bluuebunny/crossref_metadata_2025 huggingface dataset:
RESPONSE OF DIFFERENT GROWTH FORMS OF POA ANNUA L. (ANNUAL BLUEGRASS) TO HERBICIDES APPLIED BEFORE OR AFTER EMERGENCE
Authors: WARWICK S. I. , HAMILL A. S. , MARRIAGE P. B.
Published: March 2010

The response of erect/annual and prostrate/perennial strains of Poa annua to herbicides was examined by treating soil with bensulide or chlorthal-dimethyl prior to emergence and by treating immature and mature plants with endothal or linuron. Chlorthal-dimethyl gave better control than bensulide as measured by a greater reduction in the number of seedlings surviving and dry weight of the survivors. Linuron was more effective than endothal in reducing biomass production of both immature and mature plants. Differential response of the erect and prostrate growth forms was not apparent for either bensulide or chlorthal-dimethyl, or for total biomass production of immature and mature plants in response to endothal or linuron. However, a significant growth form by treatment interaction was obtained for the vegetative component of mature plants, with the prostrate plants showing a greater weight reduction than erect individuals relative to the control. The weight of the reproductive component was equally reduced in both growth forms. Percent dry weight allocated to reproductive growth, which was 35 and 15% for the erect and prostrate growth form, respectively, remained relatively constant for both growth forms for all herbicide treatments.
THE BIOLOGY OF CANADIAN WEEDS.: 40. Portulaca oleracea L.
Authors: MIYANISHI KIYOKO , CAVERS PAUL B.
Published: March 2010

A summary of biological data for Portulaca oleracea L. (purslane) is provided. A cosmopolitant weed throughout temperate and tropical areas of the world, purslane is a common garden and agricultural weed across southern Canada. Effective control has been obtained with a wide range of postemergent and residual herbicides.
AIR POLLUTION EFFECTS ON AGRICULTURAL CROPS IN ONTARIO: A REVIEW
Authors: ORMROD D. P. , PROCTOR J. T. A. , HOFSTRA G. , PHILLIPS M. L.
Published: March 2010

Photochemical oxidants, sulphur dioxide and fluoride are the major air pollutants affecting agricultural crops in Ontario, but scientific documentation of their effects is limited, particularly for sulphur dioxide and fluoride. Airborne road salt, cement dust, soot, boron, nickel, cobalt and ammonia have also been implicated in a few localized instances of crop injury. The most widespread injury to agricultural crops is caused by photochemical oxidants, mainly in southern Ontario where tobacco, bean, potato, grape, cucumber, onion, tomato and other crops have been affected. Sulphur dioxide has had significant effects on forests and natural vegetation in Ontario, and may become important in agricultural areas due to the proliferation of coal-fired electric generating stations. The effects of sulphur dioxide in combination with other gaseous pollutants such as photochemical oxidants, and the long-term effects of acid precipitation are current concerns. In addition, there have been a few cases of fluoride injury to crops localized around fluoride-emitting industries. Very few estimates of economic losses to agricultural crops have been documented anywhere and to date no assessment of the economic value of air pollution damage to agricultural crops in Ontario has been attempted.
EFFECTS OF FUNGICIDES AND HERBICIDES ON STAGHEAD OF RAPE
Authors: BERKENKAMP B.
Published: March 2010

Three foliar sprays of the fungicide CGA 48988 controlled staghead of rape. A soil application of the herbicide trifluralin increased the disease.
BYTOWN RED CLOVER
Authors: CHILDERS W. R. , DICKSON W. D.
Published: March 2010

Bytown is a tetraploid cultivar of Trifolium pratense L., developed at the Agriculture Canada Research Station, Ottawa, Ontario. The cultivar has larger leaves, stems and floral parts than its parent Ottawa diploid variety. It has shown greater persistence in Northern areas of Ontario and Quebec and will be used in dairy production as haylage. The SeCan Association will be responsible for seed increase and distribution. It was licensed in March 1979 and pedigree seed will be available to farmers in the spring of 1981.
HERITABILITIES AND RELATIONSHIPS AMONG GRAIN-FILLING PERIOD, SEED WEIGHT AND QUALITY IN FORTY ITALIAN VARIETIES OF CORN (ZEA MAYS L.)
Authors: PERENZIN M. , FERRARI F. , MOTTO M.
Published: March 2010

Forty Italian open-pollinated varieties of corn (Zea mays L.), selected to represent a wide range of plant maturity and grain weight, were evaluated in 1977 and 1978 to determine genetic variances and heritabilities for length and rate of grain-filling period, kernel weight and three seed-quality traits and to examine relationships among these traits. The results showed highly significant genotypic differences and high heritability estimates for most of the traits studied. Moreover, kernel weight and rate of grain filling were found to be closely associated, although this relationship could not be statistically tested. A relatively high correlation was also detected between kernel weight and length of the grain-filling period. The increase in seed weight obtained through a delay in black-layer formation was associated with a higher grain moisture content and a decreased grain protein percentage. A further noteworthy finding of this study was the identification of two varieties which attained a large seed weight in a relatively short time through a very high rate of dry matter accumulation. The implications of these findings are discussed from a physiological and breeding point of view.
METHIOCARB AS A BIRD REPELLENT ON RIPENING GRAIN SORGHUM
Authors: DUNCAN R. R.
Published: March 2010

