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Forage mixtures containing legume out-yield monocultures, fix atmospheric nitrogen, and have lower carbon footprints. However, evidence-based information on creating forage mixtures by direct seeding legumes into existing pastures is limited, and information on bloat-free legumes is nonexistent. Traditionally, pastures requiring improvement in western Canada were fully replaced by breaking up the old stand and reseeding. With new and improved forage cultivars, better seeding equipment, and increased knowledge about pasture management, there is a growing interest among producers in rejuvenating pastures instead of replacing them. Pasture rejuvenation refers to the improvement in biomass productivity and (or) nutritional quality of existing pasture without removing the existing vegetation. This can be done through fertilizer application, which is generally expensive and causes negative environmental impacts. Amelioration of compacted pastureland via mechanical aeration is short-lived and can lead to weed problems. As an alternative, direct seeding of productive, nutritive and bloat-free legume species into existing pasture is an attractive option for pasture rejuvenation. For high performance grazing systems, identification of suitable bloat-free legumes and methods for direct seeding into old grass and legume stands will be essential strategies. This review includes information on the benefits of mixed pastures and seeks possible methods of introducing bloat-free forage legumes into existing pastures in western Canada for rapid improvement in productivity and quality while positively influencing animal, soil, and environmental health.

Research indicates that not all crops respond similarly to cropping diversity and the response of triticale (× Triticosecale ssp.) has not been documented. We investigated the effects of rotational diversity on cereals in cropping sequences with canola (Brassica napus L.), field pea (Pisum sativum L.), or an intercrop (triticale:field pea). Six crop rotations were established consisting of two, 2-yr low diversity rotations (LDR) (continuous triticale (T-T_LDR) and triticale-wheat (Triticum aestivum L.) (T-W_LDR)); three, 2-yr moderate diversity rotations (MDR) (triticale-field pea (T-P_MDR), triticale-canola (T-C_MDR), and a triticale: field pea intercrop (T- in P_MDR)); and one, 3-yr high diversity rotation (HDR) (canola-triticale-field pea (C-T-P_HDR)). The study was established in Lethbridge, Alberta (irrigated and rainfed); Swift Current (rainfed) and Canora (rainfed), Saskatchewan, Canada; and carried out from 2008 to 2014. Triticale grain yield for the 3-yr HDR was superior over the LDR rotations and the MDR triticale-field pea system; however, results were similar for triticale-canola, and removal of canola from the system caused a yield drag in triticale. Triticale biomass was superior for the 3-yr HDR. Moreover, along with improved triticale grain yield, the 3-yr HDR provided greater yield stability across environments. High rotational diversity (C-T-P_HDR) resulted in the highest soil microbial community and soil carbon concentration, whereas continuous triticale provided the lowest. Net economic returns were also superior for C-T-P_HDR ($670 ha–1) and the lowest for T-W_LDR ($458 ha–1). Overall, triticale responded positively to increased rotational diversity and displayed greater stability with the inclusion of field pea, leading to improved profitability and sustainability of the system.

With the increasing resistance of wild oat (Avena fatua L.) to herbicides, there is a need to evaluate the potential of alternative cropping systems based on integrated weed management principles. A 5-yr field study at eight sites across Canada was used to evaluate the profitability of alternative cropping systems that have the potential to control wild oat using cultural practices in conjunction with herbicides. Cultural practices included twice the recommended seeding rates, fall-seeded winter crops, barley (Hordeum vulgare L.) silage, fallow, and alfalfa (Medicago sativa L.). Seven of the 14 cropping systems in this study did not include wild oat herbicide for three consecutive years, controlling wild oat entirely by cultural practices. Cropping system profitability varied by location. For many locations, combinations of barley silage and fall-seeded winter crops without wild oat herbicide application were as profitable as a system of canola (Brassica napus L.) and wheat (Triticum aestivum L.) with wild oat herbicide applied every year. Unprofitable systems generally included those with fallow, alfalfa, and fall-seeded winter crops in regions with rates of high winter kill. Wild oat control can be achieved with diverse cropping systems that are as profitable as conventional annual cropping that relies on herbicide control of wild oat.

Soil organic carbon (SOC) changes slowly, and final management influences can be measured only after decades. Analysis of archived samples from a site established on grassland in 1911 showed that SOC, under wheat systems, approached steady state after several decades, and that its amount reflected the inputs of residue C.

We planted continuous wheat, with and without nitrogen fertilizer, onto a preceding long-term (44 yr) experiment with contrasting cropping systems, and measured soil organic carbon (SOC) after 6 yr. Changes in SOC were driven mostly by cumulative plant C inputs, as influenced by yield response to added nitrogen.

