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We used a common garden study to investigate genetic variation in spring budburst phenology, growth, and structural traits of ponderosa pine (Pinus ponderosa Lawson & C. Lawson var. scopulorum Engelm.) seedlings from 10 provenances of different elevations in Arizona and New Mexico, United States. Seedlings were grown with ample resources for two growing seasons in a greenhouse in northern Arizona. Budburst date was measured at the onset of the second growing season; seedling growth, biomass, biomass ratios (shoot:root ratio, root mass ratio, stem mass ratio, and leaf mass ratio), and specific leaf area were measured at the end of the second season. Low-elevation provenances (2500 m) provenances. Height, leaf length, biomass, and biomass ratios were similar for elevational groups. Total biomass was positively correlated (r = 0.824) with provenance mean annual precipitation. Shoot:root ratio was positively correlated (r = 0.652) with longitude. Results suggest adaptation of low-elevation provenances to warm spring temperatures (early budburst) and aridity (low specific leaf area), inherently faster growth of provenances from wet locations, and greater allocation to shoots in eastern provenances. Such information about geographic patterns of genetic variation may be useful for selecting seed sources for planting in a changing climate.

Long-term (58 yr) cropping and fertilization effects on soil water repellency were determined for a clay loam soil in southwestern Ontario, Canada by measuring soil organic carbon (SOC), soil water repellency index (RI), and soil hydrophobicity (SH). The 12 treatments (non-replicated) included fertilized and non-fertilized legume-based crop rotation (ROT) with four phases (corn–oat–alfalfa–alfalfa), continuous corn (CC), and continuous Kentucky bluegrass (KBG). We hypothesized that SOC, RI, and SH would be greater for each phase of the ROT versus CC, KBG versus CC and ROT, and fertilized versus non-fertilized treatments. Surface (0–10 cm) soil samples were collected in the spring of 2017. Laboratory measurements were conducted to determine SOC, RI (ratio of soil sorptivity to ethanol and water), and SH (ratio of hydrophobic CH– to hydrophilic CO– functional groups). Mean SOC and SH were greater (P ≤ 0.05) for each phase of the ROT versus CC (33% to 2.4 times), KBG versus CC (3.2–6 times) and each phase of ROT (2.2–2.8 times), and fertilized versus non-fertilized rotation oats and KBG (15%–30%). Mean RI was greater for KBG versus CC (4.8 times) and KBG versus each phase of the ROT (3.0–5.5 times) under fertilization only, greater for fertilized versus non-fertilized KBG (6.8 times), but similar for each phase of ROT versus CC. In general, legume-based rotations, perennial grass, and fertilizer enhanced SOC and SH, and to a lesser extent soil RI.

In Canada, most lettuce (Lactuca sativa L.) is produced on cultivated organic soils, which can be very productive but are also very sensitive to degradation and compaction. The objective of this work was to evaluate the effect of soil compaction, irrigation thresholds, and transplant type on the growth and water-use characteristics of Romaine lettuce that is grown in organic soil. The experiments were conducted in greenhouses at Laval University. Tensiometers and time-domain reflectometer probes were used to characterize the water-use characteristics of the Romaine lettuce. Most of the growth characteristics of the Romaine lettuce, with the exception of the dry weight, were significantly influenced by the available rooting depth (soil column height) and by the irrigation threshold used. Lettuce water uptake decreased significantly as the depth increased. In addition, in drier conditions, the deeper soil layers contributed more to the total water uptake than the surface soil layers. The water productivity was lower in the presence of a compacted layer combined with a direct seeding treatment, compared with all of the other treatments. First, it is concluded that the irrigation method should allow a certain degree of dryness by use of a lower irrigation threshold (ideally between −20 and −30 kPa) to stimulate deep rooting. Second, the use of small lettuce plant preseeded in small block of peat substrate instead of direct seeding in the field can compensate for a possible compaction effect.

Short-rotation forestry relies on frequent harvests of fast-growing trees, which could deplete soil fertility and soil organic carbon (SOC) reserves. Our objective was to measure the accumulation of SOC fractions, namely the dissolved organic carbon, microbial biomass carbon, particulate organic carbon, permanganate-oxidizable carbon, and non-oxidizable organic carbon, in the soil profile of a Chinese fir plantation. Chronosequences of Chinese fir aged 7, 12, and 33 yr were sampled at depths of 0–20 cm, 20–40 cm, and 40–60 cm. The SOC stock (0–60 cm) was unchanged in the first 12 yr, but after 33 yr, there was a 41%–56% increase in the SOC stock, which reached 81.2 Mg ha−1 (P

Trees in dry forests often regenerate in episodic pulses when wet periods coincide with ample seed production. Factors leading to success or failure of regeneration pulses are poorly understood. We investigated the impacts of stand thinning on survival and growth of the 2013 cohort of ponderosa pine (Pinus ponderosa Douglas ex P. Lawson & C. Lawson) seedlings in northern Arizona, United States. We measured seedling survival and growth over the first five growing seasons after germination in six stand basal areas (BAs; 0, 7, 14, 23, 34, and 66 (unthinned) m2·ha−1) produced by long-term experimental thinnings. Five-year survival averaged 2.5% and varied among BAs. Mean survival duration was longer in intermediate BAs (11 to 16 months) than in clearings and high BAs (5 months). The BAs of 7, 14, and 23 m2·ha−1had >2600 5-year-old seedlings·ha−1. In contrast, regeneration was lower in the clearing (666 seedlings·ha−1) and failed completely in the 34 m2·ha−1and unthinned treatments. Seedling survival was highest during wet years and lowest during drought years. Many surviving seedlings had no net height growth between years 4 and 5 because of stem browsing. Results indicate that natural regeneration of ponderosa pine is influenced by stand BA, drought, herbivory, and interactions between extreme climatic events.

Nitrogen (N) release from legume cover crops is a key N source for subsequent crops in rotation. In this study, chopped fresh shoots or roots (−1. The mixtures were packed in leaching tubes (four replicates), leached with 100 mL of 5 mmol L−1 CaCl2, and then incubated for 10 wk (22 °C, 0.33 bar matric potential) with weekly leaching. Total N and inorganic N (NH4+ plus NO3−) in leachate were quantified and organic N was determined as the difference between total N and inorganic N. More N was released from shoots (63.4%–70.0% of initial N) than from roots (27.3%–50.7% of initial N). Mineralized organic N and inorganic N followed the first order, single N-pool mineralization model [Nt = N0(1 – e−kt); R2 = 0.94−0.99]. Potentially mineralizable N (N0, as % of initial N) was similar for shoots (CC = 75.1%, HV = 74.2%, and RC = 71.3%), but varied for roots (CC = 36.2%, HV = 52.6%, and RC = 53.0%). The N0 pool in shoots had a half-life (t1/2 = ln 2/k) of 11.0, 9.8, and 15.1 d for CC, HV, and RC, respectively; and a half-life in roots of 23.9, 8.5, and 25.7 d, respectively. Hence, HV released its stored N in both roots and shoots faster than CC and RC. The results in this study would help farmers optimize their choice in legume cover crops and termination times to better synchronize N release with crop uptake.

