Browsing by Author "Anderson, D.W."
Now showing 1 - 18 of 18
Results Per Page
Sort Options
Item CENTURY model simulation of soil C and N on a thin Black Chernozem(1991-02-21) Greer, K.J.; Monreal, C.; Anderson, D.W.CENTURY is a process oriented soil organic matter (SOM) model, based on the conceptual division of SOM into active, slow, and passive phases. Carbon (C) and nitrogen (N) flow, from plant residue through the SOM compartments, is driven by monthly precipitation and temperature and moderated by the nutrient content of the residue. CENTURY simulations of cultivated soils in the American Great Plains have agreed well with the changes in C and N observed over the last 100 years. However, use of this model to predict SOM in Saskatchewan soils, is limited by incomplete validation under our conditions. The thin Black Chernozemic soils of the Indian Head Experimental farm provide a unique opportunity to validate the CENTURY model, since both cropping history and soil C and N have been recorded for over 100 years. CENTURY predicted C and N levels (mass per unit area basis) within 4 to 21 % of those observed, after 26 years under fallow-wheat, fallow-wheat-wheat, continuous wheat and fallow-wheat-wheat-hay-hay-hay. Where soil erosion was not considered as a mechanism of SOM loss, CENTURY over-predicted C and N by 30 to 45 % of the observed. CENTURY prediction of mean annual C production as grain was 25 to 41% lower than the observed levels. Such yield functions, which consider the loss of available nutrients in the SOM as well as less residue returned to the system may be useful in estimating the long term direct costs of soil erosion on grain production.Item A detailed study of spring soil test nutrients along a catena sequence in a thin Black Chernozem(1991-02-21) Popoff, R.W.; Anderson, D.W.Item Developing simplified synergistic relationships to model topsoil erosion and crop yield(1992-02-20) Greer, K.J.; Hilliard, C.R.; Schoenau, J.J.; Anderson, D.W.Topsoil is highly enriched with organic matter, which provides a valuable source of plant nutrients as well as a favorable rooting environment. Over time, erosion processes selectively remove the organic matter-rich fine fraction which causes a measurable reduction in soil productivity. Assessments of past erosion are of little value in predicting future losses in productivity since the synergistic lowering of soil organic matter through lower residue inputs is not considered. Dynamic computer models, which simulate the plant/soil system, can project the long run future costs of soil erosion on crop yield. A simplified erosion-crop yield model was developed by first defining the most important soil productivity variables, then quantifying the effect of erosion on each variable. The model predicted a declining trend in grain yields similar to that observed on soil scalping experiments.Item Dynamics of microbial biomass carbon and nitrogen and extractable nitrate in long-term rotation studies at Indian Head(1989-02-16) Greer, K.J.; Anderson, D.W.Mineralization studies in the laboratory indicate that the net turnover of nitrogen is greatly affected by crop rotation. Recently, the field applicability of such incubation - intermittent leaching experiments has been questioned. Therefore, field sampling was undertaken during the summer of 1988 to determine the influence of rotation history on microbial biomass C and N, and levels of extractable NO3-N. Four long term rotation plots (Ag. Canada, Indian Head) were sampled in the fallow phase. These rotations consisted of: (1) Fallow-Wheat-Wheat, (2) Fallow-Wheat- Wheat (fertilized, straw retained), (3) Fallow-Wheat-Wheat (fertilized, straw removed), and (4) Fallow-Wheat-Wheat-Hay-Hay-Hay. Biomass C and N, as measured by a chloroform-direct extraction technique, was found to be significantly higher in the soils from the hay rotation. The proportion of organic C present as biomass was, on average, 29 % higher than in the three year rotations without hay. Similarly, nitrate levels were found to be significantly affected by rotation history and correlate strongly with the size of the microbial biomass. The prediction of microbial biomass based on carbon added as crop residue was poor since the intrinsic assumption that all carbon is equally available for decomposition does not hold for all residues. However, the levels of biomass C and N were closely related to the N content of the residues returned. This is to be expected since the N-rich "metabolic" fraction is readily decomposed and incorporated into the microbial biomass. These relationships are clearly