Canadian Prairie Soils Research Articles

Application of seed-row potash to barley (Hordeum vulgare L.) grown on soils with high “available” potassium levels

Benefits of KCl application to cereals have been documented in Great Plains soils and have been attributed primarily to a response to the Cl- portion of this fertilizer either due to disease suppression or a Cl- deficiency. The practice of placing small amounts of KCl with the seed to avert any of these undesirable effects has been gaining momentum in western Canada. However, research on benefits from KCl fertilization of barley on high K soils in western Canada is limited. A large number of trials (115) were conducted from 1989 to 1998 on western Canadian prairie soils to ascertain the response of barley to seed-row applied KCl fertilizer. All soils contained K levels in excess of what is considered a critical level for obtaining a yield response to K due to K deficiency. Statistically significant yield increases with KCl application were obtained in 37 of 115 trials (32%). There appeared to be a strong link between the probability of obtaining a significant yield response to seed-row applied KCl, and barley cultivar and previous crop. Growing Harrington barley on barley stubble resulted in a grain yield increase due to KCl seed-placement 60% of the time. However, no clearly defined mechanism for the grain yield responses could be drawn based on the determined parameters, except that the majority of responses did occur under conditions that promote disease (e.g., disease susceptible cultivar, barley sown on barley stubble, etc.) and that the lower the soil “available” K levels in those instances, the higher the grain yield increase. Hence, it is hypothesized that K may play an indirect role in suppressing disease by increasing the overall health of plants. None of the assessed plant characteristics other than yield, i.e., days to maturity, kernel plumpness, protein and root rot infection, benefited from application of Cl- as either KCl or CaCl2. Key words: Chloride, cultivar, Harrington, disease, plant health, previous crop

A prediction model for estimating the cadmium content of durum wheat from soil chemistry

A non-linear prediction model for the Cd content of durum wheat grain has been developed based on the 0.1 M Na 4P 2O 7-extractable Cd and organic carbon in the <2 mm fraction of the soil ploughed horizon. The extraction is selective for metals held as metal–organic complexes in the soil, and will also extract more loosely held metal. The prediction model explains 74% of the variability of the durum grain data ( N=34), and confirms the importance of the metal-organically held Cd, organic carbon and pH in influencing the uptake of Cd by durum wheat in Canadian Prairie soils.

Management effects on soil C storage on the Canadian prairies

The Canadian prairie, which accounts for about 80% of Canada's farmland, has large reserves of soil organic carbon (SOC). Changes in the size of the SOC pool have implications for soil productivity and for atmospheric concentrations of CO 2, an important `greenhouse gas'. We reviewed recent findings from long-term research sites to determine the impact of cropping practices on SOC reserves in the region. From this overview, we suggest that: (1) the loss of SOC upon conversion of soils to arable agriculture has abated; (2) significant gains in SOC (typically about 3 Mg C ha −1 or less within a decade) can be achieved in some soils by adoption of improved practices, like intensification of cropping systems, reduction in tillage intensity, improved crop nutrition, organic amendments, and reversion to perennial vegetation; (3) changes in SOC occur predominantly in `young' or labile fractions; (4) the change in SOC, either gain or loss, is of finite duration and magnitude; (5) estimates of SOC change from individual studies are subject to limitations and are best viewed as part of a multi-site network; and (6) the energy inputs into agroecosystems need to be included in the calculation of the net C balance. The long-term sites indicate that Canadian prairie soils can be a net sink for CO 2, though perhaps only in the short term. These sites need to be maintained to measure the effects of continued agronomic evolution and predicted global changes.

Methane emission from Canadian prairie and forest soils under short term flooding conditions

Short term flooding of usually well-drained soils is a recurrent phenomenon in many regions of the world, particularly after snowmelt in the spring and after heavy and prolonged precipitation. Using incubation-leaching and static chamber techniques, we examined the impact of short term flooding on methane emission from Canadian prairie and forest soils. The laboratory study demonstrated that flooding caused significant methane evolution from incubated soils (13 to 184 mg kg-1 over 8 weeks). In contrast, 80–95% of the atmospheric methane in the incubation jar was absorbed by nonflooded soils in a week. The field data showed that after snowmelt in the spring, the methane emission rate was highest in soils and ranged from 7.8 (cultivated) to 10.5 mg m-2 d-1 (grassland). Methane emission was also observed from low slope positions after rainfall in the summer. Three days after 23 mm of precipitation, the rate of methane evolution was 0.03 (cultivated) and 0.02 mg m-2 d-1 (grassland) whereas it was 0.11 (cultivated) and 0.07 mg m-2 d-1 (grassland) one day after 48 mm of precipitation.