Although compost is widely used as an organic soil amendment or conditioner, little is known of how it affects the characteristics or interactions among soil constituents. To address this, mixture theory was used to describe the mass–volume–density–porosity attributes and interactions among bulk soil, the mineral constituent, and the organic matter constituent of a sandy loam soil in a no-till corn field that had received one-time additions of yard waste compost at rates of 0 (control), 64, 154, and 380 dry t ha−1. Bulk density (BD, 0–10 cm depth) decreased consistently and near-linearly with increasing soil organic matter (SOM) mass fraction (FOM) for all six growing seasons (2012–2017) after compost addition. Fitting mixture theory expressions to BD vs. FOMdata and to soil particle density vs. FOMdata for 2013–2017 yielded constant mineral and SOM self-packing densities of DM = 1.673 Mg m−3and DO = 0.335 Mg m−3, respectively, and constant mineral and SOM particle densities of ρM = 2.760 Mg m−3and ρO = 1.409 Mg m−3, respectively. On a self-packing basis, soil mineral and SOM domain porosities were constants at nM = 0.39 and nO = 0.76, respectively. On a bulk soil volume basis, soil mineral and SOM porosities and volume ratios were linear functions of FOM. The porosity and volume characteristics of the SOM domain differed substantially from those of bulk soil and the mineral domain, and may therefore control the agri-environmental performance of soil, given that organic matter influences soil functioning more than mineral matter.

To evaluate the potential of soil water recovery after thinning, in situ soil water content in the 0–500 cm soil profile under thinned (50%–100%) and unthinned peashrub and alfalfa plots and a nearby natural grassland in the Liudaogou watershed in China’s Loess Plateau (CLP) was measured monthly during 2015–2017 growing season using a neutron probe. At the start of experiment, the profile soil water storage (SWS0–500 cm) under introduced peashrub and alfalfa was, respectively, 18.8% and 12.2% lower than that under natural grassland. This showed that there was higher water consumption by planted vegetation, compared with native grass. After thinning, SWS0–500 cm in thinned peashrub and alfalfa plots was significantly higher than that in unthinned plots due to decrease in both interception and transpiration. The increase in SWS0–500 cm in the 100% thinned peashrub plot (159.9–216.1 mm) was much higher than that in 50% thinned peashrub (39.1–169.8 mm) and 100% thinned alfalfa (20.3–118.1 mm) plots. This indicated that the extent of soil water recovery varied with thinning intensity and vegetation type. At the end of the third growing season, soil water restoration frontier in the thinned peashrub and alfalfa plots (>300 cm) was much greater than that in the unthinned plots (

Four field experiments were conducted over a 2 yr period (2017 and 2018) in Ontario to determine the control of annual ryegrass (ARG) seeded in the fall of 2016 and 2017 (as a cover crop) with spring-applied glyphosate alone and in a tankmixure with clethodim, fluazifop-P-butyl, quizalofop-P-butyl, sethoxydim, or saflufenacil prior to seeding glyphosate-resistant corn. The doses of glyphosate needed to provide 50%, 80%, and 90% control of ARG were 439, 1757, and >2700 g a.e. ha−1 at 3 wk after treatment application (WAA); 526, 2105, and >2700 g a.e. ha−1 at 4 WAA; and 703, >2700, and >2700 g a.e. ha−1 at 6 WAA, respectively. Glyphosate (1350 g a.e. ha−1) controlled ARG 27%, 61%, 77%, 72%, and 68% at 1, 2, 3, 4, and 6 WAA, respectively. The tankmix of glyphosate (1350 a.e. ha−1) with clethodim (30 g a.i. ha−1), fluazifop-P-butyl (125 g a.i. ha−1), quizalofop-P-ethyl (36 g a.i. ha−1), sethoxydim (150 g a.i. ha−1), or saflufenacil (25 g a.i. ha−1) controlled ARG as much as 82%, 79%, 82%, 84%, and 81%, respectively. ARG control with the tankmixes of glyphosate (1350 a.e. ha−1) with the Group 1 herbicides evaluated increased corn yield as much as 66%. Additionally, reduced ARG interference with the tankmix of glyphosate (1350 a.e. ha−1) +saflufenacil (25 g a.i. ha−1) increased corn yield 69%. The best control of ARG was achieved with high doses of glyphosate alone and glyphosate (1350 g a.e. ha−1) tankmixed with a Group 1 herbicide or saflufenacil.

Alfalfa is an important economic crop; a mutant (M) strain was identified during planting and production. M plants consistently had better relative water content and relative electrical conductivity under higher salt conditions compared with the wild type (WT) plants, suggesting that M plants have higher tolerance for salt. To understand the microRNAs (miRNAs) involved in salt stress response in alfalfa, 128 miRNAs were identified from the WT and M alfalfa plants under normal and saline conditions. Of the 128 miRNAs, 29 and 23 differentially expressed miRNAs were identified in the M vs. WT control (M-CK vs. WT-CK) and salt-stressed M vs. WT (M-salt vs. WT-salt) comparison, respectively. These miRNAs responded to salt stress and showed different expression patterns after salt treatment. Their potential target genes were predicted and further analysed by GO classification and KEGG pathway analysis, where the majority of target genes were associated with plant growth and development, and exhibited significant changes in WT and M plants. In addition, compared with the WT plants, miR172-CNGC, miR319-CAX2, miR408-NHX and miR2590-CHX14/15 showed significant upregulation in M alfalfa plants, suggesting that M plants have higher ion transport levels. The differential expression profiles of miRNAs and putative target genes were further validated by quantitative real-time polymerase chain reaction. It is speculated that these miRNAs are involved in the increased salt tolerance of the M alfalfa plants.

Knowledge of optimal conditions for germination facilitates more efficient practices, such as fodder production and restoration. We assessed seeds of three grass species harvested in winter and summer 2018. Germination ability was assessed under two night/day temperature regimes (15 °C/20 °C, 20 °C/30 °C) and two photoperiod regimes (0, 12 h light per day). Winter-maturing seeds had a slightly lower mass and reduced germination. Temperature and light requirements for optimal germination were dependent on species and harvest-time. Summer-maturing seeds of all three species had higher germination rates regardless of germination temperature. Interactions among treatment temperatures and species were 0.7- to 5.4-times higher than the control, as shown by heatmaps. Therefore, attention to these factors will improve the efficiency of seedling establishment for rehabilitation work.

