Search

Canola (Brassica napus L.) is a nitrogen (N)-demanding crop, so tissue N analysis should be related to soil N supply. We evaluated canola N uptake in relation to soil N pools in plots receiving 0, 50, 100, and 150 kg N·ha−1 from urea at three sites in eastern Canada in 2012. Soil N pools varied significantly at the rosette, flowering, pod filling, and maturity stages, but responded less predictably to urea. Canola N uptake was inconsistently related to soil N pools and urea input. This confirms the importance of site-specific N fertilizer management when growing canola in eastern Canada.

Kochia [Bassia scoparia (L.) A.J. Scott] is an invasive C4 tumbleweed in the Great Plains of North America, where it impedes crop harvest and causes significant crop yield losses. Rapid evolution and spread of glyphosate- and acetolactate synthase (ALS) inhibitor-resistant kochia in western Canada limit the herbicide options available for control of these biotypes in field pea (Pisum sativum L.); one of the predominant pulse crops grown in this region. Field experiments were conducted near Lethbridge, Alberta, in 2013–2015 and Coalhurst, Alberta, in 2013–2014 to determine which herbicide options effectively control glyphosate- and ALS inhibitor-resistant kochia in field pea. Visible injury of field pea was minor (0%–4%) in all environments except for Lethbridge 2013, where pre-plant (PP) flumioxazin and all treatments containing post-emergence (POST) imazamox/bentazon resulted in unacceptable (14%–23%) visible injury in field pea. Herbicide impacts on field pea yield were minor overall. Carfentrazone + sulfentrazone PP and saflufenacil PP followed by imazamox/bentazon POST resulted in ≥80% visible control of kochia in all environments, while POST imazamox/bentazon alone resulted in ≥80% reduction in kochia biomass in all environments compared with the untreated control (albeit, absent of statistical difference in Coalhurst 2014). These results suggest that layering the protoporhyrinogen oxidase-inhibiting herbicides saflufenacil or carfentrazone + sulfentrazone PP with the ALS- and photosystem II-inhibiting herbicide combination imazamox/bentazon POST can effectively control glyphosate- and ALS inhibitor-resistant kochia in field pea while also mitigating further selection for herbicide resistance through the use of multiple effective herbicide modes-of-action.

Interest in intercropping semi-leafless field peas (Pisum sativum L.) is increasing as a means of weed control in organic production. We evaluated field pea (cv. CDC Amarillo) grown alone or intercropped with three seeding rates of either barley (Hordeum vulgare L.), mustard (Brassica juncea L.), or oat (Avena sativa L.). A full seeding rate of field pea was used in each instance, resulting in an additive intercropping design. Each crop combination was conducted in a separate experiment, three times over two years (2019 and 2020) in Carman, MB. Measurements included crop and weed biomass production, grain yield and quality, and net return. Intercrops reduced weed biomass at maturity from 17% to 44% with barley and oat being more suppressive than mustard. Intercrops also reduced field pea yield from 6% to 26%, but increased field pea seed mass. Barley at the high seeding rate provided the most weed suppression per unit of field pea yield loss (2.62 kg of weed suppression per kg of field pea yield loss) compared with oat (1.29) and mustard (0.87). Barley and mustard intercrops decreased net return compared with monoculture field pea. Under low weed pressure (1150 kg·ha−1 weed biomass at maturity) and earlier seeding, oat intercrops reduced net return. However, under weedy conditions (2649 kg·ha−1) and later seeding, field pea-oat intercrops significantly increased net return. In conclusion, while all three intercrop mixtures reduced weed biomass, reductions in field pea yields were observed, and net return benefits were observed only in certain circumstances.

Estimating soil nitrogen (N) mineralization is critical to balance fertilizer N requirements and their environmental impacts. In this study, net N mineralization was examined in soils under different crop rotations with each phase of the rotation present every year with biologically based incubations in 2011 and 2015. Net N mineralization was significantly different among treatments when the current crop was soybean, and the effect was dependent upon the previous crop and the cropping sequence. In particular, net increases in inorganic N were greater when the previous crop was winter wheat with or without red clover than if it were corn, and greater for the first year of soybean compared with the second year for rotations with two consecutive years of soybean in the 2011 incubation. However, cropping history did not influence net soil N mineralization when the current crop was corn, winter wheat, or winter wheat with red clover. In 2015, the presence of red clover in the rotation increased net N mineralization in all phases of the rotation. These results suggest both current and previous crops should be considered when estimating the N supplying capacity (net mineralization) of the soil. Net mineralizable N was found to be significantly correlated with total amino sugars (P

Aggregate stability (AS) was measured in the 25th year of a long-term organic — conventional comparison field study. Located in southern Manitoba, the study includes two, four-year crop rotations under conventional and organic management, plus a grassland. The forage-grain rotation includes alfalfa (Medicago sativa)–alfalfa–wheat (Triticum aestivum)–flax (Linum usitatissimum). The grain only rotation includes wheat–flax–oat (Avena sativa)–soybean (Glycine max); hairy vetch (Vicia villosa) is substituted for soybean in the organic system. Composted manure was added every 4 yr to half of the organic forage-grain rotation to correct a phosphorus deficiency. The wheat and flax phases were sampled at depths (0–10 cm; 10–20 cm) in spring 2017, and wet aggregate stability was measured using the Yoder method with stacked sieves. Mean weight diameter (MWD) was calculated. AS in the organic systems was never lower than that of comparable conventional systems, but had more large aggregates in only a few cases. Our hypothesis that including alfalfa would increase AS was supported in only a few instances. The largest aggregates (1–2 mm and 2–6.3 mm) and the fewest smallest aggregates (0.25–0.5 mm) were observed in the grassland. For the intermediate aggregate size class (0.5–1 mm), the organic forage-grain systems had levels similar (P > 0.05) to the grassland. While adding manure increased plant growth by about 40% in the organic forage-grain rotation, no AS differences were observed. Limited AS response in the arable systems may be due to suboptimal soil C contents; only the grassland had a C content above the minimum 35 g·kg−1 postulated for Vertisols.

