E. Mapfumo

Soil compaction under grazing of annual and perennial forages

This study investigated the impact of heavy, medium and light grazing of meadow bromegrass an triticale on soil bulk density, relative compaction and penetration resistance. The study was conducted at Lacombe, Alberta, on a Orthic Black Chernozem of loam to silt loam texture. Sampling was conducted in fall 1995, spring 1996, fall 1996 and spring 1997. Core samples to a 15-cm depth were collected for measurement of bulk density and moisture content. Penetration resistance to 15 cm was measured with a hand-pushed cone penetrometer. The standard Proctor test was used to determine maximum bulk density. Relative compaction was the ratio of actual bulk density to the Proctor maximum bulk density expressed as a percentage. Surface (0–2.5 cm) bulk density and penetration resistance were significantly greater under heavily grazed than under medium and lightly grazed meadow bromegrass only for fall 1995. Differences in bulk density, relative compaction and penetration resistance for different grazing intensities in...

Patterns and simulation of soil water under different grazing management systems in central Alberta

A study was conducted at the Lacombe Research Centre to quantify and simulate the impacts of forage and grazing systems on soil water content. Four forages used in the study were alfalfa (Medicago sativa L.), a mixture of meadow bromegrass (Bromus riparius L.) and alfalfa, an annual pasture and an old grass pasture that was composed of mainly quackgrass (Elytrigia repens L.), smooth bromegrass (Bromus inermis L.) and Kentucky bluegrass (Poa pratensis L .). Within each 1.2-ha paddock were two grazing treatments: rotational grazed and ungrazed. Soil water measurements to a 65-cm depth were conducted between May and October of 1999 and 2000 using a neutron moisture probe. Total soil water was affected by forage species more than grazing. Actual evapotranspiration rates were 3-4 mm d-1 in both years. Simulation of daily volumetric soil water content (%) for each year was conducted using the Versatile Soil Moisture Budget (VB2000) model on grazed alfalfa, ungrazed alfalfa, grazed annual and ungrazed annual tre...

Effluent effects on the nutrient concentrations and growth of reed canarygrass (Phalaris arundinacea L.) and hybrid poplar (Populus deltoides × P. petrowskyana L.).

Using effluent as a source of irrigation water and to provide nutrients for plant growth is gaining favour as an environmentally positive practice instead of discharging effluent into surface water bodies. A growth chamber study was conducted to evaluate pulp mill wastewater as an irrigation source. This study evaluated the effects of water (TPW), municipal effluent (ME), and Kraft pulp mill effluent (KPME) and waste activated sludge (WAS) at rates of 1.5, 3, and 6 mm d-1 on available soil nutrients, nutrient uptake, and growth of reed canarygrass (Phalaris arundinacea L.) and hybrid poplar (Populus deltoides × P. petrowskyana L.). Increasing the application rate significantly increased biomass for both crops, but the KPME treatment significantly decreased leaf biomass of the hybrid poplar. Effluent applications did not result in toxic accumulations of nutrients within the analyzed tissues for either reed canarygrass or hybrid poplar. Only the WAS treatment significantly increased soil available concentra...

Simulation of soil water content on a small reclaimed watershed in northern Alberta using the Root Zone Water Quality Model (RZQWM)

A study was conducted at Syncrude Canada Ltd., Alberta, to evaluate the simulation of soil volumetric water content from the reclaimed slopes of the Southwest Sand Storage Facility using the Root Zone Water Quality Model (RZWQM). Soil water content measurements were conducted every 2 wk using a neutron moisture meter in 2001 (dry year) and 2002 (wet year). Two types of calibration and evaluation were performed: first, calibration using 2001 weather data (dry year) and evaluation using 2002 weather data (wet year) (herein referred to as method 1); second, calibration using 2002 weather data (wet year) and evaluation using 2001 weather data (dry year) herein referred to as (method 2). Results from the method 1 calibration for each tube indicated modeling efficiencies (EF) between −0.27 and 0.90, coefficients of determination (r2) between 0.13 and 0.97, and deviation (D, as %) of simulated from measured values of less than 5%. The model evaluation by tube location following method 1 calibration indicated EF ...

