Grazing impacts on bulk density and soil strength in the foothills fescue grasslands of Alberta, Canada

1995 ◽  
Vol 75 (4) ◽  
pp. 551-557 ◽  
Author(s):  
David S. Chanasyk ◽  
M. Anne Naeth

Alberta foothills fescue grasslands are very productive ecosystems but there is concern that the traditional season-long (continuous) grazing regimes may be leading to soil deterioration due to compaction and increased soil strength. The objectives of this study were to quantify grazing effects on soil bulk density and soil strength of sloped areas in the Alberta foothills fescue grasslands at the Agriculture Canada Stavely Range Substation. The effects of two grazing intensities (heavy and very heavy) for two treatments (short duration and continuous) on these two parameters were compared to an ungrazed control. Soil bulk density and soil water to a depth of 7.5 cm were measured with a surface water/density gauge. Soil strength was measured with a hand-pushed cone penetrometer to a depth of 45 cm. Cone index, the maximum penetration resistance in a given depth interval, was used as a measurement parameter for soil strength.Grazing affected both soil bulk density and penetration resistance. Even short-duration treatments affected these soil properties, although their effects were similar for both heavy and very heavy grazing intensities. Distinction between heavy and very heavy continuous grazing treatments was clear for both bulk density and penetration resistance, with the very heavy treatment having the greatest detrimental effect on these two soil parameters for all treatments. Bulk density and soil strength values were always lowest in the spring after snowmelt and highest late in the growing season, reflecting the water status of these ecosystems. Identical treatment rankings were obtained using bulk density and penetration resistance, but cone index was a more sensitive indicator of the effects of grazing than bulk density. Key words: Grazing, fescue grasslands, bulk density, soil strength

1999 ◽  
Vol 79 (1) ◽  
pp. 191-199 ◽  
Author(s):  
E. Mapfumo ◽  
D. S. Chanasyk ◽  
M. A. Naeth ◽  
V. S. Baron

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 spring and fall 1996 and spring 1997 were either small or not significant. Generally, bulk density decreased over winter in the top 2.5 cm, was not consistent in the 5- to 10-cm depth interval and did not change in the 10- to 15-cm interval. Except in fall 1995, the relative compaction values for all grazing intensities and forage species were less than 90%, a value considered critical for plant growth. Generally, within each grazing level, there were minimal differences in bulk density, relative compaction and penetration resistance under triticale compared to those under meadow bromegrass. Key words: Bulk density, relative compaction, penetration resistance


2011 ◽  
Vol 91 (6) ◽  
pp. 957-964 ◽  
Author(s):  
C. Halde ◽  
A. M. Hammermeister ◽  
N. L. Mclean ◽  
K. T. Webb ◽  
R. C. Martin

Halde, C., Hammermeister, A. M., McLean, N. L., Webb, K. T. and Martin, R. C. 2011. Soil compaction under varying rest periods and levels of mechanical disturbance in a rotational grazing system. Can. J. Soil Sci. 91: 957–964. In Atlantic Canada, data are limited regarding the effect of grazing systems on soil compaction. The objective of the study was to determine the effect of intensive and extensive rotational pasture management treatments on soil bulk density, soil penetration resistance, forage productivity and litter accumulation. The study was conducted on a fine sandy loam pasture in Truro, Nova Scotia. Each of the eight paddocks was divided into three rotational pasture management treatments: intensive, semi-intensive and extensive. Mowing and clipping were more frequent in the intensive than in the semi-intensive treatment. In the extensive treatment, by virtue of grazing in alternate rotations, the rest period was doubled than that of the intensive and semi-intensive treatments. Both soil bulk density (0–5 cm) and penetration resistance (0–25.5 cm) were significantly higher in the intensive treatment than in the extensive treatment, for all seasons. Over winter, bulk density decreased significantly by 6.8 and 3.8% at 0–5 and 5–10 cm, respectively. A decrease ranging between 40.5 and 4.0% was observed for soil penetration resistance over winter, at 0–1.5 cm and 24.0–25.5 cm, respectively. The intensive and semi-intensive treatments produced significantly more available forage for grazers annually than the extensive treatment. Forage yields in late May to early June were negatively correlated with spring bulk density.