Soil water repellency (SWR) was measured for a 28 yr field study under irrigation on a clay loam Dark Brown soil in southern Alberta. The objectives were to study the effect of legume–cereal crop rotations, feedlot manure, and phosphorus (P) fertilizer application on soil hydrophobicity (SH) and soil water repellency index (RI) under irrigation. Mean SH and RI were similar (P > 0.05) for a legume–cereal and cereal rotation and were unaffected by P fertilization. However, P fertilization shifted the RI classification from slight to subcritical. In contrast, SH was significantly greater for manured than nonmanured treatments, while RI was unaffected. Soil organic carbon (SOC) concentration was significantly (P ≤ 0.05) correlated with SH (r = 0.74), but not with RI (r = −0.17). This suggested a closer association between the quantity of SOC and quantity of hydrophobic compounds (SH method) compared with the hydrophobic coatings inhibiting infiltration of water (RI method). No significant correlation between SH and RI (r = −0.09) suggests that SH is not a good predictor of SWR using the RI method. Overall, manure application increased SH and P fertilization shifted the RI classification from slight to subcritical. In contrast, legume–cereal rotations had no influence on SH and SWR using RI method compared with continuous cereal.

The application of organic amendments to agricultural soils enables the recycling of nutrients, further reducing the inputs of synthetic fertilizers for crop production. However, the production of N2O emissions is a concern that arises from such a practice. A 35 d incubation experiment was conducted with soils receiving three contrasting types of biosolids — mesophilic anaerobic digested (BM), composted (BC), and alkaline-stabilized (BA) — at four water-filled pore spaces (WFPS): 28%, 40%, 52%, and 64%. A zero-N-addition control was also evaluated. Across all the three types of biosolids, N2O production increased with soil moisture content, with BM and BC producing the overall highest N2O fluxes. The most intense pulses of N2O production were exhibited by BC at the beginning of the incubation. The highest cumulative N2O production was found with 64% WFPS and from BC- (409 μg N2O–N·kg−1 soil) or BM-amended soils (390 μgN2O–N·kg−1 soil), which produced more than four and two times the emissions from the control and BA-amended soils at 64% WFPS, respectively. We also found the highest nitrification rates in the BM- and BC-amended soils. The total N2O production was exponentially associated with the NO3−–N concentration present at the end of the experiment (R2 = 0.83). Changes in the concentration of the soil available N indicated the occurrence of mineralization, nitrification, and denitrification over the incubation. These results provided insight into the interacting responses of N2O production to soil moisture contents, biosolids treatment stabilization and properties, and soil N availability.

To develop new barley cultivars, promising genotypes are evaluated for their performance each year at several test locations representing the target region. In this study, we analyzed the Ontario barley registration trial data from 2015 to 2020 to understand the barley mega-environment in Ontario and to evaluate the suitability of the test locations. The analysis showed that the barley test locations fall into two mega-environments, with a major mega-environment consists of five test locations and a minor mega-environment with a single test location. Among the six test locations used for the barley registration trials, Palmerston was found to be the most desirable for the barley cultivar evaluation representing the Ontario barley growing region. This study also identified OB2930-35, a recently released cultivar, to be both high yielding and stable across Ontario. These findings are useful for future barley breeding and cultivar evaluation in Ontario.

The forage value of native forbs is rarely considered in pasture mixtures, even though such species can make up a substantial proportion of the diet of cattle on native rangelands. Incorporating non-leguminous forbs into pasture grazing systems can provide additional ecosystem services such as pollination habitat, and ideally those forbs would also provide some forage value. We therefore assessed the seasonal variation in protein and fiber [neutral detergent fiber (NDF) and acid detergent fiber (ADF)] content of six common western Canadian native forb and sub-shrub species: yarrow (Achillea millefolium), smooth aster (Symphyotricum laeve), prairie crocus (Pulsatilla patens), prairie rose (Rosa arkansana), Canada goldenrod (Solidago canadensis), and American vetch (Vicia americana). The legume V. americana displayed the highest protein followed by S. canadensis and S. laeve. V. americana also has the highest fiber concentration through the growing season. S. canadensis and S. laeve had lower fiber content; thus, making them a good choice for addition in seed mixes to meet the energy and nutrient requirements of cattle. Forb protein and fiber content showed opposite trends during the growing season. Crude protein decreased while NDF and ADF increased as a general pattern tied to physiological stage and degree of senescence. The promising nutritional profile of some forb species suggests that these species should be considered in pasture mixes.

Frequent cultivation is often used to control weeds in crops such as lettuce. The efficacy of this technique on weed populations has been evaluated, but the effect on weed emergence and seedbanks is less documented. Studies in mineral soil indicate that soil disturbance can increase both weed emergence and seed persistence depending on where seeds are redistributed in the soil profile. Evaluations done in muck soil are scarce. This study evaluated the effect of two and four repetitive shallow (3.4 to 7.1 cm deep) cultivations on weed emergence and the weed seedbank in muck soil. Cultivation treatments (0, 2, and 4 cultivations using a inter-row rototiller) were done in lettuce plots from 2017 to 2019. Weed density was evaluated by species before each cultivation date and after crop harvest. Viable seedbanks were evaluated by collecting soil samples before and after each growing season and placing them in greenhouse flats. Statistical analyses were based on mixed models. Results showed that shallow cultivation modified the emergence patterns of weeds but did not reduce total emergence during the subsequent years or viable seedbanks. After two seasons without seed inputs, total emergence was reduced by 46.6% and the seedbank was reduced by 31.7% regardless of the cultivation treatment. However, the seedbank of the very abundant common purslane (Portulaca oleracea) remained high.

Increased adoption of crops with stacked traits conferring glyphosate and dicamba resistance, and recent confirmation of kochia [Bassia scoparia (L.) A.J. Scott] biotypes resistant to these herbicides in Alberta and Saskatchewan, warrant surveillance of herbicide-resistant kochia in Manitoba. A randomized–stratified survey of 315 sites in Manitoba was conducted in the fall of 2018. Overall, 58% of the kochia populations tested were glyphosate-resistant, while 1% were dicamba-resistant. This survey documents rapid increase in glyphosate-resistant kochia over a five-year time frame, and also confirms the first cases of kochia in Manitoba with dicamba resistance alone and in combination with glyphosate resistance.