Quantification and simulation of soil water on grazed fescue watersheds

Abstract A 2-year study was conducted at the Agriculture and Agri-Food Canada Stavely Range Substation, Alberta. The objective was to quantify and simulate the soil water status of small grassland watersheds under 3 grazing intensities and 4 topographic positions. The grazing treatments were ungrazed (or control), heavy (2.4 AUM ha−1) and very heavy (4.8 AUM ha−1) grazing and the topographic positions were upperslope, midslope, lowerslope and 5 m away from the collector drain. Moisture readings were taken every 2 weeks between spring and fall using a CPN 503 moisture neutron probe. Readings were taken at the soil surface and at 15-, 25-, 35-, 45- and 55-cm depths. Total annual precipitation in 1998 and 1999 was 648 and 399 mm, respectively. In both years grazing treatments did not affect total soil water in the 0–50 cm (TSW50) depth interval for the upper, middle and lower slope positions, but TSW50 close to the collector drain was significantly (P ≤ 0.05) greater for the heavy grazed compared to the very heavy grazed treatment. Within each grazing treatment, TSW50 differences among slope positions occurred mainly under the heavy grazed treatment. Simulation of soil water at each soil depth and watershed was conducted using the Versatile Soil Moisture Budget Model (VB2000). Statistical and graphical evaluations of the model results were conducted using the volumetric soil water data collected for 1998 and 1999. The statistics determined included average error (AE), root mean square (RMS), coefficient of residual mass (CRM), modeling efficiency (EF) and coefficient of determination (CD). All statistics varied with each soil depth and watershed, indicating the transient nature of the data. This is reflected in the mostly negative CRM values, which ranged between −1.0 and 0.16. Overall model fitting to the whole data for all depths, watersheds and years gave values of CRM = −0.08 and EF = 0.19, indicating a slight over-prediction by the model. Spatial variation due to presence of rocks or cracks and averaging across slopes may have partly contributed to the discrepancies between model results and observed data.

Effect of municipal and pulp mill effluents on the chemical properties and nutrient status of a coarse-textured Brunisol in a growth chamber

Maximizing productive use and minimizing the environmental impacts of effluents require research on application rates. This study evaluated the effect of effluents from a Kraft pulp mill [a final effluent (KPME) and a waste activated sludge (WAS)], a municipality (ME) and tap water (TPW) applied at rates of 1.5, 3 and 6 mm d-1 on reed canarygrass (Phalaris arundinacea L. cv. Vantage) and hybrid poplar (Populus deltoides × P. petrowskyana var. Walker). The two pulp mill effluents significantly increased soluble soil SO4, Na and Cl. Soil solution electrical conductivity (EC) and sodium adsorption ratio (SAR) increased with pulp mill effluents compared with ME and TPW. Soil solution SAR increased from less than 1 to a range of 2.7 to 4.0 for the municipal effluent and 8.4 to 14.0 for the two pulp mill effluents. Soil solution EC increased from 1.1 to 2.3 dS m-1 to a range of 1.8 to 3.4 dS m-1 for municipal effluent and 5.1 to 6.1 dS m-1 as a result of pulp mill effluent applications. Under reed canarygrass, ...

Estimating actual evapotranspiration using water budget and soil water reduction methods

Studies on estimation of actual evapotranspiration on disturbed lands are scarce and yet such data are essential in hydrologic modeling. Our study compared the variability of estimates of actual evapotranspiration (AET) from a reclaimed site in northern Alberta using the simplified water budget (WB) and soil water reduction (SWR) methods. The AET estimates from the simplified water budget equation (AET1) required field soil water content, precipitation and runoff. The AET estimates from the soil water reduction method (AET2) required daily potential evapotranspiration (PET), field capacity (FC) water content, minimum field-measured water content, and field water content. Soil water was measured using neutron moisture gauge every 2 wk during the growing season for a 2-yr period. The average AET1 and AET2 estimates for 2001 were 1.9 and 1.4 mm per day, respectively, where as those for 2002 were 2.1 and 1.2 mm per day, respectively. The paired t-tests to compare AET1 against AET2 indicated significance diffe...