Alien Registration- Lafond, Marie L. (Auburn, Androscoggin County)

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The suitability of cool and warm season annual cereal species for winter grazing in Saskatchewan

Non-Peer ReviewedCool and warm season annuals were seeded at Agri-Arm sites across Saskatchewan over three years to compare their suitability for winter grazing. Two seeding dates, eleven crops and two harvest times were used. The crops in this trial have significant differences in maturity. As expected, dry matter yield of the cool season annual cereals (oat, barley) tended to decrease with the later seeding date. Delayed seeding also decreased the yield of Golden German millet (foxtail millet) at two site years. Golden German millet had yields that were higher than oat at three site years, lower than oat at three site years and similar at 4 site years. Delaying the harvest lowered the protein level of all the crops. Seeding date did not consistently affect protein. Corn had significantly lower levels of protein than the other crops. As harvest was delayed forage biomass of the crops increased especially oat and barley. Weathering in the windrow until December had very little effect on the crude protein. Total digestible nutrients were not consistently affected by seeding date or harvest time. Temperature seemed to have a larger effect on the productivity of the warm season annuals than moisture. Golden German millet is well adapted for swath grazing on the eastern side of Saskatchewan. More data is required to determine its adaptability in central and western Saskatchewan

Yellowfeed production in Saskatchewan

Non-Peer ReviewedYellowfeed is a harvesting method where an annual cereal crop grown for forage is sprayed with glyphosate at the milk-soft dough stage and allowed to stand until dry. Once dry the crop can be cut and then immediately baled. A study was conducted at 16 site by crop combination to monitor oat and barley forage yield and quality. After the application of glyphosate, dry matter yield was maximized at 20 days and protein concentration was minimized at 25 days. ADF, NDF, and TDN did not vary after glyphosate application. Yellowfeed is a viable alternative harvesting method when annual cereals are harvested for hay

Lowbush blueberry fruit yield and growth response to inorganic and organic N-fertilization when competing with two common weed species

Inorganic N fertilizers are commonly used in commercial blueberry fields; however, this form of N can favor increased weed species’ growth, which can ultimately reduce the benefits of fertilization. We hypothesized that chipped ramial wood (CRW) compost is an effective alternative organic fertilizer for blueberry plants when weeds are present, as ericaceous shrub species are generally more efficient in utilizing organic N than herbaceous weed species. In this study, we measured the growth, fruit yield, and foliar N response of lowbush blueberry (Vaccinium angustifolium Aiton) to an application of 45 kg N ha-1 in the form of organic (CRW) or inorganic N (ammonium sulfate) in two areas of a commercial field colonized by either poverty oat grass (Danthonia spicata (L.) Beauv.) or sweet fern (Comptonia peregrina (L.) Coult.). We also assessed the impact of the fertilization treatments on litter decomposition rates. Contrary to our hypothesis, we found no significant increase in blueberry fruit yield or growth using CRW. By contrast, inorganic N-fertilization increased fruit yield by 70%. The effect was higher in the area colonized by D. spicata (+83%) than by C. peregrina (+45%). Blueberry fruit yield was on average twice higher in the area of the field having D. spicata than C. peregrina, suggesting a stronger competition with the latter. However, the increase in D. spicata density from 0–1 to >25 plants m-2 reduced fruit production by three-fold and strongly impacted vegetative growth in both fertilized and unfertilized plots. The impact of increased C. peregrina density was comparatively much lower, especially on vegetative growth, which was much higher in the area having C. peregrina. These patterns are likely due to a lower competition for N uptake with C. peregrina as this species can derive N from the atmosphere. Interestingly, the higher fruit yield in the area colonized by D. spicata occurred even in plots where the weeds were nearly absent (density of 0–1 plant m-2), revealing the influence of unidentified variables on blueberry fruit yield. We hypothesized that this difference resulted from over-optimal foliar N concentrations in the area colonized by C. peregrina as suggested by the significantly higher foliar N concentrations and by the negative correlation between foliar N concentrations and fruit yields in this area. The possibility of an influence of C. peregrina on flowering and pollination success, as well as of unidentified local site conditions is discussed. The tested N-fertilization treatments did not affect foliar N concentrations or litter decomposition rates. Overall, our results show that ammonium sulfate is very effective at increasing fruit yields but that both fruit yields and the efficiency of the N-fertilization treatment are decreased by increased D. spicata density, especially above 25 plants m-2. Although CRW did not significantly enhance fruit yields in the short term, this fertilizer may have a long-term beneficial effect

Fertilizer application and deep leaching of nitrate under long term crop rotation

