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The inclusion of pulse crops in Canadian rotations has the potential to improve cropping system efficiencies, reduce the overall amount of applied nitrogen, provide economic opportunities for producers, and reduce the overall carbon footprint of the cropping system. Although primarily grown in western Canada, many pulse species—field pea in particular, are well suited to temperate growing conditions in the Maritime region of Canada. A study was conducted over 2 years at Harrington, Prince Edward Island, and consisted of four field pea varieties including two yellow varieties (AAC Lacombe and CDC Saffron) and two green varieties (CDC Limerick and CDC Raezer) planted at three plant population densities: 75, 100, and 125 plants m−2. The study also measured the effects of nitrogen fertilizer applied pre-plant (0 kg ha−1 vs. 15 kg ha−1) and applied plant available sulfur (0 kg ha−1 vs. 25 kg ha−1). Overall, yellow pea varieties were higher yielding than green pea varieties, and there was a linear increase in yield with increased seeding rate. There were no significant effects of pre-plant nitrogen fertilizer on yield, although it did slightly increase seed protein. Applied sulfur had a positive effect on yield and a slightly negative effect on thousand seed weight. This experiment provides a recommendation for the optimal seeding rate (100 plants m−2) and fertility recommendations to achieve profitable yields growing field pea in the Maritime region of Canada. [ABSTRACT FROM AUTHOR]

Biobased residues are local and cost-effective sources of soil amendments that can efficiently provide nutrients to crops, enhance soil health and serve as alternatives to mineral fertilizers. The objective of our study was to comprehensively evaluate the soil health and crop productivity of temperate agroecosystems amended with different types of organic residues (biobased residues), including composted food waste (compost), biosolid slurry (biosolids) and liquid anaerobic digestate (digestate), compared with nitrogen fertilizer. The experiment was conducted on a silt loam soil under maize-soybean rotation in Canada, where a wide range of physical, chemical and biological indicators were measured and integrated into a soil health score. Biobased residues resulted in about 50%-60% increase in soil-exchangeable potassium and 10% soil-exchangeable sodium over levels found in nitrogen fertilizer. Soil microbial biomass and the capacity of soil microbes to utilize carbon substrates differed among growing seasons but not among amendment types (p > .05). Crop productivity was similar among amendment types (p > .05). We found that the soil health score of biosolids was positively correlated with shoot and root biomass and negatively correlated with shoot nitrogen (p < .05), while that of nitrogen fertilizer was positively correlated with shoot carbon (p < .05). This was likely because of a variation in the availability of labile carbon and nitrogen among amendment types. Our research also suggests that temperate silt loam soil amended with biobased residues, especially biosolids, supplied sufficient nitrogen without the need for additional nitrogen fertilizer. [ABSTRACT FROM AUTHOR]

The green manure residual effect on soil health 2 years later in crop rotation is understudied. Little is known about weed biomass impact on soil microbial communities or their interactions. A Colchester County, NS, Canada, organic grain research trial during 2016-2017 comprised 2 or 3-year rotations with or without green manure crop prior to wheat, and then soybeans. Fall soil sampling was conducted both years. The soybean phase of the crop rotation was managed as weedy or non-weedy. Weedy soil showed significantly increased soil respiratory activity and fungal microbial biomass. Green manure treatments did not significantly influence soil health indicators. [ABSTRACT FROM AUTHOR]

The Peace River region is one of the northern agricultural frontiers in Canada, undergoing farmland expansion as well as intensification with input-intensive industrial agriculture. The cropping systems evolved with the rotations between annual grain and perennial forage crops as a prudent adaptation to fragile, crust-forming, runoff-prone, poorly developed, platy-structured acidic Luvisolic soils. In recent years, there is a decline in the acreage of perennial forage seed crops leading to simplified low-diversity cropping systems with heavy reliance on external inputs. The production systems have been prone to the rapid evolution of herbicide-resistant weeds, and outbreaks of crop diseases and insect pests in the face of global warming. A number of studies conducted in the Peace River region and other parts of North America have shown multiple benefits of integrating perennial forage crops in the cropping systems. By virtue of high root-to-shoot ratio and perennial growth, forage seed crops can provide multiple ecological services in the fragile Luvisolic soil through increased soil organic matter, carbon sequestration, soil biological diversity, soil structural improvement, nutrient mobilization, crop protection and environmental health, thereby creating conducive effects to the resilient performance of the cropping systems. This review discusses the merits of crop rotations in general and those of perennial forage seed crops in particular in the face of changing climate, with special reference to studies conducted in the Prairies and Peace region of western Canada. Research opportunities are highlighted to elucidate multidimensional ecosystem services from diversified cropping sequences integrating perennial forage seed crops. Au Canada, la région de la rivière de la Paix marque une des limites les plus nordiques de l'agriculture. Les terres arables continuent de s'y étendre et l'agriculture industrielle s'y intensifie grâce à l'usage massif d'intrants. Les systèmes culturaux ont évolué et la prudence a voulu qu'on adopte des assolements annuels de céréales et de plantes fourragères vivaces en raison de la fragilité du sol, constitué de luvisols acides, mal développés, à structure lamellaire, qui forment des croûtes et sont sensibles au ruissellement. Depuis quelques années cependant, on assiste à une diminution de la superficie consacrée à la production de graines de plantes fourragères vivaces et à l'avènement de systèmes culturaux plus simples, moins diversifiés, qui reposent lourdement sur l'apport externe d'intrants. Avec le réchauffement climatique, pareils systèmes favorisent l'apparition rapide d'adventices résistantes aux herbicides, mais aussi de maladies et d'infestations de ravageurs. Plusieurs études réalisées dans la région de la rivière de la Paix et ailleurs en Amérique du Nord ont illustré les nombreux avantages de l'intégration de plantes fourragères vivaces aux systèmes culturaux. En raison de leur rapport racines:pousses élevé et de leur caractère vivace, les cultures grainières de plantes fourragères pourraient améliorer de diverses manières l'écologie fragile des luvisols (hausse de la quantité de matière organique, séquestration du carbone, diversité de la biologie du sol, amélioration de la structure du sol, mobilisation des éléments nutritifs, protection des cultures, vitalité de l'environnement), ce qui rendrait les cultures plus résilientes. Les auteurs examinent les avantages de l'assolement en général et des assolements de culture grainière de plantes fourragères en particulier face au changement climatique, en faisant spécialement référence aux études réalisées dans les Prairies et la région de la rivière de la Paix, dans l'Ouest canadien. Ils signalent les possibilités de recherche qui permettraient d'élucider les services multidimensionnels à l'écosystème attribuables à la diversité des séquences culturales qui intègrent la production des graines de plantes fourragères vivaces. [Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

