Gray Luvisolic Soils Research Articles

MICROMORPHOLOGY OF THREE GRAY LUVISOLS IN EAST-CENTRAL SASKATCHEWAN

Micromorphology of three Gray Luvisolic soils under Boreal Forests occurring on late Wisconsinan age glacial till were studied. Profiles 1 and 2 occurred on loam with 8–10% carbonates; Profile 3 on clay loam till with 58% carbonates. The presence of various fecal pellets shows the importance of soil fauna in the decomposition of litter and the formation of aggregates in organic horizons. Aggrotubules and fecal pellets in the lower part of the profiles testified to the presence of biological activity even at depth. Several types of banded fabrics and iron-manganese nodules were observed, and are thought to result from temporary saturated conditions of the Ae horizons. Ferri-argillans occur as both illuviation (due to lessivage) and in situ weathering cutans. The weakest ferriargillans were found in the thickest profile. The most birefringent ferriargillans with strong continuous orientation and the most abundant iron-manganese nodules were found in Profile 3 which had the thinnest solum. This indicates that high carbonate content reduces the depth of solum, but not intensity of soil-forming processes. Considerable amount of weathering of the primary minerals, particularly sand-sized micas and feldspars in the C horizons was attributed to ancient chemical weathering. Analyses indicated the physical breakdown of sand particles to silt in the Ae horizons. Neocalcitans were observable in the relatively thicker Profiles 1 and 2 and calcans were specific to Profile 3 with extremely calcareous, dominantly dolomitic parent material. Key words: Luvisols, Boreal Forest soil, micromorphology, nodules, cutans, faunal activity

Root density-soil relationships in selected boreal forests of central Alberta, Canada

Soil pits located in boreal aspen ( Populus tremuloides Michx.), jack pine ( Pinus banksiana Lamb.), and white spruce ( Picea glauca (Moench) Voss) stands were analyzed by horizon for nutrients (Ca, Mg, PO 4P, K, Na, SO 4S, NH 4N, NO 3N), physical properties (horizon depth; silt, clay, and organic content; bulk density, water-holding capacity), and root densities. Two aspen, three jack pine, and one white spruce stand were on aeolian sands with Eutric Brunisolic soils; and two aspen and one white spruce stand were on clay loa, morainal deposits with Gray Luvisolic soils. Stand ages ranged from 19 to 170 years. This study assessed the relationships of root location and density to the above-mentioned edaphic variables. The highest concentration of roots was at the organic/mineral soil interface. Correlation and Principal Components Analysis (PCA) revealed that root densities are negatively correlated with depth, clay content, and bulk density; and positively correlated with soil water-holding capacity and extractable PO 4P. Insufficient phosphorus appears to be an important growth-limiting factor in the study area. PCA ordinations of edaphic variables consistently revealed a cluster of correlated variables composed of organic matter, NH 4, NO 3, and sometimes K content, but none of these was consistently associated with root distributions. Aspen communities appear to be more dependent upon N and other organically bound nutrients than coniferous stands.

EFFECTS OF FORAGE LEGUME SPECIES ON SOIL MOISTURE, NITROGEN, AND YIELD OF SUCCEEDING BARLEY CROPS

Effects of five legume species grown for hay on yield of succeeding barley crops and on moisture and N status of five soils were measured. When N fertilizer was applied, yields of barley following alfalfa, birdsfoot trefoil, alsike clover, red clover and sweet clover were the same as those following barley grown on fallow (control). Also, soil moisture in spring and soil moisture used by barley were about the same following legumes and the control. However, without N fertilizer, the legumes caused large yield increases to barley grown on two Gray Luvisolic soils (Beryl, Davis) and a Black Solodic soil (Landry); the legumes caused little change in barley yields on another Gray Luvisolic soil (Alcan) and caused large decreases on another Black Solodic soil (Rycroft). Residual soil N contributed by the legumes, calculated from N in the succeeding barley crops, was greater for the Beryl and Landry soils than for the Alcan and Davis soils. This corresponded closely to yields of the previous hay crops on those soils. The legumes caused a decrease in residual N for the Rycroft soil. Mineral-N and Δ mineral-N in the soil were well correlated with N uptake in barley for the Alcan, Landry and Rycroft soils but were poorly correlated for the other two soils. Key words: Forage legumes, barley yields, soil nitrogen and moisture