Bird damage on grain sorghum (Sorghum bicolor (L.) Moench) crops in the United States is a multimillion dollar problem. High tannin, bird-resistant sorghum hybrids provide a non-preference type of resistance, the effectiveness of which is governed by size of bird populations and availability of other food sources. However, high tannin grain can result in nutritional and marketing problems. Chemical control agents provide alternative means of reducing bird damage. This study, by measurement of grain yield and bird damage, evaluated the bird repellency of methiocarb applied to grain sorghum at three rates. Grain yields were 1383 kg/ha (28%) higher and bird damage was 37% lower on the methiocarb-treated plots than on the check plots. Test weight was 1.2 kg/hL higher and plants were 6 cm taller on the treated plots than on the check plots, suggesting a possible growth stimulatory reaction. An application rate of 1.2 kg/ha of 75% wettable powder appeared to repel birds as effectively as higher rates. Grain yields were substantially reduced (from 8104 to 4894 kg/ha) as the rate of methiocarb treatment increased from 1.2 to 4.26 kg/ha.
INHERITANCE, CHARACTERIZATION AND SELECTION OF TANNIN-FREE FABABEANS (VICIA FABA L.)
Authors: CROFTS H. J. , EVANS L. E. , McVETTY P. B. E.
Published: March 2010

Three large-seeded, tannin-free cultivars and one large-seeded, tannin-containing cultivar were crossed with three small-seeded, tannin-containing cultivars and with a small-seeded, tannin-containing advanced line. All three large-seeded cultivars carried the same single recessive gene conferring the white-flower, the absence of pigment on the nectaries of the stipules, the absence of anthocyanic pigments on the stems and the tannin-free seed coat characteristics. Changes in seed coat weight and seed coat composition were associated with the tannin-free characteristics. It is concluded that the tannin-free characteristic can be easily introduced into fababean lines.
SPACING AND COMPETITION AMONG HIGH- AND LOW-YIELDING CLONES OF ALFALFA
Authors: HART RICHARD H.
Published: March 2010

Alfalfa (Medicago sativa L.) plants from high- and low-yielding clones were grown 15, 30, or 60 cm apart, in a design in which plants were surrounded by different ratios of high:low-yielding plants. The design made it possible to evaluate the effects of competition and spacing on yield and the ability to select high-yielding plants from the stand. Plant weights and tiller numbers of all clones declined as the number of high-yielding plants among surrounding plants increased. Correlations between plant yields and yield of surrounding plants were similar at all spacings, but the ratio of yields of high- to low-yielding plants increased as spacing decreased. Selection for high yield might be more efficient at close spacing. Individual plant weights were described by equations of the form [Formula: see text], in which n = plants/m2, and yields/ha were described by equations of the form [Formula: see text].
THE BIOLOGY OF CANADIAN WEEDS.: 47. Plantago lanceolata L.
Authors: CAVERS P. B. , BASSETT I. J. , CROMPTON C. W.
Published: March 2010

Narrow-leaved plantain (Plantago lanceolata L.) is particularly abundant in southern areas of British Columbia, Ontario and Quebec, and the coastline of Prince Edward Island and Nova Scotia. It is a serious weed of lawns, dry grasslands and roadsides, although it is a palatable species to livestock in dry pastures. This account is a summary of the most recent biological information on P. lanceolata including data heretofore unpublished.
SEASONAL VARIATION IN GLUCOSINOLATE COMPOSITION OF RUTABAGA AND TURNIP
Authors: JU HAK-YOON , CHONG CALVIN , BIBLE BERNARD B. , MULLIN W.J.
Published: March 2010

Glucosinolates, determined by quantifying their hydrolysis products, were studied in seeds and in roots of two cultuvars of rutabaga (Brassica napobrassica Mill.) and of turnip (Brassica rapa L.) sampled at 2-wk intervals during growth on both loam and organic soils. The glucosinolates generally were higher in roots of rutabaga than in those of turnip. Accumulation of different glucosinolates in roots of both species occurred at different times during the growing season in the sequence after seeding: indolyl glucosinolates yielding ionic thiocyanate at the 2-wk stage; glucosinolates yielding volatile isothiocyanate hydrolysis products at the 4-wk stage; and 2-hydroxy-3-butenyl glucosinolate (progoitrin) yielding 5-vinyl-oxazolidine-2-thione (goitrin) at the 6- or 8-wk stage. Mean total glucosinolate content of rutabaga and turnip grown on organic soil was 15 and 38% higher than those grown on loam soil, respectively. The contents of goitrin and volatile isothiocyanates were inversely correlated in the seed of both species.
AUXIN LEVELS IN TASSELS OF MAIZE CULTIVARS DIFFERING IN TOLERANCE TO HIGH POPULATION DENSITIES
Authors: SEYEDIN NADER , LAMOTTE CLIFFORD E. , ANDERSON IRVIN C.
Published: March 2010

To test the hypothesis that low tassel-auxin levels during early ear development result in high population tolerance, free plus esterified IAA was determined in tassels of three maize cultivars. IAA level was significantly higher in tassels of the most tolerant cultivar, a finding contrary to the hypothesis.
HAIRS PROTECT PODS OF MUSTARD (BRASSICA HIRTA ’GISILBA’) FROM FLEA BEETLE FEEDING DAMAGE
Authors: LAMB R. J.
Published: March 2010

