Bélanger, G., Castonguay, Y. and Lajeunesse, J. 2014. Benefits of mixing timothy with alfalfa for forage yield, nutritive value, and weed suppression in northern environments. Can. J. Plant Sci. 94: 51–60. Alfalfa can be grown alone or with a grass, but little information exists on the benefits of mixing alfalfa (Medicago sativa L.) with a grass in northern environments. Our objectives were (1) to determine the benefits in terms of forage yield, nutritive value, and weed suppression of mixing timothy (Phleum pratense L.) with alfalfa and (2) to evaluate the persistence of alfalfa cultivars of varied adaptation to cold and of alfalfa populations selectively improved for superior freezing tolerance in a grass–legume mixture and in monoculture. This study was conducted in a region with 1700 degree-days (5°C basis) with one harvest in the seeding year (2008), three harvests in each of two post-seeding years, and one harvest in the third post-seeding year. Adding timothy to alfalfa increased the seasonal total dry matter (DM) yield by an average of 0.57 Mg DM ha−1 yr−1 in the first 2 post-seeding years and this seasonal effect was due mostly to a DM yield increase at the first harvest. The weed contribution to total DM yield in the three harvests of the first 2 post-seeding years was greater in the alfalfa monoculture (16 to 47%) than in the alfalfa–timothy mixture (12 to 36%). Mixing timothy with alfalfa also increased neutral detergent fibre concentration and digestibility, decreased N concentration, and tended to increase water soluble concentration, but had little effect on forage DM digestibility. Cultivars and populations recurrently selected for superior freezing tolerance did not differ in persistence and had a limited effect on DM yield and nutritive value attributes. The positive effect on DM yield of mixing timothy with alfalfa was not accompanied by a reduction in forage digestibility that is usually observed with increased DM yield.

Jing, Q., Be´langer, G., Qian, B. and Baron, V. 2014. Timothy yield and nutritive value with a three-harvest system under the projected future climate in Canada. Can. J. Plant Sci. 94: 213Á222. Timothy (Phleum pratense L.) is harvested twice annually in Canada but with projected climate change, an additional harvest may be possible. Our objective was to evaluate the impact on timothy dry matter (DM) yield and key nutritive value attributes of shifting from a two-to a three-harvest system under projected future climate conditions at 10 sites across Canada. Future climate scenarios were generated with a stochastic weather generator (AAFC-WG) using two global climate models under the forcing of two Intergovernmental Panel on Climate Change emission scenarios and, then, used by the CATIMO (Canadian Timothy Model) grass model to simulate DM yield and key nutritive value attributes. Under future climate scenarios (2040Á2069), the additional harvest and the resulting three-harvest system are expected to increase annual DM yield ('0.46 to '2.47 Mg DM ha (1 ) compared with a two-harvest system across Canada but the yield increment will on average be greater in eastern Canada (1.88 Mg DM ha (1 ) and Agassiz (2.02 Mg DM ha (1 ) than in the prairie provinces of Canada (0.84 Mg DM ha (1 ). The DM yield of the first harvest in a threeharvest system is expected to be less than in the two-harvest system, while that of the second harvest would be greater. Decreases in average neutral detergent fibre (NDF) concentration ((19 g kg (1 DM) and digestibility (dNDF, (5 g kg (1 NDF) are also expected with the three-harvest system under future conditions. Our results indicate that timothy will take advantage of projected climate change, through taking a third harvest, thereby increasing annual DM production.Jing, Q., Be´langer, G., Qian, B. et Baron, V. 2014. Rendement et valeur nutritive de la fle´ole re´colte´e trois fois dans le futur re´gime climatique du Canada. Can. J. Plant Sci. 94: 213Á222. On re´colte la fle´ole (Phleum pratense L.) deux fois par anne´e au Canada, mais avec le changement climatique pre´vu, une troisie`me coupe pourrait s'ajouter aux deux premie`res. Les auteurs voulaient e´valuer les conse´quences du passage d'un re´gime de deux a`trois re´coltes dans les conditions climatiques pre´vues a`dix endroits du Canada sur le rendement en matie`re se`che (MS) de cette culture et sur les principaux parame`tres de sa valeur nutritive. Les sce´narios sur le climat futur ont e´te´cre´e´s graˆce a`un ge´ne´rateur stochastique de conditions me´te´orologiques (AAFC-WG), a`partir de deux mode`les du climat mondial fonde´s sur deux taux d'e´missions hypothe´tiques du GIEC. Ensuite, les auteurs ont applique´ces sce´narios au mode`le CATIMO (Canadian Timothy Model) sur la culture des gramine´es afin de simuler le rendement en MS et les principaux parame`tres de la valeur nutritive de la fle´ole. Selon les sce´narios sur le futur climat (2040Á2069), la re´colte supple´mentaire et le re´gime a`trois coupes devraient augmenter le ren...