This study was conducted to evaluate yield responses of four potato (Solanum tuberosum L.) cultivars ('Russet Burbank', 'Shepody', 'Gold Rush', and 'Russet Prospect') and soil N dynamic changes to two 3-year rotations in Prince Edward Island, Canada. The two rotations were the local industry standard potato–barley (Hordeum vulgare L.)–red clover (Trifolium pratense L.) rotation (PBC) and an alternative potato–soybean (Glycine max L.)–barley rotation (PSB). All potato cultivars received 170 kg N ha− 1 input at planting without irrigation. Soil mineral N content before potato planting was significantly higher under the PBC rotation. However, the PBC rotation produced significantly lower yields, suggesting the possibility of excessive N supply from the plowed-down red clover. While cultivar and the interaction between cultivar and rotation did not show a significant difference in yield, yields of all cultivars were positively affected by the PSB rotation. The Gold Rush cultivar was affected the most (36%), followed by Russet Burbank (17%) and Prospect (14%) cultivars, with Shepody being the least affected (3%) by the alternative PSB rotation. Russet Burbank was the highest yielding cultivar under both rotations. With the three russet cultivars combined as a single russet cultivar, the PSB rotation significantly increased tuber yields, while the Shepody cultivar did not significantly benefit from the PSB rotation, suggesting that the russet cultivars responded more sensitively to the alternative rotation. Results demonstrate that adequately accounting for N supply from a preceding green manure crop is required for sustainable potato production in this humid temperate region. [ABSTRACT FROM AUTHOR]

Biofumigation has been proposed as an alternative to soil fumigation to manage soil-borne diseases including potato early dying disease complex (PED). This study examined the potential of using brown mustard (Mustard juncea) biofumigation to manage PED under rain-fed potato production in New Brunswick, Canada in two trials between 2017 and 2020 in comparison with chloropicrin fumigation and a conventional barley rotation. Biofumigation increased yield in one trial, but not in a second trial where the potato crop experienced severe drought, whereas chloropicrin fumigation increased yield in both trials. Biofumigation was effective in suppressing root-lesion nematode (RLN, Pratylenchus spp.) counts in both trials, but was ineffective in suppressing V. dahliae population density. Chloropicrin fumigation was effective in suppressing RLN counts and V. dahliae population density only in the hill where injected, but the effect was short-lived as the population density of V. dahliae in the hill increased to the level of the control in one potato growing season. Biofumigation may be an alternative to chloropicrin fumigation in managing PED, particularly in fields with high RLN population but relatively low Verticillium population density. However, neither biofumigation nor fumigation used alone may be sustainable in the short-term potato rotations commonly used in New Brunswick, and additional beneficial practices are required to sustain productivity in the long-term. [ABSTRACT FROM AUTHOR]

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Copyright of Canadian Journal of Plant Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Field surveys indicate blackleg of canola has increased in western Canada since 2010. Earlier studies showed changes in the pathogen (Leptosphaeria maculans (Sowerby) P.Karst.; Lm) population between 2007 and 2010–2011. In this study, Lm isolates were collected from trap plots (591) and/or commercial fields (372) on the prairies between 2012 and 2014, and tested for the profile of avirulence (Av) genes on a set of host differentials for 10 Lm Av alleles. Up to 35 'Westar' trap plots were set up each year, and commercial fields were surveyed in the same area in 2012 and 2013. A similar trend was observed for Av profile between the two Lm populations; Av1, Av3, Av9 and AvLep2 were at low or very low levels, while Av2, Av4, Av6 and Av7 were present in >60% of the isolates. A total of 82 races were identified in these Lm populations, suggesting a greater diversity than those reported elsewhere. Margalef and Simpson indices also confirmed the greater genetic diversity in Lm. In fact, for each known R gene, there is at least one virulent race already existing in the Lm population. The races carrying Av2, Av4, Av6 or Av7 accounted for >70% of the Lm population, indicating that an R gene corresponding to any of these Av alleles may be effective against blackleg on the prairies. However, Av results alone appeared insufficient for explaining different levels of blackleg observed in canola fields; additional factors, possibly including crop rotation and local weather, may also play a role. [ABSTRACT FROM AUTHOR]

Simple rotations containing only corn (Zea mays L.) and/or soybean (Glycine max L.) dominate landscapes despite agronomic, soil health, and environmental benefits associated with diversification. We hypothesize that inclusion of wheat (Triticum aestivum L.) in corn-soybean (CS) rotations increases yield and net returns and that this benefit is becoming larger over time. Yields from rotation-tillage trials located near Elora and Ridgetown, ON, Canada, respectively, were used to investigate the yield and return effects of diversifying CS rotation using wheat with/without red clover (Trifolium pratense L). At Elora, wheat inclusion increased rate of yield increase in corn and soybean over 36 yr. During the latter 16 yr, adding wheat to CS rotation increased conventional tillage (CT) 1st and 2nd-year corn yields (with red clover) by 0.43 Mg ha-1 (4.2%) and 0.98 Mg ha-1 (11.8%), respectively, no-till 1st and 2nd-year corn yields (no red clover) by 0.78 Mg ha-1 (9.9%) and 0.45 Mg ha-1 (5.3%), respectively, and 1st-year soybean yield by 0.34 Mg ha-1 (11.8%). At Elora, net returns in the 4-yr wheat-containing rotations were 10% greater compared to the CS rotation. Similar corn and soybean yield responses including wheat in 2 or 3 yr rotations also occurred at the greater-yielding Ridgetown trial, however net returns were not increased relative to the CS rotation. Inclusion of wheat in CS rotation once every 4-5 yr may provide the optimal balance between accruing higher net returns from corn and soybean while minimizing direct net revenue reductions associated with wheat. [ABSTRACT FROM AUTHOR]

Sainfoin (Onobrychis viciifolia Scop.) and fenugreek (Trigonella foenum‐graecum L.) are two legumes that are being developed as forage crops in Canada with potential benefits for animal and human health. Sainfoin, a perennial crop containing condensed tannins (CTs), is gaining popularity in western Canada because of its benefits for cattle. Its CTs make the crop bloat‐free for grazing cattle while improving protein digestibility and reducing greenhouse gas emissions. The CT‐containing fenugreek is also considered as a bloat‐free annual forage legume that was developed to serve in short‐term crop rotations in western Canada. These crops are known to provide health and nutritional benefits to cattle with their high protein content and other beneficial nutraceuticals such as crude fiber, 4‐hydroxyisoleucine, steroid sapogenins, and galactomannans. Some of these nutraceuticals have the potential to benefit human health; however, such attributes have not been studied enough to harness the full potential of these legume crops in Canada. Recent research suggests that legumes are a healthy substitute for meat. However, metabolite analysis of sainfoin is mostly limited to proteins and CTs. The CTs reported in sainfoin are involved in reduction of blood pressure and detoxification and providing anticancer properties in humans. Recent studies on fenugreek have highlighted the beneficial nutraceuticals associated with human health but most of those claims are not backed by relevant clinical studies. In this article, we reviewed the nutritional quality attributes of sainfoin and fenugreek and assessed their potential as functional foods and nutraceuticals for animal and human health based on scientific evidence. [ABSTRACT FROM AUTHOR]

