'grass vegetation' is a correct and usable term in written English.
You could use it when describing the types of vegetation that are found in a particular area, such as "The grass vegetation of the Montana prairie is made up of a variety of drought-resistant plants."
The stability of aggregates increases with humus content, especially humus that originates from grass vegetation.
Mollisols are characterized by a significant accumulation of humus in the surface horizon, or uppermost layer, which is almost always formed under native grass vegetation.
In the semiarid areas bordering the desert, increased rainfall makes grass vegetation more plentiful, results in rocks becoming more weathered than in the desert, and produces better developed soils with a higher humus content.
Chernozems are characterized by a surface layer that is rich in humus and in available calcium ions bound to soil particles, resulting in a well-aggregated structure with abundant natural grass vegetation.
Mostly covered with grass vegetation dominated by Pennisetum mezianum (Heim).
This could be related to wetter conditions in the deforested area, accompanied with the emergence of grass vegetation.
Chernozems are closely related to the soils in the Mollisol order of the U.S. Soil Taxonomy that form under tall-grass vegetation.
The steppe-grass vegetation has been largely ploughed up, and many shelter belts of trees have been planted; in the north are extensive birch groves.
The Yergeni has steppe-grass vegetation and groves of deciduous trees (willow, elm, and poplar) in the valleys; elsewhere the republic is semidesert.
In the colder areas of these climatic zones, a natural tall-grass vegetation develops on soil profiles whose surface layers can be as much as two metres (about six feet) thick, with up to 16 percent humus by mass.
This research strongly suggested that the engineering runoff control practices in the study effectively reduced soil erosion, increased water storage, and eased the water demand of forest-grass vegetation at the beginning of afforestation, but over-consumption of soil water that may not have been replenished by the limited rainfall, could potentially cause the soil to dry-out.
