Gray Luvisolic Soils Research Articles

Size-resolved distribution of trace elements in lysimeter soil solutions under contrasting long-term agricultural management to assess their bioavailability

The chemical species of trace elements (TEs) in agricultural soils is highly variable under diverse conditions, requiring tools with clear resolution and minimal disturbance for exploration. A novel surgical (316L) stainless steel (SS) lysimeter with a 5 μm pore size was developed to collect field soil solutions. The size-resolved distribution of TEs were characterized into total (nitric acid digestion), particulate (0.45–5 μm), dissolved (<0.45 μm), colloidal (1 kDa to 0.45 μm), and mainly ionic (<1 kDa) fractions in the lysimeter soil solutions. Total concentrations of TEs (dry weight basis) in acid digested Gray Luvisolic soils were analyzed. Most TEs in lysimeter soil solutions were present in particulate phases, relevant to their geochemical affinities and occurrences in soil minerals. Among dissolved fractions, As, Ba, Co, Li, Mn, Tl, and V existed as mainly ionic species in the soil solutions. Copper, Pb, Al, Th, and U showed variable associations with dissolved organic matter (DOM) and/or inorganic colloids among agricultural treatments. Inorganic NPKS or NKS fertilizer applications with lower pH (5.25–5.74) enhanced mobility and potential bioavailability of Ba, Co, Li, Mn, and Pb present in mainly ionic species, compared with other locations (pH 5.82–6.37). Manure application exhibited a dual effect, potentially increasing bioavailability for As, Tl, and V due to probably enhanced cation exchange capacity (CEC), while also facilitating specific adsorption of Cu and U on DOM, potentially reducing their bioavailability depending on DOM molecular weight. Colloidal and ionic Al and Th concentrations were higher in forest soils than agricultural soils, with extremely low potential bioavailability of Th attributed to strong precipitation with inorganic colloids and adsorption on DOM. The lysimeter sampling and size fractionation method provided a clear insight into agricultural effects on TE distributions and enhancing understanding of agricultural soil health in terms of TE bioavailability in situ.

Gray Luvisols are polygenetic

With respect to the pedosphere, human activities in the last 100 years have been the major driver of soil change. Despite human activities being one of the main soil forming factors recognized by soil scientists (in addition to climate, organisms, parent material, relief, groundwater, and time), the Canadian System of Soil Classification (CSSC) emphasizes soil as a natural body. We argue human agricultural activities are direct and indirect drivers of significant changes to the carbon balance and cycling in A horizons of Gray Luvisolic soils in western Canada, resulting in changes to A horizon carbon stocks, structure, and micromorphology. Evidence from scientific literature, in-field soil profile observations, and the National Pedon Database are presented in support of our argument. We propose a polygenetic, two-stage model of Gray Luvisol soil formation. The first stage is dominated by the climate forcing of the Holocene, resulting in a relatively stable boreal forest ecosystem including perturbations from natural and human-induced wildfire and other disturbances. The second stage is dominated by direct, human-driven disturbances such as cultivation, release of exotic fauna (earthworms), and indirect human-driven disturbances associated with anthropogenic climate change. Further, we propose modest amendments to the CSSC to reflect a polygenetic model of soil genesis in Gray Luvisolic soils that preserve the balance between observation and interpretation inherent in the system.

Nitrous oxide emissions from manured soils as a function of various nitrification inhibitor rates and soil moisture contents

Application of nitrification inhibitors (NI) coupled with nitrogen additions can reduce nitrous oxide (N2O) emissions. The effectiveness of NIs can be impacted by environmental and soil conditions; however, more information is needed about their optimum application rates, in particular when applied with manure. This study investigated the effectiveness of a range of NIs application rates on reducing N2O emissions from soils receiving liquid manure additions under three moisture contents. Two incubations (A and B) were conducted in Gray Luvisolic (GL) and Black Chernozemic (BC) soils using two NIs [2-chloro-6-(trichloromethyl) pyridine (nitrapyrin) and the new 3,4-dimethylpyrazole succinic acid (DMPSA)]. Soil NH4+ and NO3− concentrations were measured. Beneficial N2O emission reductions caused by NIs were evident at the intermediate and high soil water contents. The averaged emission reductions were 60% and 56% at the 60% and 80% water-filled pore space (WFPS) of the GL soil, respectively. Likewise, a coherent reduction of 58% was also found at the 60% WFPS of the BC soil. Conversely, this emission reduction vanished in this very carbon-rich, clayey BC soil at the highest moisture (80% WFPS). Moreover, as low N2O fluxes occurred with the lowest moisture (40% WFPS), non-significant and minimal emission reductions by NIs were observed, with a null reduction in the BC soil and only 10% averaged reduction in the GL soil at 40% WFPS. Focusing on the N2O emission reduction and nitrification inhibition under a broad range of NIs rates (in incubation B), as soil moisture rose from 60 to 80% WFPS, the most efficient NI rate increased from 0.25 to 1.0 kg a.i. ha−1 for nitrapyrin and from 0.22 to 0.65 kg a.i. ha−1 for DMPSA in both soils. In sum, results inform how soil moisture and NI application rates influence the effectiveness of NIs, aiding to improve strategies to reduce N losses from agricultural systems with NI implementation.