illustrated using a conceptual model of N turnover.Item The effect of crop rotation history on nitrogen and sulphur mineralization in Luvisolic soils(1986-02-20) Cowell, L.E.; Anderson, D.W.Item Effect of incorporation of wheat straw and nitrogen addition on the flux of soil gases (CH4 and N2O) at two moisture and temperature regimes(1992-02-20) Deol, Y.S.; Monreal, C.M.; Anderson, D.W.Methane and nitrous oxide contribute to global warming of the earth's atmosphere. The concentration of CH4 and N2O in the atmosphere is increasing at an alarming rate of 1% and 0.25% yr-1, respectively. Little information is available about the effect of agronomic practices on soil gases emitted from cultivated soils in the prairies. An incubation study was undertaken to understand the effects of agronomic management practices and environmental factors on CH4 and N2O emissions from a cultivated soil. Methane production was preceded by a two week lag phase, and it was emitted only from submerged soils incubated at 25°C. Addition of straw enhanced the emission and N addition reduced the rate of CH4 production. Soil incubated at -30kPa moisture may act as a sink for methane. Emission of N2O was observed within 2 days of submergence and was maximum when nitrogen alone was added to the soil. Addition of wheat straw along with nitrogen decreased the emission of N2O as compared to nitrogen alone. Temperature of 10 °C and moisture at -30kPa limited the emissions of N2O from the soil.Item The effect of organic structures on the water stability of macro-aggregates.(1993-02-25) Monreal, C.M.; Campbell, C.A.; Anderson, D.W.; Schnitzer, M.A study was conducted to identify the chemical structures of soil organic matter and examine their effect on the water stability of macro-aggregates (>250 um) in a SiL Brown Chernozem under wheat-fallow (WF) and continuous wheat (CW) . The proportion of water stable macro-aggregates were determined by wet sieving. Chemical structures of soil organic matter were characterized by pyrolysis field ionization mass spectrometry (Py-FIMS), and grouped into seven classes: carbohydrates, phenolic and lignin monomers, lignin dimers, lipids + alkanes and alkenes, sterols, alkyl aromatic and N-compounds. In comparison with CW, there was a reduction in the proportion of macro-aggregates and an increase of micro-aggregates in the WF crop rotation. Sixty-five percent of all the soil organic matter (SOM) was identified by Py-FIMS. The average concentration of each class of compound in whole soil and macro-aggregate samples ranged between 0.1 and 15% of the total identified SOM. Carbohydrates, phenolic, and lignin monomers were the most abundant compounds (>10%). Linear regression models (r2 ~ 0.96, p=0.05) showed that the stability of macro-aggregates was highly correlated with the concentration of the least abundant (<3. 5%) structures of sterols, lipids and lignin dimers. These compounds are metabolic products of plants and soil organisms.Item Effects of soil morphology on the presence of alder within a mature jack pine forest(1996-02-22) Nerbas, T.A.; Anderson, D.W.Soil morphological differences have resulted in a distinct pattern of Green Alder growth within a predominately Jack Pine forest. Alder growth occurred mainly in an area of finer textured parent materials. After a rain these finer textured layers result in a temporary or perched zone of saturation. Materials with fine sandy loam to silty clay loam textures have volumetric moisture contents > 35 % . The ability of Alder to fix N2 results in a considerably greater accumulation of N than that found under pure Jack Pine forests. Textural bands act as a barrier to N leaching. Elevated levels of P within the finer textured materials may have caused the microsite to be more suitable for Alder growth. It appears that a dominance of fine and very fine sand, coupled with finer textured bands in the subsoil results in a more moist soil, with high P supplies, all contributing to more alder and eventually a more productive site. The greatest volume of merchantable timber corresponds to the same area where Alder growth is most significant.Item Erosion and cultivation effects on the loss of organic matter from prairie soils(1985-02-19) Anderson, D.W.; Gregorich, E.G.; Verity, G.E.Item In situ quantification of soil organic matter by CP/MAS solid state 13C NMR(1992-02-20) Monreal, C.M.; Lam, W.W.; Macconacchie, C.A.; Axelson, D.E.; Anderson, D.W.Solid state 13C NMR is an important analytical technique for the characterization of soil organic matter (SOM) in agricultural and forest ecosystems. There is