LOSS OF ORGANIC MATTER AND POTENTIALLY MINERALIZABLE NITROGEN FROM SASKATCHEWAN SOILS DUE TO CROPPING

Although it is known that considerable loss in total organic matter has occurred due to cultivation of prairie soils, there is little information on changes in the fertility-related fraction of the organic matter. Twelve prairie surface soils representing paired virgin and cultivated coarse-, medium-, and fine-textured soils from the Brown, Dark Brown, and thin Black Chernozem and Gray Luvisol soil zones were analyzed and used to assess changes in total C, N and potentially mineralizable N. Cropping caused large losses of organic C (41–53%) and N (31–56%), but losses of potentially mineralizable N (N0) were even greater for the Chernozems (55–67%) though not for the Gray Luvisols. N0 in virgin soils ranged between 133 and 401 μg N/g soil and increased from Gray Luvisol to Brown to Dark Brown to thin Black Chernozem. In cultivated soils, N0 was generally similar among soil zones and values ranged between 66 and 141 μg N/g soil. Medium-textured soils generally had the greatest organic matter content and N0. The active N fraction (N0/N) ranged between 4 and 20.5% and was greatest in Brown soils and in the coarser-textured soils. Losses of organic matter, N0, and N0/N were greatest from the coarser-textured soils. The findings of this study help to explain why a significant portion of prairie soils now require N fertilizer even after being summer-fallowed.

Sulfur transformations in relation to carbon and nitrogen in incubated soils

Changes in biomass-S in relationship to biomass-C and N were evaluated, and the transformation of 35S-labelled SO 4 2− among organic matter fractions were followed during incubation of a Black Chernozemic (Udic Haploboroll) and Orthic Gray Luvisol (Typic Cryoboralf) soils. There was a net immobilization of S with and without the addition of cellulose or sulfate after 64 days. In contrast, a net mineralization of N occurred. Cellulose decomposition rates responded to supplies of S available for new microbial cell synthesis. Fluctuations in the amounts of biomass-S during incubation of both soils followed biomass-C and biomass-N changes and C/S and C/N ratios of the biomass ranged between 47–121 and 4.9–7.7, respectively. Microbially-incorporated S was found concentrated within the biomass or partially transformed into soil organic matter. Fractionation of soils after incubation, by a 0.1 m NaOH-0.1 m Na 4P 2o 7 extraction-separation technique showed significant increases in the C and N contents of the conventional humic acid (HA-A) and fulvic acid (FA-A), and humin (<2 μm) fractions. Biomass C accounted for 20–64% of the observed increases in these fractions suggesting that the differences were due partly to transformed microbial products and partly to microbial cell organic constituents released on lysis of cells during incubation. In contrast to C and N, the contents of total S and HI-reducible S increased in the FA-A fraction only and accounted for 45–76% of the immobilized labelled S.

OCCURRENCE AND CHARACTERISTICS OF FERROMANGANIFEROUS CONCRETIONS IN SOME SASKATCHEWAN SOILS

The distribution, composition and nature of concretions occurring in some moderately well-drained to poorly drained soils of Saskatchewan were investigated. The soils selected were: Gleyed Humo-Ferric Podzol, Orthic Luvic Gleysol, Orthic Gray Luvisol and Gleyed Gray Luvisol. The concretions range from &lt; 0.1 to &gt; 15 mm in diameter and are distributed throughout the sola with maximum concentrations of about 8% in Aeg and Bf horizons. The data indicate that the concretions from Gleysolic and Gray Luvisolic soils are markedly higher in Fe, Mn and P than the surrounding soil matrix; concretions from the Podzol are high in Fe but very low in Mn and P. Mn is directly related to the size of concretions whereas Fe and P contents generally increase with decreasing size of concretions. The formation of concretions and their significance in soil genesis are discussed.

EFFECTS OF HIGH RATES OF CHEMICAL FERTILIZER AND BARNYARD MANURE ON YIELD AND MOISTURE USE OF SIX SUCCESSIVE BARLEY CROPS GROWN ON THREE GRAY LUVISOLIC SOILS

High rates of chemical fertilizer and barnyard manure were applied separately and together to barley (Hordeum vulgare L.) grown on three Gray Luvisolic soils for 6 successive yr. The fertilizers were applied annually with the N–P–K rates greater than 110–50–40 kg/ha. The manure was applied initially at 134 tonnes/ha and at 150 tonnes/ha before the fifth crop. Moisture use by the barley was measured for the last five crops. Average yields of barley were 1,530, 3,270 and 3,950 kg/ha for the nil, manure and fertilizer treatments, respectively. The manure + fertilizer treatment gave little or no further increase in yield over the fertilizer treatment. Efficiency of moisture use was generally more than doubled by the fertilizer and fertilizer + manure treatments. These treatments also greatly increased the use of soil moisture reserves, the greatest increase being for Beryl fine sandy loam, followed by Hazelmere loam and the least for Nampa clay loam. Soil moisture reserves at harvest time were depleted more under the fertility treatments than under the control plots. However, by the following spring, soil moisture reserves were nearly equal under the different plots having been replenished by fall and winter precipitation. These results show that on stubble land, moisture restricted yields much less than nutrients did and, on that basis, continuous cropping of Gray Luvisolic soils is discussed.