2016 ◽  
Vol 36 (3) ◽  
pp. 449-459 ◽  
Author(s):  
Wininton M. da Silva ◽  
Aloísio Bianchini ◽  
Cesar A. da Cunha

ABSTRACT This study aimed to describe the behavior of models for adjusting data of soil penetration resistance for variations in soil moisture and soil bulk density. The study was carried out in Lucas do Rio Verde, MT, Brazil in a typic dystrophic red-yellow Latosol (Oxisol) containing 0.366 kg kg−1 of clay. Soil penetration resistance measurements were conducted in the soil moistures of 0.33 kg kg−1, 0.28 kg kg−1, 0.25 kg kg−1 and 0.22 kg kg−1. Soil penetration resistance behavior due to variations in soil moisture and soil bulk density was assessed by estimating the soil resistance values by non-linear models. There was an increase of the soil penetration resistance values as soil was losing moisture. For the same edaphic condition studied, small differences in the data of soil bulk density affect differently the response of soil resistance as a function of moisture. Both soil bulk density and soil moisture are essential attributes to explain the variations in soil penetration resistance in the field. The good representation of the critical soil bulk density curve as a limiting compression indicator requires the proper choice of the restrictive soil resistance value for each crop.


Soil Research ◽  
2011 ◽  
Vol 49 (2) ◽  
pp. 135 ◽  
Author(s):  
M. A. Hamza ◽  
S. S. Al-Adawi ◽  
K. A. Al-Hinai

Reducing soil compaction is now an important issue in agriculture due to intensive use of farm machinery in different farm operations. This experiment was designed to study the influence of combinations of external load and soil water on soil compaction. Four soil water levels were combined with four external loads as follows: soil water—air-dry, 50% of field capacity, field capacity, and saturation; external load using different-sized tractors—no load (0 kg), small tractor (2638 kg), medium tractor (3912 kg), and large tractor (6964 kg). Soil bulk density, soil strength, and soil water infiltration rate were measured at 0–100, 100–200, and 200–300 mm soil depths. The 16 treatments were set up in a randomised block design with three replications. Combined increases in soil water and external load increased soil compaction, as indicated by increasing soil bulk density and soil strength and decreasing soil water infiltration rate. There was no significant interaction between soil water and external load for bulk density at all soil depths, but the interaction was significant for soil strength and infiltration rates at all soil depths. The ratio between the weight of the external load and the surface area of contact between the external load and the ground was important in determining the degree of surface soil compaction. Least compaction was produced by the medium tractor because it had the highest tyre/ground surface area contact. In general, the effects of soil water and external load on increasing soil bulk density and soil strength were greater in the topsoil than the subsoil.


Bragantia ◽  
2014 ◽  
Vol 73 (2) ◽  
pp. 171-177 ◽  
Author(s):  
Daniel Dias Valadão Junior ◽  
Aloísio Biachini ◽  
Franciele Caroline Assis Valadão ◽  
Rodrigo Pengo Rosa

This study aimed to evaluate the effect of penetration rate and the size of the cone base on the resistance to penetration under different soil moistures and soil bulk density. The experimental design was completely randomized in a 4x2x2x2 factorial arrangement, with the factors, soil bulk density of 1.0; 1.2; 1.4 and 1.6 Mg m-3, soil moisture at the evaluation of 0.16 and 0.22 kg kg-1, penetration rates of 0.166 and 30 mm s-1 and areas of the cone base of 10.98 and 129.28 mm² resulting in 32 treatments with 8 replicates. To ensure greater uniformity and similarity to field conditions, samples passed through cycles of wetting and drying. Only the interaction of the four factors was not significant. Resistance values varied with the density of the soil, regardless of moisture and penetration rate. Soil penetration resistance was influenced by the size of the cone base, with higher values for the smallest base independent of moisture and soil bulk density. The relationship between resistance to penetration and moisture is not always linear, once it is influenced by soil bulk density. Reduction in the area of the cone leads to an increase in the soil resistance to penetration.


2013 ◽  
Vol 59 (No. 7) ◽  
pp. 295-302 ◽  
Author(s):  
B. Ji ◽  
Y. Zhao ◽  
X. Mu ◽  
K. Liu ◽  
C. Li

Subsoil compaction can result in unfavourable soil physical conditions and hinder the root growth of maize. The effects of deep tillage and conventional tillage on soil physical properties and root growth of maize were studied during 2010–2011 at two sites (loam at Hebi and clay at Luohe) in central China. The results showed that soil penetration resistance, bulk density, water content and root length density were significantly affected by tillage, soil depth and year. Deep tillage had lower penetration resistance and lower soil bulk density, but higher soil water content than conventional tillage across years and depths. Averaged over the whole soil profile, deep tillage not only significantly decreased penetration resistance and soil bulk density, but significantly increased soil water content and root length density on loam, while deep tillage only significantly increased the root length density on clay. We conclude that deep tillage on the loam is more suitable for the root growth of summer maize.


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