1 / 19

Soil Erodibility

Soil Erodibility. Prof. Dr. EHSANULLAH. The erodibility of a soil is defined by its resistance to two energy sources: the impact of raindrops on the soil surface, and the shearing action of runoff between clods in grooves or rills. Soil Erodibility. Hjulström's Model.

corat
Download Presentation

Soil Erodibility

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Soil Erodibility Prof. Dr. EHSANULLAH

  2. The erodibility of a soil is defined by its resistance to two energy sources: the impact of raindrops on the soil surface, and the shearing action of runoff between clods in grooves or rills. Soil Erodibility

  3. Hjulström'sModel

  4. Factors influencing soil erodibility Living or dead roots increase aggregate stability and decrease erodibility. Erodibility increases with a decrease in aggregate stability. Clay and organic matter help improve aggregate stability and reduce erodibility.

  5. Erodibility decreases with an increase of large sand grains and rock fragments because these large particles are not easily moved with water. Soil conservation personnel use standard erodibility values published for each soil series in a particular county.

  6. Soil Erodibility How it is determined and used.

  7. Universal soil loss equation • The Natural Resources Conservation Service (NRCS) uses the Revised Universal Soil Loss Equation (RUSLE) to calculate soil loss by erosion as a function of 5 factors: • A = R × K × LS × C × P • A = annual soil loss (tons/A/yr) • R = erosivity of rainfall • K = erodibility of the soil • LS = slope length/steepness • C = cropping and management factors • P = erosion control practices

  8. Limitations of USLE • The USLE only predicts sheet and rill erosion. • The "soil loss" as calculated by the USLE may refer to soil either removed from the field or simply soil relocated within the same field • The calculated "soil loss" does not necessarily mean that this amount of sediment will enter a stream.

  9. How is the USLE Used? • The calculated soil loss is compared to the tolerable soil loss for a specific soil type. The tolerable soil loss (T value) is the maximum level of soil erosion that will still permit a high level of crop productivity to be sustained economically and indefinitely. The difference between the calculated soil loss and the tolerable soil loss indicates the degree to which an erosion problem exists and its potential impact on productivity.

  10. The tolerable soil loss of a particular soil type is therefore used as a base line value when you evaluate the effect that different cropping systems have on soil erosion losses.

  11. Factors influencing USLE • • soil depth, • physical properties and other characteristics affecting root development, • gully prevention, • on-field sediment problems, • seeding losses, • soil organic matter reduction, • plant nutrient losses.

  12. Importance of factor c in USLE. The C factor for a given cropping system and locality should consider. • how the crop residues will be managed, • the tillage used, • the amount of residue remaining on the surface,

  13. • the amount and distribution of rainfall, • the vegetative cover's stage of growth and development when rain occurs.

  14. How does the USLE work? The USLE, when used properly within its limitations, can be a useful tool in soil conservation planning. The soil loss equation allows a grower to compare the effect that crop management changes will have on soil loss.

  15. Possible Approaches to Improve Soil Resistance. • There are two possible approaches to improving soil resistance in order to control erosion. The first is to choose the most resistant soils in the area for those crops that provide the least cover, leaving the most fragile soils permanently under plant cover.

  16. The second solution is to control the organic matter in the soil. Ploughing organic matter into the entire tilled horizon will rarely achieve even a 1% improvement in the level of organic matter.

  17. Also, a 1% improvement in organic matter will not reduce erodibility by more than 5%. • clay and calcium carbonate, can also be introduced, improving soil resistance to rainfall aggressiveness by 5-10%.

  18. Thanks

More Related