Pulse crops (PC) have become an essential part of cropping systems in the northern Great Plains. Despite agronomic benefits of rotating pulses with cereal crops, knowledge of the economics of PC frequency and sequence in a rotation is limited. A field study was conducted from 2010 to 2014 at three locations in western Canada to evaluate the effects of rotating a cereal crop with a range of PC at different frequencies and sequences on the economic returns and risk of both the entire rotation and each individual crop. Crops in rotation included spring wheat (Triticum aestivum L.) (W), field pea (Pisum sativum L.) (P), chickpea (Cicer arietinum L.) (C), lentil (Lens culinaris Medik) (L), and Oriental mustard (Brassica juncea L.) (M). Thirteen 4‐yr‐cycle crop rotation treatments, along with a continuous wheat treatment as a baseline, were included. Treatments were arranged in a randomized complete block design with four replicates at each site‐year. The net revenue (NR) was defined as the income remaining after paying all monetary, land and ownership, and labor costs. Crop rotation had a significant effect on average annual NR. The most profitable rotations were L–L–L–W and P–M–L–W. These rotations provided CAN$330 and $235 yr–1 ha–1 higher NR, respectively, than the baseline, and were most preferable by risk‐averse producers. The economic ranking of the rotations remained the same with different crop price scenarios. Preceding PC also had a positive impact on the succeeding wheat crop NR. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Plant Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Agronomic and economic performance of the corn (Zea mays L.)--soybean [Glycine max (L.) Merr.] rotation is well documented, but few studies have investigated the addition of spring wheat (Triticum aestivum L.) to this rotation, particularly at the northern limit of corn and soybean production in North America. A 6-yr field study was initiated in 1999 on a clay soil in eastern Canada to identify the best crop rotation (continuous corn, continuous soybean, corn--soybean, corn--corn--soybean, corn--soybean--spring wheat, or corn--spring wheat--soybean) under moldboard plow (MP) and reduced tillage (RT) in terms of grain yield, soil aggregate distribution, and annual net returns. To isolate the effect of annual climatic conditions, all crop phases of each rotation were present each year for a total of 13 rotation sequences within each soil tillage practice. Corn grown in rotation had greater yield (+0.6 to +0.9 Mg ha-1) than continuous corn or second-year corn regardless of soil tillage. Soybean grown once every 3 yr had consistently greater yields (+0.20 Mg ha-1) than continuous soybean. The addition of spring wheat in the rotation improved both corn and soybean yields compared with either continuously cropped. The RT management did not affect crop yield but increased the soil macro-aggregation only when corn was present in the rotation. Economic analysis revealed that continuous soybean, the 3-yr corn--soybean--spring wheat with wheat straw being sold, and the 2-yr corn--soybean were the most profitable and most efficient rotations when averse risk is considered. [ABSTRACT FROM AUTHOR]

Organic farmers have identified soil fertility and weed management as the two highest research priority areas. No review exists of research on soil nutrient management in organic field crop systems. We conducted a comprehensive review to identify the principles and factors governing nutrient management, knowledge gaps, and future research needs in organic grain and other field crop systems in Canada and the United States. We compared results from research conducted in different climates, soils, and crop rotational sequences. Results indicate that (i) dual-use cover/ green manure crops and/or animal manure are the most common sources of plant available N and other nutrients in organic field crop systems; (ii) soil nutrient deficiencies can develop through sole reliance on cover/green manure crops; (iii) dependence on animal manure can lead to N and P excesses; (iv) conventional soil testing procedures may not accurately predict crop nutrient needs; (v) greater knowledge of microbial processes governing nutrient cycling is needed; and (vi) better understanding of the impact of weeds on soil fertility may create weed and nutrient management synergies. Knowledge gaps include a lack in understanding of how the soil and plant biomes influence nutrient-use efficiency and how crop diversity and rotations impact soil fertility, sustainability, and resilience in organic field crop systems. Likewise, interactions between weeds, crops, soil fertility, and weed management strategies are poorly understood. [ABSTRACT FROM AUTHOR]

To reduce the impacts of intensive potato (Solanum tuberosum L.) production systems on the environment, beneficial management practices (BMPs) (e.g., crop rotation and conservation tillage) have been promoted in Atlantic Canada. However, quantitative information on the impacts of BMPs on yield and farm revenue is still lacking. Direct assessment of BMPs in operating farms is difficult because producers adjust other inputs and practices when implementing BMPs. A dataset with 5 yr of crop rotation, farm inputs, and soil and climate data was obtained from farms in New Brunswick, Canada. Two-step regression with a stochastic production function method was used to assess the impacts of three crop rotations and two tillage practices on potato yield. Potato yield increased when potato frequency increased in the rotation. This effect was largely caused by increased fertilizer and other inputs on rotations with a higher potato frequency. Spring moldboard plowing had negative effects on yield compared with fall moldboard plowing. The two-step yield model was used with different scenarios to estimate the effect of crop rotation on farm revenue net of input costs. Rotations with lower potato frequency had higher net revenue for the potato year, largely because of reduced input costs. However, rotations with higher potato frequency had higher overall (multiyear) net revenues because of the more valuable potato years in the rotation. Therefore, without considering the long-term impacts on the environment, the overall financial impacts of rotations with lower potato frequency were negative. This suggests that other incentives for adopting BMPs are necessary. [ABSTRACT FROM AUTHOR]

The global demands for various grains, including durum wheat (Triticum turgidum L. subsp. durum (Desf.) Husn.), are expected to increase substantially in the coming years, due to the ever-growing human population's needs for food, feed, and fuel. Thus, providing consistent or increased durum grain to the world market is one of the priorities for policy-makers, researchers, and farmers. What are the major achievements in agronomic advancement for durum wheat cultivation in recent decades? How might the current cropping systems be improved to increase crop yield and quality and improve resource use efficiencies while minimizing input costs and decreasing negative impact on the environment? Canada is one of the major durum wheat producers in the world, as Canada contributes about 50% to global trade of durum grain. Canada's research achievements in durum wheat might serve as a guide for advancing the cultivation of the crop in other regions/countries on the planet. This review summarizes the major Canadian research findings in the aspects of durum wheat agronomics during the period 2001 to 2017 years. It highlights the main advancements in seeding and tillage, crop rotation and diversification, and use of pulse-induced microbiomes to improve soil health and feedback mechanisms. The genetic gain and breeding for resistance against abiotic and biotic stresses are discussed. Finally, we identified the main constraints and suggested some near-term research priorities. The research findings highlighted in this review will be of use for other areas on the planet to increase durum wheat productivity, improve soil fertility and health, and enhance long-term sustainability. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Plant Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Journal of Plant Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Journal of Plant Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Journal of Plant Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A critical time for both water and tillage erosion is the period between growing seasons when the field is tilled and thus bare or nearly bare. During this period, there is a high risk for water erosion, leading to water eroded channels. The existing channels, tillage operations and the combination of these two may strongly affect runoff and sediment generations in the following water erosion events. However, knowledge on this is limited. In this study, plot experiments were conducted to quantify the short-term effects of an existing channel, a single pass of tillage and their interaction on the generation of runoff and sediment. Four treatments: no channel, no tillage (NN, as the control); with a channel, no tillage (CN); no channel, with tillage (NT); and with a channel, with tillage (CT) were examined. Plots under the four treatments were placed under simulated rainfall for at least one hour. Runoff and sediment samples were collected every 5-minutes after runoff initiation. The effects of treatments on the amounts of runoff and sediment were analyzed with ANOVA and ANCOVA. We found that with an existing channel, runoff initiation has accelerated and runoff discharge and sediment export have increased whereas with a single pass of tillage, runoff initiation was delayed and runoff discharge and sediment export have decreased. When an existing channel was tilled, the effects of tillage dominated while the existing channel only demonstrated some minor impacts. Applying this knowledge to a cereal-potato crop rotation common in Atlantic Canada, we recommend spring primary tillage after cereal harvesting and late fall primary tillage after potato harvesting to reduce the overall soil erosion. • Channel accelerated runoff initiation and increased runoff and sediment. • Tillage delayed runoff initiation and decreased runoff and sediment. • When an existing channel is tilled, the effects of tillage dominate. • Spring primary tillage after cereal harvesting is recommended to reduce erosion. • Late fall primary tillage after potato harvesting is recommended to reduce erosion. [ABSTRACT FROM AUTHOR]

