Presentation on theme: "Soils. Functions of Soil Anchor rootsAnchor roots Aeration of rootsAeration of roots Supply mineral nutrientsSupply mineral nutrients Supply moistureSupply."— Presentation transcript:
Functions of Soil Anchor rootsAnchor roots Aeration of rootsAeration of roots Supply mineral nutrientsSupply mineral nutrients Supply moistureSupply moisture Maintain pH suitable for plant growthMaintain pH suitable for plant growth
Functions of Soil Do all plants require soil to grow?Do all plants require soil to grow?
Functions of Soil Do all plants require soil to grow?Do all plants require soil to grow? No… Called “Hydroponics”No… Called “Hydroponics”
Soil Classification Organic -decayed plant and animal materials (O.M.)Organic -decayed plant and animal materials (O.M.) –Unstable and breaks down over time –20% O.M. = an organic soil –Peat, bark, compost or manure added added to improve the O.M. content in soils –Good water holding capacity –Good aeration –Permeable to water –Good fertility –Reduces erosion –Easy to cultivate
Soil Classification Earthworms (Lumbricus terrestris)Earthworms (Lumbricus terrestris) –“Intestines of the earth”! –50, ,000,000/acre –Eat tons of leaves, stems & dead roots/acre and produce “castings” –Consume their body weight in plant material every 24 hours! –Turn over 40 tons of soil/acre/year
Soil Classification EarthwormsEarthworms –Brought to North America by European settlers in the 17th & 18th centuries –Charles Darwin (1881) said "It may be doubted whether there are many other creatures which have played so important a part in the history of the world.” –Inorganic fertilizers reduce the #’s of earthworms
Soil Classification Inorganic - comes from mineral rocksInorganic - comes from mineral rocks –Varies by location
Soil Texture Range is:Range is: –Sand (largest) mm –Silt (medium) mm –Clay (smallest) <0.002 mm –A combination of all three = loam Silt Clay Sand
Soil Structure Aggregates - soil particles that group into clumpsAggregates - soil particles that group into clumps –Freezing & thawing –Wetting and drying –Root growth –Earthworms OM + clay = “glue” that holds soil particles togetherOM + clay = “glue” that holds soil particles together
Rototill only when the soil is not too wet. If too wet and you rototill, you will destroy soil aggregates!
a) aggregated soilb) soil crusts after aggregates break down runoff infiltration
Soil Structure Legumes (peas, beans, clover)Legumes (peas, beans, clover) –N 2 -fixing (Rhizobium bacteria) –Makes atmospheric N available to the plant –Some are deep-rooted perennials –Opens up soil to water and aeration
Soil Structure Structure affects pore spaceStructure affects pore space –Large particles (sand) large poreslarge pores little structurelittle structure good aerationgood aeration good infiltrationgood infiltration poor water holding capacitypoor water holding capacity low fertilitylow fertility Warms quickly in springWarms quickly in spring
Soil Structure Structure affects pore spaceStructure affects pore space –Small particles (clay and silt) small poressmall pores low aerationlow aeration slow infiltrationslow infiltration high water holding capacityhigh water holding capacity high fertilityhigh fertility Warms slowly in springWarms slowly in spring –If you have a clay soil, DO NOT plow/turn when wet. This will destroy the structure!