Introductory Study of Soils For the Master Gardeners Wendy Sue Harper, Ph.D. What We Will Cover Tonight Introduction Agroecological perspective to understanding the physical, chemical and biological properties of soil for gardeners Math, so you can make organic fertilizer recommendations from a UVM soil test report. Soil: the Foundation of Gardening A Plant & Soil Ecosystem Light Air Water, etc Moisture Temperature Air Texture Structure Microbes, Earthworms, etc Pollutants Nutrients ph CEC OM = Organic Matter Microbes Organic Matter Nutrients Moisture CEC Air Soil Fertility is The ability of a soil to provide a physical, chemical, and biological environment for the plant that is health sustaining. Structure Texture ph Pollutants A Simplified Soil Ecosystem This is along term ecosystem based or agroecological perspective! 1
Seven Principles to Maintain Soil/Water/Plant Resource Base A Good Loam Soil: ➀ Maintain proper air/water balance ➁ Maintain soil tilth ➂ Prevent erosion ➃ Maintain proper SOM levels ➄ Maintain biological diversity ➅ Maintain a proper ph ➆ Maintain a proper balance of nutrients 50% Solids 50% Pores 45% Mineral 25% Water 25% Air 5% Organic Matter (A systems approach means you gotta do them all. Alone each will not build soil fertility.) So why is this important? Roots: An Undisturbed Soil Profile: 1 Support the plant 2 Absorb water and nutrients 3 Exchange gases 4 Store starches and sugars 5 Transform nutrients 6 Produce plant hormones 7 Interact with microbes for disease suppression Ap Organic matters Zone of biological activity Zone of accumulation Mix O + A + E = Ap A = topsoil p = plowed or disturbed 1.Air/Water Balance Depends On: Soil Textural Triangle: Here, amount is equal. 1 Location on the landscape 2 Soil depth 3 Soil texture 4 Soil structure: sandy vs. clayey 5 Soil organic matter content: it holds water! *Loam Soil: The influence of the sand, silt and clay on its physical properties is equal. (Not the quantity or amount, but its influence!) 2
Soil Particles That Make Up Texture Feel: Sand Gritty Soil Structure Shape of individual peds *Granular, Crumb *Prismatic Silt Smooth, like baking flour *Platy Clay Sticky *Subangular Blocky Columnar!Not apart of Texture: Organic Matter Greasy Angular Blocky * Note: found in Vermont *Structureless 1. Single grained 2. Massive You worked your soil when it was too wet? What did you get? You get: CLODS OM Additions Promote Structure And Thus: Drainage in clay soils (macropores) Water holding capacity in sandy soils (micropores) *Cause it Creates the Pores You Ain t Got!* It is called: PUDDLING YOUR SOIL Macropore hold air and drain Micropores hold water OM = Drought Prevention Insurance Soil Too Dry? Manage to Prevent Water Loss By: Mulching to conserve moisture Prevent runoff Build OM content to improve the water holding capacity Control weeds (competition) or used them to your advantage Plant tolerant species Water deeply and consistently Soil Too Wet? Manage for water loss by: Raised beds Shape of beds Follow good Management Practices Add OM to improve drainage (clays) Don t work wet soil Plant after soil warms up Plan wet in early spring areas for late season crops like tomatoes Plant tolerant species Put in a drainage system to drop the water table 3
2. Soil Tilth: All the Physical Properties of Soil Related to Plant Growth Including: structure, drainage, aeration, moisture holding capacity, bulk density. "Work a soil when it has dried out enough "Add OM to improve physical properties "Treat soil gently "Keep soil covered 3. Prevent Erosion: Erosion is the process of detachment and transport by wind or water Prevent it by: Make the wind or water less erosive by slowing it down Protect the soil from exposure to wind or water Build the soils resistance to erosive forces Seven Principles to Maintain Soil/Water/Plant Resource Base ➀ Maintain proper air/water balance ➁ Maintain soil tilth ➂ Prevent erosion ➃ Maintain proper SOM levels ➄ Maintain biological diversity ➅ Maintain a proper ph ➆ Maintain a proper balance of nutrients 4. How Can You Get OM Into Your Soils? Animal Manures Composts Cover Crops Mulches Peat Moss Others? Any Cautions? C:N Ratio or Carbon to Nitrogen Ratio 5. Maintain or Create Biodiversity & SOIL 4
5. Maintain or Create Biodiversity Rotate Crops Plant Mixtures of Species Interplant, Under-sow, Companion Plant, Polyculture Add Compost Mulch Plant Biological or Ecological Islands Habitat and Food For Beneficials Selective Weeding Change Tolerance Levels for Pest Use IPM Cautions?.. 6. Maintain A Proper ph Which is: ph 7. Maintain A Proper Balance of the Nutrients How to Know? ESSENTIAL ELEMENTS FOR PLANT GROWTH Plant Available Major Source Form of Nutrients MACRO-NUTRIENTS Carbon CO 2 Air Oxygen O 2 Air Hydrogen H 2 O Water Nitrogen NO 3-, NH + 4 Soil OM Phosphorus H 2 PO 4-, HPO 2-4 Soil OM Potassium K + Soil Minerals Calcium Ca 2+ Soil Minerals Magnesium Mg 2+ Soil Minerals Sulfur SO 2-4, SO 2 (gas) Soil OM, Air ESSENTIAL ELEMENTS FOR PLANT GROWTH Plant Available Form Major Source of Nutrients MICRO-NUTRIENTS Iron Fe 2+ Soil Minerals + OM Manganese Mn 2+ Soil Minerals + OM Copper Cu 2+ Soil Minerals + OM Zinc Zn 2+ Soil Minerals + OM Boron H 3 BO 3 Soil Minerals + OM* Molybdenum MoO 2-4 Soil Minerals* + OM Chlorine Cl - Soil Minerals + Rain* Cobalt Co 2+ Soil Minerals + OM Nickel Ni 2+ Soil Minerals + OM OTHERS?? Sodium, Selenium, Silica, Vanadium, Iodine, Fluorine??? Soil Solution: The Thin Skins of Water that Coat Everything. Cation Exchange Capacity + Cations +++ We are positive! ++ Root Hair ph near neutral Acid ph K + Mg 2+ Ca 2+ H+ Al 3+ NO 3-5
The ph of things in our lives. Neutral H+ + OH - = HOH = H 2 O soils ph Acid 0 1 2 Lemons 3 Vinegar, Grapefruit, Wine 4 Grass silage Tomatoes 5 Beer Boric Acid 6 Distilled water 7 Cows milk Human blood 8 Manure Seawater 9 Bicarb of Soda 10 Milk of Magnesia 11 Ammonia 12 ph Effects on Nutrient Availability * Distilled water or rain water = ph 5.6 13 14 Lye Basic ph Preferences for Selected Plants ph?? Heavy Metals?? DO YOU KNOW What s In Your Dirt? N-P-K?? Micronutrients?? % OM?? 6