Alternative cropping systems are gaining attention throughout the world in order to increase the sustainability of agro-ecosystems. On the Canadian prairies, the tillage-based crop-fallow system has been replaced by no-till reduced input systems or tillage-based organic systems with more diversity in crop rotations but with no external inputs. However, the long-term effects of these alternative systems on weed and yield parameters have not been assessed. A study to examine weed and crop yield dynamics under diverse cropping systems was conducted within a 18-year cropping systems study near Scott, Saskatchewan. The trial was laid out in a split-split-plot design with four replicates. The main plots were three levels of inputs; a high input system (HIGH) that used tillage and inputs to maximize yield, a reduced system (RED) that used no-till practices and minimal inputs, and a tillage-based organic system (ORG) with no external inputs. The subplots were cropping diversity (rotations); fallow-annual grains (LOW), diversified annual grains (DAG), and diversified annuals and perennial forage (DAP). The sub-sub plots were the six phases of each rotation. There was an input by rotation interaction for weed biomass but not for weed density and crop yields. ORG systems had 7× and 4× greater weed density (107 plants m −2 ), 4× higher weed biomass (154 kg ha −1 ), and 32% and 35% lower yields (1052 kg ha −1 ) than RED and HIGH systems respectively. RED and HIGH input systems had similar crop yields and lower weed density than ORG. The LOW rotation had the lowest weed density. LOW and DAG rotations had similar yields, which were higher than in DAP. All systems showed an increase in weed density and biomass over time but did not impact on crop yields which was increasing over time likely influenced by a concurrent increase in rainfall. This study concludes that eliminating tillage and reducing agrochemicals is possible but eliminating agrochemicals requires better crop rotations for weed management as well as for nutrient management. [ABSTRACT FROM AUTHOR]

A survey for the presence ofRhizoctoniaspecies on barley, bean, canola, corn, pea, soybean and wheat in 170 fields in Canada was completed during 2009–2011.Rhizoctonia solaniwas recovered from 52 (31%) of the 170 fields surveyed. A total of 191 isolates ofR. solanibelonging to anastomosis groups (AG) AG 2-1, AG 2-2, AG 4, AG 5, AG 9 and AG 11 were recovered. Fifty-two binucleate isolates ofRhizoctoniaspp. were also recovered from 35 (21%) of the crops surveyed. In growth room pathogenicity studies, isolates belonging to AG 2-1 were pathogenic primarily on canola while isolates of other anastomosis groups tended to have wider host ranges. Symptoms included pre- and post-emergence damping off, crown rot and, to a lesser extent, root rot. The majority of binucleate isolates were not pathogenic or only had low aggressiveness on the hosts tested. There was considerable variation in host range among isolates ofR. solaniwithin individual AGs, and isolates recovered from asymptomatic seedlings of some hosts were pathogenic to other hosts often used in the same rotation. Collectively, the results are important for documenting the widespread occurrence ofR. solaniin seedlings of field crops in Canada, for characterizing variation in AGs and host range, and for identifying effective crop sequences used in crop rotations. [ABSTRACT FROM PUBLISHER]

The farm-level model Holos, developed to explore mitigation options for greenhouse gas emissions (GHG) from Canadian farming systems, includes soil carbon change as a prominent component. Soil carbon was assumed to be constant, except where there was recent change in land use or management (e.g., conventional vs. reduced vs. no tillage). The factors associated with the changes were derived using CENTURY model simulations. To make Holos more responsive to farm management (e.g., crop rotation and residue management) and inter-annual climate variation, it was decided to replace the carbon change factors with the Introductory Carbon Balance Model (ICBM), a simple two carbon pool model driven by inputs from above- and belowground crop residues and manure. We showcase how the model will simulate the impact of crop rotation management decisions on soil carbon change, focussing on the choice of crop and crop residue retention, but considering also tillage and fertilization management. We argue that simulating carbon change at each field involved in the rotation is advantageous because it allows to test the rotation resilience with respect to inter-annual climate variation as well as to validate the model outputs using measurements of scientific long-term field experiments. We propose to report the farm-level carbon change results ranging from annual to centennial time frames which would be in line with the reporting requirements in carbon credit programs, while giving the user the capability to project and test new crop rotation systems using long-term carbon change forecasts. [ABSTRACT FROM AUTHOR]

Reducing tillage in herbicide-free cropping systems is a challenge for farmers and few studies have attempted to identify the limitations of organic no-till systems over a period of time greater than two years. The objective of the study was to determine the effect of tillage [no-till (NT) and conservation tillage (CT)] and management [organic (ORG) and conventional (CONV)] systems on mulch biomass, weeds, and crop productivity, over time. A six-year field study was conducted in Carman, MB, Canada, between 2008 and 2012. The crop rotation was barley ( Hordeum vulgare L.)/hairy vetch ( Vicia villosa Roth) cover crop in 2008, flax ( Linum usitatissimum L.) in 2009, oats ( Avena sativa L.) followed by a 4-species fall-seeded cover crop mixture in 2010, barley/hairy vetch cover crop in 2011, and spring wheat ( Triticum aestivum L.) followed by fall-seeded cereal rye ( Secale cereale L.) in 2012. From 2008 until mid-2010, the experiment design consisted of two tillage systems (NT and CT), both under ORG management. In mid-2010, the experiment was modified into a split-plot design to allow for the comparison between the ORG and CONV management systems, within each tillage system. In ORG NT, cash crops of flax and spring wheat were seeded into 4.5 and 4.7 Mg ha −1 of rolled cover crop mulch in 2009 and 2012, respectively. Differences in weed communities between treatments were statistically noticeable in the fifth year of the study only (2012), with higher weed biomass and weed species richness in the ORG management system. Crop yields were reduced in ORG NT in 2009 (flax) and 2012 (spring wheat). Little difference in weed and crop responses between ORG and CONV tilled systems were identified. Results suggest that additional innovative soil and weed management practices are needed to make organic continuous no-till cropping system productive for a period longer than six years, in a cool subhumid continental climate. [ABSTRACT FROM AUTHOR]

A correction is presented to the article "Improving productivity of managed potato cropping systems in Eastern Canada: Crop rotation and nitrogen source effects" which appeared in the November 10, 2002 issue.

