Healthy Soil = Healthy Plants General Training Take care of your soil and with a little help from you it will take care of your plants. A Healthy Foundation for Plant Growth Your Soil Soil is Complex 700 different soils in Wisconsin Physical texture, structure, drainage, tilth Chemical nutrient supply Biological microorganisms, organic materials, soil environment What is Soil? Compaction A good garden soil is: 50% solid material organic: decomposing plants, microbes & their waste products, humus mineral: weathered rock fragments, etc. 50% pore space Source: The Ohio State University 1
Soil Formation Physical freezing, thawing, wetting, drying, organisms Chemical dissolved minerals moved in water soil horizons formed 1 inch - 100 years 90% of organic matter dissipates as water and carbon dioxide each year. Soil Forming Factors Parent material, time, climate, living organisms, topography Deciduous Coniferous Prairie Soil Texture Textural Classes Classes: sand, silt, clay names based on proportions loam, silty clay, loamy sand changing proportions not recommended Clay is also group of minerals montmorillinite, kaolinite. nutrient storehouse Soil characteristics influenced by texture Infiltration Permeability Available water holding capacity Porosity Shrink-swell potential Erodibility Soil Structure Particles glued into aggregates organic matter, clay, bacterial secretions, Fe/Al oxide coatings granular platy blocky granular, platy, blocky finer aggregates in topsoil, massive in subsoil Improve by adding organic matter 2
Physical arrangement and pore distribution Soil Organic Matter Plants, animals, microorganisms living, dead, decay products humus complex, dark-colored, reactive Soil acidity reservoir Nutrient storehouse Difficult to significantly increase Soil Organic Matter 90% loss to CO 2 + H 2 O each year for every 100 lb. added, 90 lb. converted to water, carbon dioxide 10 lb. stable 1st year 1 lb. stable 2nd year Must keep adding organic matter Soil Organic Matter Provides food for microorganisms Microbial decay process more glue for better crumb stability nutrients released fresh surfaces for nutrient holding Problem: Heavy Soil Smaller aggregates tightly packed small pores poor drainage, roots suffocate cloddy if tilled wet cloddy if tilled wet compacts easily Improve with OM better crumb stability larger pores sand + clay = concrete 3
What about commercial additives? Clay Buster processed pine bark Canadian sphagnum peat moss limestone Gypsum with extended-release fertilizer to support healthy plant growth. Problem: Light Soil Aggregates too big to pack tightly large pore spaces droughty Improve with OM sponge better water holding capacity Adding Organic Matter Compost, grass clippings, crop residues annual gardens - 1 bu / 20 sq ft perennial gardens - 1 bu / 10 ft do not add to tree/shrub planting hole Adding Organic Matter Green manure, fall cover crops green topgrowth tilled under Extra N needed for high C residues microorganisms tie-up up N wood chips, sawdust, oat straw The 17 Essential Elements Structural nutrients C = carbon O = oxygen H = hydrogen Primary nutrients N = nitrogen P = phosphorus K = potassium Secondary nutrients Ca = calcium Mg = Magnesium S = sulfur Micronutrients B = boron Cl = chloride Co = cobalt Cu = copper Fe = iron Mn = manganese Mo = molybdenum Zn = zinc 4
The 17 Essential Elements Required for the plant to complete life cycle Directly involved in metabolism Can not be substituted by another nutrient Essential for a wide range of plants Plant Nutrition Plant, animal nutrition very different Plants manufacture basics From atmosphere and photosynthesis To create protein, carbohydrate, sugar From the soil, 14 essential elements N, P, K - primary Ca, Mg, S - secondary B, Cl, Ni, Cu, Fe, Mn, Mo, Zn trace or micro Animals must consume basics Nutrient Supply Clay main nutrient storehouse negative charge attracts, holds positive ions Ca ++ Mg ++ K + NH + Ca, Mg, K, NH 4 Easily displaced, exchanged plant uptake some leaching on sandy soils Negative ions remain in soil solution NO 3-, Cl -, SO 4 = Cation Exchange Capacity Number of negative charge sites in a soil Measure of soil s ability to hold and retain nutrients An index of potential soil fertility Higher numbers are better Clay soils naturally higher Sandy soils naturally lower Nutrients must be soluble Soil ph Nutrient exchange between clay and soil solution plant root soil solution Measure of acidity, alkalinity scale 1 14 Low numbers = more acid High numbers = more alkaline optimum 6-7+ Influences nutrient availability Most plants have a wide tolerance 5