Information on the tiller development of hybrid bromegrass (Bromus inermis × Bromus riparius) is limited. The objective of this study was to evaluate the effect of clipping frequency at the vegetative and reproductive stages on the tiller development and concentrations of sugars of c.v ‘AC Knowles’ hybrid bromegrass compared with c.v ‘Kirk’ crested wheatgrass (Agropyron cristatum L.). This experiment was conducted in a greenhouse using the tillers of the vernalized plants dug from the field. The experimental design was a randomized complete block design (RCBD). Grasses were clipped once or four times at either vegetative or reproductive stage. Regardless of the growth stage, four clippings reduced the tiller number of hybrid bromegrass by 25.9% compared with the undefoliated control, while single clipping had no impact. The four clippings had no impact on the tiller number of crested wheatgrass, while single clipping increased its tiller number on average by 50.4% at both growth stages. Crested wheatgrass produced 16.6% more tillers than hybrid bromegrass under the single clipping. The two grass species had a similar number of axillary buds under different clipping treatments. The axillary bud size of crested wheatgrass was larger than hybrid bromegrass. All axillary buds were viable under the two clipping treatments for both grasses. Four clippings significantly decreased the stem base glucose concentration of the two grasses and the root sucrose concentration of crested wheatgrass. Hybrid bromegrass was less tolerant to frequent clippings than crested wheatgrass. Therefore, intensive grazing of hybrid bromegrass pasture may result in a thin stand.

AAC Hodge (BW1069) is a hollow-stemmed, awned and high yielding Canada Western Red Spring (CWRS) wheat cultivar suited to the growing conditions in Western Canada. AAC Hodge was 6% higher yielding than AAC Viewfield, the highest yielding check in the Central Bread Wheat Cooperative (CBWC) registration trials (2017–2019). Within the same test, AAC Hodge was 16% higher yielding than Carberry. AAC Hodge matured 1 d earlier than Carberry and 2 d later than Unity; Unity is the earliest maturing check in the eastern prairie growing conditions. AAC Hodge was 7 cm shorter with better lodging resistance than Unity. The lodging score for AAC Hodge was lower than the mean of the checks. The test weight of AAC Hodge was similar to the mean of the checks. Over the 3 yr of testing (2017–2019), the 1000-kernel weight of AAC Hodge was equal to, or higher than all the checks. The grain protein content of AAC Hodge was equal to that of AAC Viewfield. AAC Hodge was rated moderately resistant to Fusarium head blight (FHB; Fusarium graminearum Schwabe) and resistant to leaf rust (Puccinia triticina Erikss.), stripe rust (Puccinia striiformis Westend), stem rust (Puccinia graminis Pers. f. sp. tritici Eriks. & E. Henn), and common bunt [Tilletia caries (DC) Tul. & C. Tul.]. AAC Hodge ranged from resistant to moderately susceptible for its reaction to the Ug99 family of stem rusts. AAC Hodge was resistant to orange wheat blossom midge (OBWM) (Sitodiplosis mosellana Géhin). AAC Hodge was registered under the CWRS class.

Ultra-early wheat growing systems based on soil temperature triggers for planting instead of arbitrary calendar dates can increase grain yield and overall growing system stability of spring wheat (Triticum aestivum L.) on the northern Great Plains. We conducted field trials at three sites in western Canada from 2017 to 2019 to evaluate the suitability of Canadian spring hexaploid wheat cultivars and market classes for use within ultra-early spring wheat growing systems. All cultivars and classes exhibited improved grain yield stability (lower adjusted coefficient of variation values) and optimal grain yield when planted ultra-early at 2 °C soil temperature rather than delaying planting to 8 °C.

Most forest soils contain substantial amounts of gravel. However, unlike the more widely known root resource uptake behaviors which respond to resource patches in substrate without gravels, how roots respond to substrate containing different gravel levels is poorly understood. We grew roots in substrates with five gravel levels (0%, 10%, 20%, 30%, and 40% of volume) in a subtropical Schima superba Gardn. et Champ plantation, determined fine root dynamics and turnover rate with minirhizotrons, measured fine root morphological, architectural, mycorrhizal colonization, chemistry, and mass allocation. The presence of gravel in the substrate delayed the timing of peak root growth. In the substrate with higher gravel content, plants produced more in roots in autumn, but there were fewer roots in summer and the roots tended to exhibit lower fine root turnover rate and mycorrhizal colonization, but higher root biomass allocation. The higher root biomass in the substrate with higher gravel content was associated with higher root carbon/nitrogen ratio. Our findings emphasize the complexity of root resource uptake behavior in response to gravel content and suggest that incorporating substrate gravel content into root studies may help to improve the prediction of patch exploitation and nutrient acquisition in stony soils.

Amending croplands with forest residues may help in restoring soil properties in fields subject to intensive land management. Despite their known benefits when applied separately, co-application of wood biochar with paper mill biosolids (PB) has seen little investigation under field conditions. A study was initiated in Québec, QC, Canada, to determine the effect of a single application of wood biochar with and without PB on the nitrogen (N) and phosphorus (P) availability of two pH-neutral to alkaline loamy soils. Biochar at 0, 10, and 20 Mg dry weight·ha−1 and PB at 30 Mg wet weight·ha−1 were applied before planting of corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] in 2018. Residual effect of this co-application was determined under soybean and corn in the subsequent year. In both years, corn received supplemental N and P from mineral fertilizers according to local agronomic recommendations. Co-applying biochar and PB reduced soil NO3-N availability in the year of application and decreased corn yield by 1.0 Mg·ha−1 compared with biochar or PB applied alone, but these amendments did not affect soybean yields. In the following year, the previous biochar addition increased soybean yield by 0.6 Mg·ha−1 but had little effect on corn. For both years, biochar addition induced a large increase in soil Mehlich-3 P. This study revealed that wood biochar positively impacted P status of these soils but was not a source of N to crops even when co-applied with PB.

A greenhouse trial assessed the effects of biochar and vermicompost as partial substitutes of conventional growing media on leafy vegetables’ yields and changes of NH4+-N and NO3−-N in growing medium and leachates. Six growing media mixtures [(a) coir, (b) coir + biochar, (c) coir + vermicompost, (d) peat, (e) peat +vermicompost, (f) peat + biochar] combined with three nitrogen (N) rates [0% (0 g N·pot−1), 50% (0.5 g N·pot−1), and 100% (1.0 g N·pot−1) commercial recommendation] were arranged in a split-plot design with three replicates. On average, the yield gap between 100% N and 50% N was improved when biochar and vermicompost were used as substitutes of coir (32% and 28% vs. 49%) and peat (14% and 18% vs. 27%). The concentrations of NH4+-N in the leachates for peat + biochar varied between 17.20 and 1.00 mg·L−1. The concentrations of NO3−-N in the leachates varied between 130.0 and 1.0 mg·L−1 for coir + vermicompost, and 60 and 1.0 mg·L−1 for peat + vermicompost. The residual NO3−-N in peat + biochar growing media and the leachates did not match the changes observed for NH4+-N, and the much lower residual NH4+-N indicates possible NH4+-N retention by biochar and loss through volatilization in the early growth stages. Our results show that partial substitution of peat with biochar and coir with vermicompost maintained acceptable crop yield at 50% N due probably to N supply by vermicompost and decreased residual mineral N and loss by biochar in the leachates which could be beneficial for the environment.