Inclusion of legumes in crop rotations is a sustainable approach to reducing nitrogen (N) fertilizer requirements and increasing subsequent crop yields. However, the magnitude of the benefit will depend on the specific legume, the subsequent crop and site-specific conditions. This study compared the effects of preceding legumes and non-legumes on yields and economic optimum N rates (EONR) in a Hard Red Spring wheat ( Triticum aestivum L.)–hybrid canola ( Brassica napus L.) cropping sequence. Field pea ( Pisum sativum L.), lentil ( Lens culinaris Medik), faba bean ( Vicia faba L.; faba bean-seed), canola and wheat grown for grain, and faba bean grown as green manure (faba bean-GRM) were the preceding crops and were direct-seeded at six locations in western Canada in 2010. Wheat was seeded in 2011 and canola in 2012, with N fertilizer applied at 0, 30, 60, 90 and 120 kg N ha −1 in each year. Averaged across preceding crops, N application increased crop yields at all sites. Wheat grain yield was greater, with a corresponding lower EONR, following legumes than non-legumes due in part to increased N availability. Greater non-N benefits to wheat following legumes than non-legumes were also evident at all but one site, with non-N benefits being lowest for preceding wheat. While preceding legumes had no effect on canola seed yield across sites, EONR for canola were >50% lower for legume-wheat than non-legume-wheat rotations. Among the legumes, growing faba bean-GRM, field pea and lentil were most likely to increase crop yields and reduce EONR as compared to faba bean-seed. Overall, growing legumes for seed before a wheat–canola cropping sequence in conventional cereal cropping systems can increase crop yields, reduce EONR and improve the long-term sustainability of cereal cropping systems. [ABSTRACT FROM AUTHOR]

Strategies to improve sustainability are important in intensively managed potato (Solanum tuberosum L.) systems. This study has assessed rotation systems and N sources to mitigate potato yield and soil organic matter decline in Prince Edward Island (PEI), Canada. Three‐year potato rotation systems were initiated in 2006: continuous potato (CP); potato–barley (Hordeum vulgare L.) underseeded with red clover (Trifolium pratense L.)–red clover (PBR); and potato–barley–sorghum sudan grass ([Sorghum bicolor L.) used as green manure])/winter rape (Brassica napus subsp. rapifera) (PBSW); and potato–barley–canola ([Brassica napus susbsp. napus] used as green manure)/winter rape (PBCW). Three different N sources (mineral N fertilizer, liquid hog manure, and lobster flake) were applied in a split‐plot fashion during the potato phase. Potatoes were grown in 2006, 2009, 2012, and again in 2013 to evaluate residual effects. In 2012, total N or total C in the whole soil, in particulate organic matter or in the slurry fractions were not affected by N sources or rotation systems. The PBSW and PBCW rotations generated significantly higher potato yields in 2009 and 2013, whereas the CP rotation produced significantly lower potato yields in 2 of 4 yr. The addition of lobster flake suppressed yield compared with other N sources in 3 of 4 yr. The PBR rotation, which is common in PEI can increase nitrate losses over winter. Alternatively, the PBSW and PBCW rotations may represent a good substitute to the PBR rotation as they can increase potato yield while minimizing nitrate losses. [ABSTRACT FROM AUTHOR]

Glyphosate (N-(phosphonomethyl)glycine) is broad-spectrum herbicide that is extensively used worldwide, but its effects on the soil microbiome are inconsistent. To provide a sound scientific basis for herbicide re-review and registration decisions, we conducted a four-year (2013-2016) study in which we consecutively applied glyphosate to a wheat (Triticum aestivum L.)-field pea (Pisum sativum L.)-canola (Brassica napus L.)-wheat crop rotation at five sites in the Canadian prairies. The glyphosate rates were 0, 1, 2, 4 and 8 kg ae ha -1 , applied pre-seeding and post-harvest every year. The wheat rhizosphere was sampled in the final year of the study and analysed for microbial biomass C (MBC), the composition and diversity of the microbiome, and activities of β-glucosidase, N-acetyl-β-glucosiminidase, acid phosphomonoesterase and arylsulphatase. Glyphosate did not affect MBC, the composition and diversity of prokaryotes and fungi, and the activities of three of the four enzymes measured in the wheat rhizosphere. The one effect of glyphosate was a wave-like response of N-acetyl-β-glucosaminidase activity with increasing application rates. The experimental sites had much greater effects, driven by soil pH and organic C, on the soil microbiome composition and enzyme activities than glyphosate. Soil pH was positively correlated with the relative abundance of Acidobacteriota but negatively correlated with that of Actinobacteriota and Basidiomycota. Soil organic C was positively correlated with the relative abundances of Proteobacteriota and Verrucomicrobiota, but negatively correlated with the relative abundance of Crenachaeota. The activity of acid phosphomonoesterase declined with increasing relative abundance of Acidobacteriota, but increased with that of Actinobacteriota and Basidiomycota. The activity of N-acetyl-β-glucosaminidase also increased with increasing relative abundance of Actinobacteriota but decreased with that of Mortierellomycota. β-glucosidase activity also decreased with increasing relative abundance of Mortierellomycota. The core fungal species observed in at least 90% of the samples were Humicola nigrescens, Gibberella tricincta and Giberella fujikuroi. Therefore, this multi-site study on the Canadian prairies revealed no significant effects of 4-year applications of glyphosate applied at different rates on most soil microbial properties despite differences in the properties among sites. However, it is important to keep evaluating glyphosate effects on the soil microbiome and its functioning because it is the most widely used herbicide worldwide., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Crown Copyright © 2022. Published by Elsevier Inc. All rights reserved.)

This review examines how changing fungicide usage in Canada is increasing the risk of fungicide insensitivity in pathogen populations, using examples from field, vegetable and horticultural crops. The current generation of systemic fungicides is selective, effective and has a reduced impact on the environment compared with older contact fungicides. However, many of these new fungicides also have an increased risk of fungicide insensitivity. On the Canadian prairies, a trend towards specialization of production within regions has resulted in limited cropping rotations, or even no rotation, in many fields, and yield targets are increasing. As a result, the frequency and extent of fungicide usage is increasing rapidly and insensitivity to certain fungicides has been identified in several crop pathogens. Case studies of fungicide insensitivity onAscochyta rabieion chickpea,Mycosphaerella pinodeson field pea,Fusarium sambucinumandPhytophthora infestanson potato,Pythium violae,P. sulcatumand other species on carrot, andBotrytis cinereaon grapes and berry crops are examined. Fungicide manufacturers have taken action to protect the efficacy of high-risk fungicides by formulating them with active compounds with a different mode of action. Also, producers have been advised to rotate fungicides with different modes of action to minimize the risk of insensitivity. Monitoring for fungicide insensitivity is central to early warning of an impending issue with insensitivity, for disease risk prediction and for avoiding disease control failures. In addition, information on insensitivity at the population level could be used to develop and implement insensitivity management programmes. [ABSTRACT FROM PUBLISHER]