Evaluation of Low Heat Unit Corn Hybrids Compared to Barley for Forage Yield and Quality on the Canadian Prairies

Corn (Zea mays L.) production is expanding in the prairie region of western Canada. The objectives of this study were to compare three new low heat unit corn hybrids to barley (Hordeum vulgare L.) for forage yield, nutrient profile, and total nutrient production. The study was conducted at 4 sites (Evansburg and Fairview, Alberta; Melfort and Scott, Saskatchewan) with different soil characteristics (Gray Luvisolic, Grey Wooded, Dark Brown, and Black soil zones) over three consecutive years (2012-2014). At each site, annually, 16 plots (2.4×7.2 m) were randomly assigned to one of four forage crops (corn:Monsanto DKC26-25, Hyland 2D093, Pioneer P7443R; barley: cv. AC Ranger) in a replicated (n = 4) trial. Number of cobs per plant was not different (p = 0.23) between corn hybrids averaging 1.22 ± 0.32/plant (mean ± sd). Forage yield among the corn hybrids was negligible (p &gt; 0.05), but the corn hybrids exhibited 40% higher yield (p &lt; 0.05; avg. 11.3 ± 3.6 t/ha on DM basis) compared to barley (avg. 6.7 ± 1.7 t/ha). Corn hybrids were lower (p &lt; 0.05) in CP content [7.6 ± 1.4% versus (vs.) 12.4 ± 0.1%] than barley. No difference was observed between the 4 forage crops in TDN content (68.2 ± 2.8% DM).Study results suggestthat new cool-season corn hybrids can produce high quality forage to meet the nutrient requirements of grazing beef cows in mid- and late-stage pregnancy.New corn hybrids may be suitable alternatives for winter grazing strategies since forage harvest costs would be eliminated.

Relative Nitrogen Fertilizer Requirements of Forage Versus Grain for Barley and Oat

Field experiments were conducted at 15 site-years with barley and 10 site-years with oat over five years to determine the relative nitrogen (N) fertilizer requirements of forage versus grain for barley and oat on Black Chernozem (Typic Agricryoll – 6 site-years on barley and 3 site-years on oat) and Gray Luvisol (Typic Haplocryalf – 9 site-years on barley and 7 site-years on oat) soils in central and north-central Alberta, Canada. Barley harvested for forage responded to higher level of applied N than when it was harvested for grain at most site-years. On average for barley, the amount of N fertilizer required to achieve maximum yield of forage was 58 kg N ha−1 greater than that of grain, and also was somewhat greater on Black Chernozem soils than on Gray Luvisol soils. The results for oat were inconclusive, with almost equal numbers of site-years showed higher N requirements for grain as for forage.

A chronsequential approach to investigating microbial community shifts following clearcutting in Boreal Plain forest soils

Impacts of forest harvesting are often assessed in short-term studies that ignore the longer term changes associated with the disturbance. A chronosequence approach was taken to investigate changes in microbial community size and composition over ∼20 years post-harvest in lodgepole pine ( Pinus contorta Douglas ex Loudon) stands of the Boreal Plain. The LFH and mineral Ae horizons of Orthic Gray Luvisolic soils were sampled in six cutblocks, aged 1–19 years since harvest, in 2009 and 2010. Changes in microbial communities were assessed using phospholipid fatty acid analysis (PLFA) and 16S rDNA analysis. Physical and chemical soil parameters were measured to delineate microsite changes impacting microbial community shifts. Total microbial biomass (PLFA) was unaffected by harvesting disturbance, although fungal biomass was significantly larger in the oldest cutblock of the chronosequence. Microbial community composition did, however, differ between younger and older cutblocks as indicated by both lipid PLFA and 16S rDNA fingerprinting techniques. Forest soil microbial communities subject to clearcutting were observed to shift in overall community composition while remaining consistent in overall community size. The shift in community composition, which occurred in concert with the maintenance of biomass, indicated that the microbial community adapted sufficiently to the new post-harvest microsite conditions.