Effect of crop rotations and rotation phase on characteristics of soil organic matter in a Dark Brown Chernozemic soil

The influence of five crop rotations and the rotation phases (i.e., rotation-yr) on some soil organic matter characteristics was investigated in a long-term (23 yr) study carried out on an Orthic Dark Brown Chernozemic soil at Scott, Saskatchewan. The cropping systems included different cropping frequencies and crop types (cereals, oilseeds, and legume-hay). Soil samples were taken from the 0- to 7.5- and 7.5- to 15-cm depths in mid-September 1988, 2 wk after harvest of the grain crops (i.e., 2 mo after hay harvest and plowdown). Most effects of rotations, and rotation phases, on soil biological characteristics assessed, were significant primarily in the top 7.5-cm soil depth. Increasing the cropping frequency did not increase soil organic matter. Excessive preseeding tillage of stubble plots may have masked any potential advantage provided by frequent cropping. Including alfalfa (Medicago sativa L.) hay crops in rotation with grain crops decreased soil organic matter in the fallow and grain crop rotation phases of rotations. This was likely due to increased moisture stress depressing associated cereal production in this semiarid environment. As expected, rotation phase did not influence soil organic C, but alfalfa under-seeded into barley (Hordeum vulgare L.) increased soil organic nitrogen. We believe this was due to crop residue inputs from the seedling alfalfa. Microbial biomass C and N, C mineralization, the specific respiratory activity (ratio of CO2-C respired/microbial biomass C) and hydrolyzable amino acids were also greater in the rotation phases in which barley was underseeded with alfalfa. Carbon mineralization and specific respiratory activity were directly related to estimated crop residue-C returned to soil, but not residue-N. However, both were increased by including alfalfa in the rotation. Carbon mineralization and specific respiratory activity were more sensitive indexes of soil organic matter quality than biomass C and N per se. Hydrolyzable amino acids and amino sugars responded to the treatments in a manner similar to total soil organic N. Relative molar distribution of amino acids was unaffected by crop rotation or rotation phase. Potentially mineralizable N in this soil was low compared to other Canadian prairie soils, even though the total soil organic N of the Scott soil was relatively high. We concluded that (i) all soil biochemical characteristics studied are useful for assessing soil quality changes; (ii) when studying soil changes, thin (0- to 7.5-cm) soil slices are more likely to reveal treatment effects than thicker slices; (iii) all rotation phases should be analyzed whenever forage legumes are constituents of crop rotations. Key words: C mineralization; microbial biomass, amino acids, N mineralization, specific respiratory activity

INFLUENCE OF SALT CONCENTRATION AND SODICITY ON THE SOLUBILITY OF PHOSPHATE IN SOILS

The effects of electrolyte concentration and exchangeable sodium (sodicity) on the solubility of native phosphate (P) in some Brown Chernozemic soils (Haploborolls) from Saskatchewan, Canada were evaluated using a flow (miscible displacement) technique. Phosphate concentration was measured in leachate from soil columns treated with a series of NaCl-CaCl2 solutions having fixed sodium adsorption ratio (SAR) with electrical conductivity (EC) decreasing from about 10 to 0.1 dS m−1. The results show that the P content of the leachate was strongly influenced by both EC and SAR and that these two variables were interactive in their effect. Leachate P was usually low (<0.1 mg L−1) when EC was high, but it increased as EC decreased, particularly when SAR was high. Values as high as 3 to 5 mg P L−1 were attained under conditions of low EC and high sodicity (SAR 20–40). Samples of leached soil were subjected to a chemical fractionation procedure to determine how the various forms of inorganic P responded to the imposed salinity and sodicity treatments. In the absence of Na (SAR O), there was relatively little change in the distribution of P during the leaching sequence but, as sodicity increased, the water-extractability of P increased substantially. The main effect of sodicity was that it made the weakly adsorbed P fraction (NaHCO3-P) more labile. Increasing sodicity had little effect on the more strongly adsorbed P fraction (NaOH-P) or on Ca-bound P (HCl-P). The results of this study suggest that electrolyte concentration and sodicity may have an important bearing on the P nutrition of crops grown on Canadian prairie soils. However, the widely-used Olsen test appears to be insensitive to the influence of these variables. It is possible that the poor performance of this test noted in recent reports is partly related to salt and/or sodicity effects.

