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Drought imposes a significant challenge for crop production. However, little is known about the impact of drought priming and nitrogen (N) application and their interactive effects on drought resilience, yield, and grain quality in wheat. Spring wheat (cv. Stettler) was grown in plastic pots (25 cm diameter) with high, moderate, and low soil water levels and received N (added N) or without N (no N added), and subjected to acute drought for 10 days, then rewatering at the tillering stage. Canopy temperature, maximum efficiency of photosystem II, and normalized difference vegetation index were measured at 3-day intervals during drought-recovery periods to quantify drought resistance and resilience. Above-ground dry matter, straw dry matter, seed dry matter, harvest index, and grain N, phosphorus (P), and zinc (Zn) concentrations were determined. Both moderate- and low-water-grown plants had higher drought resistance than high-water-grown plants. The addition of N alleviated acute drought stress in high- and moderate-water-grown plants but exacerbated drought stress in low-water-grown plants. Both high and moderate water resulted in higher grain yields, but had a lower harvest index than low water. The highest and lowest grain N were observed in the low- and high-water-grown plants, respectively. The addition of N increased N and N:P in grains but decreased grain Zn:N. This study showed that moderate drought priming along with N application can improve drought resistance, yield, and grain quality. The results also indicated that canopy thermal imaging is a useful tool for high-throughput quantification of the drought resistance of wheat. [ABSTRACT FROM AUTHOR]

Adoption of conservation practices such as no‐tillage (NT) may benefit soil properties and related yields. However, magnitude of changes is dependent upon time scale, soil characteristics, and climatic conditions, which has received little attention in eastern Canada. A 26‐yr field experiment was conducted on a clay loam soil at L'Acadie, southwestern Quebec, to evaluate the effect of NT vs. moldboard plow (MP) and mineral N (0, 80, and 160 kg N ha–1) and P (0, 17.5, and 35 kg P ha–1) fertilization on grain yields, soil properties, and annual net returns of a corn (Zea mays L.)–soybean [Glycine max (L.) Merr.] rotation. Tillage was performed every year, while fertilizers were only applied to the corn phase. Throughout the years, the site responded well to N fertilization but not consistently to P. Tillage system did not affect corn grain yield in the first 10 yr, but yield gradually declined under NT and produced 2.3 Mg ha–1 less than MP with recommended N rate in the last 8 yr. By contrast, NT reduced soybean yield in the first decade (0.32 Mg ha−1) but not thereafter. After 24 yr of implementation, NT largely increased organic matter and Mehlich‐3 P and K in the 0‐to‐5‐cm surface layer, but this did not translate into higher yields. Compared with NT, MP achieved CAN$200 ha–1 more revenue during last years at recommended N rate despite higher operation costs. Results demonstrated that under northern latitudes, this clay soil was not appropriate for NT. Core Ideas: Tillage system did not affect corn grain yield in the first 10 yr following implementation.Corn with recommended N rate yielded 2.3 Mg ha−1 more under moldboard than under NT in the last 8 yr.Soybean achieved higher yields under moldboard than under NT only in the first 10 yr.No‐tillage improved soil surface chemical properties.Moldboard plow achieved about CAN$200 ha−1 more revenue than NT in this site. [ABSTRACT FROM AUTHOR]

