Indicators of Physical Soil Healthon NY State Farms Significance, Measurement, and InterpretationOutlineSoil Health A DefinitionComponents of Soil HealthRelevance of Soil Healthin AgricultureRelevance of Physical Soil Healthin AgricultureCommon Soil Problems on NYS FarmsSoil Problems on NYS FarmsCommon Soil Problems on NYS FarmsHow Healthy/Sick is a Soil?New York State Soil Health ProjectGoal: To develop a fee-based Soil Health testing facilityMeasuring Aggregate StabilityEffects of Physical Soil Characteristics in Agriculture:We’ve measured a bunch of indicators,… Now What??Results and Interpretation of Aggregate Stability TestWillsboro Drainage Clay LoamSmall Crumbs - Aggregate Stabilityrecent NT vs PT, Orchard Grass vs CornRecommendations – a work in ProgressIndicators of Indicators of Physical Soil HealthPhysical Soil Healthon NY State Farmson NY State FarmsSignificance, Measurement, and InterpretationDecember 1, 2004Bianca Moebius MS Student with Dr. Harold van EsDepartment of Crop and Soil SciencesNY State Soil Health ProjectCornell UniversityIthaca NYOutlineOutline• Introduction: What’s Soil Health – Why do we care?• From the Farmers: Soil Health Problems in NY State• Tour of the Soil Health Lab: Goals and Methods • Results: what do we know so far?• Directions, ConclusionsSoil HealthA Definition“the capacity of the soil, within land use and ecosystem boundaries, to sustain biological productivity, maintain environmental quality, and promote plant, animal and human health” (Doran and Safley, 1997)Components of Soil HealthComponents of Soil HealthChemical –well understoodand appliedPhysical –fairly well understood,BUT barely appliedBiological –the least understoodRelevance of Soil HealthRelevance of Soil Healthin Agriculturein AgricultureChemicalPhysicalBiologicalPhysical:water infiltration, retention & conductivityaerationdensity: resistance to root growthstability of aggregatesBiological:microbial communities: symbiotic, beneficial, pestsorganic matter decomposition and thus release of nutrientsChemical:plant nutrition, acidity, toxic substancesRelevance of Physical Soil HealthRelevance of Physical Soil Healthin Agriculturein Agriculturehttp://www.blm.gov/nstc/soil/fungi/Physical Needs of a Plant Provided by the Soil:Sustained supply of: • Water•Air• Growing Medium for Roots to Stabilize Plantwww.pozzilawn.com/pozzilawn_ pozziwet_sub_menu.htmHealthy Soil Meets these Needs and more … however…Common Soil Problems Common Soil Problems on NYS Farmson NYS Farms• low organic matter content• soil compaction• decreased infiltration • reduced water holding capacity • drought-prone soils …Soil Problems Soil Problems on NYS Farmson NYS Farmsa) aggregated soilb) soil crusts over after aggregates break downrunoffinfiltrationFate of water arriving at the soil surface:excessive runoff & erosion excessive runoff & erosion ÆÆsurface crusting leads to surface crusting leads to hardsettinghardsettingwhen drywhen dryÆ increased incidence of pest outbreaksÆ lower yields with equal or even greater inputsCommon Soil Problems Common Soil Problems on NYS Farmson NYS FarmsHow Healthy/Sick is a How Healthy/Sick is a Soil?Soil?1.1.How do we measure the How do we measure the extent of the problem?extent of the problem?2. And what do we do about it?2. And what do we do about it?New York State Soil Health ProjectNew York State Soil Health ProjectGoal: To develop a feeGoal: To develop a fee--based Soil Health based Soil Health testing facilitytesting facilityTests must be:For Physical Analysis: - disturbed soil samples - undisturbed stainless steel cores• Rapid• Inexpensive• Scientifically meaningful• Agronomically usefulUse of Physical Use of Physical Characteristics of Soil as Characteristics of Soil as IndicatorsIndicatorsof Soil Health:of Soil Health:••Saturated Hydraulic ConductivitySaturated Hydraulic Conductivity••Porosity & Pore Size DistributionPorosity & Pore Size Distribution••Penetration Resistance and Bulk DensityPenetration Resistance and Bulk Density••Aggregate Stability & Size DistributionAggregate Stability & Size DistributionSaturated Hydraulic ConductivitySaturated Hydraulic ConductivityDefinition:Definition:rate at which rate at which the soil conducts water the soil conducts water when saturatedwhen saturatedSoil CoreWaterKsatAffects:Affects:••erosion and surface porosityerosion and surface porosity••availability of water to plantavailability of water to plant••aerationaerationMeasurement: rate of Measurement: rate of water flow through a water flow through a saturated saturated undisturbed soil core undisturbed soil core under a constant under a constant water head, supplied water head, supplied by siphons from a by siphons from a common reservoir.common reservoir.Saturated Hydraulic ConductivitySaturated Hydraulic ConductivitySuction Bulb to start SiphonCatch for conducted waterSiphonWaterSoil CorePore Size DistributionPore Size DistributionDefinition: The proportion of total porosity occupied by each defined size range of pores: • micropores• mesopores• macroporesPore Size Distribution has Effects on distribution, movement and holding capacity of water and air.Pore Size DistributionPore Size DistributionTotal Porosity – fraction of soil for water and airMacroporosity - drains within ~1hr of a heavy rain storm thus preventing anaerobic conditions (> 1mm)MacroporesMesoporosity - provides for air space and very readily available water (1mm – 10µm)MicroporosityMesopores- indicates drought resistance of soil (water stored in small pores, but available to plants) (10µm - 0.2µm)MicroporesResidual Porosity- pores too small to provide water to plants (<0.2µm)ResidualMeasuring Pore Size DistributionMeasuring Pore Size Distribution1. Macroporosity: weigh saturated core samples, then free drain for 3hrs and reweigh2. Mesoporosity: let core samples drain under pressure until at equilibrium at -10kPa, then use VanGenuchtenEquations to calculate approx. -30kPaTwo methods: • Pressure Cells• Sand TableMeasuring Pore Size DistributionMeasuring Pore Size DistributionWater sourceTo vaccuum pumpMesoporosity Measurement: Suction Sand Table under ConstructionSoil Core on saturated silica siltPorous ceramic cups to transfer suction to sandMesoporosity: let core samples drain under suction until at equilibrium at -10kPaMeasuring Pore Measuring Pore Size DistributionSize