Rangeland Soils Training

1. Rangeland Soils Training Kabul, 2006 8 By Dan Robinett, USDA - USAID

2. Objectives of Training • Introduce Rangeland Soils • Provide Definitions • Soil • Soil formation • Soil taxonomy • Learn About Rangeland Soils • Understand Soil Physical Properties • Understand Soil Chemical Properties • Understand Soil Compaction and Erosion

3. All human and animal life depends on plants Almost all plant life depends on soil Why are Soils Important ?

4. How Can an Understanding of Soils Help? • This knowledge will help MAAHF / FRD staff work with communities in their area to • Understand how soil compaction and erosion affect • Water infiltration and runoff • Range plant productivity • Water and air quality • Good management of rangeland soils will • Improve range plant productivity • Reduce soil erosion • Improve water and air quality

5. Soil • Soil is the resource that supports plants on the surface of the earth. • Soil consists of : • mineral particles of different sizes (sand, silt and clay) • organic matter • and many species of living organisms

6. Where Does Soil Come From ? • Soils are derived from the break-down or weathering of rocks (parent material) • The combined action of water, chemical reactions, freezing, drying and plants roots break-down rock into soil particles • The physical and chemical characteristics of soil is determined by the type of rock or parent materials it came from

7. On average soil is: 45% mineral matter 5% organic matter 25% water 25% air Therefore soil is: 50% matter 50% pore space This is very important to remember ! Composition of Soil

8. There is a world wide system of classification of soils There are twelve Soil Orders Under Soil Orders Class Family Series Taxonomy of Soils

9. Soil Regions in Afghanistan

10. Aridisols Very arid (dry) soils Very old soils Soils are well developed Desert Desert shrubland Desert grassland Classes include: Salids (salts) Gypsids (gypsum) Calcids (lime) Argids (clay) Some Soil Orders in Afghanistan

11. It is a very old soil It is well developed with several horizons It is high in lime (CaCO3) It is in a very dry (arid) environment It is a Calcid This Soil at the Ministry is an Aridisol

12. Entisols Very young soils Usually dry soils Some wet soils Always moving Soil cannot develop Classes include : Fluvents (streams) Psamments (sand) Orthents (steep slopes) Afghan Soil Orders cont.

13. Mollisols Old soils Very dark colored Not too dry Tall grasslands Some woodlands Can dry farm wheat Classes include: Ustolls (rain and snow) Xerolls (winter snow) Afghan Soil Orders cont.

14. Process begins with weathering of soil particles from bedrock and deposition as a soil body Five soil forming factors Parent material (rock) Climate Plants and animals Topography Time (days to millions years) Soil Formation

15. Soils develop, over time, into layers Topsoil – The A horizon, usually darkened by organic material. Where most root growth occurs Subsoil – The B horizon, zone where materials leached out of the topsoil accumulate (lime, clay, etc.) Bottom – The C horizon, this is the transition to the parent material or bedrock Soil Horizons

16. The physical properties of soils are those that can be seen or felt They include : Soil texture Soil structure Soil depth Soil color These properties influence what kind of plant species will grow on the soil ! Physical Properties of Soils

17. Soil texture is the proportion of sand, silt and clay particles Sand – 2 to .05 mm Silt - .05 to .002 mm Clay – less than .002 mm Sand feels gritty Silt feels smooth Clay feels sticky Soil Texture

18. Soil Texture Affects Many Things • Texture affects the amount of water the soil can hold • One meter depth of sand can hold – 2.8 cm water • One meter depth of loam can hold – 6.4 cm water • One meter depth of clay-loam can hold - 7.6 cm water • Texture also affects water infiltration into the soil and water movement through the soil • Texture also affects the supply of nutrients in the soil • Increasing clay content increases nutrient capacity • Increasing sand content increases sterility

19. Soil structure is the way soil particles are grouped together to form large or small clumps Soil structure affects Water infiltration Water movement in the soil Resistance to erosion Root growth Soil Structure

20. Soil Depth • Soil depth is the total soil available for plant growth • Soil depth classes • Deep – greater than 1 meter • Moderately deep – 0.5 meter to 1 meter • Shallow - 0.25 meter to 0.5 meter • Very shallow – less than 0.25 meter

21. Soil color can indicate Organic matter (dark brown) Lime content (white) Clays (red to black) Drainage (grey) Iron oxides (red) We use a standard color chart (Munsell) to record soil colors. Soil Color

22. Soil acidity – pH 5 – acid 7 – neutral 9 – alkaline Salinity – salts of sodium, calcium and potassium Gypsum – calcium sulfate Reaction to acid– calcium carbonates (lime) Chemical Properties of Soils

23. All Soil Properties Affect the Kind of Plants That Can Grow on a Soil Limy soil – shrub land Clay soil - grassland

24. Soil Density and Porosity • Remember most soils are 50% matter and 50% pore space • Pore space is where water moves into the soil and where roots can grow through soil • Density is weight / volume • The density of loamy soil is 1.2 gr. / cc

25. Soil compaction is the process by which soil is compressed and pore space is reduced It usually occurs in the surface 25 cm of soil It is caused by traffic of animals, people, machines, etc. Soils have to be moist for compaction to occur Soil Compaction

26. Severity of Soil Compaction • Compress soil to 70% matter, 30% pore space – water movement and root growth in the soil are restricted • Compress soil to 90% matter, 10% pore space – water and roots cannot penetrate the soil • Compaction is persistent at lower elevations • Compaction can be overcome by freeze – thaw at higher elevations

27. What Compaction Looks Like

28. Reduces root growth Reduces water penetration Increases runoff from rain and snow melt Increases soil erosion Reduces plant production Effects of Soil Compaction

29. Soil erosion is the detachment and removal of soil particles by wind and water Soil erosion is a natural process Soil erosion can be increased by poor management Soil Erosion

30. Severity of Soil Erosion Fort Huachuca, Arizona

31. Loss of soil A horizon Loss of soil productivity Excess sediment in air Excess sediment in water Can destabilize large areas Sand movement Gully formation Effects of Soil Erosion

32. Summary • Introduced Rangeland Soils • Definitions of Soil • Learned About Rangeland Soils • Physical properties • Chemical properties • Understanding of Soil Compaction • Understanding of Soil Erosion

33. The Most Important Lessons • Soils Affect What Plants Grow on an Area • Soil Compaction and Soil Erosion are Serious Problems on Rangelands • Good Range Management can Reduce Soil Compaction and Erosion by • Allowing more plant growth and root growth which can break up compaction • Allowing more plant cover on the land to protect soils from erosion • Tashakor