ALBERT

Description: The sulfur status of rapeseed (Brassica napus and Brassica campestris) plants grown in field studies was assessed using a variety of plant indices; percent sulfur, percent hydriodic acid reducible sulfur (HI-S in plant dry matter), HI-S:total S ratio, and total N:total S ratios. Of these, HI-S:total S determined at the rosette growth stage was the most accurate and consistent index of seed yield. A growth chamber study indicated that the HI-S:total S ratio would not be affected by nitrogen fertilizer application at normal field rates. Key words: Sulfur, deficiency, rapeseed (Brassica spp.), plant analysis

Description: The effect of labile inorganic phosphate (Pi) status of the soil on the decomposition of added cellulose and on the immobilization, mineralization, and redistribution of native and added P in soils was studied in a greenhouse incubation experiment. Cellulose was added at 765 μg C∙g−1 soil with and without P (9 μg∙g−1 soil) every 30 days under adequate N, H2O, and constant tempreature to two soils of different available P status. Lack of P eventually slowed down decomposition of added C, but this effect was partially compensated for by increased mineralization of organic P (Po) forms. Added P was redistributed to both P, (58–69%) and Po (42–31%) forms; higher amounts of Po were found in the soil with the highest Pi status. The correlation between microbial P uptake and solution P values was significant, and microbial C:P ratios ranged from 12:1 under high available P conditions to 45:1 where P was in low supply.

Description: not available

Description: Organic C, N, P, and S contents in soil are thought to be the result of interactions among soil-forming processes, which occur in all soils but to different degrees. To test this hypothesis, the effect of climate, vegetation and topography on the organic matter composition in cultivated soil profiles was examined along an environmental gradient, from semiarid to subhumid regions in Saskatchewan. This transect encompasses a narrow environmental gradient of decreasing evapotranspiration and increasing precipitation (350–450 mm). Representative catenas selected from Brown, Dark Brown, Black and Gray Luvisol soil zones showed changes in the quantity and composition of organic matter. Concentrations of organic C, N, P and S progressively increased from the Brown to the Black soils and then decreased substantially in the Gray soils. Nutrient concentrations also increased from the upper to the lower slope positions of the catenas and decreased with depth in the soil profile. However, the distribution of organic elements across the soil zones, relative to each other (i.e. C:N, C:P, or C:N:P:S ratios), did not follow the same trends as concentration of the individual elements. The most consistent trends were observed in the lower slope soils, where organic C:N (9.8 to 12.5:1), C:P (48 to 78:1) and C:N:P:S (68:6.9:1.4:1 to 145:11.6:1.8:1) ratios widened from the Brown to the Gray soils. Within any one catena, organic C:N:P:S ratios narrowed with depth in the soil profile, often showing a several-fold decrease relative to the C:N:P:S ratios of the surface horizons. This study demonstrates the value of recognizing integrative relationships among soil processes. It provides a mechanism for better understanding and explaining the patterns of distribution and behavior of various soil chemical, physical and biological properties. Key words: Catenary sequence, Chernozem, Luvisol, hierarchical relationships

Description: In northeastern Saskatchewan on Gray Luvisolic soils, rapeseed (Brassica napus L. and B. campestris L.) grown on many fields does not set seed, possibly because of deficiencies of S and B. Therefore, experiments were begun in 1979 to determine (1) the effect of N, S and B fertilizers on yield and quality of rapeseed; (2) if cultivars (B. napus and B. campestris L.) responded differently to these nutrients; and (3) nutrient and nutrient interaction effects of five rates of N, S and B in a composite rotatable design on yield and quality of the cultivar Regent (B. napus L.). Rates of up to 200 kg N ha−1, 50 kg S ha−1 and 2.8 kg B ha−1 were applied. The experiments were conducted on 13 sites. Nine were in N.E. Saskatchewan on Sylvania f1, Waitville 1 (Luvisolic) and Melfort sicl (Black Chernozemic) soils. Four were in N.W. Saskatchewan on Loon River 1 and Waitville 1, (Luvisolic) soils. In N.W. Saskatchewan there was a significant yield increase because of N (1.00 t ha−1) and S (1.06 t ha−1). In N.E. Saskatchewan on Sylvania f1, rapeseed yields were increased by 0.38 t ha−1 by a combination of S and B and by 0.78 t ha−1 by N. Sylvania f1 soils were lower in soluble B than other experimental sites. At other sites in N.E. Saskatchewan, N but not S increased rapeseed grain yield significantly. Significant response to a combination of S and B was obtained with the cultivar Regent, and both species of rapeseed responded to S fertilizer. Sulphur fertilizer increased the glucosinolate concentration in rapeseed meal at all sites. Sulphur increased oil concentration of rapeseed on all sites except one where frost damaged the crop and increased protein of grain on sites where there was yield response to S. Nitrogen increased protein of rapeseed grown on all sites whereas N combined with B decreased protein and increased oil percentage on all sites except Sylvania f1. The yield response of the cultivar Regent to B was not significantly related to soluble soil B. The combined yield response to S and B in relation to soluble soil S and B was significant (R2 = 0.60). Yield response of rapeseed to S was significantly related to soluble soil S (R2 = 0.35). In conclusion, S fertilizer solved the problem of poor seed set in rapeseed cultivars, but B also enhanced yield by decreasing the number of sterile florets and improving pod development. Key words: Nitrogen, sulphur, boron, rapeseed, oil, protein, glucosinolates

