- Basis for Soil Testing - Result Interpretation Soil Tests - Basis for Soil Testing - Result Interpretation

Why Carry Out a Soil Test? Identify nutrient deficiencies in the soil. Identify problems which can be addressed before a maintenance program is initiated on a particular soil.

Benefits of Soil Testing Optimise plant health Reduce unnecessary maintenance practices and fertiliser applications Opportunity to save both time and money Removes guesswork from formulating fertiliser programs

Sampling Procedure Reliable results depends on correct sampling Aim to provide a representative sample Sampling depth important due to profile horizon variation

Sampling Instructions Approximately 200g of soil necessary for nutrient analysis Depth of cores should measure 10cm Small cores more suitable than hole changer- sized cores

Sampling Instructions cont. Take samples from areas of average growth Take cores from poorer spots only if they are numerous Cores should not be taken from recently fertilised areas Time of year is important for historical analysis

Soil Properties Analysed Soil pH (water, and CaCl2) Cation Exchange Capacity (CEC) or Sum of Cations Total Soluble Salts (TSS)/Electrical Conductivity (EC) Phosphorus (Olsen)

Soil Properties Analysed cont. Potassium (Skene) Ca/Mg Ratio % Base Saturation Ca, Mg, Na, K

Interpretation of Results Results interpreted specifically in relation to turf growth Turf has specific nutrient requirements and tolerance to toxicities of various elements Turf Use is used to assist in determining recommendations

pH

Total Soluble Salts (TSS)/ Electrical Conductivity(EC) Reports the TSS in parts per million and the EC in dS/m. TSS(ppm) = EC (dS/m) x 2970 Ideal TSS level is <1000ppm or EC<0.34

Salinity

Cation Exchange Capacity (CEC) Is equal to the sum of the of the 4 major cations (Ca, Mg, Na, K) measured in milli-equivalents/100g Is largely dependent on soil type low CEC: < 4 meq/100g (sands) moderate CEC: 4-10 meq/100g (loams) high CEC: >10 meq/100g (clays)

To Raise CEC Incorporate organic matter Increase % of loam and clay-sized particles in soil

Phosphorus (P)

Potassium (K)

Base Saturation Used to assess the levels of Ca, Mg, Na and K as percentages of the total CEC. Optimum Extractable level of an ion such as Ca is dependent on the CEC of the soil Presenting levels as Base Saturation (or % of CEC) eliminates the need to consider CEC. Recommendations based on ideal ranges of % base saturations

Base Saturations

Ca/Mg Ratio Low: <2 Apply Gypsum Optimal: 2-5 High: >5 Apply Dolomite

Remedial Action Products used in remedial treatments can have complimenting or conflicting effects on other soil properties. Must take into account this range of effects when recommending remedial action. Eg. Treatment of pH can effect the Ca/Mg Ratio

E.g. Remedial Treatments knowing the pH and Ca/Mg ratio

Nutrition Targets Soil Mix pH E.C dSm P mg/kg Na %CEC K %CEC Ca %CEC Mg %CEC O.M% A 5.5-6.5 <0.3 17-35 <5 5-15 65-75 12-20 2-2.5

Conclusion Soil testing is an important tool for turf management. Results are most useful prior to renovation, but can be conducted year round