Diagnosing problems in horticultural soils

Soil color should be your first clue

Water movement in soils Not always down hill!!

Causes of Drainage Problems CompactionCompaction Excessive Tillage – No organic matterExcessive Tillage – No organic matter Lack of topsoil – Exposed parent materialLack of topsoil – Exposed parent material Pore size discontinuityPore size discontinuity

Idealized Kentucky Soil Pore Space 50% Soil Minerals (Silt loam) 47% Organic Matter 3%

Macropores Include earthworm channels Old root channels Surface Cracks Controls soil permeability and aeration Beach sand is almost entirely macropores – infiltration is very high, but water holding capacity is very low

Micropores Very fine pores Similar to pores in a sponge or towel Hold water against the force of gravity Much of the water held in micropores is available to plants, but some is held so tightly that plant roots cannot use it. 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 Air 5% Soil Minerals (Silt loam) 72% Water 20% Organic Matter 3%

Characteristics of soil with poor internal structure Slow permeability Very wet natured Crust easily Poor plant productivity Once lost, soil structure is very hard to rebuild – prevention is the key

Maintaining Soil Structure Prevent soil compaction Potential Compaction Soil Moisture Content (%) Optimum M.C.=14.3% for a silt loam

Higher Yield Potential?

Maintaining Soil Structure Use roto tiller sparingly

Compaction caused by tillage 4 – 8” 0.5 – 2” Inaccessible water and nutrients Slide 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 fall – Provide ground cover to prevent erosion – Have strong tap roots to break compaction and provide future root channels for better infiltration Wheat – Roots provide organic matter – Improves soil structure – Reduces winter annual weed pressure

Incorporate Compost or Organic Material when Tilling Don’t exceed 10% per year – ½ inch mixed into the surface 5 inches Stabilized compost is much better – Fresh manure use very sparingly – Uncomposted leaves or straw tie up soil nitrogen Wood ash is a good sources of nutrients, but doesn’t contain organic matter

Soil Minerals Macropores 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 eye Silt – Much smaller than sand – feel smooth about the size of flour particles Clay – So small particles can only be seen under a microscope – Chemically active part of the soil

Changing Soil Texture To change soil sand content by 10% would require more than 200,000 lbs/a if mixed only in the top 6 inches To 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. Its probably better to learn to deal with what Mother Nature gave us. Contractor left us.

Cation Exchange Capacity Ca ++ Plant Root H+H+H+H+ K+K+K+K+ H+H+H+H+ K+K+K+K H+H+H+H+ NH 4 + Ca ++ H+H+H+H+ H+H+H+H+ K+K+K+K+ K+K+K+K+ Mg ++ Ca ++ Mg ++ H+H+H+H+ H+H+H+H+ H+H+H+H+ K+K+K+K+ K+K+K+K+ H+H+H+H+ K+K+K+K+ Ca ++ NH 4 + Clay Soil Solution

Soil pH is the most important soil test conducted azaleas Vegetables Vegetables

A handheld pH meter is a good investment Forestry Suppliers Inc ~$76.00 Also needed buffers for calibration and distilled water

Estill County Soil Test Results Elemental Sulfur Reduces pH Lime Increases pH Gypsum Has No Effect

Gypsum Has No Effect??

Dunn, 2002, Cotton Study Southeast Missouri MaterialTons/aCa:MgpHPlant Ca CaSO CaSO CaSO Untreated MgSO MgSO MgSO MgSO MgSO LSD (0.05) 316

What About Gypsum’s Effects on Bulk Density and Compaction?? Mark Schonbeck Soil Nutrient Balancing in Sustainable Vegetable Production, In Organic Farming Research Foundation Project Report No Five locations in Virginia and eastern Tennessee for three years with three replications.

Vegetable Study (Cont) Low and high Ca treatment –Low Ca:Mg = 2.64 –High Ca:Mg = 4.00 Created using Calcitic and Dolomitic limestone Measured effects of ratio on soil physical properties and soil biological properties.

Soil Physical Properties

What About Gypsum’s Effects on Biological Properties??

Positive Effects of Gypsum Used to replace sodium on soil exchange sites Used to replace sodium on soil exchange sites Does increase infiltration if soil is saturated with sodium. Does increase infiltration if soil is saturated with sodium. Only used to reclaim soil in arid regions or salt spills. Only used to reclaim soil in arid regions or salt spills.

Soil Testing - Nitrogen Nitrogen is the fertilizer needed most in KY soils Nitrogen is the fertilizer needed most in KY soils – Very little soil nitrogen is in the plant available form so soil testing is not generally recommended – Soil testing can be used to diagnose excessive fertilizer applications – Plants take up inorganic (NO 3 and NH 4 ) 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 DON’T 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 Analysis % N – 0% P 2 O 5 – 0% K 2 O % N – 5% P 2 O 5 – 5% K 2 O Analysis Nutrient Concentration Fertilizer recommendation is for 1 lb N per 1000 sq ft how much or is needed? 1 lb N/1000 sq ft 0.34 lb N/lb material 3 lbs per 1000 sq ft

Nutrient Content of Manure

Other Essential Elements Sulfur, Calcium, Magnesium, Zinc, Iron, Copper, Manganese, Boron, Molybdenum, and Chlorine Are almost always adequate if soil pH is adjusted for the crop

Questions ???