Soil moisture level is crucial to soil phosphorus (P) availability; however, there is no quantitative research on the relation between soil P availability and moisture level. In addition, biochar application could also alter soil P availability at different moisture levels. In this study, a 16 d soil incubation experiment was conducted at a laboratory scale to analyze the effects of soil moisture and P fertilization regimes (P-laden biochar fertilizer and conventional mineral P fertilizer) on soil P availability and fractionation. The results showed that soil P availability was positively correlated with soil moisture level (Pearson coefficients ranged from 0.46 to 0.91). High moisture level would lead to less amount of P in readily available fractions under P-laden biochar application. However, even with less P in readily available fractions, P-laden biochar could maintain soil P availability (117.7 mg P·m−2) at a similar level as the conventional P fertilizer (116.1 mg P·m−2).

Warmer atmospheric temperatures (eT) will increase plant nutrient uptake, and elevated atmospheric CO2 (eCO2) is expected to enhance plant growth, whereas a multicomponent eTeCO2 effect should also be beneficial for agroecosystems. Our goal was to understand if single- (eT, eCO2) or multicomponent (eTeCO2) climate effects, predicted for southern Ontario, Canada, will affect soybean and soil properties differently when soil is amended with manure and biochar (MB) or with manure, nitrogen (N) fertilizer, and biochar (MNB) compared with the addition of manure and N fertilizer (MN). We hypothesized that biochar regulates climate effects and causes soybean and soil properties to be similar to ambient climate conditions than soil without biochar. However, soil amended with biochar functioned independently of single- or multicomponent climate effects. Soybean pod and shoot biomass, shoot height, and shoot:root ratio were greater (p 2 increased (p 4+ and NO3−), and the C/N ratio but increased (p

Tremendous benefits of biochar (BC) amendment to soil have been reported, including their role in alleviating the impact of salinity stress in plants. The aim of this study was to evaluate the effects of BC produced at 300 °C (BC300) and 700 °C (BC700) on the germination rate (GR) and selected growth characteristics of corn plants irrigated with salinized water over a growth period of 6 weeks. The experimental treatments included three biochar treatments: BC0 (control, without biochar addition), BC300, and BC700. The treatments also included three salinity levels of irrigation water: 0, 3, and 6 dS·m−1. The biochar was applied at a rate of 3%. The GR decreased with increasing salinity level, which was more evident in the first week. This stress impact was reduced when treated with the BC700 relative to the saline treatments without BC. Both BC treatments demonstrated contrasting effects on corn growth, nutrient uptake, and Na+ and K+ content in plant tissue. The effect of BC700 treatment on plant height and root length was limited, but the impact of salinity stress on chlorophyll meter readings, chlorophyll fluorescence parameter (Fv/Fm), dry matter yield, and N and P uptake were largely mitigated. It also increased K+ and decreased Na+ content in plant tissue. However, the BC300 treatment adversely affected plant growth parameters at each salinity level. Overall, the BC produced at a higher temperature significantly alleviated the impact of salinity stress on plant growth characteristics, which is probably attributed to their higher surface area and porosity, enhancing their salt ion sorption capacity.

Liquid hog manure (LHM) and solid cattle manure (SCM) co-applied with biochar could beneficially influence soil nitrogen (N) and phosphorus (P) dynamics. A split-plot design was used at two sites (Brown and Black) in Saskatchewan to assess LHM and SCM (100 kg N·ha−1) applied alone or in combination with biochars (8 Mg carbon·ha−1) produced using slow or fast pyrolysis. Crop growth and nutrient uptake, along with fertilizer 15N recovery, were followed over four years in a cereal–oilseed rotation. Crop growth on the Brown soil was more responsive to the treatments than the Black soil, reflecting lower fertility of the Brown soil. The manure and biochar, applied alone or in combination, had little impact on available soil P. Manure and biochar effects on crop growth and nutrient uptake were attributed to temporal effects on soil N immobilization–mineralization influencing plant-available soil N. A negative impact of the fast pyrolysis biochar on growth and plant uptake was observed and attributable to its greater labile-carbon content, which likely promoted soil N immobilization. Synergism observed between SCM and the slow pyrolysis biochar may reflect enhanced net SCM-N mineralization and increased water-holding capacity. The majority (55%–80%) of plant 15N recovery occurred during the first year, with 86% of fertilizer 15N conserved within the soil–plant system after four years. Greater (40%) plant 15N recovery without biochar addition, coupled with increased (38%) soil 15N recovery with added biochar, suggests biochar-related immobilization and (or) sorption in the biochar-amended soils.

This is the first study testing the effectiveness of semiochemical treatments to protect individual trees from a range-expanding mountain pine beetle (MPB; Dendroctonus ponderosae Hopkins, 1902) attack into newly exposed host populations of endangered whitebark pine (Pinus albicaulis Engelm.). We investigated the effectiveness of a combination of verbenone and green-leaf volatiles (GLV) to protect rare and valuable disease-resistant trees during a MPB epidemic from 2015 to 2018 in Jasper National Park, Canada. Treatments reduced the proportion of trees attacked by MPB for all diameter classes, across all stands, from 46% to 60%. We also evaluated the effect of the exotic disease white pine blister rust (caused by the fungus Cronartium ribicola J.C. Fisch.) — the species’ other main regional threat. MPB were less likely to attack large rust-infected trees than healthy trees, emphasizing the value of the semiochemical treatment. Protecting large cone-bearing disease-resistant whitebark pine trees is fundamental to whitebark pine recovery. Maintaining reproductive trees on the landscape increases the frequency and diversity of rust-resistant genotypes more effectively than just planting seedlings to replace MPB-killed trees, because this slow-growing species takes over 80 years to reproduce. Our study confirmed that protecting large rust-resistant trees with verbenone and GLV is a proactive and effective treatment against MPB for whitebark pine in naïve populations.