Witchweed [Striga hermonthica (Del.) Benth] is a major parasitic weed of most cereal crops in Africa, including maize. Seed treatment with low doses of acetolactate synthase–inhibiting herbicides, such as imazapyr, was introduced in the 1990s to control witchweed. Field trials were conducted in four locations in Nigeria in 2007 and 2008, to assess the effect of coating seeds of several maize hybrids with imazapyr on witchweed control. The hybrids had genes for imidazolinone herbicide resistance (IR), as well as genetic tolerance to witchweed (ST). Treatments were 12 IR maize hybrids with ST and three checks without the IR gene (commercial, witchweed tolerant, and witchweed susceptible hybrids). Averaged across all locations, the coated IR hybrids with ST yielded more and supported fewer witchweed plants than the uncoated IR hybrids with ST. The IR hybrids with ST yielded 57%–60% more than the commercial and witchweed tolerant hybrid checks that were not coated. The witchweed susceptible hybrid check suffered a yield loss of 88% under infestation without seed coating. The IR hybrids with ST yielded 3564 kg ha−1 of grain when coated with imazapyr and 3266 kg ha−1 otherwise. The findings indicate that coating of IR/ST maize seeds with imazapyr improved tolerance to witchweed.

Amaranthus hybridus L. is a nutritious leafy vegetable amaranth species grown primarily in tropical regions. Weedy amaranth species thriving in southern Ontario suggest the edible biotype could also grow efficiently as a crop. Field trials in Guelph, Simcoe, and Stouffville, Ontario, examined yield in response to three harvest frequencies (weekly, every 2 wk, and every 3 wk) cut at 15 cm above ground level, using two traditional harvest practices (Afro-Caribbean and European) cut every 2 wk, and a control which was not cut until the final harvest. The highest marketable yields and quality measures were observed in plants cut every 2 wk, every 3 wk, and using the Afro-Caribbean cutting technique which selects and harvests thicker stems while leaving new shoots for later harvests. The difference in growth among sites suggests plants prefer warm, well-drained soil. Marketable yield was as high as 4.02 ± 0.340 kg m−2 in Simcoe with an average yield across all three sites of 2.37 ± 0.229 kg m−2. This demonstrates that A. hybridus has the potential to be grown as a vegetable crop in southern Ontario and that marketable yield can be optimized by method of harvest.

Climate change is causing significant shifts in tree species distributions to higher elevations and latitudes. Seed germination and seedling establishment are particularly important steps in tree range expansion under warmer conditions, yet seedling establishment is influenced by a range of factors beyond temperature, including herbivory, microenvironment, and the timing and amount of precipitation. We conducted an experiment to assess how augmented precipitation regimes, wildlife herbivory, and microclimate influence germination and first-season survival of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) near the upper elevational limit of its range in the southern Rocky Mountains. Germination was strongly influenced by moisture, with over three times higher germination in watered treatments. Seedling survival was similar across watered treatments but was negatively associated with microenvironments with higher maximum temperatures. These results indicate that soil moisture effects on germination and the negative impact of hot growing-season temperatures on seedling survival limit initial seedling establishment in Douglas-fir, even at the cooler and wetter end of its range, suggesting that the planting of this species will be most successful in cooler and wetter microsites. Taken together, this study suggests that continued warming and projected increases in droughts may strongly limit Douglas-fir regeneration and thus its ability to shift upwards with climate change.

Grain yield and its variability is a major driver of seeding rate and inorganic fertilizer use at planting among grain growers. Recommended rates for fertilizer application with regard to crop utilization and soil management are discretionary and vary between producer and agronomist. This observational case study with Bayesian inference examines the association between application rates of inorganic nitrogen, phosphorus, potassium chloride and sulphur at planting, and yield of durum wheat (Triticum turgidum L.), large green lentils (Lens culinaris Medik.), canola (Brassica napus L.), canaryseed (Phalaris canariensis L.), and spring barley (Hordeum vulgare L.). Using precision agriculture, input and crop yield information for each parcel of cultivated land was collected over a 4 yr period from 2015 to 2018 on a continuous no-till farming operation in the semiarid region of Saskatchewan, Canada. Hierarchical models were derived that accounted for yield variability in crop types due to the random effects of field, cultivar, crop planted in previous year, planting year, combine machine, observation location within field, and elevation. Evidence from this longitudinal study suggests that seed-placed fertilizer above the recommended safe rate can be associated with yield decline on farming operations in the semiarid environment of Saskatchewan, Canada.

Complex pasture mixtures are advantageous, but little information exists on the best forage species and nitrogen (N) management in eastern Canada. We compared under mob stocking four complex mixtures of one of two legume species [alfalfa (Medicago sativa L.) and birdsfoot trefoil (Lotus corniculatus L.)] plus one of two grass mixes [No. 1 — timothy (Phleum pratense L.), meadow fescue (Schedonorus pratensis (Huds.) P. Beauv.), reed canarygrass (Phalaris arundinacea L.), and Kentucky bluegrass (Poa pratensis L.); No. 2 — tall fescue (Schedonorus arundinaceus (Schreb.) Dumort., nom. cons.), meadow bromegrass (Bromus biebersteinii Roem. and Schult.), reed canarygrass, and Kentucky bluegrass] under three N application rates at three sites over the first three post-seeding years. Legume species had little effect on most forage attributes mainly because of their low contribution to forage dry matter (DM) yield (30%.

This study aimed to identify possible relationships between corn (Zea mays L.) productivity and its endosphere microbial community. Any insights would be used to develop testable hypotheses at the farm level. Sap was collected from 14 fields in 2014 and 10 fields in 2017, with a yield range of 10.1 to 21.7 tonnes per hectare (t/ha). The microbial sap communities were analyzed using terminal restriction fragment length polymorphism (TRFLP) and identified using an internal pure culture reference database and BLAST. This technique is rapid and inexpensive and is suitable for use at the grower level. Diversity, richness, and normalized abundances of each bacterial population in corn sap samples were evaluated to link the microbiome of a specific field to its yield. A negative trend was observed (r = –0.60), with higher-yielding fields having lower terminal restriction fragment (TRF) richness. A partial least square regression analysis of TRF intensity and binary data from 2014 identified 10 TRFs (bacterial genera) that positively, or negatively, correlated with corn yields, when either absent or present at certain levels or ratios. Using these observations, a model was developed that accommodated criteria for each of the 10 microbes and assigned a score for each field out of 10. Data collected in 2014 showed that sites with higher model scores were highly correlated with larger yields (r = 0.83). This correlation was also seen when the 2017 data set was used (r = 0.87). We were able to conclude that a positive significant effect was seen with the model score and yield (adjusted R2 = 0.67, F[1,22] = 46.7, p < 0.001) when combining 2014 and 2017 data. The results of this study are being expanded to identify the key microbes in the corn sap community that potentially impact corn yield, regardless of corn variety, geographic factors, or edaphic factors.