Pods of the mustard Brassica hirta ’Gisilba’, which have stiff hairs, showed no significant flea beetle damage, while adjacent rapeseed plots showed heavy pod damage. Removal of hairs from mustard pods caused an increase in feeding damage by the flea beetles. Breeding for pod hairiness in rapeseed may reduce pod damage caused by this pest to an insignificant level.
RELATIONSHIPS BETWEEN WHEAT SEED ATP CONTENT, GERMINATION AND SEEDLING VIGOR OF DIFFERENT SPRING WHEAT GENOTYPES
Authors: BRIGGS K. G. , HORAK A.
Published: March 2010

In a study of 75 spring wheat (Triticum aestivum L.) genotypes, no relationship was found between seedling vigor and establishment in the field and ATP content of dry seed, or with seedling vigor by controlled germination tests in growth cabinets at 14 or 18 °C. In any search for genotypic variability for stand establishment in spring wheat, differential seedling mortality rates and dry weight accumulation at the five-leaf stage appear to be useful characters to measure.
DIFFERENTIAL APPARENT INFECTION RATES OF EAR MOLD INCITED BY GIBBERELLA ZEAE BETWEEN TWO ARTIFICIALLY INOCULATED HYBRIDS OF MAIZE
Authors: ENERSON P. M. , HUNTER R. B.
Published: March 2010

Two hybrids artificially inoculated with Gibberella zeae ear mold showed markedly different rates of "simple-interest" infection. It is concluded that the two hybrids differ in horizontal resistance to this pathogen.
RESPONSE OF MAIZE HYBRIDS TO ARTIFICIALLY INOCULATED EAR MOLD INCITED BY GIBBERELLA ZEAE
Authors: ENERSON P. M. , HUNTER R. B.
Published: March 2010

Differences in inherent resistance to Gibberella ear mold were found among 13 maize hybrids. Upright ears and ears with tight husk coverage at harvest were found to have more ear mold than corresponding pendant ears and ears with loose husks.
EFFECTS OF IMAZALIL SEED TREATMENT ON SUBCROWN INTERNODE LENGTHS AND COLEOPTILE-NODE-TILLERING IN WHEAT
Authors: CHINN S. H. F. , VERMA P. R. , SPURR D. T.
Published: March 2010

The effects of seed treatment with imazalil at 0.2 and 0.3 g a.i./kg seed on subcrown internode length and occurrence of coleoptile-node-tillers (CNT) was studied in four spring wheat cultivars at two locations in Saskatchewan. Without treatment, Cypress had the longest internodes followed in descending order by Glenlea, Neepawa, and Wascana. Generally, plants from imazalil-treated seed had significantly shorter subcrown internodes. Only a few plants from nontreated seed produced CNT and of these, many were soft or aborted, while the treated seed produced a number of CNT and many of these were firm tillers. The possible importance of these morphological changes in the reduction of common root rot, on drought resistance, cold hardiness, and yield is discussed.
ELBEE NORTHERN WHEATGRASS
Authors: SMOLIAK S. , JOHNSTON A.
Published: March 2010

Elbee is the first cultivar of northern wheatgrass (Agropyron dasystachyum (Hook.) Scribn.), a native species, to be released in Canada. It was developed at the Agriculture Canada Research Station, Lethbridge, Alberta. The main attributes are excellent germination, high seedling vigor and drought tolerance, moderately aggressive creeping root system, early spring growth, and perennial growth habit.
Phosphorus fertilizer by-product effect on the interaction of zinc and phosphorus in corn and soybean
Authors: Hernandez Jorge David , Killorn Randy
Published: March 2010

The application of high phosphorus fertilizer by-products to farmland is a common practice used to reduce storage volume and disposal cost. However, because Iowa soils are generally high in both phosphorus and zinc, there are environmental and fertility questions concerning their application to farmland. A greenhouse study was conducted to determine the effect of a soil-applied fertilizer by-product on the zinc-phosphorus relationship in corn and soybean plants grown on three Iowa soil series: Belinda, Downs, and Haig. The soils were mixed with a high-phosphorus fertilizer by-product and plants were also collected and analyzed for phosphorus and zinc content and uptake. Soil samples were analyzed for phosphorus and zinc content. The experiment was repeated, switching pots to assess the residual effect after one cycle of rotation. The treatments were arranged in a totally randomized design with three replications. The results indicated that the high phosphorus fertilizer by-product increased soil and plant concentrations of phosphorus in soybean and corn plants and soils. However, the increase of P concentration did not induce changes in the phosphorus-zinc interaction in corn and soybean plants in any of the studied soils. Key words: Phosphorus, corn, soybean, zinc, sludge, by-products, Zn-P relationship, zinc-phosphorus interaction
Estimation de la fertilité potentielle des ferralsols par la couleur
Authors: Koné B. , Diatta S. , Sylvester O. , Yoro G. , Mameri C. , Desiré D. D. , Ayemou A.
Published: March 2010

A farmer-friendly method of determining the most suitable cultivation soils would help in transferring new integrated soil management technologies. The potential for using soil color (Munsell data) was tested by physico-chemical analysis of 1028 ferrallitic soil samples from 289 profiles unequally allocated above 7 deg N in Côte d’Ivoire. Soil hue variations in depth and along the toposequence revealed the existence of vertical and lateral gradients of soil hue. The relative contribution of the different descriptors (clay, sand, carbon, total nitrogen, total phosphorus, potassium, magnesium and calcium) to the three functions extracted using a discriminant analysis to differentiate the four groups of soils with different hues was evaluated as well as the analysis of variance to determine the possible groups number for each one of the descriptors. Differences between physico-chemical components of red (2.5YR and 5YR) and yellow (7.5YR and 10YR) soils were determined, especially for P, Mg and K in extension. A decreasing gradient of inherent soil fertility indicators with an increasing yellowness in soil hue was revealed using multiple regression models. The soils 2.5YR and 5YR were therefore deemed more appropriate for stable and sustainable agriculture.Key words: Hue, ferralsols, fertility, soil use
Soil microbial response to wood ash or lime applied to annual crops and perennial grass in an acid soil of northwestern Alberta
Authors: Lupwayi N Z , Arshad M A , Azooz R H , Soon Y K
Published: March 2010

