YOUTH & Soil: The excited skin of the earth’s surface AGRICULTURE HEALTH ECONOMY ENVIRONMENT ENERGY COMMUNITIES FAMILIES Ecological Soil Management Doug Collins WSU Small Farms Extension Specialist Growing Groceries September 30, 2015 Soils are formed from the interaction between parent During the Pleistocene (2-3 million years ago) large glaciers material, climate, organisms, aspect, and time. covered most of the north 1/3 of Washington State. Good dirt here! OSU Special Collections and Archives Glacial deposition Parent material Even more good dirt here More good dirt here! OSU Special Collections and OSU archive Archives 1
Alluvial and aeolian processes transport and deposit parent Climate influences the speed of weathering for minerals material National Archives and Records Administration Vaquero Francis Aspect influences water and light dynamics Above and below-ground organisms also influence soil development Farming practices also influence soil processes Cover cropping is a management practice to influence soil processes organism 2
Soils are stratified vertically by horizons. Soils in the same Time is also an important factor in soil processes. soil series have similar characteristics There are more than 20,000 soil series • Soils formed on glacial terraces Lynden, Kickerville, Laxton, Tromp • Soils formed on flood plains: Mt. Vernon, Puyallup Photo by Wolfgang Staudt Ecological Soil Management Outline I. Natural history, soil formation, general soil information II. Soil fertility, productivity, health, and tilth III. Soil nutrients, nutrient pools and pH IV. Organic matter, nitrogen mineralization and cover crops V. Compost and other amendments VI. Double Digging Experiment November 11: Interpreting soil test Photo by Dennis Wilkinson Productivity Fertility is one component of soil health and productivity. “Quality” or “healthy” soil has the continued capacity to provide A fertile soil may not be a productive soil functions and does not degrade the surrounding environment Limits to productivity: • Light • Water • Nutrient availability • Plant pathogens/pests • Herbicide use • Overworked Photo by Kate Halstead Gene Williams, Snohomish County Surface Water Management 3
Soil texture Soil with good tilth contains: sand Particle size • Stable soil aggregates distribution affects: • Even moisture levels . • Drainage . . . . . . . . . . . . • Pathways for air and water clay . . . . • Aeration . • Good drainage • Water retention silt • Nutrient exchange Extremes such as excessive tillage can degrade soil tilth. 0.05mm Soil texture can be estimated by hand with the ribbon test. Soil texture is inherent and cannot be changed http://soils.puyallup.wsu.edu/video_soiltexture/ websoilsurvey.nrcs.usda.gov Organic matter Mix organic matter into the soil by hand or with a machine Adding organic matter : • Helps build soil structure • Improves water retention • Adds slow-release source of nutrients Photo by Amy Zarrett Photo by Craig Cogger 4
Double digging to add organic matter and improve tilth Organic matter can be left on the soil surface Plant Nutrients Percentage of elements present in a healthy plant Macronutrients Micronutrients Carbon (C) 45.00% Chlorine (Cl) 0.01 % Oxygen (O) 45.00% Iron (Fe) 0.01% 6.00% Hydrogen (H) Manganese (Mn) 0.005% 1.50% Nitrogen (N) Boron (B) 0.002% 1.00% Potassium (K) Zinc (Zn) 0.002% 0.50% Calcium (Ca) Copper (Cu) 0.0006% 0.20% Phosphorus (P) Molybdenum (Mo) 0.00001% 0.20% Magnesium (Mg) Nickel (Ni) 0.000001% 0.20% Sulphur (S) Percentages by plant dry weight Nutrient pools: Parent material (e.g. rocks/minerals), is a source Ions are forms of nutrients available for plant uptake of very slowly available nutrients. Parent material = rich, frugal uncle – v. slowly available Anions Cations (negative) K + (positive) Fe 2+ Nitrate Mn + Ammonium - NO 3 NH 4 + Ca 2+ Weathering Elements Elements Potassium Phosphorus physical and chemical unavailable available K + H 2 PO 4 - “nutrients” Minerals e.g.: Hornblende (Ca 2 Al 2 Mg 2 Fe 3 Si 6 O 22 (OH) 2 ) Potassium Feldspar (KAlSi 3 O 8 ) 5