Defoliation level and site type are thought to influence tree response during spruce budworm (Choristoneura fumiferana (Clemens)) outbreaks. We determined the effects of four manual defoliation treatments (0%, 50%, 100%, and 100% + bud removal of current foliage) for 3 years on foliage production of balsam fir (Abies balsamea (L.) Mill.), black spruce (Picea mariana (Mill.) Britton, Sterns & Poggenb.), and white spruce (Picea glauca (Moench) Voss) trees on four site-quality classes. After 3 years of defoliation and 2 years of recovery, foliage biomass was reduced by 34%–98%. During defoliation, the number of shoots generally increased and shoot length of spruce generally decreased, especially on rich sites. During recovery, the number of shoots increased substantially, shoot length decreased, and bud destruction reduced the number of shoots by about 50% compared with that of trees that received the 100% defoliation treatment. Defoliation did not substantially affect needle length. Trees on rich sites had two- to fourfold greater foliage production than trees on poor sites. Effects of site and defoliation differed among species, but site quality, especially nutrition, played an important role in production of shoots and needles and the tree’s ability to withstand defoliation. Black spruce had more limited ability to recover foliage biomass, only producing more shoots, whereas balsam fir and white spruce had stronger ability to recover needle and shoot length, respectively.

In barley cropping systems of northern Spain, agronomic practices and weather conditions are key components of weed control efficacy. We compared the short-term effects of conventional tillage with minimum tillage (MT) and zero tillage (ZT), in barley monoculture and barley rotation systems. Weed density and weed species number were measured at tillering and flowering barley stages. We found that tillage system can influence weed density and weed species establishment due to, in part, the available light for weed seeds. The results obtained indicate that the MT system facilitates the prevalence of the grass weed Bromus diandrus Roth (50.37%) and the annual dicots Galium aparine (L.) and Buglossoides arvensis (L.) I.M. Johnst. abundant were high in the MT system too, 43.71% and 43.97% respectively. The germination of these species showed a high dependence on light availability. We saw that barley-monoculture plots had a large infestation of Bromus (71.29%) and barley-rotated plots presented more infestation of Galium and Buglossoides (74.36% and 84.4%, respectively). After herbicide application, weed infestation in conservation systems was reduced in barley-rotated plots compared with barley-monoculture. If conservation systems avoided the presence of dominant weeds, the weight of each weed species was balanced within competitive relationships of the cropping systems. Our results confirmed that MT and ZT systems favour different weed species emergences in barley-rotated plots. The combination of MT and barley-rotated cropping system resulted in greater weed diversity and lower total weed density.

Greenhouse floriculture operations pose significant environmental risk due to extensive inputs of fertilizer, especially nitrogen and phosphorus (P). Recent evidence shows that the use efficiency for nitrogen or sulphur is markedly improved in subirrigated potted chrysanthemums (Chrysanthemum morifolium Ramat.) by supplying a moderate level of the nutrient during vegetative growth, and removing the entire nutrient suite at the onset of reproductive growth, without adverse effects on plant quality. Here, two split-plot experiments were conducted with subirrigated, potted, disbudded chrysanthemums grown in a peat:perlite mixture under greenhouse conditions (high- or low-ambient light) with inorganic orthophosphate (Pi) treatment (2.6 mmol L−1 Pi supplied during the vegetative and reproductive stages, and 2.6, 1.95, or 1.3 mmol L−1 Pi supplied during the vegetative stage only) as the main plot and cultivar (‘Olympia’ and ‘Covington’) as the subplot. Market quality plants with sufficient tissue P were produced even when Pi delivery was reduced by approximately 75% over the crop cycle, compared with industry standards. The primary mechanism for sustaining plant growth with decreasing Pi delivery was improved acquisition or uptake efficiency, although some changes in internal P-utilization efficiency were evident, including the remobilization of both organic P and Pi during inflorescence development. Differences in biomass yields, tissue P concentrations, content-based P-use efficiency (PUEC = mg shoot dry mass/mg shoot P content) with constant Pi acquisition, and uptake- versus remobilization-based P supply for inflorescence growth established that ‘Olympia’ has a greater P-utilization efficiency than ‘Covington’. This modified subirrigation practice could contribute significantly to low-input production of floricultural crops.

High costs from external inputs in small-scale dairy systems (SSDS) and possible effects of climate change, require forage alternatives as silage for the dry season, from small-grain cereals that have short cropping cycles, winter hardiness, and good nutritional quality. The objective was to assess the provision of 10 kg dry matter (DM) cow−1d−1of barley (BLY) or black oat (BKO) silages in three treatments: T1 = 100% BLY; T2 = 50% BLY + 50% BKO; T3 = 100% BKO for milking cows. All treatments also received 4.6 kg DM cow−1d−1of concentrates and access to pasture. Nine Holstein cows in groups of three were randomly assigned to a 3 × 3 Latin square design repeated three times, with 14 d experimental periods. Measurements of animal variables and sampling for chemical analyses of feeds were done during the last 4 d of each period. Feeding costs were by partial budgets. There were no differences (P > 0.05) for milk yield, milk fat and protein content, milk urea nitrogen, body condition score, or live weight. The cost of BLY silage was 8% less than BKO silage. T1 had the higher margin over cost of feeds followed by T2. Both silages alone or in combination are viable options for SSDS, as there were no differences in performance, or in feeding costs or margins.

Excess water in the rooting zone critically reduces tree growth and may even kill trees; however, the relative importance of damage to roots versus aboveground parts and the time course of damage are not well understood. We studied the dynamics of fine-root growth and mortality of 7-year-old Scots pine (Pinus sylvestris L.) saplings affected by a 5-week period of waterlogging (WL) during the growing season. Two out of six WL-exposed saplings survived the treatment. After 1–2 weeks of WL, the mortality of the first-order short roots (usually mycorrhizas) started to increase and the production of these roots started to decrease. WL decreased the longevity of short and long roots. Total root length (especially of fine roots with a diameter < 0.5 mm), specific fine-root length, total root dry mass (including stump), and reverse-flow root hydraulic conductance were lower in WL saplings than in control saplings at the end of the experiment; however, several root traits were similar in control and surviving WL saplings. Because of the high importance of fine roots for tree growth and carbon sequestration, their responses to elevated water tables should be considered in sustainable use and management of boreal peatland forests, for example, by continuous cover forestry and (or) ditch network maintenance.

The objective of this paper was to estimate the effect of either missing or dominated plants (those that developed poorly) in experiments evaluating progenies or clones of Eucalyptus. Additionally, it was to investigate whether the use of the area available per plant is a suitable strategy to mitigate the effect of missing plants. Lastly, it was to evaluate whether missing or dominated plants in the experiments affected the association between plant performance in a progeny trial (PT) and their respective clones in a clonal trial (CT). Five 5-year-old PTs and four 3-year-old CTs were used. The recorded trait was diameter at breast height (DBH). The area available per plant was used to carry out the adjustment, taking into consideration the absence of neighboring plants as well as dominated plants. It was found that with the level of missing plants below 20% in experiments, the adjustment using the area available per plant did not improve the efficiency of the selection of either PTs or CTs. The strategy of considering not only missing plants but also dominated plants is not beneficial for the adjustment.