Non-native earthworm influences on ectomycorrhizal colonization and growth of white spruce

Exotic earthworms are entering previously uninhabited soils of boreal forests, their invasion largely facilitated through human activities. As ecosystem engineers, earthworms are capable of causing dramatic changes in above- and belowground forest composition, but whether they have the same effects in all forests remains unclear. Forest compositional changes caused by earthworms may be mediated by interactions between earthworms and mycorrhizal fungi. Specifically, tree seedling growth may be altered by the presence of exotic earthworms and their subsequent impact on mycorrhizal fungi. In this study, we investigate the effects of exotic earthworms on ectomycorrhizal colonization and seedling growth of the conifer Picea glauca (white spruce) in gray luvisolic soils from the Boreal Plains. Anecic Lumbricus terrestris and epigeic Dendrobaena octaedra earthworms were added to mesocosms each containing a white spruce seedling in a greenhouse experiment. Impacts on the composition of ectomycorrhizal fungi in the mesocosms were determined using a combination of morphological and molecular techniques, and effects on seedling growth were assessed through above- and belowground measurements. The proportion of ectomycorrhizal root tips and ectomycorrhizal community composition did not vary as a function of earthworm species or density. Similarly, exotic earthworms had no significant effect on spruce seedling growth or survival.

Improving organic C and N fractions in a sulfur-deficient soil with S fertilization

A field experiment was conducted over 9 years (1999 to 2007 growing seasons) in northeastern Saskatchewan on a S-deficient Gray Luvisol (Typic Haplocryalf) soil. The objective was to determine the relative effectiveness of N alone versus combined annual application of N (120 kg N ha−1) and S (15 kg S ha−1) fertilizers to a wheat–canola rotation on storage of total organic C (TOC) and N (TON) and on the light fraction organic C (LFOC) and N (LFON) in soil. Compared to N alone, annual applications of S fertilizer in spring in a combination with N resulted in an increase in soil of TOC (by 2.18 Mg C ha−1), TON (by 0.138 Mg N ha−1), LFOC (by 1,018 kg C ha−1), and LFON (by 42 kg N ha−1). The relative increases in organic C or N due to S fertilizer application were much higher for the light organic fractions (36.9% for LFOC and 27.5% for LFON) than for the total organic fractions (9.2% for TOC and 7.3% for TON). The findings demonstrate the importance of a balanced/combined application of N and S fertilizers to crops in storing more organic C and N in this S-deficient soil.

Long-term tillage, straw and N rate effects on some chemical properties in two contrasting soil types in Western Canada

Long-term use of soil, crop residue and fertilizer management practices may affect some soil properties, but the magnitude of change depends on soil type and climatic conditions. Two field experiments with barley, wheat, or canola in a rotation on Gray Luvisol (Typic Cryoboralf) loam at Breton and Black Chernozem (Albic Argicryoll) loam at Ellerslie, Alberta, Canada, were conducted to determine the effects of 19 or 27 years (from 1980 to 1998 or 2006 growing seasons) of tillage (zero tillage [ZT] and conventional tillage [CT]), straw management (straw removed [SRem] and straw retained [SRet]) and N fertilizer rate (0, 50 and 100 kg N ha−1 in SRet, and 0 kg N ha−1 in SRem plots) on pH, extractable P, ammonium-N and nitrate–N in the 0–7.5, 7.5–15, 15–30 and 30–40 cm or 0–15, 15–30, 30–60, 60–90 and 90–120 cm soil layers. The effects of tillage, crop residue management and N fertilization on these chemical properties were usually similar for both contrasting soil types. There was no effect of tillage and residue management on soil pH, but application of N fertilizer reduced pH significantly (by up to 0.5 units) in the top 15 cm soil layers. Extractable P in the 0–15 cm soil layer was higher or tended to be higher under ZT than CT, or with SRet than SRem in many cases, but it decreased significantly with N application (by 18.5 kg P ha−1 in Gray Luvisol soil and 20.5 kg P ha−1 in Black Chernozem soil in 2007). Residual nitrate–N (though quite low in the Gray Luvisol soil in 1998) increased with application of N (by 17.8 kg N ha−1 in the 0–120 cm layer in Gray Luvisol soil and 23.8 kg N ha−1 in 0–90 cm layer in Black Chernozem soil in 2007) and also indicated some downward movement in the soil profile up to 90 cm depth. There was generally no effect of any treatment on ammonium-N in soil. In conclusion, elimination of tillage and retention of straw increased but N fertilization decreased extractable P in the surface soil. Application of N fertilizer reduced pH in the surface soil, and showed accumulation and downward leaching of nitrate–N in the soil profile.