Legume crop rotational effects are usually studied in only the first subsequent non‐legume crop even though several consecutive crops usually follow a legume. We studied the effects of field pea (Pisum sativum L.), faba bean (Vicia faba L.), faba bean green manure (faba GM), lentil (Lens culinaris Medik.), canola (Brassica napus L.), and wheat (Triticum aestivum L.), on soil microbial biomass carbon (MBC), β‐glucosidase enzyme activity, and bacterial physiological diversity in three subsequent crops at four locations. Generalized linear modeling (SAS PROC GLIMMIX) indicated that, when canola is grown 3 yr after an initial canola crop in the rotation, MBC is 4–40% (Bonferroni‐adjusted limits at 95% confidence) greater than when faba bean is the initial crop. Path modeling (SAS PROC CALIS) confirmed the negative effect on MBC by faba bean (relative to canola) as an initial crop. According to Bonferroni‐adjusted limits at 95% confidence, where faba GM was the initial crop, β‐glucosidase activity was 2–24% greater than where faba bean was the initial crop and 0.4–21.8% greater than where wheat was the initial crop. Similarly, where lentil was the initial crop, β‐glucosidase activity was 2–23% greater than where pea was the initial crop and 3–5% greater than where wheat was the initial crop. Path modeling revealed direct causal relationships from faba GM and lentil to β‐glucosidase activity. The legume crop effects on soil microbial properties were: faba GM > lentil > pea > faba bean, but we did not observe diminishing effects of the initial legumes to consecutive subsequent crops. [ABSTRACT FROM AUTHOR]

Long‐term field experiments are useful for determining cropping system productivity, stability, and resource use efficiency. With 12 yr (2004–2015) of data from five cropping systems on a long‐term experiment (> 30 yr) under semiarid conditions in Saskatchewan, Canada, a systems‐approach was used to compare grain and protein yield, stability, nitrogen (N) dynamics, N fertilizer (FUEG,P), and available N use efficiency (NUEG,P) for grain and protein. Annualized grain and protein yields for wheat (Triticum aestivum L.)‐canola (Brassica napus L.)‐wheat‐field pea (Pisum sativum L.; W‐C‐W‐P) were 2244 and 372 kg ha−1, respectively, 14 to 38% and 33 to 66% higher, respectively, than continuous wheat (ContW), summer fallow‐wheat‐wheat‐wheat (F‐W‐W‐W), F‐W‐W, and lentil (Lens culinaris Medik) green manure‐wheat‐wheat (GM‐W‐W). Fallow systems were the most stable, but less productive and well‐adapted to low‐yielding conditions, while GM‐W‐W was the least stable and poorly adapted. The ContW had below‐average stability and was better suited to high‐yielding conditions for grain. The W‐C‐W‐P consistently produced above‐average yields, and was best suited for high‐yielding conditions for grain and protein. The ContW and W‐C‐W‐P had the highest NUEG (26.4 g kg−1) and NUEP (4.1 g kg−1), respectively, with GM‐W‐W having the lowest (18.1 and 2.7 g kg−1); FUE was the reverse of NUE. This long‐term study showed that diversified cropping systems that include pulses can more consistently produce higher grain and protein yields, regardless of growing conditions, than most other systems with lower N fertilizer inputs, thereby potentially reducing the negative environmental consequences associated with N fertilizer application. [ABSTRACT FROM AUTHOR]

Currently available regression equations developed to predict pre-harvest nutritive attributes from simple field measurements taken in alfalfa (Medicago sativa L.)--grass mixtures can help producers determine when to best harvest their forages but they are applicable to only spring growth. Our objective was to develop and validate predictive equations of pre-harvest forage nutritive attributes of mixed alfalfa--grass stands for the spring and first summer growth cycles. Forage samples (n = 1856) were collected in 2015 and 2016 from three research sites in Quebec, Canada, and used to develop predictive equations that were then validated using samples (n = 315) collected on commercial farms across Quebec and compared to equations previously developed in New York State for use during spring growth. For newly developed equations with two to four field measurements, R² ranged from 0.70 to 0.84. The best equation developed to estimate a neutral detergent fiber assayed with a heat stable α-amylase and corrected for the ash content of the residue (aNDFom) had an R² of 0.82 and a root mean square error (RMSE) of 29.3 g kg-1 dry matter (DM). Some equations can be used to predict aNDFom concentration and the relative feed value of samples from commercial farms, but only if alfalfa proportion can be precisely determined. Locally developed equations resulted in better predictions than equations developed only for spring growth in New York State. Forage producers now have access to a tool to predict the pre-harvest nutritive value of their forages for two growth cycles. [ABSTRACT FROM AUTHOR]

