divers paramètres météorologiques. La proportion de NH 3 qui s'évapore pendant les 10 h suivant l'épandage varie d'un minimum < 2 % à environ 66 %. L'application en fin de journée diminue la densité du flux de NH 3 d'au moins 30 %, principalement à cause d'une réduction importante des pertes de NH 3 durant les dix heures qui suivent l'épandage. Les bienfaits d'un épandage tardif sont plus prononcés par temps chaud et sec. Les auteurs ont établi une corrélation linéaire positive significative (P < 0,05) entre la vaporisation du NH 3 au cours des 10 h suivant l'épandage et le rayonnement solaire (r 2 = 0,56), la vitesse du vent (r 2 = 0,53), la température (r 2 = 0,34) et la différence de pression de vapeur (r 2 = 0,53). Les résultats de la recherche indiquent qu'...