More than 90% of acid soils in western Canada are in Alberta, yet the use of agricultural lime is limited because it is expensive. Wood ash, a by-product of pulp and lumber mills, can be used for liming acid soils. We investigated the effects of amending an acid Luvisol with wood ash or lime on soil microbiological properties at Beaverlodge, Alberta. Both soil amendments were applied at a calcium carbonate rate of 6.72 t ha-1, which was 8.40 t ha-1 for wood ash and 7.47 t ha-1 for lime, in 2002. Soil microbial biomass C (MBC) and the functional diversity and community structures of soil bacteria (indicated by substrate utilization patterns) were measured from 2002 to 2005 under barley (Hordeum vulgare L.), canola (Brassica napus L.), field pea (Pisum sativum L.), and timothy grass (Phleum pratense L.). In the rhizosphere, wood ash increased soil MBC between 2.4-fold in 2002 and 1.3-fold in 2005, and lime increased MBC from 3.2-fold in 2002 to 1.3-fold in 2005. In bulk soil, the increases in MBC ranged from 3.0-fold in 2003 to 1.8-fold in 2005 for wood ash, and from 4.9-fold in 2002 to 2.0-fold in 2005 for lime. Crop effects on MBC were not consistent. Because annual crops were grown in rotation, it is possible that the results obtained in one crop were confounded by effects of the preceding crop. In 2003 and 2004, both amendments increased Shannon index (H’) of bacterial functional diversity in the rhizosphere, and similar results were observed in 2005 in bulk soil. Shifts in the functional structure of bacterial communities due to soil amendment were observed in bulk soil, and shifts due to crop effects were observed in the rhizosphere. In 2003, the average soil pH(CaCl2) increased from 4.91 in control treatments of different crops to 6.60 in lime-amended plots and 6.70 in wood ash-amended plots. In 2004, both wood ash and lime significantly increased soil C mineralization (up to 10 d incubation), but basal respiration (11-24 d incubation) was not affected. The large effect (up to about fivefold) of soil amendments on MBC implies that soil acidity is a major limiting factor for biological processes and the productivity of some Luvisolic soils in Alberta. Wood ash could be used to alleviate these limitations. Key words: C mineralization, microbial diversity, microbial biomass, soil amendment, soil acidity
Impact of natural or industrial liming materials on soil properties and microbial activity
Authors: Lalande Roger , Gagnon Bernard , Royer Isabelle
Published: March 2010

Soil acidity is a major problem in agriculture because it limits plant growth and reduces crop productivity. The neutralizing potential of industrial by-products and their impact on soil properties were evaluated in two acidic soils characterized by contrasting textures, and submitted to intensive agriculture practices. Soil pH, microbial (dehydrogenase and alkaline phosphatase) activity, and Mehlich-3 extractable P, K, Ca and Mg were monitored in the year of soil incorporation of eight liming products and in the following 2 yr. In the sandy loam, liming products did not result in significant increases in soil pH in the 0- to 7.5-cm soil layer. Lime mud (LM) significantly increased soil pH by 0.4 units in the 7.5- to 20-cm layer compared with cement kiln dust (CKD). In the silty clay, calcium-phosphate-magnesium (CalPoMag) significantly raised pH by 0.65 units over both natural calcitic lime (NCa) and the magnesium dissolution product (MgD) in the first soil layer, and by 0.5 units over carbide lime (CL) treatment in the second soil layer. Activities of dehydrogenase and alkaline phosphatase were increased to various degrees by all liming materials, especially on the silty clay; LM and CalPoMag were the most beneficial materials. The exception was MgD, which did not result in any impact on microbial activity relative to the control. Both enzymatic activities were related to the increase in soil pH, particularly the alkaline phosphatase. Ion leaching was more pronounced in the sandy loam than in the silty clay soil, where large differences in the Ca and Mg ion levels were still detected in the 20- to 40-cm layer of the sandy loam. In this study, LM and CalPoMag are interesting liming products, particularly in the silty clay soil. Key words: Enzymatic activity, soil pH, lime, soil cations
Effect of humic acid coating on arsenic adsorption on ferrihydrite-kaolinite mixed systems
Authors: Martin M , Celi L , Barberis E , Violante A , Kozak L M , Huang P M
Published: March 2010