Description: The effects of application of manure and P fertilizer on wheat yields in a fallow-wheat-wheat rotation on a Black Rego Chernozemic clay soil have been studied for 36 yr. The objective of this study was to identify the effects of manure on soil characteristics that could be related to the reported progressive yield increases over time and an apparent improvement in soil tilth. Soil samples were taken in 1982 from the check (no treatment), and from treatments receiving 13.4, 20.2 and 26.9 t ha−1 of manure applied each fallow year, and 112 kg ha−1 of seed-placed 11-48-0 applied to wheat after summerfallow. Soil physical and P-related parameters were determined for depth increments to 30 cm; the total-N and 15N data to 90 cm; other data were for the 0- to 7.5-cm depth. Manure had no effect on bulk density or hydraulic conductivity. However, it increased the total C and humic acid (HA) content of the soil, the percent of soil C as HA-C, the C concentration in humin, and the percent of total soil N as humin-N. Manure significantly increased the percent of HA-N but not humin-N present as amino acid and amino sugar-N, but increased amino acids and the amino sugars in the humin hydrolysate. The net rate of N mineralization and the available forms of inorganic P were all increased significantly by manure. The natural 15N-abundance technique showed that a significant though small proportion of soil N was derived from manure. Manure had no effect on soil microbial biomass C and N, soil respiration, and the quantity of potentially mineralizable N. Applied P had no effect on N-related parameters measured; its effect on available P was not measured. It was concluded that manure increased crop yields by improving the N- and P-supplying power of the soil, and improving the physical environment of the soil through its effects on the humic colloids. Key words: Humic substances, soil P fractions, soil biological properties, natural 15N abundance, net N mineralization

Description: Growth chamber and laboratory studies were conducted to investigate the distribution and plant availability of copper (Cu) fractions in Saskatchewan soils. These studies included an examination of the distribution of Cu fractions in 27 soils and an evaluation of plant availability of native and added Cu fractions in beans (Phaseolus vulgaris L.) grown in seven soils. The soils in these experiments were selected to give a wide variation in physical and chemical properties. Total Cu content of the 27 soils ranged from 6.5 to 39.0 μg g−1 with an average of 21.0 μg g−1. A seven-step sequential fractionation showed that most of the total Cu (49.0–78.0%) was present in the residual fraction (Res-). The percentages of soil Cu in the exchangeable (Ex-), Pb-displaceable (Pb-), acid soluble (Aci-), Mn oxide bound (MnO-), organically associated (OM-) and Fe, Al oxide bound (FeO-) fractions averaged 2.2, 1.5, 2.0, 4.8, 7.9 and 11.1%, respectively. Amounts of Cu in MnO-, FeO-, Res- fractions and total Cu were interdependent and varied directly with DTP A- extractable Cu and clay content. The growth chamber experiment showed that the most of the applied Cu was accumulated in MnO-, OM-, FeO-, and Res- fractions. Therefore, sesquioxides and organic matter are the major components responsible for the adsorption of added Cu. The concentration of Cu and its uptake into navy beans were positively correlated with DTPA-extractable Cu, MnO-Cu, FeO-Cu and total Cu, which in turn were correlated with clay content. Plant Cu concentration and uptake can be predicted by an equation which includes DTPA-extractable Cu and clay content. These results showed that DTPA-extractable Cu is a good predictor of Cu availability in prairie soils. Key words: Cu fractions, distribution, availability, DTPA-extractable Cu, clay content, navy beans

