diagnosing problems in horticultural soils
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DESCRIPTIONDiagnosing problems in horticultural soils. Soil color should be your first clue. Water movement in soils. Not always down hill!!. Causes of Drainage Problems. Compaction Excessive Tillage No organic matter Lack of topsoil Exposed parent material Pore size discontinuity. - PowerPoint PPT Presentation
Diagnosing problems in horticultural soils
Soil color should be your first clue
Water movement in soils
Not always down hill!!
Causes of Drainage ProblemsCompactionExcessive Tillage No organic matterLack of topsoil Exposed parent materialPore size discontinuity
Idealized Kentucky Soil Pore Space 50%Soil Minerals(Silt loam)47%Organic Matter 3%
MacroporesInclude earthworm channelsOld root channelsSurface CracksControls soil permeability and aerationBeach sand is almost entirely macropores infiltration is very high, but water holding capacity is very low
MicroporesVery fine poresSimilar to pores in a sponge or towelHold water against the force of gravityMuch of the water held in micropores is available to plants, but some is held so tightly that plant roots cannot use it.
Idealized Kentucky Soil Macropores 25%Soil Minerals(Silt loam)47%Miropores 25%Organic Matter 3%
Disturbed/Compacted KY Soil Air5%Soil Minerals(Silt loam)72%Water 20%Organic Matter 3%
Characteristics of soil with poor internal structureSlow permeability Very wet naturedCrust easilyPoor plant productivityOnce lost, soil structure is very hard to rebuild prevention is the key
Maintaining Soil StructurePrevent soil compaction
Higher Yield Potential?
Maintaining Soil StructureUse roto tiller sparingly
Compaction caused by tillage4 80.5 2Inaccessible water and nutrientsSlide by: R. Pearce
Pore Size Discontinuity Coarse Texture Soil Fine Textured Soils
Pore Size Discontinuity Fine Texture Soil Coarse Textured Soil
Use mulch to control weeds and conserve moisture and reduce tillage
Use Cover Crops Turnips and mustard greens Grow very good in the fallProvide ground cover to prevent erosionHave strong tap roots to break compaction and provide future root channels for better infiltrationWheat Roots provide organic matter Improves soil structureReduces winter annual weed pressure
Incorporate Compost or Organic Material when TillingDont exceed 10% per year inch mixed into the surface 5 inchesStabilized compost is much betterFresh manure use very sparingly Uncomposted leaves or straw tie up soil nitrogenWood ash is a good sources of nutrients, but doesnt contain organic matter
Soil MineralsMacropores 25%Soil Minerals(Silt loam)47%Miropores 25%Organic Matter 3%
Soil Mineral Phase Sand Large soil particles feel gritty and can be seen with the naked eyeSilt Much smaller than sand feel smooth about the size of flour particlesClaySo small particles can only be seen under a microscopeChemically active part of the soil
Changing Soil TextureTo change soil sand content by 10% would require more than 200,000 lbs/a if mixed only in the top 6 inches
Its probably better to learn to deal with what Mother Nature gave us.Contractor left us.
Cation Exchange Capacity Ca++H+K+H+K+ClayClayClayClaySoil Solution
Soil pH is the most important soil test conducted
A handheld pH meter is a good investmentForestry Suppliers Inc~$76.00
Also needed buffers for calibration and distilled water
Estill County Soil Test Results Elemental Sulfur Reduces pHLime Increases pHGypsum Has No Effect
Gypsum Has No Effect??
Dunn, 2002, Cotton Study Southeast Missouri
MaterialTons/aCa:Mg pHPlant CaCaSO45.611.76.32868CaSO43.711.66.22572CaSO41.710.56.42502Untreated010.26.22472MgSO22.214.171.12422MgSO43.77.06.22389MgSO45.64.06.32128MgSO126.96.36.19986MgSO188.8.131.52149LSD (0.05)316
What About Gypsums Effects on Bulk Density and Compaction??Mark Schonbeck. 2000. Soil Nutrient Balancing in Sustainable Vegetable Production, In Organic Farming Research Foundation Project Report No 99-05.
Five locations in Virginia and eastern Tennessee for three years with three replications.
Vegetable Study (Cont)Low and high Ca treatmentLow Ca:Mg = 2.64High Ca:Mg = 4.00Created using Calcitic and Dolomitic limestoneMeasured effects of ratio on soil physical properties and soil biological properties.
Soil Physical Properties
What About Gypsums Effects on Biological Properties??
Positive Effects of GypsumUsed to replace sodium on soil exchange sitesDoes increase infiltration if soil is saturated with sodium. Only used to reclaim soil in arid regions or salt spills.
Soil Testing - NitrogenNitrogen is the fertilizer needed most in KY soilsVery little soil nitrogen is in the plant available form so soil testing is not generally recommendedSoil testing can be used to diagnose excessive fertilizer applicationsPlants take up inorganic (NO3 and NH4) nitrogen Organic sources must be mineralized before they are plant available
Fertilizer Recommendations Soil Testing is the only way to know for sure how much phosphorus and potassium is needed. If soil test phosphorus is above 100 lbs/a PLEASE DONT apply any more phosphorus
Fertilizer Recommendations Soil Testing is the only way to know for sure how much phosphorus and potassium is needed. Potassium has no negative environment effects
Fertilizer Analysis34-0-0 34% N 0% P2O5 0% K2O5-5-55% N 5% P2O5 5% K2OAnalysisNutrient ConcentrationFertilizer recommendation is for 1 lb N per 1000 sq ft how much 34-0-0 or 5-5-5 is needed?1 lb N/1000 sq ft0.34 lb N/lb material3 lbs 34-0-0 per1000 sq ft
Nutrient Content of Manure
Other Essential ElementsSulfur, Calcium, Magnesium, Zinc, Iron, Copper, Manganese, Boron, Molybdenum, and ChlorineAre almost always adequate if soil pH is adjusted for the crop