The reactivity of the colloids formed in soil environments results from complex interactions between clay minerals, (oxy)hydroxides and organic matter of soils. The adsorption/desorption equilibria and kinetics of anionic and cationic species on/from natural colloids could substantially differ compared with their interaction with pure minerals. The objective of this study was to investigate the arsenite and arsenate equilibria and the kinetics of arsenite adsorption on ferrihydrite-coated kaolinite as influenced by the presence of humic acid coverage. The Langmuir adsorption maximum and affinity of arsenite and arsenate adsorption on the kaolinite-ferrihydrite system was reduced by the presence of the humic acid. The enthalpy of adsorption on the kaolinite-ferrihydrite system, measured with isothermal titration calorimetry, was –24.4 kJ mol–1 for arsenite and –39.9 kJ mol–1 for arsenate, and was only slightly decreased by the humic acid coating. The kinetics of arsenite adsorption was substantially influenced by the presence of the humic coverage, resulting in the decrease in the rate constant, the Arrhenius heat of activation, and the pre-exponential factor (indicative of the collision frequency of the sorbate and the sorbent). The hampering effect of the humic acid on arsenic adsorption was attributable to the blocking by the organic ligand of the adsorbing sites, coupled with the steric hindrance of the large organic molecules, which restricted the arsenic to approach the surfaces. Key words: Arsenic, adsorption, kinetics, kaolinite, ferrihydrite, humic acid
Simulating ammonia loss from surface applied manure
Authors: Smith E. , Gordon R. , Bourque C. , Campbell A. , Génermont S. , Rochette P. , Mkhabela M.
Published: March 2010

The land spreading of manure can result in significant nitrogen (N) losses to the atmosphere through ammonia (NH3) volatilization. It is estimated that agricultural activities, including manure spreading contribute approximately 50% of the total global NH3 emissions. Computer simulation models have been developed in an attempt to predict NH3 losses resulting from manure spreading. Few models have been validated with success and no validation has been completed for conditions found in eastern Canada. The mechanistic model Volt’Air was implemented and tested to estimate NH3 emissions using field-based wind tunnel data from three field locations in eastern Canada. The model was validated using data from 27 wind tunnel trials, which measured NH3 loss over 5-19 d. Sensitivity analysis revealed that Volt’Air was most sensitive to pH. Good overall agreement was observed between measured results and model simulations over 5-19 d (R2 = 0.91, RMSE = 2.9 kg ha-1). Short-term flux simulations (kg ha-1 h-1) within the first 24 h after spreading were underestimated by 29.5% and fluxes on subsequent days were slightly underestimated by 3.7%. Error with Volt’Air appears to be largely confined to the first day following manure application. Volt’Air offers potential for predicting NH3 losses (i.e., 5-19 d) from manure application within eastern Canada. Improving the simulation of short-term pH changes, however, may result in enhanced overall model performance.Key words: Ammonia volatilization, flux, mechanistic model, swine manure, wind tunnels
Effects of peat source and length of storage time in bales on selected properties of Sphagnum peat
Authors: Mofidpoor M , Krzic M , Principe L
Published: March 2010

Peat is a common ingredient of growing media used in the horticultural industry in North America and Europe, yet Canada does not have formal standards for peat quality assessment. This study evaluated selected properties of baled peat as affected by peat source and length of storage time under conditions typically occurring at a commercial growing media firm. Nine bales of peat (dominated by fibric white peat) from the upper, less-decomposed layers of a Sphagnum bog in Manitoba in the early stage of exploitation (ESE) and nine bales of peat (dominated by hemic brown peat) from the lower, more-decomposed layers of a Sphagnum bog in Alberta in the late stage of exploitation (LSE), were sampled after 1, 3, and 10 mo of storage. The ESE peat had a larger particle size (determined by both dry and wet sieving), and a higher content of total elements (Fe, Mn, Cu, Zn, Mo, Al, As, Cd, Co, Na, Ni, Pb, and Si), water content, and NH4-N than the LSE peat. The LSE peat had higher pH and NO3-N content. Plant-available water, air-filled porosity, and the number of germinated weeds were similar in ESE and LSE peat. In both sources of peat, organic particle size (determined by wet sieving) was lower after 10 mo of storage relative to 1 and 3 mo of storage. Similarly, the NH4-N content decreased from 120 mg kg-1 after 1 mo of storage to 90 mg kg-1 after 10 mo of storage. Hence, the growing media industry should monitor particle size distribution and available N at the time when peat is incorporated into growing mixes.Key words: Growing media; particle size; horticulture; wet sieving
Influence of 10 years of conservation tillage on some biological properties of a fine sandy loam in the potato phase of two crop rotations in Atlantic Canada
Authors: Carter M R , Peters R D , Noronha C , Kimpinski J
Published: March 2010

Conservation practices in potato (Solanum tuberosum L.) cropping systems can reduce excess tillage, provide crop residue cover, and maintain crop productivity; however, little is known about their long-term influence on soil biota and biological properties. Conservation tillage was evaluated in two potato rotations: a 2-yr barley-potato rotation and 3-yr clover-based (barley-red clover-potato) rotation initiated in 1994 on a fine sandy loam (Orthic Podzol) in Prince Edward Island, eastern Canada. Soil samples were obtained in 2003 from the 0- to 10-cm soil depth of the potato phase of both rotations to evaluate the influence of conservation, compared with conventional tillage, on changes in soil fertility, soil structural properties, soil C and N fractions, soil-borne pathogens, nematode communities, and micro-arthropod (Collembola and Acari) communities. The 3-yr conservation tillage practice improved soil structural stability, increased soil extractable P and K, increased soil organic C and total N and their particulate fractions, compared with the other treatments. Comparisons with earlier studies indicated that soil organic C had reached an equilibrium level at the 0- to 10-cm soil depth. Reduction of potato disease caused by Rhizoctonia solani was evident in the 3-yr rotation, compared with the 2-yr rotation, but was not influenced by tillage practice. Plant parasitic nematodes were not greatly influenced by rotation and tillage treatments; however, densities of the beneficial bacterial-feeding nematodes were increased under the 3-yr conservation tillage treatment. The abundance of micro-arthropods was increased by conservation tillage, while their diversity was mainly influenced by the rotation cycle rather than tillage practice. Overall, the 3-yr conservation tillage treatment provided a more beneficial soil biological condition than the other treatments, especially when compared with the 2-yr conventional tillage practice. Key words: Conservation systems, potato rotation, fine sandy loam, soil fertility, soil organic C and N fractions, soil structure, soil-borne pathogens, nematode, Collembola; Acari
Using artificial neural network models to produce soil organic carbon content distribution maps across landscapes
Authors: Zhao Z. , Yang Q. , Benoy G. , Chow T L , Xing Z. , Rees H W , Meng F -R
Published: March 2010

