1. Soil Productivity and Conservation THE GMIS

2. Importance of Soil • As the key resource in crop production • It supports the physical, chemical, and biological processes • Regulates water flow such as • Infiltration • Root-zone storage • Deep percolation • Run-off

3. Importance of Soil • Acts as a buffer between inputs and environment • Functions as “degrader” or “immobilizer” of agricultural chemicals, wastes, or other pollutants • Soil also sequesters carbon from the atmosphere

4. Important Soil attributes • Texture • Structure • Bulk density and rooting depth • Permeability and water storage capacity • Carbon content • Organic matter and biological activity • pH • Electrical conductivity

5. Importance of Soil • Soil: the layer of material that covers the land • Where plants anchor and grow • Made of weathered rock, decomposing plant and animal matter • Has spaces for air and water movement • Soils differ in organic content which effects the ability to support plant life.

6. Layers of composition • 3 major types of soil • Horizon A: Topsoil • Horizon B: Subsoil • Horizon C: Parent Rock • Horizon D: Bedrock • Each layer has different characteristics depending on where it is found.

7. Grasslands • Horizon A is deep and supports root growth; small particles of rock mixed with decaying plant and animals (Humas). • Horizon B is the subsoil (mix of dirt and rock). • Horizon C is mostly large pieces of rock. • Horizon D is bedrock solid rock.

8. Forest

9. Deserts • Horizon A: limited plant growth so little decomposition, so thin top soil or none at all.

10. Disturbing soils • Soils change over time naturally • Human impact: deforestation leads to increased erosion of topsoil (no roots to hold soil in place)

11. Productivity of Ecosystems • Ecosystems have different productivities, based on light availability, soil types, precipitation, temperature, nutrients. • Productivity: the quantity of biomass of plants produced each year on a given area (g/m2)

12. Productivity of different ecosystems:

13. Three functions of soil(from NRC) • Provides the physical, chemical, and biological processes for the growth of plants • To store, regulate, and partition water flow through the environment • To buffer environmental change by decomposing organic wastes, nitrates, pesticides, and other substances that could become pollutants

14. Soil Quality • Defined: The capacity of soil to function or the fitness for use • Can be maintained through use of appropriate crop production technologies and resource management systems • Two concepts of measuring soil quality • More traditional: focuses on inherent soil properties • More recent: focuses on dynamic properties of soil

15. Land capability and suitability • Two types of measurements: • Land Capability Classes (LCC’s) • Prime farmland designation • Used to measure land capabilities for a particular purpose: • Growing crops and trees • Grazing animals • Nonagricultural uses

16. Prime Farmland • Based on physical and morphological soil characteristics: • Depth of water table to the root zone • Moisture-holding capacity • Degree of salinity • Permeability • Frequency of flooding • Soil temperature • Erodibility • Soil acidity

17. Prime Farmland • Factors needed to sustain high yields when treated and managed • Growing season • Moisture supply • Soil quality • Totals 222 million acres, or 54% of US cropland excluding Alaska

18. Productivity • Measures output per unit input • Often measured as crop yield per acre • Can reflect soil degradation if yields decline as soils become degraded and more inputs are used to compensate for decline in soil quality

19. Erodibility • Highly erodible lands (HEL) is a soil quality measure that is important to USDA conservation policy • USDA uses the erodibility index (EI) to classify erosion potential

20. Erosion Productivity Loss • Measure of productivity loss that converts total erosion from tons per acre per year to inches per year • 3 factors reflected in this measure: • Erosion rates • Soil depth • Rental values of land