Several quantitative trait loci (QTL) have been identified for Fusarium head blight (FHB) resistance in the cultivar Sumai 3. Wheat breeders need to know which Sumai 3 loci are present in derived lines used as parents for effective marker-assisted selection for genetic improvement. This study was conducted to identify the loci in Sumai 3 derived parents that contribute FHB resistance in breeding populations. Three doubled haploid (DH) populations utilizing Sumai 3 derived parents, ND3085, ND744, and Alsen, were evaluated during 2007 and 2008 in FHB nurseries near Carman, MB, Ottawa, ON and Charlottetown, PE. The percentage of incidence, severity, Fusarium-damaged kernels (FDK), and deoxynivalenol (DON) accumulation were measured, and FHB index calculated. DNA markers at six FHB resistance loci detected in Sumai 3 were evaluated on the populations. For each trait, a t test was applied to means of observations pooled by parental type of each marker to determine which loci contributed to resistance. The alleles at 3BS and 5AS most frequently contributed to Type I and Type II FHB resistance, as well as to reduced FDK and DON in all three populations. Markers revealed resistance on 3BS and 5AS in Alsen, ND3085, and ND744, on 3BSc, 4D, and 6BS in ND744, on 4D in ND3085, and on 6BS in Alsen. In some environments, the susceptible parent Infinity contributed minor QTL on 2D, 3BSc, and 6BS. Likewise, Helios contributed minor QTL on 5AS and 6BS.

A total of six field experiments were conducted in southwestern Ontario over a 3-yr period (2016, 2017, 2018) to evaluate the efficacy of trifluralin and halosulfuron applied preplant incorporated (PPI) for weed management in white bean. Trifluralin, halosulfuron, and trifluralin + halosulfuron applied PPI caused as much as 2%, 6%, and 8% white bean injury, respectively. Weed interference delayed maturity and reduced white bean yield 56% compared with the weed-free control. Weed interference with trifluralin and halosulfuron applied alone reduced white bean seed yield as much as 35% and 29%, respectively; however, white bean seed yield with the trifluralin + halosulfuron tankmixes was similar to the weed-free control. Trifluralin, halosulfuron, and trifluralin + halosulfuron applied PPI provided 6%–12%, 75%–92%, and 71%–95% control of velvetleaf; 89%–95%, 93%–98%, and 96%–99% control of pigweed species; 5%–18%, 82%–96%, and 90%–97% control of common ragweed; 90%–97%, 81%–97%, and 95%–99% control of common lambsquarters; 23%–43%, 55%–88%, and 83%–96% control of flower-of-an-hour; 4%–25%, 94%–100%, and 95%–100% control of wild mustard; 96%–100%, 18%–45%, and 97%–100% control of barnyardgrass; and 92%–98%, 21%–40%, and 93%–98% control of green foxtail, respectively. Results indicated that low rates of trifluralin tank-mixed with halosulfuron has the potential to control problematic weeds and improve white bean yields in Ontario.

Field experiments were conducted to evaluate the effects of wheat straw return methods, which included the use of surface straw mulch and a buried straw layer, on soil water content, electrical conductivity (EC), and sodium adsorption ratio (SAR) of saline sodic soils in an effort to identify useful ways for reducing soil salt accumulation and enhancing soil water content. The results showed that the straw return treatments were effective for inhibiting salt accumulation and soil water loss, resulting in a reduction of EC and SAR but an enhancement of soil water content. After a year-long experiment, compared with the treatment with no straw return, the straw burial and straw mulching treatments decreased the EC by 10.5% and 3.5%, reduced the SAR by 7.4% and 21.5%, and increased the soil water by 0.9% and 4.4%, respectively. Furthermore, the combined application of straw layer burial and surface straw return had a more significant effect than the individual treatments; the positive effect of straw return occurred mainly focused in the topsoil (0–40 cm) and decreased with increasing soil depth. Our results allowed us to conclude that burial of the straw layer was necessary to enhance the effects of surface mulch, and the combination of surface mulch (3.0 t ha−1 of wheat straw) and straw layer burial (6.0 t ha−1 of wheat straw) proved to be a better straw return method than the others.

No information exists on the susceptibility of arbuscular mycorrhizal fungal (AMF) communities in Canadian prairie agriculture soils to climate change. An experiment was initiated in mid-May 2011 in which replicated soil cores were transplanted reciprocally from four cultivated prairie sites in Saskatchewan, Canada, representing different regional climatic zones ranging from semiarid to subhumid regional climates, such that replicated (n = 4) soil cores from each site were present at all sites. Field pea was grown in all cores and at harvest in early-September 2011; soil samples were collected to analyze the changes of AMF communities over the cropping season. A total of 82 operational taxonomic units belonging to eight AMF genera were identified using 18S rRNA gene pyrosequencing. When soils were transplanted to new environments, the relative abundance of AMF changed considerably. Typically, Shannon diversity declined when soil cores were transplanted to new environments. We present evidence that with the altered climatic conditions following transplantation of soil cores, the relative abundance of AMF was significantly altered, and some taxa were enhanced, suppressed, or disappeared in the home-away soils compared with home-site soils. This study implies that the future climate change effects on AMF may impact specific phylogenetic taxa differently, such that rare species or those with low abundance may increase or decrease with unknown consequences. Understanding the potential responses of AMF communities to soil–climate interactions is important when considering the impacts of climate change on soil microbial communities.

Increasing the use of nitrogen fertilizers in tea orchards has led to intense nitrous oxide (N2O) emissions. Foliar application of Paenibacillus polymyxa biofertilizer has been proven to be beneficial for organic tea production. In this study, tea yield and quality were significantly improved after application of P. polymyxa biofertilizer compared with the control but were not significantly different from chemical fertilizer treatments. However, the average N2O fluxes in tea fields treated with chemical fertilizers and biofertilizers (225 kg N·ha−1·year−1 for both) were 50.6–973.7 and 0.6–29.1 times higher than those in the control treatment, respectively. Pot experiments conducted to explore the mechanism of N2O reduction induced by P. polymyxa biofertilizer showed that applying P. polymyxa in addition to urea could reduce N2O fluxes by 36.5%–73.1%. Quantitative PCR analysis suggested that a significant increase in the quantity of nirK and nosZ genes was linked to the reduction of N2O, and high-throughput sequencing of nosZ revealed active and potentially efficient denitrifiers in different treatments. Our findings suggest that P. polymyxa biofertilizer is in line with the requirements of modern agriculture, which aims to increase product yield and quality while reducing negative environmental impacts.