Soil organic carbon (SOC) content is an important soil quality indicator that plays an important role in regulating physical, chemical and biological properties of soil. Field assessment of SOC is time consuming and expensive. It is difficult to obtain high-resolution SOC distribution maps that are needed for landscape analysis of large areas. An artificial neural network (ANN) model was developed to predict SOC based on parameters derived from digital elevation model (DEM) together with soil properties extracted from widely available coarse resolution soil maps (1:1 000 000 scale). Field estimated SOC content data extracted from high-resolution soil maps (1:10 000 scale) in Black Brook Watershed in northwestern New Brunswick, Canada, were used to calibrate and validate the model. We found that vertical slope position (VSP) was the most important variable that determines distributions of SOC across the landscape. Other variables such as slope steepness, and potential solar radiation (PSR) also had significant influence on SOC distributions. The prediction of the selected two-input-node SOC model (VSP and coarse resolution soil map recorded SOC as inputs) had a correlation coefficient of 0.92 with measured values, and model predicted SOC values had 47.9% of the total points within ±0.5% of the measured values and 70.6% within ±1% of the measured values. The prediction od the selected four-input-node model (VSP, slope steepness, PSR and coarse resolution SOC values as inputs) had a correlation coefficient of 0.98 with measured values and model predicted SOC values had 75% of the total points within ±0.5% of the measured values and 87% within ±1% of the measured values. The prediction of the five-input-nodes model with soil drainage as additional input had a correlation coefficient of 0.99 with measured values, and model predicted SOC values had 87% of the total points within ±0.5% of the measured values and 98% of the total points within ±1% of the measured values. The calibrated SOC prediction model was used to produce a high-resolution SOC map for the Black Brook Watershed and the resulting SOC distribution map is considered to be realistic. Results indicated that DEM-derived hydrological parameters together with widely available coarse resolution soil map data could be used to produce high-resolution SOC maps with the ANN method.Key words: Soil organic carbon, artificial neural network model, high-resolution soil maps, digital elevation model, vertical slope position
Effect of growing season rainfall and tillage on the uptake and recovery of 15N-labelled urea fertilizer by spring wheat in a semi-arid environment
Authors: Malhi S S , Soon Y K , Brandt S
Published: March 2010

Growing season rainfall affects fertilizer N recovery, particularly in semi-arid environments. However, the influence of rainfall distribution during the growing season is not well-understood. We conducted a 7-yr study (from 1997 to 2006) to assess this effect, and that of no-till (NT) vs. conventional tillage (CT), on fertilizer N recovery by spring wheat (Triticum aestivum L.) fertilized with 15N-labelled urea at 40 kg N ha–1 and grown on stubble on a Dark Brown Chernozem soil in Saskatchewan, Canada. Two of the seven experimental years had growing season rainfall close to normal, one was above normal and four were below normal. Tillage treatment did not affect 15N recovery by wheat; however, 15N recovery in the top 15 cm of soil averaged 47% under NT vs. 39% under CT (P = 0.02). Total N and 15N uptakes were most affected by "year" due to variation in growing season rainfall distribution. Excluding an ultra-low value of 3.8% (or 1.5 kg N ha–1) in 2002, due to extreme drought, 15N recovery by wheat averaged 47.5% (range 30–57%), and percent N derived from fertilizer was 12–20%. Rainfall in May correlated significantly with 15N and total N uptake (r = 0.605 and 0.699, respectively). The recovery of 15N in wheat head correlated negatively with June rainfall (r = –0.624), probably because more moisture increased soil N mineralization, which diluted the 15N pool. During grain filling, soil N uptake was 12–30 kg ha–1, compared with negligible amounts (< 7%) of 15N; however, about 15 kg ha–1 of 15N were remobilized vs. 34–74 kg ha–1 of soil N. It is concluded that, in this semi-arid region, fertilizer N uptake is influenced more by rainfall in May than other months of the growth period.Key words: 15N-labelled urea, fertilizer N recovery, N uptake, rainfall, remobilized N, tillage
Availability of single spring applications of three sulphur fertilizer sources to grass under humid weather conditions
Authors: Kowalenko C G
Published: March 2010

