Abstract
Weight of organic matter aboveground and underground in ungrazed natural grassland in sand-, loam-and clay-textured soil and the effects of grazing and cultivation in modifying the weight and distribution of organic matter in loam-textured soil were studied near Saskatoon, Saskatchewan.Mean weight of organic matter in ungrazed sand, loam and clay sites was, respectively, 2 2 213, 358 and 262 glm canopy; 274, 299 and 263 glm mulch; and to 2 a depth of 35 cm, 1 004, 1 480 and 1 218 glm underground plant 2 parts; and 14.2, 24.5 and 28.3 kglm soil organic matter.The proportion of total system organic matter aboveground and underground as plant parts was respectively, 3.1 and 6.4 percent in sand soil, 2.4 and 5.6 percent in loam soil and 1.7 and 4.1 percent in clay soil, the remaining proportion in each case being soil organic matter.Heavy grazing in loam soil transformed a Festuca, Agropyron, Stipa community to a Stipa, Agropyron, Festuca community, and reduced organic weight of the canopy from 2 258 to 82 g/m , mulch from 299 to 186 g/m 2 and soil organic matter in the upper 15 cm by 16.7 percent in comparison to ungrazed natural grassland.Weight of underground plant parts was not affected by grazing.Replacement of the dominant grasses with shallow-rooted species such as Koeleria cristata, Carex spp., Bouteloua gracilis and Phlox hoodii apparently maintained underg round biomass.Aboveground biomass accounted for 1.1 percent and underground biomass accounted for 6.2 percent of the total -iv system organic matter in grazed sites.Cultivation of loam soil for a period averaging 21 years reduced soil organic matter weight by 26 percent in the plough layer.The decline in soil organic matter content in grazed and cropped land is attributed to a reduction in the amount of plant material returned to the soil under grazing and cropping and the increased rate of decomposition as a result of tillage.The significance of the reduction in organic matter content is discussed.
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Claims 7
Claim · model-written summary
Ungrazed sand, loam and clay sites differed in canopy, mulch, underground plant matter and soil organic matter.
Verbatim
e0“Mean weight of organic matter in ungrazed sand, loam and clay sites was, respectively, 2 2 213, 358 and 262 glm canopy; 274, 299 and 263 glm mulch; and to 2 a depth of 35 cm, 1 004, 1 480 and 1 218 glm underground plant 2 parts; and 14.2, 24.5 and 28.3 kglm soil organic matter.”
Claim · model-written summary
Heavy grazing shifted the grassland community from Festuca dominant to Stipa dominant.
- Treatment
- Heavy grazinge0
- Outcome
- communitye0
- Direction
- transformede0
- Comparator
- Festuca, Agropyron, Stipae0
Agropyron
Festuca
StipaOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Heavy grazing in loam soil transformed a Festuca, Agropyron, Stipa community to a Stipa, Agropyron, Festuca community”
Claim · model-written summary
Heavy grazing reduced canopy organic weight from 258 to 82 g/m².
Verbatim
e0“Heavy grazing in loam soil transformed a Festuca, Agropyron, Stipa community to a Stipa, Agropyron, Festuca community, and reduced organic weight of the canopy from 2 258 to 82 g/m”
t0“grassland”
Claim · model-written summary
Grazing reduced mulch from 299 to 186 g/m².
Verbatim
e0“mulch from 299 to 186 g/m 2”
t0“grassland”
Claim · model-written summary
Grazing reduced soil organic matter in the upper 15 cm by 16.7%.
Verbatim
e0“soil organic matter in the upper 15 cm by 16.7 percent in comparison to ungrazed natural grassland.”
t0“grassland”
Claim · model-written summary
Underground plant matter was unaffected by grazing.
Not reportedComparator
Verbatim
e0“Weight of underground plant parts was not affected by grazing.”
Claim · model-written summary
Cultivation reduced soil organic matter weight by 26 percent.
- Taxon
- grasslandt0
- Treatment
- Cultivation of loam soile0
- Outcome
- soil organic matter weighte0
- Direction
- reducede0
- Value
- 26 percente0
Not reportedComparator
Verbatim
e0“Cultivation of loam soil for a period averaging 21 years reduced soil organic matter weight by 26 percent in the plough layer.”
t0“grassland”