Soil ph Effect of soil ph on nutrient availability Soil Testing The only preplant method of knowing nutrient need Soil testing tells us Crop N need Plant available P and K Crop P and K need Soil organic matter Soil ph and lime requirement Other tests if required Soil Testing A shovel is ok, too Mix a small amount in a bucket The Soil Test Rapid chemical analysis Index of potential nutrient supply deficiency excess Sample to show true variation Composite UWEX lab in Madison Sampling Soils Sample depth established turf - 4 inches new turf, gardens - 6 inches or tillage depth raised beds - depth of bed Probe best, spade OK Combine 5 subsamples composite Soil Sampling Be random Avoid unusual areas Backfill Wet spots Wet spots Etc. 6
Sampling Soils Useful Lab Tests Annual gardens, new turf fall, spring before tillage Perennials, problems, established turf Anytime Suspected salt damage very early spring Sample each area separately Repeat every 2-3 yrs Routine soil ph, buffer ph organic matter % available P and K Other Ca, Mg, S, Zn, B, Mn No good test/need N, Fe, Cu, Cl, Mo, Ni Problem solving texture, soluble salts Cl, Pb, As,... UW Soil and Plant Analysis Lab 8452 Mineral Point Rd, Verona 53593 (West Madison Ag. Research Station) Soil Test Report Potential for deficiency Which nutrient needed How much to apply fertilizer for nutrient need lime, sulfur amendments for ph change When to apply When to STOP! Soil Test Report Excessively high common for residential areas not detrimental adding more not beneficial avoid balanced blends, most organics Low build to optimum turf fertilizer blends Soil Test Results - ph Measure of acidity, alkalinity scale 1-14, optimum 6-7+ Add lime only if recommended incorporate 6-8 inches Add aluminum sulfate to acidify new turf if strongly alkaline blueberry, rhododendron Optimum ph for Turf, Gardens Depends on species** ph range kentucky bluegrass 6.0-7.6 creeping red fescue 5.3-7.5 sweet corn 6.0 potato 5.4 6.0 green bean 6.8 tomato 6.0 7
Soil Organic Matter 2-4% most soils impractical and difficult to change Nutrient reservoir Used for calculating N and lime recommendations Soil Test Result: N No direct measures on report N rec from crop need, organic matter Promotes leaf growth Excess N delays maturity moves below root zone and may contaminate ground water Soil Test Results: P Stimulates root growth and flowering shallow rooted greater need Optimum soil test P for turf and gardens - established turf 11-15 ppm - sweet corn 16-25 ppm - green bean 16-25 ppm - tomato 31-45 ppm - potato 161-200 ppm Soil Test Results: K Promotes disease resistance, winter hardiness root crops require most optimum soil test K for turf and gardens - established turf 41-60 ppm - sweet corn 101-120 ppm - green bean 101-120 ppm - tomato 121-180 ppm - potato 121-160 ppm Inorganic Fertilizer Sold on a percent by weight basis N + P 2 O 5 + K 2 O Chemically simple N in air plus natural gas rock phosphate, potash mined, sized and cleaned very soluble salts easily blended must be careful with rates Inorganic Fertilizer Nutrient Type N P 2 O 5 K 2 O --------------% --------------- urea 46 0 0 ammonium nitrate 33 0 0 triple super P 0 46 0 ordinary super P 0 20 0 muriate of potash 0 0 60 potassium sulfate 0 0 50 di-ammonium phos. 18 46 0 8
Recommended Fertilizer For gardens Avoid high N fertilizers for most crops sweet corn, potato are exceptions Uniform, low grade (e. g.10-10-10) 10) does not match plant need over supply P and K Micronutrients generally not needed Adjust ph as necessary Organic Fertilizer Chemically complex, contains C naturally occurring byproducts Microorganisms must degrade slow release, rate??? Improve structure with long-term use Organic Fertilizer Nutrient Type N P 2 O 5 K 2 O ---------------%---------------- blood meal 13.0 1.5 0.6 bone meal 2.2 27.0 0 seaweed 1.5 1.0 4.9 tree leaves 0.7 0.1 0.8 greensand 0 1.4 6.3 activated biosolid 6.0 3.0 0.2 Organic Fertilizer May contain unnecessary nutrients, compounds nonessential elements Does not add nutrition, improve flavor, enhance food safety and quality Often more expensive per pound of nutrient Foliar Sprays For fruits, sensitive ornamentals Trace, secondary elements soil Fe, Mn fixed at high soil ph Supply by spraying leaves Temporary fix, requires repeating No substitute for soil applied nutrients Leaf burn, expensive, extra work Most spray falls on soil Recommended Fertilizer Turf blends Regular or maintenance - high N soil test P, K optimum, above Starter - high P 2O 5 soil test P below optimum Winterizer - high K 2 O soil test K below optimum Use a Holiday schedule sweep off driveways and sidewalks 9