Recent canola acreage and production in western Canada have reached record high levels. Field experiments were conducted from 2014 to 2016 on land previously seeded to continuous canola for 6 yr at three Canadian Prairie sites. We determined that more intensive seed inputs, fertilizer, fungicide, tillage, or chaff removal could increase continuous canola yields compared with a “standard practice” (SP) treatment or match yields compared with canola in rotation. Recommended or 50% higher fertility levels alone or in combination with a higher seeding rate, tillage, chaff removal, or additional fungicide were applied to the same plots in three successive years to determine effects after 1, 2, and 3 yr of treatment imposition. In continuous canola, blackleg incidence and severity were both reduced by fungicide treatment. In rotations where canola was preceded by wheat, blackleg incidence and severity were much lower than in continuous canola. None of the treatments improved continuous canola yields compared with SP after a single year of treatment imposition. In subsequent years, canola yield increases compared with SP usually occurred as a result of additional fertilizer, seed, or fungicide. In the final year, canola yield loss due to continuous canola was largely rescued by additional seed and fertilizer. Without additional inputs, and when preceded by a different crop, canola yields averaged 11% greater than the average of all continuous canola treatments. High fertility regimes generally reduced oil content and increased protein content relative to standard fertility in continuous canola or relative to canola preceded by wheat.

Long-term field trials are ideal for characterising soil microbial communities because lasting communities in a given cropping system evolve over a long time. However, the soil microbiome has not been characterized in most long-term trials. We used a field trial established in 1911 to identify the core soil bacteria and their functioning in century-old wheat rotations, and how soil moisture deficit affected them. We collected soil samples from three wheat rotations: continuous wheat (W), fallow-wheat (FW) and fallow-wheat-wheat (FWW), all with or without N + P fertilizer, and incubated them with or without soil moisture deficit. The crop rotation effects on microbial biomass C (MBC) were in the order: W > FWW = FW. Fertilizer increased soil MBC by 21%. The activities of β-glucosidase (C cycling), N-acetyl-β-glucosaminidase (C and N cycling), and acid phosphomonoesterase (P cycling) followed similar trends, as did soil N supply measured in the field. The α-diversity of the soil bacteria was lower in continuous wheat than in the other rotations, and decreased with fertilizer application. Actinobacteria and Bacteroidetes were more abundant in continuous wheat than other rotations, and the relative abundance of Bacteroidetes increased with fertilizer application. By contrast, Acidobacteria were less abundant in continuous wheat than in other rotations. Soil moisture deficit during incubation had no effects on the soil microbiome. The core bacterial genera present in 90% of the soil samples were Bradyrhizobium, Rubrobacter, Friedmanniela and Marmoricola. β-diversity analysis revealed that the bacterial community structure in continuous wheat with fertilizer application was different from the structures in the other treatments. These and previously-published soil organic C, N and wheat yield results suggest that microbe-mediated nutrient cycling enabled sustainable continuous wheat cropping when fertilizer was applied.

Managing the land properly can help conserve the soil which is critical for sustaining our life and the global society. However, measuring the quality of the soil explicitly is still a challenge. Therefore, this study was conducted to identify suitable soil quality indicators among contrasting land managements (i.e., simple vs. complex crop rotations; manure vs. balanced fertilization) at two long-term experimental fields. The fractal structure of soils was documented by the mass-diameter relationship of soil aggregates using 3D laser scanning. Hydraulic conductivity (K), pore size fractions, and soil physical S parameter (S-index) were determined from moisture retention curves using a HYPROP system. Soil microbial community structure was characterized using phospholipid fatty acid analysis. Our results demonstrated an improved hierarchical fractal aggregation in soils under perennial legumes and grasses (Dm = 0.97) compared to nonfractal aggregation under fallow phases (Dm = 0.99). In addition, across nutrient managements, only balanced fertilization exhibited significantly enhanced fractal aggregation. Moreover, complex crop rotations and balanced fertilization also improved S-index, saturated water content (sat. WC), and plant available water (PAW) compared to their counterparts (Ps