THE WIND ERODIBILITY OF SOME ALBERTA SOILS AFTER SEEDING: AGGREGATION IN RELATION TO FIELD PARAMETERS

Average percentages of soil material &gt; 0.84 mm diameter estimated from wind erodibility groups (WEG) are commonly employed in the appraisal of the wind erodibility of soils. Soil samples taken after seeding from four areas of Alberta were sieved on a Modified Rapid Rotary Sieve. Agreement between the sieving data and estimates of material &gt; 0.84 mm made using the WEG was poor (r = 0.33). Samples from soil textural groups generally had twice as much material &gt; 0.84 mm than predicted by the WEG. Using 350 soil samples the relationship between soil aggregates &gt; 0.84 mm and (1) field estimated soil properties, and (2) soil management was investigated by multiple regression analysis. Aggregation was strongly dependent on soil texture (r = 0.67) with coarser-textured soils having fewer aggregates &gt; 0.84 mm and thereby being more erodible. Increasing quantities of soil carbonates (up to 10%) increased soil erodibility. Preseeding tillage decreased erodibility. Conversely, postseeding packing operations increased erodibility except when a rodweeder was used. Type of seeding implement, rotations, and type of crop seeded (oilseeds versus grains) had no statistically significant effect on aggregation. The coefficient of multiple determination (R2) for the final model was 0.61. Results were corroborated by previous experimental findings and confirmed that the WEG are not accurate for Canadian Prairie soils. The study demonstrated that although soil texture and carbonate content played an important role, tillage had a considerable effect on soil erodibility. Key words: Wind erosion, soil erodibility, WEG, aggregation, soil management

SURVIVAL OF Bradyrhizobium japonicum IN CANADIAN PRAIRIE SOILS

The study was conducted to determine whether Bradyrhizobium japonicum can over-winter in Canadian prairie soils, and whether prolonged storage in soil exposed to various environmental conditions affects its nodulating activity. In 1984, Maple Amber, an early-maturing Canadian soybean cultivar was grown in the field on two soils that had never been contaminated with B. japonicum. Two single strains and a commercial mixture of four strains were used as inoculants. In 1985, the soils were cropped again to soybean, but the 1984 inoculated plots were split to permit noninoculated and inoculated treatments. In both years, the inoculants increased seed yield and protein content over the noninoculated treatments. Plants grown on soils inoculated in 1984, but not in 1985, had no nodules, indicating that the Rhizobia did not survive over the winter; seed yield and protein content were similar to plants grown on soils that were never inoculated. Further, the two strains of B. japonicum, 61A148 and 61A196 were more effective than the multistrain inoculant, producing more nodules and greater seed yield, but similar protein content. In the fall of 1984, soil was removed from the inoculated and noninoculated plots and subjected to storage treatments prior to cropping to inoculated soybeans in a growth chamber. Immediate cropping of soils in the growth chamber, following removal from the field, showed that Bradyrhizobia were present at the time of sampling. Prolonged storage in a frozen or severe drying condition completely destroyed the nodulating activity of the Bradyrhizobia and may have killed them; storage in a moist refrigerated state reduced their nondulating activity and may have adversely affected their survival.Key words: Glycine max (L.) Merrill, soybean, Bradyrhizobia nodulation, survival, freezing, drying

THE SULPHUR STATUS OF EASTERN CANADIAN PRAIRIE SOILS: SULPHUR RESPONSE AND REQUIREMENTS OF ALFALFA (Medicago sativa L.), RAPE (Brassica napus L.) AND BARLEY (Hordeum vulgare L.)