With soybean [Glycine max (L.) Merr.] seed cost increasing in Alberta, understanding economic optimum plant density (EOPD) could help growers save on input expenses. A study was conducted at two irrigated locations in southern Alberta (Bow Island and Lethbridge), in three growing seasons (2014–2016), using two maturity group (MG) 00 soybean genotypes, two row spacings (RS; narrow, 17.5 cm; wide, 35 cm), and three seeding densities (SD; 30, 50 and 80 seeds·m−2). Exponential plant density–yield relationships were used to estimate EOPD. The earlier MG 00.4 genotype compensated yield at lower plant density (39 vs. 43 plants·m−2) and emergence (74% vs. 80%) than the later MG 00.8 genotype. The EOPD gaps between environments, genotypes, and RS were minimal (from 1–3 plants·m−2), resulting in only 1.3%–2.0% differences in grain yield (37–56 kg·ha−1), and gross revenue at EOPD ($16–24·ha−1). The overall EOPD estimate was 46 plants·m−2, regardless of environment, genotype or RS. The study highlighted the difference between agronomic production and profit maximization in choosing an optimum plant density, and the need to establish a seeding density calculator for irrigated soybean in southern Alberta.

AAC Oravena is a white-hulled spring oat (Avena sativa L.) cultivar selected and developed under organic management. AAC Oravena yields well under organic and conventional production systems, compared with check cultivars. AAC Oravena has good milling quality. AAC Oravena was registered (Reg. No. 7561) by the Variety Registration Office, Canada Food Inspection Agency, on 3 July 2014.

Miscanthus is a C4 herbaceous perennial genus, and it was chosen as a bioenergy crop due to high biomass yield. Miscanthus sinensis has many phenotypes which are adapted to various environments in China. In this study, 421 accessions of M. sinensis were collected from 22 provinces, and the genetic polymorphisms amongst these germplasm collections were identified using 20 primer pairs designed against 10 each from expressed sequence tag-simple sequence repeats [EST-SSR (eSSR)] and genomic SSR (gSSR) transferable markers from barley. A total of 95 SSR polymorphic bands were detected producing a 100% polymorphic rate among these M. sinensis accessions. The gSSR markers showed a richer genetic polymorphism than eSSR markers. Based on the unweighted pair group method with arithmetic mean (UPGMA) clustering, there was a distinct sub-population separation in M. sinensis, which indicates that geographical differences and natural selection are the driving forces for genetic variation and evolution in the species. The 20 pairs of barley markers matched to 26 polymorphic bands associated with date of heading, plant height, leaf weight, stem weight, leaf/stem ratio, and total biomass yield. Eleven marker polymorphic bands were associated with the date of heading, 4 with plant height, 10 with leaf weight, 7 with stem weight, 3 with leaf/stem ratio, and 10 with biomass yield.

Composts can be efficient organic amendments in potato culture as they can supply carbon and nutrients to the soil. However, more information is required on the effects of composts on denitrification and nitrous oxide emissions (N2O) and emission-producing denitrifying communities. The effects of three compost amendments (municipal source separated organic waste compost (SSOC), forestry waste mixed with poultry manure compost (FPMC), and forestry residues compost (FRC)) on fungal and bacterial denitrifying communities and activity was examined in an agricultural field cropped to potatoes during the fall, spring, and summer seasons. The denitrification enzyme activity (DEA), N2O emissions, and respiration were measured in parallel. N2O emission rates were greater in FRC-amended soils in the fall and summer, whereas soil respiration was highest in the SSOC-amended soil in the fall. A large number of nirK denitrifying fungal transcripts were detected in the fall, coinciding with compost application, while the greatest nirK bacterial transcripts were measured in the summer when plants were actively growing. Denitrifying community and transcript levels were poor predictors of DEA, N2O emissions, or respiration rates in compost-amended soil. Overall, the sampling date was driving the population and activity levels of the three denitrifying communities under study.

Recent confirmations of glyphosate-resistant Russian thistle (Salsola tragus L.) in Montana, Washington, and Oregon, warrant greater surveillance of herbicide-resistant Russian thistle in western Canada. A randomized-stratified survey of 315 sites in Manitoba was conducted in 2018 to determine the incidence of herbicide resistance in Russian thistle and other weeds sampled post-harvest. Russian thistle populations were collected from 14 of the 315 sites surveyed. None of these populations exhibited resistance to acetolactate synthase inhibitors (tribenuron/thifensulfuron), synthetic auxins (2,4-D ester or fluroxypyr), or glyphosate. This Manitoba survey of herbicide-resistant Russian thistle serves as a baseline for future surveillance efforts.

Production of fruits and vegetables provides nutrient dense and high value crops. However, horticulture production is often very intensive and degrading to soil, with high levels of soil disturbance, high use of fertilizer inputs, and with prolonged periods of exposed soil. This can lead to increased soil degradation when compared to other types of cropping. We used a subset of the Atlantic Soil Health Laboratory’s database of on-farm soil samples collected between 2016 and 2018 to assess the impact of cover crop (CC) use in horticulture production in Nova Scotia on soil health. We analyzed 21 soil health parameters on soil collected from 14 fields, seven of which incorporated CCs in their crop rotation and seven of which used no CCs. The inclusion of CCs significantly increased permanganate oxidizable carbon (POX), soil respiration, autoclaved-citrate extractable (ACE) protein, residual soil nitrogen (N), and biologically available N. However, we also found that the variation in these parameters was greater when CCs were part of the rotation. This is likely attributable to the wide range of CC species used and differences in their management, such as the chosen termination method. While cover cropping is seen as a best management practice to improve soil health, simply using a CC in a horticulture rotation does not necessarily lead to improved soil health. Research trials on specific CC species and management to target soil degradation are needed to tailor recommendations to ensure the desired soil health outcomes can be achieved with CC use.

Fertilization of hybrid poplar (HP) plantations with papermill by-products is a promising solution to improve soil fertility and nutrient availability, increase plantation productivity, and provide added value to these materials that would otherwise be incinerated or sent to the landfill. We assessed the growth and foliar nutrition of a HP clone (Populus ×canadensis × Populus maximowiczii) at six plantation sites aged 3–5 years in southern Quebec, Canada. Sites received a fertilization treatment consisting of a mixture of papermill biosolids (120 to 140 t·ha−1, depending on site) and lime mud (10 to 15 t·ha−1) before being planted, or no fertilization (control). Tree growth was significantly improved by fertilization, with fertilized trees showing a mean annual height increment of 1.3 m (all-site mean; SD = 0.2), compared with 0.5 m (SD = 0.4) for unfertilized trees. Foliar calcium and magnesium increased following fertilization and levels met optimal thresholds at all sites, whereas nitrogen, phosphorous, and potassium concentrations also increased, but nutritional deficiencies remained for these elements at several sites. Our results confirm the benefits of fertilizing hybrid poplars with papermill by-products, but they also indicate that adjustments in application rates or type of by-products could be made to fully satisfy nutritional requirements and thus optimize tree growth.