Abstract: The government of Ontario, Canada, has committed to stopping the use of coal for electrical generation by 2014 and agricultural biomass is being considered as replacement. However, there is limited information on whether the annual 2 million Mg of biomass required to replace coal could be sustainably supplied by agriculture and at what costs. This study assesses the sustainable availability and the farm-gate break-even cost of residue biomass from three crops (corn, soybean and winter wheat) grown under two common rotation scenarios in Ontario. Sustainably removable residue (SRR) rates are determined using a five-step approach that accounts for maintenance soil organic matter (MSOM) in the presence of yield and rotation variations across counties. Under typical SOM formation and decomposition conditions and assuming typical corn-soybean and corn-soybean-winter wheat rotation scenarios, about 1.1 million Mg of residue could be sustainably removed each year, primarily from the major agricultural counties in the province. While rotational complexity enhances SRR, the inclusion of soybean decreases available residue compared to corn and winter wheat. The break-even price for crop residues, representing the minimum price necessary to cover all variable and fixed costs for the farmer, is between $57 Mg−1 and $87 Mg−1. However, the actual amount supplied for each biomass price depends critically on the opportunity costs associated with not growing typical crops in the conventional manner. [Copyright &y& Elsevier]

Abstract: Tillage and rotation are fundamental factors influencing soil quality and thus the sustainability of cropping systems. Many studies have focused on the effects of either tillage or rotation, but few have quantified the long term integrated effects of both. We studied the issue using a 30-year old long-term rotation and tillage treatment experiment on a Canadian silt loam soil. Topsoil measurements were carried out for three different rotations: R1, (C–C–C–C) continuous corn (Zea mays L.), R6, (C–C–O(RC), B(RC)) corn, corn, oats (Avena fatua L.) and spring barley (Hordeum vulgare L.) and R8, (C–C–S–S) corn, corn, soybean (Glycine max L.), soybean. A red clover (Trifolium pretense L.) cover crop was under seeded in oats and spring barley in R6. In 2010, first year corn was grown in R6 and R8. The tillage treatments included no tillage, NT and mouldboard ploughing, MP. Topsoil structural quality was visually evaluated in early June and mid October. Minimal disturbed soil cores collected in early June were used for X-ray CT scanning and to quantify water content and porosity. Soil friability was determined on the soil samples using a drop shatter test. Crop yield was determined and correlated to the soil quality estimates. We found significant effect of both rotation and tillage on visual soil structure at both times of assessment. Poor soil structure was found for NT except when combined with a diverse crop rotation (R6). The soil core pore characteristics data also displayed a significant effect of tillage but only a weak insignificant effect of rotation. The drop shatter results were in accordance with the visual assessment data. Crop yield correlated significantly with the visual soil structure scores. We conclude that a diverse crop rotation was needed for an optimal performance of NT for the studied soil. [Copyright &y& Elsevier]

The article presents a study on stubble options for winter wheat in the Black soil zone of western Canada. The researchers grew winter wheat, hard red spring wheat, barley, and oats on each stubble type at each study area. The results of the study indicate that stubble alternatives are available for winter wheat plantings in western Canada.

Abstract: Agricultural soils are a significant anthropogenic source of nitrous oxide (N2O) to the atmosphere. Despite likely having large emissions of N2O, there are no continuous multi-year studies of emissions from poorly drained floodplain soil. In the present study, the micrometeorological flux of N2O (F N ) was measured over three years (2006–2008) in a maize (Zea mays L.)/faba (Vicia faba minor L.)/spring-wheat (Triticum aestivum L.) rotation in the Red River Valley, Manitoba, Canada on a gleyed humic verticol soil. Comparison of newly established reduced and intensive tillage treatments showed no difference in F N within the constraints of the high variability between duplicate plots. The annual gap-filled ΣF N across tillage treatments was 5.5, 1.4, and 4.3kgNha−1 in the maize, faba, and spring-wheat crop years, respectively. Emissions from fertilizer N addition and soil thaw the following spring was responsible for the greater ΣF N in the maize and spring-wheat years. Using four approaches to approximate background ΣF N resulted in estimates of 3.5–3.8% and 1.4–1.8% of applied fertilizer N emitted as N2O for the maize and spring-wheat crops, respectively. The CO2 global warming potential equivalent of ΣF N over the three study years was an emission of 5.4MgCO2-equiv.ha−1 which adds to the previously determined C balance emission of 11.6MgCO2-equiv.ha−1. [Copyright &y& Elsevier]

Abstract: Growing interest in environmental quality has provided a strong incentive to examine how farming practices affect agricultural products’ carbon footprints (CF), an environmental quality indicator. This study determined (i) the CF of spring wheat (Triticum aestivum L.) grown in different cropping systems over 25 years, and (ii) the effect of soil organic carbon (SOC) changes over years on wheat CF. Wheat was grown in four cropping systems: (a) fallow-wheat (FW), (b) fallow-wheat-wheat (FWW), (c) fallow-wheat-wheat-wheat-wheat-wheat (FWWWWW), and (d) continuous wheat (ContW), in replicated field plots in Saskatchewan, Canada. Wheat CF was calculated at a system level with measured variables coupled with modeling approaches. Over the 25-year period, the soil under the ContW system gained organic C of 1340kgCO2 eqha−1 annually, or 38%, 55%, and 127% more than those gained in the FWWWWW, FWW, and FW systems, respectively. The SOC gain more than offset the greenhouse gas (GHG) emissions occurred during wheat production, leading to negative emission values at −742kgCO2 eqha−1 annually for ContW, and −459, −404, and −191kgCO2 eqha−1 for FWWWWW, FWW, and FW systems, respectively. Wheat in the ContW system produced the highest grain yield and gained highest SOC over the years, leading to the smallest (more negative) CF value at −0.441kgCO2 eqkg−1 of grain, significantly lower than the CF values from the three other systems (−0.102 to −0.116kgCO2 eqkg−1 of grain). Without considering the SOC gain in the calculation, wheat CF averaged 0.343kgCO2 eqkg−1 of grain and which did not differ among cropping systems. Wheat is the largest agricultural commodity in Saskatchewan, and the way the crop is produced has significant impacts on environmental quality, reflected by its carbon footprint. Cropping systems with decreased fallow frequency was shown to significantly enhance soil carbon gains over the years, increase annualized crop yields, and effectively lower the carbon footprint of this important commodity. [Copyright &y& Elsevier]

Strong market demand for canola, Brassica napus L., has prompted some wester Canadian producers to increase the frequency of this crop in rotations with other crop species, but the impact of this practice on canola insect pests has not been determined. Here, we investigate 12 cropping sequences involving canola over a 3-yr period (2008-2010 inclusive) at five locations across western Canada. Cropping sequences varied from continuous production of two herbicide-tolerant canola varieties, to production in two of 3 yr, to canola production in one of the 3 yr. Treatments analyzed were the frequency and timing of canola within the rotational sequence. Damage by larvae of root maggots (Diptera: Anthomyiidae: Delia spp.) to canola taproots increased as the study progressed, particularly in 2010 after canola had been grown continuously for 3 yr. Yield declined with continuous canola production, and differences were greatest in 2010. At mean canola crop prices for 2010, the yield reduction from continuous production amounted to economic losses of approximately Can$282-$377/ha. Crop quality, in terms of oil and protein concentrations of harvested seed, was affected more by crop variety than cropping sequence. Crop sequence effects for root maggot damage, yield, and seed quality were relatively stable in the presence of environmental (location) variation. Results of our study suggest that continuous canola production could be unsustainable over the long-term even though market forces currently provide incentive for this practice. [ABSTRACT FROM AUTHOR]

The article discusses the results of experiments that determined if high level of crop inputs could increase canola seed yield and oil concentration over yield levels during the experiment period. Herbicides, insecticides and fertilizers were applied during planting as required for optimal production. Results indicate that canola oil concentration varied among cultivars but consistently low when nitrogen rates were high, although in some cases normal seeding rates led to high oil concentration.