Description: The kinetics of the adsorption of orthophosphate (Pi), inositol hexaphosphate (IHP), inositol monophosphate (IMP) and glucose 6-phosphate (G6P) by short-range ordered precipitate of Al were studied at the initial pH 4.50 and in the temperature range of 278–308 K. This information is essential for understanding the rate and energy relationship of the adsorption of phosphates by short-range ordered Al precipitate. The amounts of Pi and IHP adsorbed by the Al precipitate were much higher than those of IMP and G6P adsorbed in the temperature range and reaction periods studied. The adsorption can be divided into two stages, a fast adsorption before 1 h and a slow adsorption between 1 and 24 h. The adsorption at both stages obeyed the first-order kinetics. Among all the phosphates studied, the adsorption of Pi proceeded most rapidly. The rate constants for the adsorption of IHP were much greater than those of G6P and IMP at the same temperature; this was attributed to the functionality of multiple phosphate groups of IHP. The Arrhenius activation energies for the adsorption of Pi, IHP, IMP and G6P, which were estimated from the slow reaction, were 48 ± 2, 89 ± 4, 100 ± 8 and 108 ± 10 KJ/mol P adsorbed, respectively. Key words: Organic phosphate, precipitate of aluminum, adsorption, rate constant, Arrhenius activation energy

Description: Changes in soil phosphorus (P) forms, as determined by a sequential fractionation procedure, were used to assess the influence of soil texture and management practices on the forms and distribution of soil P in a Brown Chernozemic loam soil at Swift Current, Saskatchewan. Significant proportions of the variability of all P fractions except residual-P could be attributed to changes in sand content. Changes in the forms and distribution of soil P with decreasing sand content followed patterns similar to those associated with a weathering sequence. The proportion of total soil P in inorganic and organic extractable forms that were extractable sequentially with anion exchange resin (resin-Pi), sodium bicarbonate (bicarb-Pi and -Po), and sodium hydroxide (NaOH-Pi and -Po) increased with decreasing sand content. Acid-extractable inorganic P (HCl-Pi) was the only P fraction positively correlated with sand content. The presence of a crop increased the proportion of soil P present as the more labile organic-P fractions (bicarb-Po and NaOH-Po) but not as total soil organic P (soil-Po). The presence of a crop also increased the proportion of soil P present as the labile inorganic fractions (resin-Pi and bicarb-Pi), possibly due to a decrease in soil pH. Application of inorganic-P fertilizer caused significant increases in the proportion of soil P as these labile inorganic-P fractions (resin-Pi and bicarb-Pi) and as total soil organic-P (soil-Po), but did not affect the more labile organic-P fractions. Key words: P fractionation, labile P, organic P, inorganic P, texture, management practices

Description: Short-term root processes can influence chemical and biochemical conditions at the soil–plant–root interface. In this study, soil phosphorus forms, pH and biochemical properties within and adjacent to the rhizosphere of hard red spring wheat (Triticum aestivum L. ’Katepwa’) and canola (Brassica napus L. ’Westar’) seedlings were studied over a 5-wk period. Soils were from the Ap horizon of a Calcareous Dark Brown Chernozemic soil (Lethbridge, Alta) and an Orthic Gray Luvisolic soil (Breton, Alta) obtained from fertilized and unfertilized long-term continuous-cropped and wheat–fallow rotation plots. Wheat and canola both absorbed more total phosphorus (P), produced more aboveground material and had higher dehydrogenase and alkaline phosphatase activities when grown in Lethbridge soils than when grown in Breton soils. Canola took up more P from both the resin-extractable inorganic P (resin-Pi) and hydrochloric acid extractable (HCl-Pi) fractions than wheat, indicating a greater ability to extract P from soil. Acid phosphatase levels increased over time in the rhizospheres of both wheat and canola. Dehydrogenase activity was greater in the rhizospheres of wheat than of canola, indicating greater microbial activity. Canola roots frequently lowered pH within their rhizosphere which apparently suppressed microbial activity. Dehydrogenase activity in the relatively acidic Luvisolic soils was lower than in the near-neutral Chernozemic soils. The plant-root chemical and biochemical changes in the rhizosphere varied depending on soil chemical characteristics and past soil management history. Results showed canola and wheat utilize different mechanisms to influence their root rhizospheres and obtain their nutritional requirements. Rhizosphere changes were a function of plant species, soil type and previous soil management history. Key words: Rhizosphere, pH, phosphatase, dehydrogenase, P bioavailability, soil phosphorus transformations, wheat, canola