Ecological Soil Management Doug Collins WSU Small Farms Extension Specialist

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1 YOUTH & AGRICULTURE FAMILIES HEALTH ECONOMY ENVIRONMENT ENERGY COMMUNITIES Soil: The excited skin of the earth s surface Ecological Soil Management Doug Collins WSU Small Farms Extension Specialist Growing Groceries September 30, 2015 Soils are formed from the interaction between parent material, climate, organisms, aspect, and time During the Pleistocene (2-3 million years ago) large glaciers covered most of the north 1/3 of Washington State Good dirt here! OSU Special Collections and Archives Glacial deposition Parent material More good dirt here! Even more good dirt here OSU Special Collections and Archives OSU archive 1

2 Alluvial and aeolian processes transport and deposit parent material Climate influences the speed of weathering for minerals 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

3 Time is also an important factor in soil processes Soils are stratified vertically by horizons Soils in the same 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 A fertile soil may not be a productive soil Quality or healthy soil has the continued capacity to provide 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

4 Soil with good tilth contains: Soil texture Stable soil aggregates Even moisture levels Pathways for air and water Good drainage Extremes such as excessive tillage can degrade soil tilth silt clay sand Particle size distribution affects: Drainage Aeration Water retention Nutrient exchange 005mm Soil texture is inherent and cannot be changed Soil texture can be estimated by hand with the ribbon test websoilsurveynrcsusdagov 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 Craig Cogger Photo by Amy Zarrett 4

5 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) 4500% Chlorine (Cl) 001 % Oxygen (O) 4500% Iron (Fe) 001% Hydrogen (H) 600% Manganese (Mn) 0005% Nitrogen (N) 150% Boron (B) 0002% Potassium (K) 100% Zinc (Zn) 0002% Calcium (Ca) 050% Copper (Cu) 00006% Phosphorus (P) 020% Molybdenum (Mo) % Magnesium (Mg) 020% Nickel (Ni) % Sulphur (S) 020% Percentages by plant dry weight Ions are forms of nutrients available for plant uptake Cations (positive) Ammonium NH 4 + Anions (negative) Nitrate NO 3 - Nutrient pools: Parent material (eg rocks/minerals), is a source of very slowly available nutrients Parent material = rich, frugal uncle v slowly available K + Fe 2+ Mn + Ca 2+ Potassium K + Phosphorus H 2 PO 4 - Elements unavailable Weathering physical and chemical Elements available nutrients Minerals eg: Hornblende (Ca 2 Al 2 Mg 2 Fe 3 Si 6 O 22 (OH) 2 ) Potassium Feldspar (KAlSi 3 O 8 ) 5

6 Nutrient pools: Organic matter is a source of slowly available nutrients Parent material = rich, frugal uncle v slowly available Nutrient pools: Surfaces of humus and clay store quickly available nutrients Parent material = rich, frugal uncle v slowly available Mineralizeable = Stocks and Bonds slowly available Mineralizeable = Stocks and Bonds slowly available SH C-C-C-C- PO 3 Organic matter unavailable NH 2 mineralization NH 4 + NO 3 - SO 2-4 PO - 4 NH 2 available Adsorbed nutrients= Checking acct quickly available Ca 2+ Mg 2+ K K clay OM K + NH 4+ Ca 2+ SO 2-4 soluble, available Nutrient pools: Nutrients in the soil solution are immediately available Parent material = rich, frugal uncle v slowly available Mineralizeable = Stocks and Bonds slowly available Adsorbed nutrients= Checking acct quickly available Soil solution = Cash available now Typical CEC values for different soil textures Soil Type CEC meq/100g Sands (light colored) 3 to 5 Sands (dark colored) 10 to 20 Loams 10 to 15 Silt Loams 15 to 25 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 VALUE TABLE ACID NEUTRAL ALKALINE ph Measure of how acid or alkaline a substance is (related to H conc) 60 to 75 ideal for most crops Blueberries 45 to 55 6