Nutrient pools: Organic matter is a source of slowly available Nutrient pools: Surfaces of humus and clay store quickly available nutrients. nutrients. Parent material = rich, frugal uncle – v. slowly available Parent material = rich, frugal uncle – v. slowly available Mineralizeable = Stocks and Bonds – slowly available Mineralizeable = Stocks and Bonds – slowly available NH 2 Adsorbed nutrients= Checking acct– quickly available + - NH 4 NO 3 C-C-C-C- Mg 2+ SH Ca 2+ 2- SO 4 K + - - PO 3 - - - - - K + - - PO 4 - - - - - - - Organic matter OM clay NH 2 K + NH 4 + Ca 2+ SO 4 2- mineralization unavailable available soluble, available Nutrient pools: Nutrients in the soil solution are immediately Typical CEC values for different soil textures available. Parent material = rich, frugal uncle – v. slowly available Soil Type CEC meq/100g Sands (light colored) 3 to 5 Mineralizeable = Stocks and Bonds – slowly available Sands (dark colored) 10 to 20 Loams 10 to 15 Adsorbed nutrients= Checking acct– quickly available Silt Loams 15 to 25 Soil solution = Cash – available now Clay and clay loams 20 to 50 Organic soils 50 to 100 K + NH 4 + Ca 2+ SO 4 2- soluble, available Soil pH and nutrient availability pH Measure of pH VALUE TABLE how acid or alkaline a substance is (related to H conc.) 4.0 5.0 6.0 6.6 7.0 7.6 8.5 9.0 9.5 10.0 6.0 to 7.5 ideal for most crops ACID NEUTRAL ALKALINE Blueberries 4.5 to 5.5 6
Nitrogen cycles from cover crops and amendments through Soil organic matter is split between active organic matter the microbial biomass and humus. atmospheric N 2 legume Active Clay Organic amendment Organic Matter Sand Matter Silt Soil Soil OM C, N available N Humus Water Microbial Biomass Air N excreted Bacteria Fungi Isopods Living Collembola protozoa nematodes Organisms earthworms Cover crops improve soil quality, protect soil, smother weeds, PAN from organic fertilizers ranges from $5 to $9 per pound. take up excess nutrients from the soil, and legumes add nitrogen Legume cover crops can provide PAN at $1 to $3 per pound. Clover & rye mix in garden bed, 7 days after planting Vetch & rye mix in farm field, 45 days after planting Cover Crops for Home Gardens East of the Cascades: Winter Cover Crops for Home Gardens West of the Cascades: Winter Cover Crop Comments Planting Rate Planting Date Cover Crop Comments Planting Rate Planting Date lbs/a c/100ft 2 Aug Sept Oct Nov lbs/a c/100ft 2 Aug Sept Oct Nov Cereal Rye Hardy 180 1 Cereal Rye Hardy 180 1 Winter Wheat 180 1 Winter Wheat 180 1 Winter Oats 180 1 ½ Winter Oats 180 1 ½ Triticale 180 1 Annual Ryegrass Good in wet 90 ½ Annual Ryegrass Good in wet 90 ½ Spring Barley Winterkills 180 1 Spring Barley Winterkills 180 1 Spring Oats Winterkills 180 1 ½ Spring Oats Winterkills 180 1 ½ Hairy Vetch Reliable 90 ½ Hairy Vetch Reliable 90 ½ Crimson Clover Soil builder 20 ¼ Crimson Clover 20 ¼ Red Clover Soil builder Austrian Winter Pea Not wet soil 90 1 Austrian Winter Pea Not wet soil 90 1 Fava Beans-small May winterkill 100 1 Fava Beans-small May winterkill 100 1 Mustard/Canola Winterkills 20 1 / 8 Phacelia Pollinators 20 1 / 8 7
Cover Crops for Home Gardens East of the Cascades: Summer Cover Crop Comments Planting Rate Planting Date lbs/a c/100ft 2 Apr May June July Aug Short season Buckwheat 50 1 Short season Brassicas 15 1 / 8 Legume Crimson Clover 30 ¼ Legume Red Clover 15 ¼ Legume Sweet Clover 20 ¼ Legume Annual Alfalfa 20 ¼ Sorghum/Sudan Hot weather 1 / 8 50 Hot weather Millets 20 1 / 8 Cover Crops for Home Gardens West of the Cascades: Summer Cover Crop Comments Planting Rate Planting Date lbs/a c/100ft 2 Apr May June July Aug Short season Buckwheat 50 1 Short season Brassicas 15 1 / 8 Legume Crimson Clover 30 ¼ Sorghum/Sudan Hot weather 50 1 / 8 Cool weather Fava Bean 100 1 8
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