Canada recently implemented a federal mandate of 2% of renewable content in diesel fuel and heating oil. Federal-level biofuel strategy is currently more geared to bioethanol, as nonfood oils continue to be more cost-competitive and canola seeded area is forecast to increase 10% as a new record due to strong prices and high expected yields. Increasing focus is therefore being placed on alternative oilseeds as nonfood crops for biodiesel and their ability to adapt to the semiarid conditions of the Canadian Prairies and provide benefits in nutrient and water-use efficiency when introduced into the crop rotation. Systems engineering and supply-chain modeling and optimization will have an increasingly important role in decision making for designating supply units, the linkage of processes and chains, and biorefinery system design. However, current models require further enhancement to address current challenging questions: (1) changing spatial considerations (e.g., land use and suitability for feedstocks), (2) changing temporal dynamics of supply and risk of climate extreme impacts on transportation networks (road, rail, pipeline), price volatility, changes in policy targets and subsidy regimes, process technological change, and multigenerational biorefinery systems engineering advancements. Greater integration internationally in model development and testing would improve sensitivity and reliability in their system-level predictions and forecasts. [ABSTRACT FROM AUTHOR]

The article discusses the results of a study on the influence of nitrogen and phosphorus fertilizer on the nitrogen use efficiency (NUE) of continuous wheat and fallow-wheat-wheat using balance and difference methods. The study revealed that nitrogen use efficiency (NUE) in the balance method was not affected by fertilizer or crop rotation. It mentioned that NUE was greater in continuous wheat than in fallow-wheat-wheat in the difference method.

Surface water sampling in 2006-2008 measured the occurrence of sulfonylureas and related herbicides (SUs) during base flow conditions and wet weather events. Flumetsulam (29.2%), diuron (36.5%) and fomesafen (25.3%) were most frequently detected over the course of the study. Typical SU concentrations were in the low parts per trillion range; however, maximum concentrations of fomesafen (873 ng/L), linuron (856 ng/L) and diuron (2,900 ng/L) approached or exceeded 1 μg/L. The temporal trend in SUs showed a correlation with application periods. In general, detections of SUs were more frequent where rotation of row crops was more intense. Sampling during wet-weather events indicated potential for a range of SUs to be flushed into surface waters at relatively high concentrations. [ABSTRACT FROM AUTHOR]

The depth of sampling has recently been highlighted as critical to making accurate measurements of changes in Soc stocks. This paper aimed to determine the effects of land management changes (LMC) on soil organic carbon (SOC) by re-sampling long-term agoecosystem experiments (LTAEs) across Canada using identical sampling and laboratory protocols. The impact of sampling depth on the monitoring of LMC-induced differences in soc stock in LTAEs in Canada, and the implications on statistical power and sampling design, were assessed. In most cases, four cores would be suitable for detecting a significant difference in SOC stock of 5 Mg ha-1 at 95% confidence for LMCs in western canada. The impact of eliminating fallow on SOC stocks was typically restricted to the surface 15 cm. The impact of perennial forages on the average cumulative SOC was sufficiently large to be detectable at all sampling depths (to 60 cm). In three of the six LTAEs sampled in western canada comparing conventional tillage to no-till, there was a significantly greater SOC storage in the 0- to 30-depth than the 0- to 15-cm depth, suggesting that sampling below 15 cm could be necessary. The same comparisons in eastern Canada suggested that sampling often must exceed the 30-cm depth to account for any changes in SOC due to moldboard plow tillage. Nonetheless, there was little evidence to suggest that increasing sampling intensity or sampling deeper would improve the ability to detect a difference in SOC stocks foe this LMC. [ABSTRACT FROM AUTHOR]

Increased farm salmon production has heightened concerns about the association between disease on farm and wild fish. The controversy is particularly evident in the Broughton Archipelago of Western Canada. where a high prevalence of sea lice (ectoparasitic copepods) was first reported on juvenile wild pink salmon (Oncorhynchus gorbuscha) in 2001. Exposure to sea lice from farmed Atlantic salmon (Salmo salar) was thought to be the cause of the 97% population decline before these fish returned to spawn in 2002, although no diagnostic investigation was done to rule out other causes of mortality. To address the concern that sea lice from fish farms would cause population extinction of wild salmon, we analyied 10-20 y of fish farm data and 60 y of pink salmon data. We show that the number of pink salmon returning to spawn in the fall predicts the number of female sea lice on farm fish the next spring, which, in turn, accounts for 98% of the annual variability in the prevalence of sea lice on outmigrating wild juvenile salmon. However, productivity of wild salmon is not negatively associated with either farm lice numbers or farm fish production, and all published field and laboratory data support the conclusion that something other than sea lice caused the population decline in 2002. We conclude that separating farm salmon from wild salmon-proposed through coordinated fallowing or closed containment-will not increase wild salmon productivity and that medical analysis can improve our understanding of complex issues related to aquaculture sustainability. [ABSTRACT FROM AUTHOR]

Field studies were conducted over 4 years at two locations in Manitoba, Canada to evaluate effects of preceding crop, tillage and phosphorus (P) fertilization on Cd and Zn concentration in oilseed flax (linseed— Linum usitatissimum L.). Canola ( Brassica napus L.) and spring wheat ( Triticum aestivum L.) were grown under conventional and reduced tillage with three rates of monoammonium phosphate. Flax was seeded the year following the spring wheat or canola, with or without P fertilizer, and Cd and Zn concentration and accumulation were determined in the flax tissue at 5 weeks and in the mature seed. Flax following canola had lower Zn concentration and accumulation and higher Cd concentration and Cd:Zn ratio in the tissue and seed relative to flax following wheat. Phosphorus fertilization tended to increase Cd concentration and Cd:Zn ratio and decrease Zn concentration in the tissue and seed. Effects of tillage and interactions among tillage, preceding crop, and P fertilization were inconsistent. Changes in flax Cd and Zn concentration may be due to changes in mycorrhizal colonization or by the high concentration of Cd in the decomposing canola residue. Crop sequence and P management can be used to improve flaxseed food quality, by increasing Zn and decreasing Cd concentration. [ABSTRACT FROM AUTHOR]