Long-term tillage, straw and N rate effects on quantity and quality of organic C and N in a Gray Luvisol soil

Long-term use of soil, crop and fertilizer management practices alters some soil properties, but the magnitude of change depends on soil type and climatic conditions. A field experiment with a barley (Hordeum vulgare L.)–wheat (Triticum aestivum L.)–canola (Brassica napus L.) rotation was conducted on a Gray Luvisol (Typic Cryoboralf) loam soil at Breton, Alberta, Canada. Effects of 19 or 27 years (from 1980 to 1998 or 2006 growing seasons) of tillage (zero tillage [ZT] and conventional tillage [CT]), straw management (straw removed [SRem] and straw retained [SRet]) and N fertilizer rate (0, 50 and 100 kg N ha−1 in SRet, and 0 kg N ha−1 in SRem plots) were determined on total organic C (TOC) and N (TON), light fraction organic C (LFOC) and N (LFON), macro organic matter C (MOM-C) and N (MOM-N), microbial biomass C (MB-C), and mineralizable C (Cmin) and N (Nmin) in the 0–7.5 and 7.5–15 cm or 0–5, 5–10 and 10–15 cm soil layers. Zero tillage and SRet tended to have higher, and N fertilizer treatment usually had higher mass of TOC, TON, LFOC, LFON, Cmin and Nmin in soil compared to the corresponding CT, SRem and zero-N control treatments, especially in the surface soil layers. Soil MB-C, MOM-C and MOM-N in soil generally tended to be higher with SRet than SRem, and also with N fertilizer than zero-N. There was no additional beneficial effect of ZT in increasing MB-C in soil. There were close and significant correlations among most soil organic C or N fractions, except for MB-C which did not correlate with MOM-N, and Nmin did not correlate with MOM-C. Linear regressions between crop residue C input and soil organic C or N were significant in most cases, except for MB-C and Nmin. Compared to the 1979 data, all treatments that did not receive N fertilizer (CTSRem0, CTSRet0, ZTSRem0 and ZTSRet0) showed a decrease in TOC concentration in the 0–15 cm soil layer over time, with the highest decrease in the CTSRem0 treatment. Straw retention and N fertilizer application at 50 and 100 kg N ha−1 under both ZT (ZTSRet50 and ZTSRet100) and CT (CTSRet50 and CTSRet100) resulted in a strongest increase in TOC during the first 11 years, and since then the TOC decreased under both N rates but 50 kg N ha−1 rate under CT (CTSRet50) showed the strongest negative effect on TOC in soil. In conclusion, elimination of tillage, straw retention and N application all improved organic C and N in soil, and generally differences were more pronounced for light fraction organic C and N, and between the most extreme treatments (CTSRem0 vs. ZTSRet100) for each dynamic organic fraction. This may be better for the long-term sustainability of soil quality and productivity.

Influence of controlled-release urea on seed yield and N concentration, and N use efficiency of small grain crops grown on Dark Gray Luvisols