Jake hard red spring wheat (Triticum aestivum L.) was developed using a modified bulk breeding method at the University of Alberta, Edmonton, AB. Jake is an awned, hollow-stemmed line with high yield potential, medium tall plants, and medium maturity. During the three years (2015–2017) of evaluation in the Parkland Wheat Cooperative test, Jake yielded 6% higher than the mean of all of the checks, and matured 0.7 and 1.7 d later than Parata and Splendor but 2.9 d earlier than Glenn. Jake was 91.2 cm tall, shorter than AC Splendor (95.8 cm), but similar in height to Glenn (91.8 cm) and Parata (92 cm). The lodging score of Jake (2.2) was lower than Parata (3.1) and AC Splendor (3.1), but similar to Glenn. The test weight of Jake (80.8) was higher than AC Splendor (78.3), similar to Parata (80.5), but lower than Glenn (82.5). The grain weight of Jake (35.6 g) was similar to Parata (35.6 g), but lower than Glenn (36.7 g) and AC Splendor (37.4 g), while the NIR Protein of Jake (15.9%) was higher than Glenn (15.5%) and similar to the other checks. Jake was moderately resistant to resistant to leaf, stem, and stripe rusts, and moderately resistant to common bunt during the 3 yr of testing. The reaction of Jake to Fusarium head blight was variable and ranged from moderately susceptible to moderately resistant, with DON values similar to Carberry and Glenn. Three years of end-use quality evaluation has indicated that Jake is acceptable for the CWRS class.

Sustainable production of biomass crops is important in the development of feedstocks for the production of biofuels and other bioproducts. This study investigates the use of nine beneficial soil microbes and a plant biostimulant (i.e., Ascophyllum nodosum seaweed extract) to increase the growth of two giant Miscanthus (Miscanthus × giganteus) cultivars, ‘Amuri’ and ‘Nagara’, under greenhouse conditions and in the field on poor-quality, marginal land. Greenhouse trials indicated increases in shoot dry weight (DW) in ‘Amuri’ in treatments with Gluconacetobacter diazotrophicus PAL5T LsdB++, Gluconacetobacter johannae UAP-Cf-76, and Variovorax paradoxus JM67 by 15%–24% compared with untreated controls. In ‘Nagara’, shoot DW was increased in the treatments with Penicillium bilaiae by 11% and the seaweed extract by 10%. The nutrient content of shoot tissues increased in the same treatments in which biomass was increased. Despite a lack of treatment effects on shoot DW in ‘Amuri’ in the field, several treatments increased Fe and Zn content in shoots by up to 1.9×. In ‘Nagara’ in the field, treatment with G. johannae UAP-Cf-76 and the seaweed extract resulted in increases in shoot DW by 16% and 23%, respectively, and several treatments resulted in increases in shoot Fe and Zn concentrations. The productivity enhancements in giant Miscanthus by beneficial soil microbes and the seaweed extract may be associated with increasing access to limited soil nutrients. These findings suggest that the use of beneficial soil microbes and plant biostimulants may aid in the sustainable production of giant Miscanthus on marginal lands.

Extreme cold events can damage plant tissues, altering growth and reproduction. Soil fungi may help plants tolerate environmental stressors, but the role these microbes play during episodes of severe cold warrants further examination. Using the bunchgrass Elymus canadensis L., we tested how inoculation with mycorrhizal fungi alters plant tolerance to freezing temperatures (tested at –8 °C and –16 °C). We found that, regardless of mycorrhizal inoculation, E. canadensis exposed to –16 °C exhibited greater tissue damage, less tiller growth, and fewer reproductive tillers than plants exposed to the control or –8 °C conditions. Plants exposed to –8 °C and –16 °C displayed greater levels of visible damage compared with the control plants. Mycorrhizae reduced damage to tillers in the –8 °C treatment, but had less effect on tiller damage in the control or –16 °C treatments. Inoculation with arbuscular mycorrhizal fungi limited the tiller number for E. canadensis, but only at the control temperature, suggesting that mycorrhizae may impose costs on E. canadensis under benign thermal conditions. Our study demonstrates that extreme temperatures can affect multiple components of growth in E. canadensis, and that the costs and benefits of arbuscular mycorrhizal fungi, where found, depend upon the thermal environment. Our findings reinforce the overarching importance of historically rare, but increasingly common, environmental extremes in shaping the growth of plants.

A 21 yr field study comparing zone tillage (ZT), no-tillage (NT), and moldboard plow tillage (MP) was used to elucidate tillage effects on soil hydrophobicity (SH) and soil water repellency index (RI) in a cool, humid clay loam soil in southwestern Ontario. The SH was 38% (P ≤ 0.05) greater for ZT and NT than MP, and it was similar between crop row (0.34) and crop inter-row (0.37) for ZT. The RI values were not different among tillage systems, or between the crop row versus crop inter-row positions under the three tillage systems.

White spruce (Picea glauca (Moench) Voss) plantations have historically been an important source of high-quality forest products in the Great Lakes Region of North America. Thinning in spruce plantations is a common silvicultural practice for reducing competition and promoting resiliency to forest health threats such as eastern spruce budworm (Choristoneura fumiferana Clemens), a native forest pest of eastern North America. Spruce budworm larvae feed on the foliage of trees, which reduces growth and potentially causes mortality during an outbreak. There has been continual spruce budworm defoliation in northern Minnesota, U.S.A., since the mid-1950s, with higher levels of defoliation in the late 1990s. This research modeled the diameter growth response of white spruce 18 years after initial thinning in stands that presently range between 44 and 64 years old. Some stands received a second thinning in recent years. We used generalized nonlinear least squares and nonlinear mixed-effects models to estimate annual diameter growth using common tree and stand metrics. Growth model performance was improved by including thinning and frequency of spruce budworm defoliation as modifiers of diameter growth. Results of this study highlight how thinning in combination with insect disturbance affect diameter growth in white spruce plantations of northern Minnesota.

The aim of this study is to investigate impact of soil amendments (4% biochar, 0.4% polymer, and a combination of them) on soil moisture and salinity distribution, tomato yield, and water-use efficiency (WUE). Open-field experiments were conducted during two successive growing seasons in 2017 and 2018. The experiment consisted of three levels of irrigation treatments: 100%, 80%, and 60% of crop evapotranspiration (ETc); and two different water qualities: fresh 0.9 dS m−1 and saline electrical conductivity 3.6 dS m−1. Results revealed that at 100% of ETc, soil water distribution increased by 12.94%, 37.87%, and 42.21% at depths 0–15, 15–30, and 30–45 cm, with the addition of biochar, respectively, compared with control at same depths under freshwater, but the addition of polymer was increased by 6.35%, 16.56%, and 16.37%, respectively. While combination treatments increased by 15.70%, 24.80%, and 41.26%, at the depths aforementioned. Salt concentration was increased by 59.10% with biochar, whereas decreasing by 7.19% and 57.63% with polymer and mixture treatments, respectively. The results also showed that biochar and mixture treatments improved yield compared with the polymer and control, whereas saline water decreased the yield compared with freshwater. With deficit irrigation, WUE was increased by 28.54%, 40.98%, and 68.93% at 100%, 80%, and 60% of ETc, respectively, indicating it could be used as an irrigation management strategy under arid and semiarid field conditions.