Contarinia nasturtii (Kieffer) (Diptera: Cecidomyiidae), a common insect pest in Europe and a new invasive pest in North America, causes severe damage to cruciferous crops. Many counties in Canada and the USA, in which C. nasturtii has not been previously reported, are at risk of being infested by C. nasturtii. Effectiveness of chemical control is limited, especially under high population pressure in fields. Alternative management strategies against C. nasturtii are sorely needed in order to protect crucifers. Under controlled laboratory conditions, the effectiveness on C. nasturtii control by 11 simulated cauliflower-sweet corn and cauliflower-kidney bean crop rotation systems was evaluated, with and without the presence of cruciferous weeds as alternative hosts. Our results indicated that when soil was infested with C. nasturtii pupae, the emergence pattern from the soil was very similar regardless whether the soil was later planted to host or non-host plants. As emergence was not affected, we examined whether manipulating host availability for oviposition through crop rotation would be effective. Our results indicated that the simulated cauliflower-sweet corn and cauliflower-kidney bean rotation systems provided full control of C. nasturtii. The effectiveness of one cycle of non-host crop rotation was reduced when cruciferous weeds were present. However, the C. nasturtii population in a one-cycle non-host rotation system with cruciferous weeds present was significantly lower than that in a non-rotation system. Two consecutive cycles (simulating a cropping season) of non-host plant crop rotations provided full control of C. nasturtii, regardless of the presence of the cruciferous weeds. The importance of cruciferous weed management and how to implement a successful crop rotation in fields to control C. nasturtii are discussed. [ABSTRACT FROM AUTHOR]

Abstract: Conservation tillage in potato (Solanum tuberosum L.) systems, in cool-humid climatic regions, can benefit soil physical and biological properties. However, insight is needed on how the combination of conservation tillage and crop rotation enhances the resilience of intensive short-term potato cropping systems, specifically the restoration of the soil condition after the perturbations that occur in the potato phase. A long-term 3-year rotation (potato-barley-red clover) and conservation tillage study was initiated in 1994 on a fine sandy loam in Prince Edward Island, eastern Canada. Over a 3-year period (2004–2006), soil physical (bulk density) and biological (C and N fractions, structural stability; densities of plant parasitic and bacterial-feeding nematodes, and micro-arthropod abundance and diversity) properties were monitored over each phase of the crop rotation cycle to assess the restoration or rejuvenation of the surface (0–10cm) soil condition. Conservation compared to conventional tillage, increased soil organic C, large water-stable macro-aggregates, and soil particulate C and N in the potato year only. After the potato phase, rotation crops were associated with the further restoration of all soil C and N fractions and soil structural stability indices; and also increases in soil microbial biomass C and microbial activity indices, and soil Collembola abundance. Soil nematode densities showed some incidences of treatment differences but no clear trends. The study indicated that conservation tillage has a positive influence on soil biological properties and that the 3-year rotation successfully restored many of the soil parameters that had declined in the potato year. [Copyright &y& Elsevier]

Tillage and crop residue management can have large impacts on soil organic carbon (SOC) sequestration, as well as additional feedbacks on crop productivity and agricultural sustainability. The objectives of this study were to (i) evaluate the effects of summer fallow, legume green manure, pea or canola in rotation with spring wheat on crop yields, biomass production and SOC dynamics (0–15 cm) from six long-term cropping systems under semiarid conditions in western Canada, (ii) calibrate and validate three process-based models (DNDC, DayCent and DSSAT) using experimental data, and (iii) investigate the long-term impacts of tillage (no-tillage (NT) vs. conventional tillage (CT)) and straw residue (returned vs. removal) on SOC changes from diverse rotation systems. Over the experimental period from 1987 to 2015, the average wheat yields in Wheat (W)-Canola (C)–W-Pea (P) and legume green manure (LGM)-W-W rotations increased by 33.5 and 10.8%, respectively, compared to the continuous wheat (ContW) cropping systems. Higher SOC sequestration rates were found under ContW, LGM-W-W and W–C–W–P cropping systems mainly due to higher residue C input and larger nitrogen (N) inputs/fixation when compared to fallow-wheat systems. All three models performed "fair" to "good" in simulating crop yield, biomass and SOC content over time across all treatments. DSSAT had the lowest errors of prediction for yields (e.g., normalized RMSE (nRMSE) ≤ 27.2%, index of agreement (d) ≥ 0.79), while DNDC had better estimates of SOC content (e.g., nRMSE ≤ 4.5%, d ≥ 0.74). Long-term scenario analysis demonstrated that the mean annual changes in SOC across rotations based on model ensemble ranged from 0.03 Mg C ha−1 y−1 under CT with straw removal to 0.31 Mg C ha−1 y−1 under NT with straw returned. Predicted SOC sequestration potential of NT was relatively small compared to crop straw return for all rotation systems. This study suggests that diverse crop rotations which include canola and legume crops have the potential to store more SOC than traditional wheat-based cropping (e.g., fallow-wheat, ContW) for the semiarid prairies of Canada. These diverse rotations are already becoming more common and can help to enhance crop yields and maximize SOC sequestration when they are coupled with NT and residue management. • DNDC, DayCent and DSSAT well predicted grain yield and SOC for diverse rotations. • Wheat (W) yield and SOC increased when in rotation with canola and legumes. • DNDC more accurately simulated SOC in comparison to DSSAT and DayCent. • Higher SOC sequestration rates were estimated for straw return than for no-tillage. • Long-term rotations W–C (canola)-W-C and C–C–C–P (pea) had the largest increases in SOC. [ABSTRACT FROM AUTHOR]

• Long-term rotations with/without nitrogen (N) and phosphorus (P) fertilization. • Multiple techniques: P-NMR, P K-edge XANES, P fractionation, phosphatase assays. • Soil pH and organic carbon were significant predictors of soil P forms. • Long-term fertilization altered P forms by changing soil chemistry. • Rotation phase altered total and organic P concentrations regardless of fertilization. Efficient phosphorus (P) management is important for crop production and environmental sustainability of cropping systems. The effects of the agricultural management practices of crop rotation and fertilization on soil P forms and cycling were investigated in plots in Swift Current, SK, Canada, under three crop rotation phases [fallow (F), wheat after fallow (WF), and wheat after wheat (WW)], with four nitrogen (N) and/or P fertilizer treatments (+N+P, -N+P, +N-P, and -N-P), using techniques including sequential fractionation, 31P nuclear magnetic resonance (P-NMR), and P K-edge X-ray absorption near-edge (P-XANES). Soil total P (TP) and organic P (P o) concentrations were significantly reduced in F and WW phases compared to WF regardless of fertilization practice. Compared to WW, WF had the highest grain yield and nutrient uptake. Fertilization with N and P significantly influenced soil total carbon (C), total N, TP, and Mehlich 3-P concentrations and acid phosphatase activities, as well as the concentration of some P pools by sequential fractionation and stable P determined by P-XANES. Stopping P fertilization significantly increased the proportions, but not concentrations, of soil P o determined by P-NMR compared to plots still receiving P fertilizers, while the concentration of total diesters increased in plots fertilized with N. Redundancy analysis showed that soil pH and organic C were the significant predictors of P forms in these soils, suggesting that long-term N and P fertilization altered soil P forms by changing soil chemical properties. [ABSTRACT FROM AUTHOR]