Field experiments were conducted on Dark Gray Luvisolic soils (Typic Cryoboralf) from 2004 to 2006 (wheat-canola-barley rotation) near Star City, Saskatchewan, and from 2004 to 2007 (barley-canola-wheat-barley rotation) near Beaverlodge, Alberta. The aim was to compare the effects of controlled-release urea (CRU) vs. conventional urea (hereafter called urea) on seed yield and N (i.e., protein) concentration, and N use efficiency (NUE). The treatments were combinations of tillage system [conventional tillage (CT) and no tillage (NT)], and N source (urea, CRU and a blended mixture), placement method (spring-banded, fall-banded and split application) and application rate (0-90 kg N ha-1). There was no tillage × fertilizer treatment interaction on the measured crop variables. Seed yield and crop N uptake and, to a lesser degree, seed N concentration generally increased with N application to 90 kg N ha-1. Fall-banded CRU or urea generally produced lower crop yield and N uptake than spring-banded CRU or urea. Split application of urea (half each at seeding and tillering) resulted in higher seed yield and N concentration in at least 3 of 7 site-years than did CRU and urea applied at a similar rate. A blend of urea and CRU was as effective as spring-banded CRU (at Star City only). Seed yield, N recovery and NUE were higher with spring-banded CRU than urea in 2 site-years, and similar to urea in other site-years. We conclude that for boreal soils of the Canadian prairies, spring-banded CRU is as effective as urea, and in some years more effective, in increasing crop yield and N recovery; however, urea split application can be even more effective in addition to having an advantage in managing risk.Key words: Controlled-release urea, Gray Luvisol, nitrogen source, nitrogen recovery, nitrogen use efficiency, tillage systems

Differences in initial root development and soil conditions affect establishment of trembling aspen and balsam poplar seedlings

Three studies examined the establishment and early growth of trembling aspen ( Populus tremuloides Michx.) and balsam poplar ( Populus balsamifera L.) from seed. To better understand the differences in initial developmental patterns between both species, we monitored germination and early growth in a washed sand medium with a balanced fertilizer added. Two additional studies used the Ae, Bm, and Bt horizons of a Brunisolic Gray Luvisol soil to test the impact of different soil horizons and conditions (compaction and moisture) on the establishment and early growth of trembling aspen and balsam poplar seedlings. Balsam poplar had faster radicle and leaf area development than trembling aspen and grew similarly in all soil horizons, while trembling aspen only grew well in the Ae horizon, where it outgrew balsam poplar. The superior growth of trembling aspen in the Ae horizon was associated with higher P and organic C relative to the lower horizons. Although germination was lowest on the low-compaction – low-moisture treatment for both species, balsam poplar establishment and early growth were higher than for trembling aspen in all combinations of compaction and moisture. Compared with trembling aspen, the wider establishment niche of balsam poplar is attributed to its faster root development and ability to grow in a range of soil substrates and conditions.

Comparative Forage Yield of “Poor” Versus “Good” Grass Stands under Different Soil Fertility Regimes in Northeastern Saskatchewan

ABSTRACT Forage yield and its response to fertilizers are affected by the condition of forage stands. A field experiment was conducted on a Gray Luvisol (Typic Croyoboralf) soil at Pathlow in northeastern Saskatchewan, from 2004 to 2006, to determine if low forage yields in “poor” grass stands are due to nutrient deficiencies, other soil properties and/or species composition, and to determine if forage dry matter yield (DMY), protein concentration (PC), and protein yield (PY) in these areas could be improved by fertilization. The four fertilizer treatments: no fertilizer—nil, plus three combinations of increasing amounts of nitrogen (N), phosphorus (P), potassium (K), and sulfur (S) fertilizers (i.e., 45 kg N + 10 kg P + 12.5 kg K + 5 kg S ha−1; 90 kg N + 20 kg P + 25 kg K + 10 kg S ha−1; and 135 kg N + 30 kg P + 37.5 kg K + 15 kg S ha−1) were applied annually to the same plots in early spring of 2004 and 2005. The lower forage yield in “poor” compared to “good” grass stand areas was most likely due to differences in plant species composition, although other factors such as soil fertility and compaction may have also contributed to lower DMY. There was a significant response of DMY, PC, and PY to applied N, P, K, and S fertilizers in both “good” and “poor” grass stands in both years. The DMY, PC, and PY in the first year (2004) continued to increase up to the highest fertilizer rate used in this study, but in the second year (2005) there was no increase in total DMY in both grass stands, and in PC and PY in “good” grass stand with application of fertilizer blend beyond the 90 kg N + 20 kg P + 25 kg K + 10 kg S ha−1 rate. Fertilizer application for two years also increased the proportion of smooth bromegrass in both stands, indicating that proper nutrient management may increase the proportion of smooth bromegrass (high yielding grass species) in the “poor” growth area, thereby improving forage yields. Overall, the findings indicate that forage yields and quality in “poor” grass stand areas can be improved considerably by applying fertilizer nutrients that are lacking in the soil. Also, the significant responses observed in the “good” grass stand areas suggest that these regions of the field can also benefit from additional fertilization.