Alfalfa (Medicago sativa), rape (Brassica napus) and barley (Hordeum vulgare) were grown in a growth chamber with and without sulphur (S) on surface samples (0–15 cm) of 17 eastern Canadian prairie soils. The soil varied in pedological origin and were divided into three groups based on their total nitrogen:total sulphur (N:S) ratios. Herbage yield of alfalfa (full bud) and rape (flowering) were highly correlated (P &lt; 0.01) with soil (N:S)s ratios and soil SO4-S, while for barley (shot blade) the relationships were significant [Formula: see text]. Herbage yields of the three crops were also significantly correlated [Formula: see text] with plant (N:S)p ratios. Soil (N:S) ratio was considered the best predictor of herbage yield because it is more stable over time than soil SO4-S and because plant (N:S)p ratio only indicates a need for future fertilization. The highest yields and S and N composition of plant tissues were obtained on soils with SO4-S concentrations greater than 12 mg kg−1 and an (N:S)s ratio of approximately 6. These soils had sufficient S to meet the requirements of all three crops. Addition of S had no effect on herbage yield but did increase S uptake. Results indicated that soils with (N:S)s ratio of 9 and SO4-S concentration of 7 mg kg−1, may have sufficient S to meet the requirement of barley but not alfalfa and rape. However, soils with higher (N:S)s ratios and lower SO4-S content were deficient in S for all crops. Barley was the most responsive to applied S of the three crops, although it had the lowest concentration of S (0.15 mg S g−1 dry herbage) and highest plant (N:S)p ratio (16) at its highest yield. Rape was more responsive to applied S than alfalfa but the concentration of S in the herbage of both crops at their highest yields were similar, 0.27 and 0.26 mg S g−1 dry herbage, respectively. Both crops also had lower (N:S)p ratios than barley at the highest yield (14 (alfalfa) and 12 (rape)), reflecting their greater S uptake. Key words: Plant-available S, soil (N:S)s ratio, plant (N:S)p ratio, plant uptake of S, plant uptake of N

Copper Deficiency in Cereal and Oilseed Crops in Northern Canadian Prairie Soils1

AbstractTransitional grassland/forest light soils in Saskatchewan are often deficient in Cu. The high cost of micronutrient fertilizers necessitates extreme care in identifying micronutrient deficiencies and selecting effective products and methods of application. Comparison of tissue and grain or seed analysis for spring wheat (Triticum aestivumL.), canola (Brassica napusL.), and flax (Linum usitatissimumL.) vs. DTPA‐extractable soil Cu levels revealed that diagnosis of Cu deficiencies can more accurately be achieved via the latter. The critical DTPA‐extractable Cu levels were 0.40 mg Cu kg−1of soil for spring wheat and 0.35 mg Cu kg−1of soil for canola and flax. A series of field experiments comparing different forms of soil and foliar Cu fertilizers were conducted on several transitional grassland/forest soils. Copper oxide applied in the spring was generally ineffective in the year of application but alleviated Cu deficiencies in the following year. Copper‐sulfate (blue stone) and chelated products (polylignosulphonic acid) were effective in the year of application. However, the latter had no residual value at the rates of application used. This, combined with their extremely high current prices, makes them an undesirable Cu fertilizer source for the soils in the study area. Foliar Cu applications of either Cu‐sulfate or Cu‐chelate may be effective, but their performance has been erratic; hence, they should only be considered as an emergency measure for correcting of Cu deficiency.

PERSISTENCE AND AVAILABILITY OF PARAQUAT IN A LETHBRIDGE CLAY LOAM SOIL

To determine the capacity of the Lethbridge soil to inactivate paraquat, applications equivalent to a maximum of 3000 kg/ha of paraquat were made in growth chamber and field experiments. In the growth chamber and field, more than 600 and 1000 kg/ha, respectively, of paraquat in one application were required to reduce wheat growth by 10%. Paraquat residue levels in the field soil did not decrease after the first summer. Paraquat residue was not found in wheat grain growing in soil with 1650 kg/ha of paraquat in the 0–15 cm layer, but it was detected in plant leaves. The paraquat associated with plant leaves could have resulted from contamination of the leaves by soil rather than from translocation from roots to leaves. The 500 kg/ha rate of paraquat reduced the cation exchange capacity by 5%; however, further paraquat additions did not cause additional reductions. Paraquat could likely be applied for several hundred years at currently recommended rates for weed control on chemical fallow and not exceed the ability of Canadian Prairie soils to inactivate it. Key words: Paraquat, persistence, availability, inactivation, wheat, soil