Phosphorus (P) loss to freshwater is a key driver of eutrophication, and understanding the scale and spatial distribution of potential P sources is a key pre-requisite for implementing policies for P management to minimize environmental impacts. Soil test P (STP) is a useful indicator of the accumulation of P in soils, but these data are not readily available for most agricultural land in Canada, so the cumulative P balance (P inputs as manure or fertilizer minus removal of P in crops) is calculated as a proxy for this value. Cumulative P balance is an important calculation within the indicator of risk of water contamination by P, so allocations of manure and fertilizer P to cropland were updated within the calculation of P balance, and for Ontario, data from 1961 to 1980 were added to account for P applications during that period. The STP concentrations were calculated from the resulting cumulative P balances. When compared with reported STP concentrations, the predicted concentrations showed a statistically significant regression at the national (R2 = 78%) and provincial scale (Ontario, R2 = 36%; Prince Edward Island, R2 = 36%; Manitoba, R2 = 72%; British Columbia, R2 = 40%). There was significant variation in the cumulative P balance across Canada, with the highest values corresponding with areas of high livestock density, whereas large zones of P deficit were detected across the Prairies.

We examined the effects of foliar supplementation of different nitrogen sources (urea, Nitamin, NH4NO3, and arginine) to study their efficacy as fertilizers for growth of two clonally propagated shrub willow cultivars; namely, ‘Fish Creek’ (Salix purpurea L.) and ‘Preble’ (Salix viminalis L. × (Salix sachalinensis F. Schmidt × Salix miyabeana Seemen)). Our objectives were to determine (i) if foliar nitrogen application is an effective method of fertilization for the two shrub willows and (ii) if different nitrogen sources are metabolized similarly by the plants. The analyses involved soluble leaf polyamines, amino acids, total protein, total nitrogen and carbon, and plant biomass in response to short-term treatments with four sources of nitrogen. The effects of foliar nitrogen application on leaf chemistry, biomass, and foliar nitrogen content varied according to the form of nitrogen used. The data indicate that (i) urea is the most suitable nitrogen source for foliar spray (29% higher N accumulation vs. Nitamin), whereas arginine is the least suitable, and (ii) different nitrogen sources are metabolized differently by the plant. While the foliar nitrogen application method could become a practical and sustainable way to fertilize shrub willows and other short-rotation biofuel crops, it may also help reduce nitrogen loss to the environment.

AAC Magnet (BW1045) is an awned, hollow-stemmed, high-yielding Canada Western Red Spring (CWRS) wheat adapted to growing conditions in the Canadian Prairies. AAC Magnet was 5% higher yielding than Glenn and yielded 2% more than Carberry, a popular CWRS wheat variety across the Canadian Prairies. AAC Magnet matured 2 d earlier than Carberry and a day later than Unity, the earliest maturing check. AAC Magnet had the same height as Glenn and was shorter with better stem strength compared with Unity. AAC Magnet had better lodging scores compared with Unity. Over the 3 yr of testing (2015–2017), the test weight of AAC Magnet was slightly lower than the lowest checks, whereas the 1000-kernel weight of AAC Magnet was higher than all of the checks. The grain protein content of AAC Magnet was 0.3% lower than Carberry. AAC Magnet was rated moderately resistant to Fusarium head blight (Fusarium graminearum Schwabe), resistant to leaf rust (Puccinia triticina Erikss.) and stem rust (Puccinia graminis Pers. f. sp. tritici Erikss. & E. Henn). AAC Magnet was moderately susceptible/susceptible to resistant to the Ug99 family of stem rusts, resistant to loose smut [Ustilago tritici (Pers.) Rostr.], intermediately resistant to stripe rust (Puccinia striiformis Westend.), susceptible to common bunt [Tilletia caries (DC.) Tul. & C. Tul.], and moderately susceptible to leaf spot complex. AAC Magnet was susceptible to orange wheat blossom midge (Sitodiplosis mosellana Géhin). Based on the milling and baking performance over 3 yr (2015–2017) evaluated by the Grain Research Laboratory, Canadian Grain Commission, AAC Magnet was classified as CWRS wheat.

Long-term application of feedlot beef cattle manure amendments to cropland may enhance earthworm abundance by increasing soil organic carbon. The objective of this study was to determine the legacy effects of feedlot manure type [stockpiled (SM) vs. composted (CM)], bedding material [straw (ST) vs. woodchips (WD)], manure rate (13, 39, or 77 Mg ha−1), unamended control, and inorganic fertilizer treatments on earthworm abundance in a clay loam soil after 3–4 yr of discontinued applications following 17 annual applications. Earthworms were sampled (20 cm depth) in 2 yr (2017–2018), and ancillary soil properties also determined. The Aporrectodea genus was the dominant earthworm identified. Earthworm abundance was similar (P > 0.05) for amended and unamended or inorganic fertilizer treatments. Abundance at the 39 Mg ha−1 rate in 2018 was significantly (P ≤ 0.05) greater by four times for SM than CM with ST, but it was two times greater for CM than SM with WD. Abundance at the 13 Mg ha−1 rate in 2017 was significantly greater by 91% for ST than WD, but at the 39 Mg ha−1 rate, it was 10 times greater for WD than ST. In 2018, abundance was five times greater for WD than ST with CM, but it was similar with SM. Overall, short-term legacy effects occurred on earthworm abundance, but these effects varied with manure rate. Earthworm abundance was not increased by manure application, which suggested a carrying capacity not directly related to food resource.

The disruptive land-use change during forage grass conversion to annual crop can be critical for determining nitrous oxide (N2O) emissions, but this is an understudied period. We measured soil N2O fluxes (using closed static vented chambers) together with potential environmental drivers of these fluxes from liquid pig manure (LPM) and solid pig manure (SPM) applied to an annual crop (ANN) and perennial forages (FPP) that was converted to annual crop. Unamended plots were used as a control (CON). The results showed that in 2013, average soil nitrate-N was significantly higher on the recently converted FPP (ranging from 19 to 83 mg N kg−1) than the continuous ANN plots (from 16 to 35 mg N kg−1). The recently converted perennial forage system produced three times greater N2O than the continuous annual system, which is likely a result of accelerated N mineralization from the accumulated soil organic matter (over 4 yr) and grass residues of the recently killed forage grasses. However, during the second year of the study when the FPP plots were reseeded to perennial grasses, the system emitted 30% less N2O than the ANN system. These results suggest that including perennial forage grass in rotation with annual crops can provide N-saving and climate change mitigation benefits; however, some of the N stored in the soil would be lost when the perennial grass plots are cultivated to grow annual crops.