Immediate Effects of Time and Method of Alfalfa Termination on Soil Mineral Nitrogen, Moisture, Weed Control, and Seed Yield, Quality, and Nitrogen Uptake

ABSTRACT Three field experiments were conducted on Gray Luvisol (Typic Cryoboralf) soils in northeastern Saskatchewan to compare the effects of alfalfa (Medicago sativa Leyss) stand termination with tillage and herbicides at different times on mineral nitrogen (N) (ammonium-N and nitrate-N) and moisture content of soil in spring (experiments 1 and 2), soil moisture, volunteer alfalfa and dandelion control, plant density, seed yield, protein concentration and N uptake for wheat (Triticum aestivum L.), barley (Hordeum vulgare L), canola (Brassica rapa L.), and pea (Pisum sativum L.) crops (experiment 3). Termination treatments included combinations of times (in mid-June after cut 1, in mid-August after cut 2 and in mid-May during spring) and methods [tillage alone, herbicides alone (glyphosate + 2,4-D amine and also clopyralid + 2,4-D ester in experiment 3) and these herbicides + tillage]. Tillage alone significantly increased spring soil nitrate-N levels over herbicides alone or herbicides + tillage. Termination after cut 1 had the highest levels of soil nitrate-N. There was little effect of time and method of termination on soil ammonium-N and moisture content in spring. Herbicides + tillage generally provided better control of both volunteer alfalfa and dandelion in the four crops than tillage or herbicides alone. In general, alfalfa termination with herbicides alone significantly reduced plant density, seed yield, and N uptake of all crops and protein concentration of cereals only due to effects on levels of soil nitrate-N, dandelion control, and crop injury by clopyralid or 2,4-D residues in soil. Plant density, seed yield, N uptake and protein concentration of crops tended to decline with delay in termination time. The results of this study support the use of some tillage in alfalfa stand termination in helping to control volunteer alfalfa and dandelion and optimize annual crop yields and quality.

Tillage System and Seeding Time Effects on Forage and Seed Yield of Alfalfa and Bromegrass

Perennial forages are an important component for the cropping systems of the Parkland region in the Canadian prairies, but only a few studies have reported on direct seeding of forages in northeastern Saskatchewan. The objective of this study was to compare the effects of tillage (conventional tillage, CT, and zero tillage, ZT) for seedbed preparation and different seeding times (October 1993, May 1994, and June 1994) on forage and seed yield of alfalfa (Medicago sativa Leyss) and bromegrass (Bromus inermis Lyess) on Gray Luvisol (Typic Cryoboralf) soils (sandy at Gronlid and clayey at Ridgedale) in northeastern Saskatchewan. Visual inspection of plant stands in the establishment year indicated that plant densities were generally higher under CT than ZT and with spring than autumn seeding. Forage yield in 1994 was greater under ZT than CT for alfalfa at both sites and for bromegrass at Ridgedale. In 1995 and 1996, tillage had no effect on forage yield in most cases. The 3‐year forage production was greater under ZT than CT for alfalfa by 647 and 770 kg ha−1 at Gronlid and Ridgedale, respectively, and for bromegrass at Ridgedale (by 697 kg ha−1), with the opposite result at Gronlid (by 237 kg ha−1). The effect of seeding time on forage production was not consistent. The seed yield in 1995 and 1996 was somewhat greater with ZT than CT, with autumn than spring seeding, and with May than June seeding for alfalfa, whereas the opposite was true for bromegrass, except at Ridgedale when autumn seeding produced greater seed yield than spring seeding. In summary, the lower plant population under ZT than CT in the establishment year did not necessarily result in lower forage and seed yield of alfalfa and bromegrass, suggesting that ZT can replace CT for forage production, and seeding time effect was mainly observed in the first year.