Non-Peer ReviewedIt is commonly believed that the use of nitrogen fertilizers in agriculture will lead eventually to the loss of nitrate via leaching. The nitrate leached below the root zone has the potential to contaminate underground water. The results obtained from various long term crop rotation studies in Saskatchewan suggest that this common belief may not hold in general. This is especially true where nitrogen fertilizers were applied based on soil test recommendation and the land was continuously cropped. Under long term crop rotation studies in the Black Soil Zone at Melfort, the application of nitrogen fertilizer in recent years were based on the general recommendation for wheat. The deep core sample revealed that more nitrate was present in the soil profile under fertilized continuous wheat compared to the unfertilized plots. However, in the Black Soil at Indian Head, where fertilizer application was based on soil test values, similar amounts of nitrate were found below the root zone of fertilized and unfertilized plots after 34 years of continuous wheat. This was in spite of applying 1584 kg of N ha-1 to the fertilized plot over 34 years. A result similar to that at Indian Head was obtained from the crop rotation experiment in the Brown Soil Zone at Swift Current. In the Brown Soil Zone, the inclusion of a fallow phase in the rotation, increased the amount of nitrate found below the root zone although this system had received less fertilizer over the years than the continuously cropped plots. The fallow phase appeared to provide a window for the leakage of nitrate accumulated within the root zone. This was attributed to a better moisture (antecedent moisture) regime and higher amount of mineralized nitrate during the fallow phase. On the other hand, frequent summerfallow can deplete the soil of its N supplying power and this may eventually result in less nitrate leached as was found for the 2-yr rotation at Indian Head after 34 yr

On strongly chordal graphs that are not leaf powers

A common task in phylogenetics is to find an evolutionary tree representing proximity relationships between species. This motivates the notion of leaf powers: a graph G = (V, E) is a leaf power if there exist a tree T on leafset V and a threshold k such that uv is an edge if and only if the distance between u and v in T is at most k. Characterizing leaf powers is a challenging open problem, along with determining the complexity of their recognition. This is in part due to the fact that few graphs are known to not be leaf powers, as such graphs are difficult to construct. Recently, Nevries and Rosenke asked if leaf powers could be characterized by strong chordality and a finite set of forbidden subgraphs. In this paper, we provide a negative answer to this question, by exhibiting an infinite family \G of (minimal) strongly chordal graphs that are not leaf powers. During the process, we establish a connection between leaf powers, alternating cycles and quartet compatibility. We also show that deciding if a chordal graph is \G-free is NP-complete, which may provide insight on the complexity of the leaf power recognition problem

The long-term agronomic and economic effects of crop rotations in western Canada

Non-Peer ReviewedAgriculture Canada Research Stations in western Canada have conducted more than 68 long-term crop rotation experiments since the early 1900's; twenty of these are still ongoing. A committee of scientists, representing all Research Stations on the Prairies has just completed an in-depth review and summary of the major findings from these studies. Based on their findings, they also developed recommendations that can be used by managers in decision making and rationalization of resource use for current and future studies of this kind. The resulting two publications which will be released in early 1990 include: i) a bulletin entitled 'Benefits of Crop Rotation for Sustainable Agriculture in Dryland Farming', 'Which presents producer recommendations on how to run an efficient, economical, and environmentally responsible cropping operation, and ii) a detailed technical book entitled 'Crop Rotation Studies on the Canadian Prairies', which is directed at the scientific community but is also useful for extension personnel and producers. This paper highlights some of the main aspects reported in these publications and attempts to give a coherent and broader interpretation of the underlying principles and processes of crop production. The discussion focuses on the effects of rotation length, crop sequence, substitutes for summerfallow, and N and P fertilizer, on crop production, grain and forage quality, soil moisture conservation and moisture use efficiency, N and P uptake by the plants, nutrient losses, soil quality, profitability, nonrenewable energy efficiency, and crop pests

Expérimentation de systèmes viticoles à faible usage d’intrants phytosanitaires en Val de Loire.

Ce numéro est constitué d’articles de synthèse des projets DEPHY EXPE publiés à l’occasion du colloque national DEPHY, qui s’est déroulé les 13 et 14 novembre 2018 à la Cité des Sciences et de l'Industrie (Paris). Nous vous invitons à découvrir le bilan et les enseignements des 21 projets conduits sur la période 2012-2017.The EcoViti Val de Loire project evaluated various viticulture systems during 6 years. One system wasbased on a combination of already assessed practices (at the time of design), a second one on theimpact of the pruning system on diseases susceptibility, and the last on the association of grapevineand roses. These systems led to significant TFI reductions, with sometimes some drawbacks in terms ofyield. They also allowed to show the importance of the transition period in system experimentations, andthe interest to lead these experimentations from the plantation for perennial crops. The time for thesystem to get back in balance is not to be underestimated, even a plant as plastic as grapevine takesseveral years ti adapt to a change in pruning or soil management.Le projet EcoViti Val de Loire a évalué trois systèmes de culture viticoles pendant 6 ans. Le premiersystème était basé sur la combinaison de pratiques déjà éprouvées au moment du lancement du projet,un second sur l’impact du mode de taille de la vigne sur la sensibilité aux maladies, et le dernier surl’association de vigne et rosiers. Ces divers systèmes ont permis des réductions significatives d’IFT,avec parfois des revers, en termes de rendement notamment. Ils ont également mis en évidence lanécessité de prendre en compte la phase de transition dans les essais systèmes, et l’intérêt de menerles essais systèmes en culture pérenne dès la plantation. En effet, le temps de rééquilibrage d’uneplante pérenne n’est pas à sous-estimer, et même une plante aussi plastique que la vigne met plusieursannées pour s’adapter à une modification de taille ou de mode d’entretien du sol