Field experiments were conducted to compare the effectiveness of single spring applications of three sulphur (S) fertilizers (powdered and granulated elemental S, and granulated sparingly soluble gypsum) to supply S to tall fescue grass (Festuca arundinacea 'Festorina') under humid weather conditions of coastal British Columbia. The treatments were three rates (30, 60 and 90 kg S ha-1) of each of the three fertilizers and control (No S) in three plots initiated in1997, 1998 and 1999 in different locations in an uniformly managed field. The relative effectiveness of the fertilizers was detected by plant uptake of S since the site was only marginally S deficient resulting in only occasional yield increases. The fertilizers were also evaluated by the increase of inorganic sulphate in the soil. The plant and soil measurements showed that S was available to the plant earlier from the granular gypsum than the elemental forms, and the powdered form was available slightly earlier than the granular form of elemental S. Some uptake of all three fertilizers occurred early in the season, i.e., by the first cut of the crop, showing that elemental S was oxidized relatively quickly. The delayed uptake of S from the granulated elemental S compared with the powdered form reflected the need for the granule to disintegrate before it could be oxidized in the soil. This study showed that S is not always available in soils at the time it is required by plants within a growing season of multiple-cut grass. Knowing the pattern of the release of S from various fertilizer forms in relation to within-season variations of soil S availability and plant requirement of S can provide the basis for optimum amendment decisions.Key words: S fertilizers, elemental S, sulphate-S, crop response, crop S uptake, soil sulphate, SulFer 95
Biomolecule-induced carbonate genesis in abiotic formation of humic substances in nature
Authors: Hardie A G , Dynes J J , Kozak L M , Huang P M
Published: March 2010

Most soil C sequestration research has focused on organic C stabilization, while carbonate precipitation has received little attention. Mineral colloids can accelerate abiotic humification reactions of biomolecules such as amino acids, sugars, and polyphenols, derived from the breakdown of biological residues and metabolites. During these reactions CO2 is produced as a result of the oxidation of biomolecules. However, the biomolecule-induced formation of carbonate during abiotic humification remained to be uncovered. Here we demonstrate using X-ray diffraction, Fourier transform infrared spectroscopy and C K-edge and Mn L-edge near edge X-ray absorption fine structure spectroscopy that the Maillard reaction (glucose and glycine) and the integrated polyphenol-Maillard reaction pathway (catechol, glucose and glycine), in the presence of birnessite (δ-MnO2) produce MnCO3 (rhodochrosite). Increasing the molar ratio of catechol to glucose and glycine dramatically hampered carbonate formation, which is attributed to the enhanced formation of humic polymers, which increased proton generation and perturbed rhodochrosite crystallization through Mn(II)-humic complexation in the reaction systems. Thus, rhodochrosite formation was a competing reaction with humic substance formation. Our findings are of fundamental significance in understanding the vital role of the nature and relative abundance of biomolecules in abiotic carbonate formation, which merits close attention in understanding and regulating C sequestration in natural environments.Key words: Abiotic humification, polyphenol-Maillard reaction, rhodochrosite, birnessite, C K-edge and Mn L-edge NEXAFS
Mycorrhizal networks and complex systems: Contributions of soil ecology science to managing climate change effects in forested ecosystems
Authors: Simard S W
Published: March 2010

Soil ecology science has contributed a rich understanding of natural soil patterns and processes, and played a role in revolutionizing the management of ecosystems. This basic understanding is also providing a foundation for predicting and managing the consequences of climate change on ecosystems, including their resilience to disturbance, biotic diversity, and carbon and nutrient dynamics. To help address the challenges of climate change, future soil ecology research and management would benefit from a complex systems approach, where network and dynamics systems theory are used to predict plant community and ecosystem responses to disturbance. A reductionist approach to management that ignores networks and system dynamics, by contrast, is destined to contribute to ecological degradation as climate changes. In this paper, I describe mycorrhizal networks as models of biological networks in the interior Douglas-fir forests of British Columbia, and the role they play in carbon flux and regeneration dynamics following disturbance. I propose a conservationist approach for managing forest mycorrhizal networks and hub trees that can facilitate native plant migrations, limit exotic plant invasions, and bolster ecological resilience. Interdisciplinary research that integrates the dynamics of multiple, overlapping networks will help develop management practices that sustain ecosystems in our changing climate. Key words: Climate change, complex systems, mycorrhizal networks, species migrations
Improving SHAW long-term soil moisture prediction for continuous wheat rotations, Alberta, Canada
Authors: Wang H. , Flerchinger G N , Lemke R. , Brandt K. , Goddard T. , Sprout C.
Published: March 2010

The Decision Support System for Agrotechnology Transfer-Cropping System Model (DSSAT-CSM) is a widely used modeling package that often simulates wheat yield and biomass well. However, some previous studies reported that its simulation on soil moisture was not always satisfactory. On the other hand, the Simultaneous Heat and Water (SHAW) model, a more sophisticated, hourly time step soil microclimate model, needs inputs of plant canopy development over time, which are difficult to measure in the field especially for a long-term period (longer than a year). The SHAW model also needs information on surface residue, but treats them as constants. In reality, however, surface residue changes continuously under the effect of tillage, rotation and environment. We therefore proposed to use DSSAT-CSM to simulate dynamics of plant growth and soil surface residue for input into SHAW, so as to predict soil water dynamics. This approach was tested using three conventionally tilled wheat rotations (continuous wheat, wheat-fallow and wheat-wheat-fallow) of a long-term cropping systems study located on a Thin Black Chernozemic clay loam near Three Hills, Alberta, Canada. Results showed that DSSAT-CSM often overestimated the drying of the surface layers in wheat rotations, but consistently overestimated soil moisture in the deep soil. This is likely due to the underestimation of root water extraction despite model predictions that the root system reached 80 cm. Among the eight growth/residue parameters simulated by DSSAT-CSM, root depth, leaf area index and residue thickness are the most influential characteristics on the simulation of soil moisture by SHAW. The SHAW model using DSSAT-CSM-simulated information significantly improved prediction of soil moisture at different depths and total soil water at 0-120 cm in all rotations with different phases compared with that simulated by DSSAT-CSM. Key words: Soil moisture, modeling, Decision Support System for Agrotechnology Transfer-Cropping System Model, Simultaneous Heat and Water Model
Monthly ammonia emissions from fertilizers in 12 Canadian Ecoregions
Authors: Sheppard S C , Bittman S. , Bruulsema T W
Published: March 2010