Crop rotation and nitrogen (N) fertilization can influence soil N cycling, however, less is known about their interactive effects under varying soil and climatic conditions. We examined the interactive effects of preceding crops and N fertilizer rates on soil N cycling in canola ( Brassica napus L.) and spring wheat ( Triticum aestivum L.) cropping systems in no-till soils in the Canadian prairies. 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 green manure (faba bean-GRM) were the preceding crops and were direct-seeded at 7 and 6 locations in 2009 and 2010, respectively. Canola and wheat were seeded in 2010 and 2011 (2012 for wheat at one site), respectively with N fertilizer applied at 0, 30, 60, 90 and 120 kg N ha −1 . Above-ground residue N returned was greatest for faba bean-GRM and lowest for canola and wheat. On average across sites, apparent in-crop N mineralization (ANM) under canola was greater following faba bean-GRM than all other preceding crops, except field pea, while under wheat, ANM was greater following all the legumes than following canola and wheat. Crop N uptake increased with N fertilizer rate, but the response was generally lower following faba bean-GRM and lentil. The N budget showed that 40–65% of crop N uptake (35–100% at highest ANM site) was possibly derived from ANM, more so following legumes, as compared to 35–60% from N fertilizer. The surplus and unaccounted N were particularly pronounced when canola and wheat were preceded by legumes rather than by canola or wheat. Our findings indicate that legumes can enhance soil N supply in no-till soils, and also highlight the importance of adjusting N fertilizer rates based on preceding crops to minimize the potential for N losses. [ABSTRACT FROM AUTHOR]

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]

Past agronomic practices, particularly cropping sequence and the balance between N applications and crop N removal, will influence soil N supply and crop yield potential. Nitrogen (N) fertilizer applications required to optimize crop yield and quality will be a function of the difference between crop N demand and the amount of N supplied by the soil. Therefore, assessment of the effect of past management practices on crop yield potential and soil N dynamics is important to accurately predict crop fertilizer N requirements. Field studies were conducted at seven locations representative of the varying soil types and ecozones across the Canadian prairies to determine the persistence of the effects of legume and non-legume crops and repeated N fertilizer applications on soil N supply and on the yield and N uptake of spring wheat ( Triticum aestivum L.) and canola ( Brassica napus L.) for two seasons after fertilization had ceased, corresponding to the fourth and fifth season after legume crop production. Field pea ( Pisum sativum L.), lentil ( Lens culinaris Medik.), faba bean ( Vicia faba L.), canola and wheat harvested for grain, and faba bean grown as a green manure were direct-seeded in 2009. Canola was seeded in 2010, barley ( Hordeum vulgare L.) in 2011, and canola again in 2012 with fertilizer N applied at 0, 30, 60, 90 and 120 kg ha −1 in each crop. Fertilizer N applications were then halted and spring wheat was grown in 2013 and canola in 2014, without fertilizer N applications. Very few effects of crops grown in 2009 were apparent on soil NO 3 -N supply, crop yield or crop N accumulation by 2013, which was the fourth year after crop growth, and no effects were observed in 2014. In contrast, fertilizer N applied from 2010 to 2012 had persistent effects, increasing soil NO 3 -N concentration, crop yield and crop N accumulation for two growing seasons after fertilization had ceased, although the magnitude of response varied considerably with location. By fall of 2014, effects of preceding fertilizer applications on soil NO 3 -N were no longer significant. Accumulation of N in wheat grain and straw was closely related (R 2 = 0.86) to soil NO 3 -N across locations while the relationship between soil NO 3 -N and N accumulation in canola seed was not as strong (R 2 = 0.60). Therefore, measurement of soil nitrate is a valuable tool for producers in this region to use when selecting fertilizer N application rates, but mineralization of N over the growing season will also contribute to crop N uptake. Residual effects of N fertilization can be substantial under prairie conditions, increasing N supply to crops for up to two years after the final application, and should be taken into account when assessing fertilizer use efficiency and N requirements for crop production. [ABSTRACT FROM AUTHOR]