Effect of Soil Moisture Tension and Amendments on Yields and on Herbage N, P, and S Concentrations of Alfalfa1

AbstractLow protein concentration has been observed in alfalfa herbage grown on Gray Wooded Luvisol soils, particularly in cool, wet years. Nutrient deficiencies of N, P, and S also occur on these soils. The objectives of this experiment were to determine how soil moisture and soil type interact with amendments to increase yield and change N, P, and S concentrations in alfalfa (Medicago media Pers.) herbage grown in the greenhouse.Three Gray Wooded Luvisols, Typic Cryoboralf (Arborfield clay, Garrick clay loam, Mollic Cryoboralf, and Waitville loam) and one Dark Gray Luvisol soil (Nipawin sandy clay loam) × two soil moisture tensions (100 and 151 millibars) were main treatments. Amendments of cattle manure, sedge peat, and wheat straw were applied on subplots at 2.5y0 of soil weight. Additional subplots of a control and nitrate (70 μg N/g soil before each crop) were added. Two crops of barley (Hordeum vulgare L.) and one of rape (Brassica napus L.) were grown before ‘Rambler’ alfalfa.Yield of alfalfa was significantly related to moisture use (r2 = 77% in cut 1; r2 = 78% in cut 2). Moisture use by alfalfa was higher with cattle manure incorporated in the heavier textured Garrick clay loam and Arborfield clay soils than for other amendments or soil types. The manure treatment applied to Garrick clay loam and Arborfield clay soils under low soil moisture tension (LSMT = 100 millibars) produced the highest herbage yields.In the first‐cut only, N concentration of alfalfa herbage was higher under high soil moisture tension (HSMT = 151 millibars) than LSMT (5.0 vs. 4.8% N) and was higher for ammonium nitrate than for manure or peat amended soils. Concentration of P in alfalfa herbage was significantly higher under LSMT than HSMT. Concentration of S in herbage was significantly lower under LSMT than under HSMT only for cut 1.In general, LSMT interacting with soil type and amendments markedly increased alfalfa yields, reduced N and S, and increased P concentration in herbage as compared with HSMT.

A COMPARISON OF HUMIC FRACTIONS OF CHERNOZEMIC AND LUVISOLIC SOILS BY ELEMENTAL ANALYSES, UV AND ESR SPECTROSCOPY

The Ah horizons of a Brown–Dark Brown–Black–Dark Gray–Gray Luvisolic sequence of Canadian grassland and forest soils were studied. Clay-associated humus was present in greater proportions in the grassland than in forest soils, particularly in the grassland soils of the more arid regions. Amounts of alkali-pyrophosphate-extractable humus increased in the Brown to Gray Luvisolic sequence. Alkali-pyrophosphate-extractable humic acid (HA-A) contents were greatest in the Black and Dark Gray soils. C:H ratios, extinction coefficients at 280 nm (E280), and resistance to acid hydrolysis of the HA-A and clay-associated HA-B increased in the Brown to Gray Luvisolic sequence. Free radical concentrations were least for the Brown and Dark Brown soils, moderate for the Black and greatest for the Gray Luvisolic soils. The data suggest an increase in the proportion of aromatic components in the humic acids in going from the Brown to the Gray Luvisolic soils. An objective, multivariate similarity analysis based on 22 humus characteristics showed a relationship between soil zone or soil environment and the nature of the soil's humus.

CHEMICAL AND MINERALOGICAL CHARACTERISTICS OF CUTANS FROM B HORIZONS OF THREE MANITOBA SOILS

Cutans separated from the B horizon of an Orthic Black, an Orthic Dark Gray, and an Orthic Gray Luvisol soil from southwestern Manitoba had higher total nitrogen and dithionite-extractable iron contents than their corresponding horizon samples. The cutans from the Bt2 horizon of the Orthic Gray Luvisol profile contained, in addition, considerably larger amounts of organic matter and fine clay, and had a slightly different distribution of clay minerals than the horizon sample. Within each soil, the differences between the properties of the cutans and those of the bulk samples were generally small. This was attributed to the method employed to isolate the cutanic material and to the impossibility of collecting all cutans from the samples.