Sulfur and nitrogen mineralization in soils compared using two incubation techniques

Net mineralization of sulfur and nitrogen was studied in three Canadian Prairie soils using two commonly used incubation methods. In the open system technique, where the soils were leached periodically II.3–11.8 μ g SO 2− 4 -S g −1 soil was mineralized in 17 weeks. Little mineralization or a net immobilization of sulfur (from 1.4 to 1.3 μ g SO 2− 4-S g −1 soil) was observed in a closed system where the soils were left undisturbed throughout incubation. Changes in the specific activity of 35S-labelled soil solution sulfate during the closed incubation indicated that mineralization-immobilization processes were occurring simultaneously resulting in minimal net changes in CaCl 2-extractable SO 2− 4 concentrations. The amounts of mineralized nitrogen (32.6–57.8 μg N g −1 soil) were found to be independent of the incubation method employed.

Nonbiological degradation of the herbicide metribuzin in Manitoba soils.

Degradative loss of herbicides in soil can take place by chemical or biological means. HYZAK and ZIMDAHL (1972) bave suggested that non-biological degradation of metribuzin in soil may be the most important mode of breakdown following application to San Luis sandy loam. Later work by HYZAK and ZIMDAHL (1974) suggests that degradatlon of metribuzin in soil is an approximately first order phenomenon at 5 ~ 20 ~ and 35~ yielding a linear plot of log (residual metribuzin) vs time. Their results show no induction period following application of metribuzin. Several variables have been suggested to influence metribuzin persistence in Canadian prairie soils; e.g., temperature, organic matter content, and adsorption properties of soils. HYZAK and ZIMDAHL (1974) show that degradation of metribuzin in soil increases with temperature, and increased degradation in the field in Almasippi very fine sandy loam has been shown by WEBSTER and REIMER (1976a) to correspond to temperature increases in the soil. The latter two variables, however, are characteristics of specific soil types, and attention was turned in this study to an evaluation of the ~fluence of four Manitoba soils on non-biological degradation of metribuzin.

Mobility of Dicamba, Picloram and 2,4-D in Soil Columns

The movement of dicamba (3,6-dichloro-o-anisic acid), picloram (4-amino-3,5,6-trichloropicolinic acid), and 2,4-D [(2,4-dichlorophenoxy)acetic acid] was studied in five Canadian prairie soils using soil columns. The three acid herbicides showed the following general order of decreasing mobility in the five soils: Asquith sandy loam &gt; Indian Head loam &gt; Regina heavy clay &gt; Weyburn Oxbow loam &gt; Melfort loam, thus indicating an inverse relationship between adsorption and mobility. In general, the distribution coefficients (kd) were comparable to the corresponding Freundlich constants (k) and these were significantly related to the soil organic matter content, to a lesser extent to soil pH, and not correlated with soil clay content. The maximum concentrations of all three herbicides in the column effluents were well below their respective water solubilities and were inversely related to the distribution coefficients. The calculated values for the amounts of precipitation required to leach the three herbicides to a depth of 10 cm showed the following order of mobility: dicamba &gt; picloram &gt; 2,4-D.

ADSORPTION STUDIES WITH THE ACID AND DIMETHYLAMINE FORMS OF 2,4-D AND DICAMBA

The adsorption of acid and dimethylamine salts of 2,4-D and dicamba was studied on Canadian prairie soils and various other adsorbents, using slurry-type adsorption experiments. The amount of adsorption of both the acid and dimethylamine forms of the two herbicides was minimal. The results were explained on the basis of dissociation of the acidic and dimethylamine salts to the respective anionic forms in the near-neutral prairie soils. This conclusion was supported by (1) the strong adsorption of these herbicides to the anion-exchange resin but not to the cation-exchange resin; (2) the strong adsorption of the 14C-dimethylamine cation to these soils; and (3) the leaching patterns of the 14C-dimethylamine salts of both herbicides from soils and resins. Only the anionic species were eluted from columns containing soils and cation-exchange resin whereas only the 14C-dimethylamine cation eluted from columns containing anion-exchange resin. Both forms of 2,4-D and dicamba were strongly adsorbed to activated charcoal, cellulose triacetate, and peat. There was little or no adsorption of these herbicides to montmorillonite and kaolinitic clays, cellulose powder, or wheat straw.