H. 2011. Cadmium accumulation in wheat grain as affected by mineral N fertilizer and soil characteristics. Can. J. Soil Sci. 91: 521Á531. Cadmium (Cd) is a heavy metal distributed in soil by natural processes and anthropogenic activities. It can accumulate in crops, such as spring milling wheat (Triticum aestivum L.), and its accumulation depends on crop species, soil factors, and agricultural practices like fertilizer inputs. Our objective was to study the effect of mineral N fertilizer and soil characteristics on wheat grain Cd concentration. A field study was conducted over 12 site-years (2004Á2006) in Que´bec, with four N application rates (0, 40, 120, and 200 kg N ha (1 ). Wheat grain samples (n 0192) were analysed for their Cd and N concentrations. Soil samples (n 048) taken before N fertilizer application were characterised for their chemical and physical properties, including Mehlich-3 extractable Cd concentration. Wheat grain Cd concentration increased significantly with increasing N application rates at 11 of the 12 site-years. Averaged across the 12 site-years, Cd concentration ranged from 53 mg kg (1 dry matter (DM) without N applied up to 87 mg kg (1 DM when 200 kg N ha (1 was applied. Wheat grain Cd concentration also varied significantly with site-years (34Á99 mg kg (1 DM), but never exceeded the proposed tolerance for wheat grain of 235 mg kg (1 DM. Wheat grain Cd concentration was significantly related to Mehlich-3 extractable Cd in soil (R 2 00.44, P 00.021) and nitrogen nutrition index (R 2 00.69, P00.001). We conclude that soil Cd concentration and the crop N nutrition status affect Cd accumulation in spring wheat grain produced in eastern Canada.

Morel, C., Ziadi, N., Messiga, A., Bélanger, G., Denoroy, P., Jeangros, B., Jouany, C., Fardeau, J. C., Mollier, A., Parent, L. E., Proix, N., Rabeharisoa, L. and Sinaj, S. 2014. Modeling of phosphorus dynamics in contrasting agroecosystems using long-term field experiments. Can. J. Soil Sci. 94: 377–387. Long-term field experiments on phosphorus (P) fertilization were originally designed to study crop needs in different soil types by analyzing the effects of several rates of P fertilization on yields, their P concentrations and dynamics of plant-available soil P. The objective of this study was to test a computer-based model to simulate the P dynamics at the field scale using plant database and analyzing for plant-available P by a hierarchical process-based approach. It predicts both the concentration (CP) of phosphate ions (Pi) in soil solution and the associated Pi amounts that in time equilibrate with Pi in solution. Five experiments, representative of contrasting soil types, land-use, and climates were selected. Our model equilibrates the change in plant-available P in the upper soil layer to the P budget between annual P inputs and outputs. Rates of P fertilization affected simulations following the same expected pattern across sites. Field-observed and simulated values are in good agreements in all sites. The field-observed variations of CP per unit of P budget ranged from 0.007 to 2.49 (µg P L−1) (kg P ha−1)−1. The predictions are of the same order of magnitude. Predictions were compared with empirical long-term data and mismatches were discussed. This investigation highlights the scientific interest of long-term field P experiments to test and validate models describing P dynamics at the scale of the agricultural fields under different agricultural management practices.

Bélanger, G., Savoie, P., Parent, G., Claessens, A., Bertrand, A., Tremblay, G. F., Massé, D., Gilbert, Y. and Babineau, D. 2012. Switchgrass silage for methane production as affected by date of harvest. Can. J. Plant Sci. 92: 1187–1197. Switchgrass (Panicum virgatum L.) is a warm-season grass recognized as a potential biomass crop for energy production in North America, but little information exists on the effect of harvest date on forage and silage characteristics of switchgrass grown in eastern Canada. Our objectives were to determine how harvest date affects several forage and silage characteristics of switchgrass and to relate these to specific methane yield from anaerobically digested switchgrass silage. Switchgrass, seeded in 2002 and 2006, was harvested and ensiled as a one-cut system on three dates in 2007: late July, early September, and early October. The regrowth from the late July harvest was also harvested in early October as a two-cut system. Silage quality parameters [pH, and concentrations of N, N-NH3, total amino acids (TAA), and volatile fatty acids (VFA)] indicated adequate fermentation of all silage samples. In a one-cut system, delaying harvest from late July to early September increased forage dry matter (DM) yield from 9.0 to 11.5 Mg ha−1, forage soluble carbohydrate (SC) concentration from 51 to 85 g kg−1 DM, and silage SC concentration from 13 to 25 g kg−1 DM; delaying harvest from late July to early October decreased forage in vitro true digestibility (IVTD) from 720 to 582 g kg−1 DM, forage in vitro digestibility of the neutral detergent fibre (dNDF) from 590 to 409 g kg−1 DM, and silage acetate concentration from 7.7 to 2.6 g kg−1 DM. The regrowth had higher IVTD and dNDF, lower acid detergent fibre concentration, and higher silage lactate and acetate concentrations than a single harvest taken in early September or early October. The two-cut system and the single harvest in early September produced the highest seasonal forage DM yields (11.5 and 11.9 Mg ha−1). High specific methane yield was (i) correlated with low forage fibre concentration and high DM digestibility and (ii) more correlated to silage concentrations of lactate and acetate than to silage SC concentration.