Emissions of ammonia (NH3) from agriculture have been associated with transboundary atmospheric pollutant transport and potential human health problems. Specifically, NH3 gas reacts in the atmosphere to form fine particles (PM2.5) that are subject to long range transport and are considered to be associated with elevated risk of all-cause, lung-cancer and cardiopulmonary mortality. Agriculture is a major source of atmospheric NH3, and, of this, NH3 from fertilizers is perhaps the most easily managed. Recent shifts in nitrogen (N) fertilizer materials and improved placement of urea and related fertilizers have resulted in marked changes in emissions. This paper describes a model developed to predict month-by-month emissions of fertilizer NH3, supported by surveys of farmers and fertilizer industry personnel that update information on fertilizer use. Compared with previous estimates by Environment Canada, the fraction of fertilizer N emitted as NH3 is estimated to be 50% lower in the vast prairie regions (a very large reduction in total NH3), and about 30% lower in eastern Canada. The estimate for 2006 is 1.0 × 108 kg NH3 emitted directly from fertilizer application, 73% of this in the prairie region, and much of this in May. Overall, this indicates 6% of the applied fertilizer N is lost as NH3 gas. Clearly, emission estimates are strongly dependent on up-to-date information about farm practices.Key words: Model, urea, volatilization
Surface application of cement kiln dust and lime to forage land: Effect on forage yield, tissue concentration and accumulation of nutrients
Authors: Rodd A V , McRae K B , MacLeod J A , Warman P R , Grimmett M G
Published: March 2010

Cement kiln dust (CKD), a by-product of the cement industry currently being landfilled, may be a beneficial soil amendment. A 2-yr field forage trial compared the effect of surface applications of CKD and lime on forage yield and the concentration and accumulation of N, P, K, Ca, Mg, Mn, Cu, Zn and B in the forage tissue. Seven soil treatments in three blocks were established on three low pH sites: (1) a check plot with neither lime or CKD added; (2) lime application based on the recommendation from soil analysis; (3) lime at 1.5 times the recommended application; (4) CKD applied at the recommended application; (5) CKD at 1.5 times the recommended application; (6) CKD applied on a neutralizing equivalent basis at the recommended application rate; and (7) CKD on a neutralizing equivalent basis at 1.5 times the recommended lime application; equivalence based on CKD’s apparent neutralizing value at 75% that of lime. In 1998, as tissue concentrations of K, Ca, Cu, and Mn increased with CKD application, the concentrations of N, P and Mg decreased, and in 1999, as the concentrations of Ca, K increased, the concentrations of N, P, Mg Mn, Zn decreased. Lime application increased the concentration of Mg (1998) and Ca and Mg (1999). The concentration of the other nutrients either decreased or were not significantly affected. In1998, forage yield and accumulation of Ca, K, Mn, Cu, Zn and B all increased with CKD addition, whereas the accumulation of Mg increased with lime addition. In 1999, forage yield and accumulation of N, P, K, Ca, Cu, Zn and B in the forage tissue all increased with CKD addition. These results were identified by principal component analysis (PCA). Surface applied CKD increased forage yield to a greater extent than lime. It was also a more readily available source of Ca and K than lime.Key words: Cement kiln dust
Mehlich 3 extractable nutrients as determined by near-infrared reflectance spectroscopy
Authors: Nduwamungu C , Ziadi N , Parent L -É , Tremblay G F
Published: March 2010

Near-infrared reflectance spectroscopy (NIRS) is a cost-effective and environmentally friendly technique of soil analysis that is particularly advantageous in intensive soil sampling and soil nutrient management as well. This study evaluated the potential of NIRS for predicting P, K, Ca, Mg, Cu, Zn, Mn, Fe, and Al extracted by Mehlich 3. We used 150 air-dried samples collected from a 15-ha site dominated by Orthic Humic Gleysol and Gleyed Dystric Brunisol soils. Calibration equations were developed using modified partial least squares regression. The accuracy of NIRS prediction was evaluated using the coefficient of determination (R2), the ratio of performance deviation (RPD), and the ratio of error range (RER). Reliable calibrations were found for Ca, Cu, and Mg (R2 ≥ 0.7, RPD ≥ 1.75, and RER ≥ 8). Less-reliable calibrations were found for Al, Fe, K, Mn, P, and Zn (R2 < 0.7, RPD < 1.75, and RER < 8). In the validation with independent samples, acceptable regression coefficients (i.e., 0.8 ≤ slope ≤ 1.2) were only found for Ca, Mg, and Mn. We presumed that the pH of the Mehlich 3 extractant (2.5 ± 0.1) may affect the solubility of most of these nutrients, regardless the soil texture and, consequently, the potential of NIRS to predict them. The more a nutrient was correlated to clay content, the more it was likely predictable by NIRS. The prediction models obtained for Al, Ca, Cu, Fe, K, Mg, and Mn could still be used for screening purposes in cases where high accuracy is not required. These NIRS prediction models should be validated across larger geographic areas of geological homogeneity. Key words: Soil analysis, Mehlich 3, near-infrared reflectance spectroscopy, calibration