Interactive effects of N and S fertilizers on canola yield and seed quality on S-deficient Gray Luvisol soils in northeastern Saskatchewan

On marginally S-deficient soils in the Parkland region, application of high rates of N and other fertilizers in combination with more frequent productionof canola (Brassica napus L. or B. rapa L.) causes rapid depletion of S and nutrient imbalance in soil, and S deficiency and yield reductionfor canola. Field experiments on Gray Luvisol (Boralfs) soils deficient in available N and S were conducted in northeastern Saskatchewan. Interactive effects of N (0, 50 100 and 150 kg N ha-1) and S (0, 10, 20 and 30 kg S ha-1) rates on yield, seed quality, and uptake of S and N in canola were determined. In the absence of S application, increasing N rate made the S deficiency symptoms more severe, and reduced yield, S concentration, oil concentration, S uptake and N uptake of seed, but there was a general response of no effect or some increase in protein concentration, S and N uptakein straw up to 50 or 100 kg N ha-1. When S was applied, canola yield, S concentration, S uptake and N uptake of seed as well as the yield and S uptake of straw increased with increasing N rate. Irrespective of S rate, fertilizer N reduced oil concentration and increased protein concentrationin canola seed. With S fertilization, yield, S uptake and N uptake of seed and straw, and total S concentration and oil concentration in seed were substantially increased, whereas there was no consistent change in protein concentration of seed. The response of these parameters to S application was generally greater at higher N rates. Sulphur and N uptake measured data indicated that significant N × S interaction effects were more frequent and pronounced for seed yield than for straw yield, indicating that the response to N rate was relatively more dependent on the S level for seed than for straw. In summary, the results suggest that an increased amount of S is needed on these S-deficient Gray Luvisol soils in northeastern Saskatchewan to adequately meet the S requirements at high N rates for optimum yield and quality of canola. Key words: Canola, N and S concentration and uptake, N and S fertilization, oil concentration, S-deficient soil, seed yield and quality

Yield, Seed Quality, and Sulfur Uptake of Brassica Oilseed Crops in Response to Sulfur Fertilization

Field experiments were conducted in 2003, 2004, and 2005 on a S‐deficient Gray Luvisol (Boralf) soil near Star City, in northeastern Saskatchewan, to determine yield, seed quality and S uptake response of different Brassica (B.) oilseed species/cultivars to S deficiency and S fertilization. A total of 20 treatments were tested in a factorial combination of four oilseed crops (B. juncea canola cv. Arid, B. juncea canola cv. Amulet, B. juncea mustard cv. Cutlass, and B. napus cv. InVigor 2663 hybrid canola) and five rates of potassium sulfate fertilizer (0, 10, 20, 30, and 40 kg S ha−1). All B. species/cultivars responded positively for seed yield and most other parameters to S fertilizer in all 3 yr, but the magnitude of response varied with species/cultivar and year. Seed yield was highest with Cutlass juncea mustard in a dry year (2003), but was highest with InVigor 2663 hybrid canola in years with above‐average precipitation (2004 and 2005). Seed yield was usually maximized at the rate of 30 kg S ha−1 for all B. species/cultivars. Oil concentration in seed increased with S fertilization for all B. species/cultivars. There was a significant (albeit small) increase of protein concentration in seed due to S fertilization. Cutlass juncea mustard accumulated considerably high concentrations of glucosinolates in seed, but glucosinolate concentrations were low in other B. species/cultivars. Sulfur uptake in seed was highest with Cutlass juncea mustard in all years. The effects of S deficiency and applied S were more pronounced on seed than straw. In conclusion, S fertilizer requirements for optimum seed yield were similar for all the B. species/cultivars used in this study on S‐deficient soil, but higher yielding types of B. would produce greater seed yield by using S more efficiently.

Crop Response to Elemental S and Sulfate-S Sources on S-Deficient Soils in the Parkland Region of Alberta and Saskatchewan

ABSTRACT Six field experiments were conducted on sulfur-(S) deficient Gray Luvisol (Typic Cryoboralf) and Dark Gray Chernozem (Typic Cryoborolls) soils at various locations in Alberta and Saskatchewan to evaluate the effectiveness of elemental S (ES-90, ES-95, Urea S, Fine S Powder), sulfate-S (ammonium sulfate, sodium sulfate), and elemental S + sulfate-S (Sulgro-68, Agrium Plus) fertilizers, and their rates and placement methods on seed yield and S uptake of canola and barley, and forage dry matter yield of pure bromegrass and bromegrass-alfalfa mixed stands. There was a substantial increase in yield and/or S uptake from sulfate-S application in most experiments. This indicated that the soils used in these experiments were deficient in plant-available S, especially for canola. In the initial year, the performance of elemental S fertilizers was usually inferior to sulfate-S fertilizers. Among the elemental S fertilizers, the ES-95 tended to produce greater yield and S uptake than ES-90. In general, there was no difference in seed yield between early (May 1) and late (May 23) spring applications for the elemental S (Urea S). The results indicated that from the second or third year of initiating annual applications the effectiveness of some elemental S fertilizers almost approached the level of sulfate-S fertilizers. Residual effect of S application lasted for at least three years. Overall, the findings suggest that correction of a severe S deficiency by elemental S alone may be risky in the short term, and thus addition of some sulfate-S in the initial 1 or 2 years to supplement the sulfate-S from elemental S is advisable. Increased exposure of elemental S fertilizers to oxidation either by incorporation and broadcast methods or by application ahead of plant use time tends to improve crop response.