7 Nitrogen cycles from cover crops and amendments through the microbial biomass atmospheric N 2 legume available N N excreted protozoa amendment Soil OM Microbial Biomass Bacteria Fungi nematodes C, N Isopods Collembola earthworms Soil organic matter is split between active organic matter and humus Clay Silt Water Sand Air Organic Matter Soil Humus Active Organic Matter Living Organisms Cover crops improve soil quality, protect soil, smother weeds, take up excess nutrients from the soil, and legumes add nitrogen Clover & rye mix in garden bed, 7 days after planting PAN from organic fertilizers ranges from $5 to $9 per pound Legume cover crops can provide PAN at $1 to $3 per pound Vetch & rye mix in farm field, 45 days after planting Cover Crops for Home Gardens East of the Cascades: Winter Cover Crop Comments Planting Rate Planting Date lbs/a c/100ft 2 Aug Sept Oct Nov Cereal Rye Hardy Winter Wheat Winter Oats ½ Triticale Annual Ryegrass Good in wet 90 ½ Spring Barley Winterkills Spring Oats Winterkills ½ Hairy Vetch Reliable 90 ½ Crimson Clover 20 ¼ Austrian Winter Pea Not wet soil 90 1 Fava Beans-small May winterkill Mustard/Canola Winterkills 20 1 / 8 Cover Crops for Home Gardens West of the Cascades: Winter Cover Crop Comments Planting Rate Planting Date lbs/a c/100ft 2 Aug Sept Oct Nov Cereal Rye Hardy Winter Wheat Winter Oats ½ Annual Ryegrass Good in wet 90 ½ Spring Barley Winterkills Spring Oats Winterkills ½ Hairy Vetch Reliable 90 ½ Crimson Clover Soil builder 20 ¼ Red Clover Soil builder Austrian Winter Pea Not wet soil 90 1 Fava Beans-small May winterkill Phacelia Pollinators 20 1 / 8 7

8 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 Buckwheat Short season 50 1 Brassicas Short season 15 1 / 8 Crimson Clover Legume 30 ¼ Red Clover Legume 15 ¼ Sweet Clover Legume 20 ¼ Annual Alfalfa Legume 20 ¼ Sorghum/Sudan Hot weather 50 1 / 8 Millets Hot weather 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 Buckwheat Short season 50 1 Brassicas Short season 15 1 / 8 Crimson Clover Legume 30 ¼ Sorghum/Sudan Hot weather 50 1 / 8 Fava Bean Cool weather

9 Compost management C:N ratio of different amendments Carbon to Nitrogen (C:N) ratio between 10:1 and 20:1 Goals for application influences type and amount Compost applied at 10 ton / acre Compost applied at 2 ton / acre Hot : less than 10:1 Cool : 15:1 to 25:1 Woody : over 30:1 Photo by: Scot Nelson C:N less than 10:1 HOT C:N from 15:1 to 25:1 COOL Photos by Peter Moon, O2 Composting Fish and feather meals Poultry/ Fresh rabbit manure Seed meals Easy to over-apply Leads to excess nutrient levels Potential to harm crop Degrade water quality Slow-release nitrogen Use as soil amendment Releases additional nutrients in subsequent seasons Composted: yard debris most manures biosolids Fresh materials: yard debris coffee grounds dairy manure solids C:N over 30:1 Practice safe manure Photo by Andy Bary, WSU Straw Sawdust Paper waste Horse bedding Leaves Nitrogen immobilization Use as mulch Carbon resource in compost Photo by: Len Radin Incorporate compost well before planting Apply to rotation crops not harvested as food Use legumes instead Use processed, not raw, manures Waiting periods between application and harvest (90 or 120 days for National Organic Program) are general recommendations, not infallible truth Also raw versus cooked foods NEVER apply manure or manure-based teas to food crops nearing maturity or harvest 9