Although it is well established that soil temperature has substantial effects on the agri-environmental performance of crop production, little is known of soil temperatures under living cover crops. Consequently, soil temperatures under a crimson clover and white clover mix, hairy vetch, and red clover were measured for a cool, humid Brookston clay loam under a corn–soybean–winter wheat/cover crop rotation. Measurements were collected from August (after cover crop seeding) to the following May (before cover crop termination) at 15, 30, 45, and 60 cm depths during 2018–2019 and 2019–2020. Average soil temperatures (August–May) were not affected by cover crop species at any depth, or by air temperature at 60 cm depth. During winter, soil temperatures at 15, 30, and 45 cm depths were greater under cover crops than under a no cover crop control (CK), with maximum increase occurring at 15 cm on 31 January 2019 (2.5–5.7 °C) and on 23 January 2020 (0.8–1.9 °C). In spring, soil temperatures under standing cover crops were cooler than the CK by 0.1–3.0 °C at 15 cm depth, by 0–2.4 °C at the 30 and 45 cm depths, and by 0–1.8 °C at 60 cm depth. In addition, springtime soil temperature at 15 cm depth decreased by about 0.24 °C for every 1 Mg·ha−1 increase in live cover crop biomass. Relative to bare soil, cover crops increased near-surface soil temperature during winter but decreased near-surface soil temperature during spring. These temperature changes may have both positive and negative effects on the agri-environmental performance of crop production.

Crested wheatgrass (CWG) [Agropyron cristatum (L.) Gaertn.] is a commonly introduced grass in the Canadian prairies, but concerns remain about its possible long-term effects on soil quality, and its influence on soil water repellency (SWR) has not been determined. The long-term (24 yr) effects of CWG on SWR in comparison to seeded native grasses and annual cropping were determined for a clay loam soil in southern Alberta, Canada by measuring SOC concentration and SWR using soil hydrophobicity (SH) and soil water repellency index (RI) methods. The cropping treatments were CWG, seeded native grass mix (NGM), continuous wheat, and wheat–fallow rotation, each with fertilized (nitrogen) and non-fertilized subplots, replicated four times. Mean SOC concentration, SH, and RI in samples of surface soil were similar (P > 0.05) for CWG and seeded NGM, and they did not support our hypothesis (seeded NGM > CWG). Mean SOC was significantly greater for seeded perennial grasses than annual crops by 1.7–2 times and SH by 2.1–2.5 times, which supported our hypothesis, but RI was similar among treatments. As expected, nitrogen fertilization significantly increased SOC concentrations, but the effects on SH and RI were undetectable. A strong positive correlation occurred between SOC concentration and SH (r = 0.92) but not for RI (r = 0.10). Our findings suggested that SWR was similar for CWG and seeded NGM. The SWR as measured using SH was greater for seeded perennial grasses than annual cropping but was similar using RI.

Termination by tillage is one strategy used for regenerating pasture stands. Yet, research gaps exist on how tillage affects carbon (C) and nitrogen (N) forms and amounts in western Canadian soils. We measured total soil organic C (SOC), dissolved organic C (DOC), total dissolved N (TDN), light fraction organic C (LFOC) and light fraction organic N (LFON), microbial biomass C (MBC) and microbial biomass N (MBN), and inorganic N as indicators of soil organic matter (SOM) dynamics. After tillage termination in fall 2018, we sampled soils (0–10 cm; 0–15 cm) under three legume species (alfalfa, cicer milkvetch, and sainfoin) three times (spring, summer, and fall of 2019) across three landscape positions. Legume species did not affect the measured parameters. Over time, tillage affected DOC, TDN, and inorganic N. Averaged across three pasture legumes and three landscape positions, tillage increased DOC 29% by summer. Fall-applied tillage led to 59% and 33% higher TDN in the succeeding summer and fall. Inorganic N increased by 14% and 40% across landscape positions and sampling after tillage. Averaged across landscape positions, MBC decreased by 31% from spring to summer and increased by 51% from summer to fall. However, MBN increased by 53% and decreased by 5% within the same period. The seasonal fluctuations in MBC and MBN reflected variations in moisture, temperature, and substrate quality. Total SOC, LFOC, and LFON increased on the upper slopes and fall sampling time. Although single intensive tillage did not affect total SOC, several tillage operations could accelerate SOM loss and reduced total C storage over time.

Nitrogen (N) management is critical for sugarbeet (Beta vulgaris L.) because N inversely influences root yield and recoverable white sucrose per tonne (RWST). In Ontario, from 2015 to 2017, the use of optical sensors (e.g., a soil plant analysis development (SPAD) chlorophyll meter, GreenSeeker handheld crop sensor) was evaluated as a method to guide N application and harvest date (late-September, late-October) selection by predicting root yield RWST and partial profit margins. In a commercial field, 4 to 5 fertilizer N rates, and 8 to 12 cultivars were tested in a split block design experiment with three replications and two harvest dates. In all years, few cultivars (≤2) had a root yield response to applied N, which was attributed to high inherent soil fertility, and limited our evaluation of optical sensors to adjust in-season N applications. The optimal N rate to maximize RWST and profits was 0 to 45 kg N·ha−1 and confirmed their negative relationship to applied N. Optical sensor readings correlated negatively with RWST across the majority (>60%) of cultivars tested in mid-August and September. Across all cultivars, the regression model of optical sensors to predict RWST at early harvest was strongest (R2 = 0.48 for SPAD; 0.24 for GreenSeeker) when readings were taken in early September. Although future research to refine this relationship is needed, we recommend the use of optical sensors, particularly the SPAD meter, in early September to guide harvest selection to maximize RWST.