MOVEMENT OF PICLORAM IN SOIL COLUMNS

The movement of picloram (4-amino-3,5,6-trichloropicolinic acid) was studied in various Canadian Prairie soils, using soil columns. Picloram was readily leached in all soil types. The movement was greatest in the soil with the lowest organic matter and clay contents, and lowest in black soils that are high in soil organic matter content. It was related, in general, to the adsorptive and water-holding capacities of these soils. The extent of leaching of picloram was also related to the total amount of water applied; the greater the amount o¡ water the greater the downward movement. Increasing the intensity of water increments from 0.25 to 2.5 cm enhanced the movement of picloram in the clay soil but had no effect in the sandy loam. There was little or no difference in the movement of picloram when the herbicide was applied at 2.0 or 0.2 kg/ha, Picloram leached to a greater depth when the sandy loam soil was initially dry than wet and the converse was true for the clay soil. Picloram moved readily upwards when the soil columns were subirrigated.

THE ADSORPTIVE BEHAVIOUR OF ACID AND ESTER FORMS OF 2,4‐D ON SOILS

Summary. The adsorption of acid, n‐butyl, and iso‐octyl ester forms of 2,4‐D (2,4‐ dichloiophenoxyacetic acid) was studied for several Canadian prairie soils. The k values for the acid ranged from 0·09 to 1·30 and were correlated to the soil organic matter and not to the clay content. The Q, values (μg adsorbed/g of organic matter) for the acid were 7–2±l. The n‐butyl and the iso‐octyl esters hydrolysed to the acid form in the aqueous medium and this process was accelerated in the presence of the moist soil. Consequently, the k values for the esters, using slurry type adsorption experiments, or their distribution coefficients, using leaching columns, could not be determined. It was concluded that the adsorptive behavior of the two esters in moist soil was similar to that of the acid form.Comportement des formes actde, et ester du 2,4‐D quant à leur adsorption dans tes sols

Adsorption of Picloram by Soil Colloids and Various Other Adsorbents

The adsorption of picloram (4-amino-3,5,6-trichloropicolinic acid) was studied for several Canadian prairie soils and for various other adsorbents. The kd values for the soils ranged from 0.09 to 0.75 and were correlated only with soil organic matter. The kd values for other adsorbents varied from 0 to 232, the order of adsorption being activated charcoal &gt; anion exchange resin &gt; peat moss &gt; cellulose triacetate. There was no adsorption of picloram on montmorillonite and kaolinite clays, cation exchange resin, wheat straw (Triticum aestivumL.), or cellulose powder. The differences in the adsorption of picloram were explained on the basis of the relative affinities of the various adsorptive surfaces for the molecular or the ionized forms of the acid.

Influence of Certain Pedogenic Factors on Potassium Reserves of Selected Canadian Prairie Soils

AbstractThe nature of K reserves of five prairie soil profiles developed from glacial till deposits and lacustrine sediments in Saskatchewan, Canada was studied.The fraction of soil K extracted by the pretreatments prior to size fractionation was quite comparable to that of the exchangeable K. Potassium in the residue of various size fractions after sodium pyrosulphate fusion was allocated to feldspar, and the total K minus feldspar K was taken to be mica K. The fraction of K from feldspar usually increased as particle size increased. From south to north in the Prairie region under study, the fraction of K from feldspar of the soils developed from glacial till deposits increased, indicating the influence of local bedrocks on the nature of K reserves. The fraction of K from feldspar in the soil developed from lacustrine sediments was lower than that formed from glacial till deposits.Mica genesis was evident in the Chernozemic soil, but not in the Luvisolic soil studied. In the comparable size fractions of the Gleysol and Orthic Black soils in the Oxbow catena, the lower fraction of K from feldspar in the former reflects the influence of drainage on the K reserves. Colluviation processes coupled with eluviation and illuviation have modified the nature of soil K reserves as shown by the different percent distribution of mica K and feldspar K among various size fractions.