10 Does double digging to establish a garden bed increase yield? Prior to starting the experiment, compaction increased to 25 inches and was essentially impenetrable at 6 to 7 inches An experiment with 4 replications was conducted to compare soil garden bed preparation with double digging and rototilling Initial Soil Parameters Depth ph lime req t/a OM % Pb ppm As ppm P ppm Thatch in in After treatments, double dug soils had much less compaction between 8 and 40 inches 10

11 Double digging did not improve lettuce yield Lettuce plants did look more uniform and healthy with rototilling Double digging increased carrot yield by 23% Double Dug Rototilled Rototilled Double Dug Double Dug Rototilled Double digging did not improve lettuce yield Lettuce plants did look more uniform and healthy with rototilling 1600 tomatoes, 330 lbs, average of 103 lbs/plant (1 plant/4 ft 2 ) Considerations for ecological soil management Five soil forming factors - parent material, climate, aspect, time, and organisms - interact to form specific soil types Soil nutrients exist in different pools with varying levels of availability Soil tests approximate nutrient availability Utilize cover crops and proper amounts of organic amendments to feed crops, build humus, and develop a bank of slow-release nutrients Thank you! Doug Collins WSU Small Farms Program dpcollins@wsuedu Resources Collins, DP 2012 Soil Testing: A Guide for Farms with Diverse Vegetable Crops Washington State University Extension Publication EM050E Collins, DP, C Miles, CG Cogger, and R Koenig 2013 Soil Fertility in Organic Systems: A Guide for Gardeners and Small Acreage Farmers Pacific Northwest Extension Publication PNW 646 Horneck, DA, DM Sullivan, JS Owen, and JM Hart 2011 Soil Test Interpretation Guide Oregon State University Extension EC Solomon, S 2007 Growing Vegetables West of the Cascades, 6 th Edition Sasquatch Books, Seattle, WA 368 pgs All photos were taken by Doug Collins, unless otherwise noted Cogger, C, C Benedict, N Andrews, S Fransen, and A McGuire Cover Crops for Home Gardens East of the Cascades Washington State University Extension Publication FS117E Cogger, C, C Benedict, N Andrews, and A McGuire Cover Crops for Home Gardens West of the Cascades Washington State University Extension Publication FS111E 11

12 Extractants are used to indicate plant nutrient availability, not total nutrient content Plant Nutrient Common Extractants NO 3 - KCl, CaCl 2 NH4+ H 2 PO 4- /HPO -2 4 K + KCL NH 4 F/HCL (Bray-P) NH 4 F/CH 3 COOH/H NO 3 (Melich-P) NaHCO 3 (Olsen-P) NH a OAc SO -2 4 Ca(H 2 PO 4 ) 2, CaCl 2 Zn +2,Fe +3,Mn +2,Cu +2 DTPA,EDTA H 3 BO 3 Hot Water Cl- Water Soil nutrients cycle through different pools in the soil Soil tests indicate how much of a nutrient is likely to be available to plants Different soils will have different initial soil quality Monitoring through time is the best way to evaluate management Soil Quality Soil A Soil B Time 12

13 In the maritime northwest, nitrogen sampling is done in fall for report card nitrate test NO 3- -N in surface foot (ppm) Low <10 Medium High Excessive >30 Soil test vs probability of crop response Soil phosphorous transported off-farm can degrade surface water quality Base Cations Photo by: Gene Williams, Snohomish County Surface Water Management 13

14 Reserve acidity is the store of hydrogen ions on exchange sites How much lime is required to change the soil ph? Ca 2+ K + Ca 2+ K + clay H Ca Mg 2+ H Mg 2+ H + H + H + H+ H + H + H - + -H + K + - -Ca OM 2+ -H H H + + -K + High reserve acidity Low reserve acidity Planning for Soil Testing Group soil tests by management zones: contiguous areas that are planted, fertilized, and otherwise managed together 14