Subirrigation systems are popular for reducing nutrient usage in indoor floricultural production. Two open subirrigation experiments were conducted in a commercial setting using multiple chrysanthemum cultivars and up to 75% less N–P–K than industry standards. The lowest N–P–K levels supplied in the nutrient solution (in mmol·L−1: 5.4 N, 0.71−0.97 P, 1.9−4.1 K) up to bud break, were associated with acceptable leaf N–P–K levels [4.5−5.4% dry matter (DM), 0.23−0.60% DM, and 3.3−5.6% DM, respectively]. These findings validate our modified delivery practice and the use of lower N–P–K inputs in the production of subirrigated pot chrysanthemums.

Soil structure plays a critical role in agroecosystems because it controls soil air and water capacity, nutrient availability, and crop root growth. A field experiment was conducted to evaluate the effect of bentonite on soil relative water content, soil cone penetration resistance, soil bulk density, aggregate size distribution, and millet crop yield components in a semi-arid region in northern China from 2011 to 2015. Treatments consisted of six bentonite rates (0, 6, 12, 18, 24, and 30 Mg·ha−1) applied only in the initial year. Addition of bentonite significantly increased soil relative water throughout the profile (0–60 cm) and aggregates in 0.25–2 mm class in 0–40 cm depth; it significantly decreased soil bulk density, soil cone penetration resistance, and aggregates in 0.053–0.25 mm class in the 0–40 cm depth. All of the bentonite treatments significantly increased 1000-kernel weight and panicle number up to 16% and 33%, respectively, but did not affect kernels per spike. Treatment with 24 Mg·ha−1 bentonite achieved the greatest effect on all the soil physical parameters and crop yield components averaged over all years; the highest application rate (30 Mg·ha−1) had an increasing effect over time. This study indicates that application of bentonite improves soil health in sandy-loam soil in a semi-arid region, and thus it would help promote sustainable agriculture development in regions with similar soil and climate.

This study aimed to estimate leaf litter decomposition rates in eastern beech (Fagus orientalis Lipsky) and sweet chestnut (Castanea sativa Mill.) mixed stands in Akçakoca in the province of Düzce, located in the Western Black Sea region of Turkey. The sampling areas represent four different elevations and two aspects at each elevation. Amounts of annual beech and chestnut litterfall were estimated at 5.19 and 4.61 Mg·ha−1, respectively. Litter decomposition was examined over five time periods (0.25, 0.50, 1.25, 2.25, and 4.25 years) by using the litterbag method. The mass of remaining beech leaf litter was found to be 1.1, 1.2, 1.2, 1.4, and 1.3 times greater than the mass of chestnut leaf litter, respectively. However, estimated values for the decomposition rate constant (k) of chestnut for all time periods were found to be approximately 1.5 times greater than those of beech leaf litter. Litter in beech stands decomposed more rapidly at higher elevations during the first year but at lower elevations during the second year, likely due to increased temperature and precipitation for the corresponding years. Leaf litter in chestnut stands decomposed more rapidly at lower elevations in the second and fourth years, reflecting higher precipitation for those years.

Cover crops have the potential to immobilize nitrogen (N) that would otherwise be lost before or after the main crop production, leading to improved N management. However, information on how cover crops influence N management in intensive vegetable cropping systems is scarce. This study aimed to determine how an overwintering rye cover crop impacts crop yield and N cycling, for three common prairie vegetable crops. From 2017 to 2019, a broccoli – sweet corn – root crop sequence was tested (in which all crops of rotation were present each year), with each crop type receiving five N fertilizer treatments, ranging from 0 to 300 kg N·ha−1. After harvest each year, sub-plots were established with vs. without a rye cover crop, and the effect on vegetable yield, soil inorganic N, and N use efficiency (NUE) was followed into the subsequent growing season. In most cases, the cover crop increased vegetable crop productivity and N content in the subsequent growing season. The cover crop also lowered soil inorganic N levels at vegetable planting but increased levels at harvest. Vegetable crop NUE indices were frequently improved with vs. without the cover crop. As for the N fertilizer response, increasing N fertilizer rate did not continually increase vegetable crop productivity and N content. Higher N fertilizer rates increased soil inorganic N levels at vegetable planting and harvest, and often lowered vegetable crop NUE indices. These results demonstrate the importance of adjusting soil N levels to better align with crop needs — and that including a rye cover crop in the vegetable rotation is one method of doing so.

Long winters in the Red River Valley (RRV) of eastern North Dakota and western Minnesota result in short growing seasons for corn (Zea mays L.)–soybean (Glycine max L. Merr.) systems. Historically, producers implement aggressive tillage to warm the soil, which has caused hesitation when considering reduced tillage systems. The association between soil warming–drying and crop yields via research at farmer-operated, production-scale systems practicing reduced tillage is lacking. A two-year study was conducted at three producer-operated, corn–soybean fields in the RRV with five soil series ranging from sandy loams to silty clays. Soil temperature (T), soil volumetric water content (θ), and crop yields were measured to evaluate the effects of soil warming and drying and crop performance under reduced tillage practices of vertical tillage (VT), strip tillage with shanks (STS), strip tillage with coulters (STC), and chisel plow (CP). Results showed that daytime soil T and θ in the tilled strips for STC and STS (i.e., in the plant rows) were similar to CP and significantly different from VT. The ST treatments demonstrated added benefits of higher soil θ between the tilled strips (i.e., between the plant rows) during the mid-growing season when plant water needs are at their highest. However, daily averaged soil T and θ demonstrated little to no significant differences among the tillage treatments. Moreover, crop yields were inconsistent with soil T and θ, indicating weak to no practical association in these on-farm settings.

The impact of winter bale grazing on forage productivity and nutrient cycling was determined near Winnipeg, MB, Canada. Variable distribution of nutrients and forage yield within bale-grazed plots on a perennial grass–legume forage field was identified using an intensive grid sampling method. In bale-grazed plots, mean dry matter (DM) yield of forage decreased 68% in year 1 following bale grazing, with no difference in DM yield in year 2 following bale grazing, relative to an untreated control. Decreased yield was attributed to the large mass of waste feed and feces (21% of feed delivered) that remained at the centre of each bale-grazed plot, where each bale was placed. Concentrations of crude protein, total digestible nutrients, phosphorus (P), and potassium in forage increased in the first growing season following winter bale grazing compared with the control, particularly at the centre of each bale-grazed plot. Concentrations of residual nitrate-nitrogen and Olsen P in soil were 15 and 2.5 times greater, respectively, at the centre of the bale-grazed plots compared with untreated control plots. Dispersion of waste feed packs when bale grazing in subhumid climates on clay soils is recommended to minimize smothering and encourage rapid decomposition of waste feed and feces. Long-term studies are needed to determine the potential benefits and risks of bale grazing to forage productivity and soil nutrient status in the eastern Canadian Prairies.