Crop production in the semiarid Northern Great Plains has historically been limited to wheat (Triticum aestivum L.), with fallow every second or third year. In response to current prices and new production technologies, these cropping systems have been replaced with reduced frequency of fallowing and inclusion of oilseed and pulse crops in the rotation. This study examined the long-term changes that producers can expect in their production levels and economic returns for five wheat-based rotations with different fallow frequencies, use of an annual legume green manure to partially replace fallow, and a continuous diversified rotation of cereal–oilseed–cereal–pulse crops. The findings were based on the last 11 yr of a 28-yr (1987–2014) crop rotation experiment performed at Swift Current, SK, Canada. Despite the higher grain yield on fallow versus stubble, total grain production increased as fallow frequency decreased. The continuous wheat rotation produced 21% more wheat than the rotations with fallow. Wheat protein was highest for the rotation containing the legume green manure. Since its establishment in 2003, a wheat–canola (Brassica napus L.)–wheat–dry pea (Pisum sativum L.) rotation was more profitable than the traditional wheat systems. Participation in a crop insurance program reduced the financial risk from low crop yields, particularly for continuous cropping. We concluded that under current economic conditions and production practices, producers can indeed enhance production levels and farm profitability with adoption of more intensive (reduced fallow) crop rotations, particularly those that also include oilseed and pulse crops.

After 47 yr of no-till and reduced summerfallow at Lethbridge, Alberta, soil organic carbon concentration and stocks increased 2.14 g kg−1 and 2.22 Mg ha−1, respectively, in the surface 7.5 cm layer. These findings confirmed the conservation value of reducing tillage and summerfallow. The annual changes were relatively small.

Profitable malting barley (Hordeum vulgare L.) production systems are required to reverse the decline in area seeded to malting barley in western Canada. Systems that could increase the profitability of growing malting barley considered the previous crop, nitrogen (N) rate, and fungicide application. The net return (NR) and risk for these systems were computed from western Canada field data. Analysis of variance was used to evaluate the impact of systems on NR over 21 site-years of field data. Risk was evaluated with a stochastic simulation model. NR was higher and risk lower for malting barley when the preceding crop was field pea (Pisum sativum L.), when fungicide was applied at the flag leaf stage for leaf disease control, and when N was 50% of the recommended N rate. Therefore, malting barley should be grown on field pea stubble at a lower N rate, with fungicide applied when there are leaf diseases.

Field studies with two types of alfalfa (Medicago sativa L.) cultivars were conducted at Lethbridge in 2012 and 2013 and at Picture Butte in 2012 to determine the effects of irrigation on the dry matter (DM) yield and on net returns. The irrigated cultivars (Longview and Blue J) and dryland cultivars (Rangelander and Rambler) were arranged on plots in a randomized complete block design with four irrigation treatments and replicated five times. For the optimal irrigation treatment (W1), soil water content was maintained between 60 and 90% of available water in the designated root zone. Other irrigation treatments received 75% (W2), 50% (W3), and 25% (W4) of the irrigation water applied to the optimal treatment. The mean DM yields of irrigated alfalfa cultivars were greater than one of the dryland cultivars in both locations. The mean total DM yields for W2and W3at Lethbridge for Blue J, Longview and Rambler were greater than those of W1, although the differences were not always significant. The net returns, calculated by using the same price for all alfalfa harvests were similar across the cultivars and irrigation treatments excepting Rangelander, where the returns were lower. The results obtained from this study indicated a trend towards comparable yields and net returns between the optimal and the 75% irrigation treatment with 40% depletion of available water at the root zone, for the irrigated alfalfa cultivars and a dryland type Rambler.

In western Canada, more money is spent on wild oat herbicides than on any other weed species, and wild oat resistance to herbicides is the most widespread resistance issue. A direct-seeded field experiment was conducted from 2010 to 2014 at eight Canadian sites to determine crop life cycle, crop species, crop seeding rate, crop usage, and herbicide rate combination effects on wild oat management and canola yield. Combining 2× seeding rates of early-cut barley silage with 2× seeding rates of winter cereals and excluding wild oat herbicides for 3 of 5 yr (2011 to 2013) often led to similar wild oat density, aboveground wild oat biomass, wild oat seed density in the soil, and canola yield as a repeated canola–wheat rotation under a full wild oat herbicide rate regime. Wild oat was similarly well managed after 3 yr of perennial alfalfa without wild oat herbicides. Forgoing wild oat herbicides in only 2 of 5 yr from exclusively summer annual crop rotations resulted in higher wild oat density, biomass, and seed banks. Management systems that effectively combine diverse and optimal cultural practices against weeds, and limit herbicide use, reduce selection pressure for weed resistance to herbicides and prolong the utility of threatened herbicide tools.