Effects of four consecutive annual applications of elemental S and sulphate-S fertilizers on yield, S uptake and seed quality of wheat

A field experiment from 1999 to 2002 was carried out near Tisdale in northeastern Saskatchewan on a S-deficient Gray Luvisol (Typic Cryoboralf) soil to compare the effects of elemental S and sulphate-S fertilizers on yield, seed protein, total S concentration, S uptake, and recovery of applied S in wheat (Triticum aestivum L.) and residual SO4-S in soil. Treatments were combinations of 10 and 20 kg S ha-1 rates applied in autumn and spring for two granular bentonitic elemental S fertilizers (ES- 90 and ES-95), one fertilizer containing both elemental S and sulphate-S (Agrium Plus), and ammonium sulphate, plus a zero-S control. The S fertilizers were surface-broadcast and all plots had a preseeding rotovation in spring to incorporate fertilizers into the soil. Seed (1 yr) and straw (3 yr) yield, seed protein concentration (1 yr), and total S concentration and S uptake in seed and straw (all years except uptake of S in seed in 2001 and 2002) showed significant response to S fertilization. Ammonium sulphate and Agrium Plus were generally more effective compared with the elemental S fertilizers, when there was a significant response to sulphate-S containing fertilizers. Autumn application of elemental S fertilizers was sometimes more effective than spring application, while an opposite trend was observed for sulphate-S containing fertilizers in some cases. The increase in S rate from 10 to 20 kg S ha-1 tended to increase the measured wheat parameters in many elemental S treatments, but for sulphate-S fertilizers the effect was less pronounced. The concentration of total S in seed and straw was relatively more responsive to S fertilization than yield and S uptake, particularly for seed. The effect of S fertilization on wheat was less pronounced in drought years, particularly on seed yield, suggesting that drought rather than S availability was limiting wheat growth. There was some build-up of residual SO4-S in the 0-60 cm depth of soil in many S fertilizer treatments after four successive applications, but there was little or no difference in soil SO4-S between elemental S and sulphate-S fertilizers. In conclusion, the results from four successive annual applications of elemental S and sulphate-S fertilizers in autumn and spring on the same area indicate that bentonitic granular elemental S fertilizers had comparatively less influence on wheat than granular sulphate-S fertilizers and further research to improve the effectiveness of these elemental S fertilizers is suggested. Key words: Elemental S, fertilizer, protein, seed quality, sulphate-S, wheat, yield

Effect of forest harvest on soil temperature and water storage and movement patterns on Boreal Plain hillslopes

Through its effect on vegetation, forest harvesting affects soil moisture storage, water movement processes, and soil temperature. The effects of harvest on water storage and movement patterns and on soil temperature during the snowmelt period were studied 3 years after harvest on hillslopes in northern Alberta, Canada. Measurements of soil water content, soil temperature, and bromide tracer concentrations were made at 11 pairs of forested and harvested plots, which are all dominated by Gray Luvisol soils but possess a range of topographic characteristics. Compared with forested sites, harvested sites were expected to have higher soil water content, display more interflow, and thaw earlier. Harvested sites were wetter on only one of four dates sampled, reflecting dry weather and rapid aspen regrowth. Greater loss and shallower penetration of bromide tracer in plots indicate that harvested sites had more interflow than forested sites. Despite a trend to higher temperatures, harvested sites did not thaw earlier than forested sites. Our inability to detect dramatic treatment effects reflects the need for large sample sizes for soil properties that display high local spatial and temporal variability. Key words: forest harvest, soil moisture, soil thaw, bromide, interflow, boreal.