Herbicide resistance is selected for within a weed population through the recurrent use of an herbicide. Once the use of the herbicide is reduced or discontinued, the trait may persist in the population unless resistance endows a fitness penalty. Few studies have examined the long-term persistence of an herbicide resistance trait in a weed population once the selection pressure that led to its prevalence has been removed. The objective of this research was to re-survey the locations described by A.J.J. Smisek in her 1995 study of a paraquat resistant biotype of C. canadensis on the grounds of the Harrow Research and Development Centre. Results indicate that, ∼20 yr after paraquat use was significantly reduced, a glyphosate resistant biotype had replaced the paraquat resistant biotype at all but one of the original locations surveyed by Smisek. The sole location where the paraquat resistant biotype was observed was an old, un-treed orchard row currently managed by mowing. This location not only served as a refuge for the paraquat resistant biotype, ensuring its persistence in the face of strong selection for glyphosate resistance at all other locations, but it facilitated the co-occurrence of glyphosate and paraquat resistant biotypes. The observation of a multiple resistant biotype at this location alone, with resistance to both paraquat and glyphosate, suggests a role for refugia in the stacking of herbicide resistance traits. Given that this stacking occurred in the absence of either herbicide, we hypothesize that the multiple resistant biotype arose through pollen mediated gene flow among biotypes.

CO468, CO469, CO470, CO471, CO472 and CO473 are the first corn (Zea mays L.) inbred lines released from the northern corn leaf blight [Exserohilum turcicum (Pass.) K.J. Leonard & E.G. Suggs; syn. = Helminthosporium turcicum Pass.] resistance breeding program of Agriculture and Agri-Food Canada. All six inbreds possess intermediate to very high levels of resistance, which is expressed in hybrids when these inbreds are combined with susceptible test lines. Expression is even higher when some of these lines are combined with each other. Acceptable grain yields and moistures are also achieved in several hybrid testcrosses. All six inbreds also possess intermediate to high levels of resistance to eyespot, common rust, Goss’s bacterial wilt, and grey leaf spot.

In western Canada, short-season corn silage production is increasing due to its potentially high nutritive value. The objective of this study was to determine variability and relationships among nutrient concentration, degradability, and methane (CH4) production of short-season whole-plant corn hybrids harvested before or after light frost (−1.5 °C). Four hybrids, based on their corn heat unit rating (≤2600, CHU rating), were grown in 2 yr in central and southern Alberta (AB) with two field replications. The batch culture and Daisy fermenter techniques were used to characterize degradability and gas production measurements. At both locations, dry matter (DM) concentration was affected by harvest and hybrid (P ≤ 0.02). However, starch and neutral detergent fiber (NDF) concentrations differed (P ≤ 0.01) or tended (P = 0.07) to differ among harvest and hybrid only in central AB. Over both locations and harvest times, CH4production was related negatively to propionate and positively to acetate proportions. In conclusion, harvesting southern AB hybrids after frost increased DM concentration and NDF degradability with no effect on CH4emissions, but the high DM concentration may negatively affect silage quality and animal performance. Harvesting central AB hybrids after frost increased DM and starch concentrations, while reducing CH4emissions but had limited effects on nutrient degradability.

Fertilization is a common practice, as it improves plant yields. In many areas, biosolids (remains from treated wastewater) are used instead of chemical fertilizers owing to multi-year nutrient release and positive changes in soils and water retention. Little is known about whether biosolids affect animal consumers. Here, we examine diets and nesting sites of American Kestrels (Falco sparverius Linnaeus, 1758) in British Columbia, Canada. Our major study area was a large cattle ranch that has been grazed for over a century and where biosolids were applied in the previous 1–3 years. Kestrels selected nests in areas with higher Northern Flicker (Colaptes auratus (Linnaeus, 1758)) nest density and with a higher proportion of pastures with biosolids applications, but with less forest. Kestrels were observed more often on biosolids-amended pastures than in untreated areas. Kestrels primarily ate voles (genus Microtus Schrank, 1798), but also consumed grasshoppers (Orthoptera) late in the breeding season when grasshoppers were abundant. Kestrel diets were slightly more varied on a nearby control area than on the ranch. Our results suggest that biosolids applications improve prey availability for Kestrels, thus potentially acting as a restoration tool in areas with degraded habitats or where Kestrels have declined.

While northern temperate grasslands are important for supporting beef production, it remains unclear how grassland above- and belowground biomass responds to long-term cattle grazing. Here, we use a comprehensive dataset from 73 grasslands distributed across a broad agro-climatic gradient to quantify grassland shoot, litter, and shallow (top 30 cm) root biomass in areas with and without grazing. Additionally, we relate biomass to soil carbon (C) concentrations. Forb biomass was greater (p −1 for grazed vs. 2210 kg ha−1 for non-grazed; p > 0.05). Forb crude protein concentrations were lower (p −1) and without (7130 kg ha−1) grazing (p > 0.05). Surface mineral soil C concentrations were positively related to peak grassland biomass, particularly total (above + belowground) biomass, and with increasing forb biomass in grazed areas. Finally, total aboveground shoot biomass and soil C concentrations in the top 15 cm of soil were both positively related to the proportion of introduced plant diversity in grazed and non-grazed grasslands. Overall, cattle grazing at moderate stocking rates had minimal impact on peak grassland biomass, including above- and belowground, and a positive contribution exists from introduced plant species to maintaining herbage productivity and soil C.

The influence of surface mulching on soil aggregation and associated carbon (C) and nitrogen (N) varies by mulching materials and crop types. The 6 yr effect of straw mulching (SM), plastic film mulching (PM), and no mulching (CK) on soil aggregation and associated C and N concentrations at 0–20 and 20–40 cm soil layers were studied under dryland winter wheat (Triticum aestivum L.) and spring corn (Zea mays L.) in the Loess Plateau of China. Regardless of crop types, aggregate proportion was greater in macroaggregates (2.00–10.00 mm), but lower in microaggregates (

Soybean crops face drought as one of their major yield barriers. Dissecting the complete genetic architecture of drought tolerance (DT) is an ongoing challenge for soybean breeders. A half-sib population with 404 lines consisting of two recombinant inbred line (RIL) populations with M8206 as the joint parent (M8206 × TongShan and ZhengYang × M8206) was established and tested for their DT under sand culture. The population was sequenced using RAD-seq (restriction-site-associated DNA sequencing) filtered with minor allele frequency (MAF) ≥ 0.01, and 55 936 single nucleotide polymorphisms (SNPs) were obtained and organized into 6137 SNPLDBs (SNP linkage disequilibrium blocks). The innovative RTM-GWAS (restricted two stage multi-locus genome-wide association study) identified 46 novel QTLs with 107 alleles on an average of 38.67% of the phenotypic variance (PV) collectively for relative plant length (RPL) and relative plant dry weight (RPDW). The identified quantitative trait loci (QTLs) with their corresponding alleles for RPL and RPDW were structured into QTL-allele matrices, showing the DT genetic architecture of the three parents and half-sib population. From the matrices, the possible best genotype was predicted to have their weighted average value (WAV) over two indicators 1.663, while the top 10 optimal crosses among RILs with 95thpercentile WAV was 0.872–0.960, transgressive over the parents (0.469–0.675) but much less than 1.663, depicting further pyramiding potential. From the detected QTL-allele system, 63 potential candidate genes collectively for both RPL and RPDW indicators explaining on average of 26.94% PV were annotated and χ2-tested as a DT potential candidate gene system involving nine biological processes, endorsing the genetic complexity of DT.