Soil organic matter (SOM) is a major driver of key agroecosystem functions. Our objective was to examine the dynamics of organic matter in whole soil, particulate (POM; > 53 mu m size), and mineral-associated (MAOM) fractions under varying crop rotations and nutrient managements at two long-term experimental sites (Breton and Lethbridge). Soil samples were collected from simple (2 yr) and complex (5 or 6 yr) crop rotations at the 5 - 10 cm depth. We found associations between SOM pools versus microbial community and soil aggregation. Compared to cropped soils, an adjacent forest exhibited a significantly higher soil total organic carbon (TOC) and a shift in SOM fractions with substantially higher POM. However, the forest soil had the lowest microbial biomass C among all the assessed land use systems (P

Wheat (Triticum aestivum L.) is a major food source supplying nutrients required for adequate human nutrition. Changing fertility and cropping practices could alter the concentration of essential e...

Managing nitrogen (N) inputs to sustain high yields while minimizing losses to adjacent environments remains among the foremost aims in agroecosystems. We studied the N balance in a study established in 1911 at Lethbridge, AB, Canada. The experiment includes three cropping systems — continuous wheat (W), fallow–wheat–wheat (FWW), and fallow–wheat (FW) — with a factorial of two N rates (0 and 45 kg N ha−1) and two phosphorus (P) rates (0 and 20 kg P ha−1) superimposed beginning in 1967. In unfertilized subplots, grain yields generally increased for the first eight decades, but then declined, perhaps partly because of growing N deficiency. Yield response to N increased over time, especially under continuous cropping and when co-applied with P. Soil N concentration in the surface 15 cm declined in the first few decades, and then approached an apparent steady state. Application of N increased soil N, roughly in proportion to the amount of residue returned. For the first half-century (1911–1967), N removal was...

Canola (Brassica napus L.) is the most widespread profitable cash crop in Canada. In 2014 and 2015, direct-seeded experiments were conducted in 16 western Canada environments. “Small” canola seed (average 3.32–3.44 g 1000−1) was compared to “large” canola seed (average 4.96–5.40 g 1000−1) at five seeding rates (50, 75, 100, 125 or 150 seeds m−2). Large canola seeds increased crop density and crop biomass but decreased plant mortality, days to start of flowering, days to end of flowering, days to maturity, and percent green seed. Seed size did not influence harvested seed weight, seed oil content or seed protein content. Increasing the seeding rate of small seeds improved canola yield, but the same response did not occur for large seeds. Increasing seeding rates also increased crop density, plant mortality, crop biomass, and seed oil content, but decreased days to start of flowering, days to end of flowering, days to maturity, percent green seed, and seed protein content. Seeding rate had no impact on harv...

We assessed the extent to which summer fallow in the Dark Brown soil zone is likely to return as a response to net return (NR) risk. An economic model was used to identify, delineate, and quantify ...

A western Canada field study investigated the effects of seeding date and rate on malting barley quality. Seeding date had little effect on quality. Increasing the seeding rate up to 300 seeds m-2 resulted in higher germination and Kolbach indices, lower β-glucan, and better endosperm modification without compromising malt extract.

Integrated weed management (IWM) decision strategies in herbicide-resistant canola-production systems were assessed for net returns and relative risk. Data from two field experiments conducted during 1998 to 2000 at two locations in Alberta, Canada, were evaluated. A herbicide-based experiment included combinations of herbicide system (glufosinate-, glyphosate-, and imazethapyr-resistant canola varieties), herbicide rate (50 and 100% of recommended dose), and time of weed removal (two-, four-, and six-leaf stages of canola). A seed-based experiment included canola variety (hybrid and open-pollinated), seeding rate (100, 150, and 200 seeds m−2), and time of weed removal (two-, four-, and six-leaf stages of canola). For the herbicide-based experiment, strategies with glyphosate were profitable at Lacombe, but both imazethapyr and glyphosate strategies were profitable at Lethbridge. Weed control at the four-leaf stage was at least as profitable as the two-leaf stage at both sites. For the seed-based experiment, the hybrid was more profitable than the open-pollinated cultivar, seed rates of 100 and 150 seeds m−2were more profitable than 200 seeds m−2, and weed control at the two- and four-leaf stages was more profitable than at the six-leaf stage. When risk of returns and statistical significance was considered, several strategies were included in the risk-efficient set for risk-averse and risk-neutral attitudes at each location. However, the glyphosate-resistant cultivar, the 50% herbicide rate, and weed control at four-leaf stage were more frequent in the risk-efficient IWM strategy set. The open-pollinated cultivar, 200 seeds m−2rate, and weed control at the six-leaf stage were less frequent in the set. The risk-efficient sets of IWM strategies were consistent across a range of canola prices.