considerable uncertainty, however, concerning the reliability of NMR spectra for the quantification of . functional groups in SOM. As part of the National Soil Conservation Program, a study was undertaken to define an analytical protocol to enable the quantification of soil c by CP/MAS 13C NMR in intact soil samples. This study indicated that the proportion of soil C observed by solid 13C-NMR varied between 79 and 103% of the soil organic C. The %C observed was described as a logarithmic function of the magnetic susceptibility/organic-C ratio. Aromatic-C in a cultivated Gleysol was 1.0 t ha-1 5 cm and it represented 9% of the total soil organic carbon. The proportion of c aromaticity in solid soil samples is lower than average values reported earlier for soil humic and fulvic acid fractions.Item Productivity studies in the Weyburn map area(1976-02-11) Anderson, D.W.; Wilkinson, D.B.Item Productivity studies on Solonetzic soils in the Weyburn area – a progress report(1977-02-08) Anderson, D.W.; Wilkinson, D.B.Item Rapid assessment of soil salinity(1986-02-20) Moulin, A.; Anderson, D.W.; Martz, L.Item Relationships among landform elements, soil properties, and crop yields on Blaine Lake-Hamlin Soils(1990-02-22) Popoff, R.W.; Anderson, D.W.Soil properties are an important part of the complex framework in the crop production system. Soil properties may vary over short distances, but are related to position within the landscape. This study investigated the relationships among pH, salinity, bulk density, horizon thickness, depth to carbonates, and soil moisture according to landform position. Four catenas were studied under different crop rotations: summerfallow-canola-wheat, summerfallow-wheat-wheat, continuous cereals, and continuous cereals plus a legume. Total plant biomass and crop yields were determined on hand harvested samples from each slope position. Best yields in 1989, generally occurred in back and shoulder slopes and lowest yield in footslope areas that were flooded out by intense summer showers.Item Short term effect of breaking and cultivation on properties of an Oxbow landscape(1992-02-20) Anderson, R.F.; Pennock, D.J.; Anderson, D.W.; de Jong, E.Changes in soil quality over the first six years of cultivation were studied for an Oxbow landscape dominated by Black Chernozems. Bulk density at shoulder, footslope, and level landforms was found to increase by 15-20 % from 1985 to 1988 and by 3-4 % from 1988 to 1991. Similarly, organic carbon concentration declined by 17-37 % and 0-10 %, respectively, over the same periods. These results demonstrate that cultivation of virgin land has an almost immediate impact on soil quality. 137Cesium measurements indicated that appreciable soil erosion has not occurred in this landscape since cultivation began.Item Simulating the dynamics of soil organic matter in long-term rotation plots of Saskatchewan and Alberta(1992-02-20) Monreal, C.; Zentner, R.P.; Campbell, C.A.; Nyborg, M.; Greer, K.J.; Gregorich, E.; Anderson, D.W.This study used the Century soil organic matter (SOM) model to simulate the dynamics in soil organic carbon, nitrogen, and phosphorus in long-term crop rotation studies established in Saskatchewan and Alberta. Observed losses of organic C, N, and P in the top 30 cm of a Brown Chernozem under fallow-wheat (FW) were 8.2, 1.7, and 1.0 g m-1 y-1. Soil erosion was responsible for 47% of the organic-N losses. The Century model closely mimicked the direction and magnitude of SOM change, within 10% of measured values. Similar SOM declining trends were observed in a thin Black Chernozem under FW and continuous wheat (CW), although soil erosion losses were higher than in the Brown Chernozem. Soil organic matter increased in the Brown Chernozem under CW and in the Black Chernozem under zero-tillage. Under no-till, the organic C, N, and P accumulated at an average rate of 101.7, 5.3, and 2.0 g m-2 y-1. In comparison, the Century model predicted a depletion of organic-C and N in the Brown Chernozem under CW and of organic-C under no-till. Model sensitivity analyses indicated that the rate of erosion and the fixed rate of organic matter decomposition had greater effects than plant biomass production on soil organic matter levels. Under aggrading SOM conditions, the Century model predicted organic carbon accumulation only after the respiration rate for the slow organic matter fraction was reduced by 50%.Item Soil degradation in Saskatchewan – a pedological perspective(1989-02-16) Anderson, D.W.Item Soils and vegetation within coal strip-mine spoils near Estevan, Saskatchewan(1975-02-12) Anderson, D.W.