2 Three approaches Observations in the field On‑site measurements Laboratory measurementsSoil Analysis Ch 8
3 Field ObservationsField observations of properties which can be observed after digging a soil pitSemi‑quantitative assessments of properties rather than direct measurements.Soil Analysis Ch 8
4 Field MeasurementsOn‑site measurements using equipment inserted into soil, without significant disturbance of the soil.This approach applies particularly to soil water studies.Soil Analysis Ch 8
5 Laboratory AnalysisMeasurements made in the laboratory on soil samples taken from the field.Sub-sampling down to an analytical sample also occursSoil Analysis Ch 8
6 Soil Survey Reports what kinds of soil exist in an area described in terms of location, profile characteristics, relationship to each other, suitability for various uses, and needs for particular kinds of managementtwo major parts in a soil survey report:the soil mapthe narrativeSoil Analysis Ch 8
7 SALIS NSW soil survey database Soil And Land Information Service run by Dept of Natural ResourcesSoil Analysis Ch 8
8 Field Analysis of Soils How can we Analyse Soil in the Field?
9 Field investigation soil pits expose the soil profile and horizons allow field testing of parameters that would be destroyed by coresin-situ testing devicessemi-quantitative assessmentsfield data minimises sampling errordoes not guarantee reliable or even consistent datasoils have very poor homogeneitySoil Analysis Ch 8
11 Choosing Sites for Soil Pits Avoidareas close to gateways, paths and tracksheadlands of arable fields (the outer 10 m)sites where straw or fertiliser have been storedsites used for localised burning of crop residues or hedge trimmingsold field boundaries where a hedge or bank has been removed and the land levelledSoil Analysis Ch 8
12 Choosing Sites for Soil Pits soil varies spatially (from one place to another)some properties vary in timeeg nutrient levels, moistureothers are more permanenthorizon depth, texture, stone content and ion exchange capacitySoil Analysis Ch 8
13 Is it just digging holes? How do we Sample Soil?Is it just digging holes?
14 Sampling questions How many samples do I take? Do we composite lots of sub samples?How deep do we take the samples?Do we replicate the sampling?What quality control do we need?What tools do I need?How do we transport, store and prepare the samples?Soil Analysis Ch 8
15 Information we need to know Why are we analysing the soil?Surveys, chemical analysis etc.How large is the area of interest?Large areas require lots of samplingDo we now the soil profile at all?If we don’t, how deep do we sample?What are we analysing the soil for?Physical, chemical or biological parametersSoil Analysis Ch 8
16 Amount of sample depends upon; Time constraints Topography Cost factorsReasons for samplingThere are no specific guidelinesSoil Analysis Ch 8
17 Soil Sampling undisturbed stratification: remove a core with all horizon information retained, eg with augerdisturbed stratificationno attempt to keep the vertical connection between horizons, eg with a shovelSoil Analysis Ch 8
18 Soil Sampling How many samples do we take? At least 20 single samples per m2 must be taken with an earth boring tool (or spade) and combined to a mixed sample.To what depth do we sample?The usual sampling depth is up to 20 cm in arable land or 10cm in pasture. Undisturbed soil samples are obtained with a cutting cylinder with minimum capacity of 100cm3 .Soil Analysis Ch 8
19 How do we sample? test lot diagonal line cross line random Soil Analysis Ch 8
20 Sampling using Augerspressed and rotated into the soil to take samples from depth increments of between 15 and 20cm.samples are 'disturbed' to varying degreesobservations that can be made on the samples will be restrictedcolour, texture, stones, roots and horizon depth can be recordedsoil structure cannotspecial coring equipment is required to obtain 'undisturbed' samplesSoil Analysis Ch 8
21 Sampling for lab testing normal sampling depth for horticultural and tree crops is 0-15 cmdeep sampling down to cm may be necessary to better assess soil salinity, acidity, S, and mineral N statussampling depth must be recordedprotocols relevant to important crop and soil tests should be followedusually involves making a composite from around 15 to 30 sub-samples from the area in questionSoil Analysis Ch 8
22 Transportation, preparation and storage of samples Now that you have your soil samples, what do you do with them?
23 Laboratory Preparation of Samples should be kept cool or cold between during transportmay be air-dried remote from the laboratory (max. 40C) when moisture content is not requiredbreaking up any large cores or peds on a clean surfaceremove rocks by hand or sievingretain a representative portion in a sealed polyethylene bag or 'moisture container' for moisture determinationsample size reduction: coning and quartering or rifflerSoil Analysis Ch 8
24 Laboratory Preparation of Samples Soil Analysis Ch 8
25 Laboratory Preparation of Samples Next spread the soil samples on drying trays (if applicable) and air-dry at up to 40C.When the soil is thoroughly air-dry, mix, roll, and/or grind.Retain the <2mm fraction, preferably in an air-tight plastic or inert container, for subsequent laboratory analyses.Soil Analysis Ch 8
26 Laboratory Preparation of Samples When required, determine the weight percentage (oven-dry basis) of the residual >2-20 mm size fraction.When fine grinding is specified, take a representative sub-sample (usually around 30g) from the <2 mm portion.Pass the entire sub-sample through the required mill and store in a small air-tight container.Soil Analysis Ch 8