Management of glyphosate resistant volunteer soybean can be challenging and costly in other glyphosate resistant crops. This study examined the effect of elk (Cervus elaphus) grazing on volunteer soybean (Glycine max) management. Volunteer soybean density was assessed in four fields grazed by elk and three without elk in western Manitoba, Canada. This study determined that elk grazing of soybean stubble significantly reduced soybean volunteer density in the following crop. These results demonstrate that winter elk grazing can be an effective management technique for volunteer soybeans.

AAC Profit is a semi-leafless, yellow cotyledonary field pea (Pisum sativum L.) cultivar developed at Agriculture and Agri-Food Canada Lacombe Research and Development Centre, Lacombe, Alberta, Canada. It has a maturity of 101 d, thousand-seed weight of 218 g, and a lodging score of 4.1 on the scale of 1–9 (1 = upright, 9 = prostrate). The seed crude protein content of AAC Profit is 24.5%. AAC Profit is resistant to powdery mildew (caused by Erysiphe pisi), and moderately susceptible to mycosphaerella blight (caused by Mycosphaerella pinodes) and fusarium wilt (caused by Fusarium oxysporum).

AAC Delhi is a semi-leafless, large-seeded yellow field pea (Pisum sativum L.) variety developed at Agriculture and Agri-Food Canada Lacombe Research and Development Centre, Lacombe, AB, Canada. It has high yielding potential, medium maturity and good lodging resistance. AAC Delhi has the maturity of 95 d, and one-thousand-seed weight of 288 g. AAC Delhi is resistant to powdery mildew (caused by Erysiphe pisi Syd.) and is moderately susceptible to mycosphaerella blight (caused by Mycosphaerella pinodes) and fusarium wilt (caused by Fusarium oxysporum). AAC Delhi is adapted to all field growing regions in western Canada.

Noor hard red spring wheat (Triticum aestivum L.) was developed using a modified bulk breeding method at the University of Alberta, Edmonton, AB Canada. Noor is an apically awnletted, hollow-stemmed line with a combination of high yield potential, good lodging tolerance, and medium maturity. During the three years (2016–2018) of evaluation in the Parkland Wheat Cooperative test, Noor yielded 12% higher than the mean of all the checks and matured similarly to Carberry and Glenn, but 3.1 and 2.6 d later than AC Splendor and Parata, respectively. Noor was 94.9 cm tall, shorter than AC Splendor (98.4 cm), similar in height to Glenn (94.0 cm) and Parata (93.5 cm), but taller than Carberry (86.0 cm). The lodging score of Noor (2.1) was lower than Parata (3.0) and AC Splendor (3.0), but similar to Carberry (2.3) and Glenn (2.1). The test weight (kg·hL−1) of Noor (80.0) was higher than AC Splendor (78.6), similar to Carberry (80.2) and Parata (80.4), but lower than Glenn (82.2). Grain weight (35 g) and NIR protein of Noor (14.1%) was lower than all the checks. Overall, Noor was rated resistant (R) to the prevalent races of leaf, stem, and stripe rusts during the three years of testing. Noor was rated intermediate (I) to common bunt and Fusarium head blight. Three years of end-use quality evaluation indicated that Noor is acceptable for the Canada Western Red Spring class, with fewer flags.

Protection from fungal plant pathogens is key for optimizing the yield and quality of wheat (Triticum aestivum L.). However, current grower practices and historical research do not always align with respect to optimum fungicide timing to maximize disease control, yield, quality, and profitability of Canadian Western Red Spring (CWRS) wheat. Six fungicide treatments were evaluated at eight site–years across Alberta in 2018 and 2019 to determine the optimum time for fungicide application. The treatments included early fungicide applications at BBCH 22–23 (herbicide timing), early- to mid-season application at BBCH 30–32 (plant growth regulator timing), ‘traditional’ timing at BBCH 39–45 (flag leaf), and head timing at BBCH 61–63 (Fusarium head blight timing) and were compared with a non-treated control. Yield responses to fungicide treatments occurred at 50% of the site–years when disease pressure was 32% higher than in non-responsive site–years. Responsive site–years were characterized by higher relative humidity (65.4%–74.0%) and an average 273 mm of precipitation. At responsive site–years, McFadden leaf spot disease severity ratings were 50% greater in early August when fungicides were applied at BBCH 22–23 and 30–32 versus at BBCH 39–45. At responsive sites, yield and thousand-kernel weight were 9.3% and 5.2%, higher, respectively, for fungicide applications at BBCH 39–45 and BBCH 61–63 compared with fungicide applications at BBCH 22–23 and BBCH 30–32. The most economically beneficial practices were applications of propiconazole, benzovindiflupyr and azoxystrobin (Trivapro A+B) at BBCH 39–45 or prothioconazole and tebuconazole (Prosaro XTR) at BBCH 61–63 when environmental conditions were conducive for disease development.

Many questions remain concerning the viability and productivity of seeding native legumes in the Canadian Prairies for forage production. Field research was conducted with four native legume species (Astragalus flexuosus, Dalea purpurea, Hedysarum boreale, and Vicia americana) to evaluate performance in Swift Current and Saskatoon, SK. The experimental design was a randomized complete block design with four replicates to evaluate legume–grass mixtures and monoculture performance, botanical composition, and effect of harvest dates (July and August) from 2016 to 2018. The native legume–grass mixtures performed differently at the sites, with greater foliar cover at Saskatoon but a greater proportion of legumes in mixtures at Swift Current. The mixtures had similar forage nutritive value as monoculture Bromus riparius, with legumes contributing 10% or less of the forage dry matter yield (DMY) at both sites. Astragalus flexuosus showed the greatest foliar cover and produced the greatest DMY in monoculture at both sites. Based on this study, native legumes would need to make up a larger proportion of forage dry matter yield to change the nutritional value of mixtures. In a subsequent seeding rate evaluation, the four legume species were planted at three seeding rates [300, 200, and 100 pure live seeds (PLS) per metre] and tested for DMY one year following establishment near Swift Current. Increasing seeding rates up to 300 PLS·m−1 corresponded with an increase in seedling density and foliar cover, but DMY was not affected. Additional research with A. flexuosus is needed to demonstrate its value as a forage.