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Soil Analyses:

Short Test: pH, EC, NO₃-N, BSES P, K, Ca, Mg, Na, S, Cu, Zn
Long Test: pH, EC, NO₃-N, BSES P, Colwell P, K, Ca, Mg, Na, S, Cu, Zn, Mn, Fe, B, Cl, Organic Carbon
Super Test: pH, EC, Total N, NH₄-N, NO₃-N, BSES P, Colwell P, K, Ca, Mg, Na, S, Cu, Zn, Mn, Fe, B, Cl, Organic Carbon, Soluble Silicate, ECEC, Al, H

A soil analysis with an independent fertiliser recommendation is the first requirement for nutrition management. Results of soil tests are used as a guide to soil chemistry, plant nutrition and fertiliser management.

The analysis of soil is a process that is designed to estimate the portion of various elements in the soil that is available for plant uptake. It is not a measure of the total amount of elements in the soil. Various extractants are used to estimate the amount of each particular element that can be used by the plant.

Accuracy in different soil types and pH regimes is variable with the type of extractant used, and therefore the final figure is only an indication as to the actual availability in almost all soil tests.

To interpret the needs of the crop the whole soil chemistry is considered with the physical soil characteristics, cropping history, crop performance, and any local knowledge of district problems to arrive at a fertiliser programme.

View example soil report - Recommendations are provided with reports, these are not shown on this sample.

New SoilPlus soil test:

The SoilPlus soil test is the Crop Tech’s standard long soil test, plus a P Retention and Soluble Silicate test. Our weathered, leached Australian soils are prone to increased acidification and removal of the alumino silicate clay minerals. The result of this is a decline in CEC and loss of plant available silicate. This affects soil structure and reduces the ability to retain nutrients. Large areas of coastal soils, particularly, have been found to be deficient in plant available silicate. Identification of deficient soils is the first step in correcting the problem.
The inclusion of the Phosphate retention test combined with the conventional Phosphate tests provides the advisor greater ability to match the rate of phosphate required by the cropping system.

In a conventional nutrient management system, the decision for the rate of phosphate is based on soil test levels, crop requirement and a best guess at the amount that will be locked up by the soil.

The P retention test provides a figure to quantify the ability of the soil to lockup or bind free phosphate. The advisor is then able to have a greater understanding of the effect the soil will have on phosphate availability to the plant and compensate for this in the recommendation.
The P retention test that Crop Tech uses provides a value from 1 – 100%. The optimal range for “normal” soils is between 15 and 30%. For soils with a value less than 15%, the rates of P applied can be reduced. For soils with values greater than 30%, the rates of phosphate need to be increased to compensate for the lock up of free phosphate.

The P retention test is one more piece of information that allows advisors and growers alike to be able to make better, more accurate decisions of fertiliser requirements for any crop, as well as ensuring crop production is not impeded.

Brief Interpretation Notes:

pH: has a major impact on nutrient availability and the effectiveness of applied fertiliser. High or low pH, i.e. above 7.5 or below 5.5, can indicate that various elements will be insoluble and not available to plants for immediate uptake.

EC: Electrical Conductivity is basically a relative measure of soluble salts in the soil solution. The application of gypsum or fertiliser can raise the conductivity significantly. Where gypsum or fertiliser has not been applied, a high conductivity usually signifies high chloride and sodium. EC should thus be interpreted in conjunction with nutrient levels.

Nitrate: The nitrate measured is a water extract and reflects the available nitrate nitrogen and not the total soil nitrogen. The cropping history and organic matter should be taken into account in assessing the total amount of nitrogen expected to be released through the crop cycle.

Levels are a guide to basal dressings and losses due to leaching and volatilisation are generally considered when calculating side dressings and follow up fertiliser. Sap analysis is a useful guide when planning ongoing fertiliser programs.

Phosphorous: Available phosphorous is normally determined from acid extracts where pH is below 7.0 and bicarbonate extracts if pH is above 7.0.

Many vegetable crops will respond to applied phosphorous even when "adequate" levels are detected from soil testing. pH is taken into account when recommending phosphorous as the acidity has a marked effect on phosphorous availability.

Basal rates of phosphate are a guide, and are set from commercial experience, and from responses measured by sap analysis. Phosphate is important in the early stages of growth for root development and flower initiation. Excessive rates of P can cause zinc, calcium and manganese to be less available.

Ca, K, Mg, Na: Recommendations for soil ameliorants such as lime, dolomite, gypsum and other products are based on soil test levels of the major cations - calcium, potassium, magnesium and sodium.

Cation Ratios: The cations can compete for uptake by plants, and, if a major imbalance of these elements is present, particular deficiencies can occur in the plant even if that element is present in amounts that have been thought to be adequate.

Balancing of these major cations, calcium, magnesium, sodium and potassium is therefore an important part of soil nutrient management.

Trace Element: Tests are conducted using various extraction methods and give an indication as to high or low levels available in the soil. These levels are used in conjunction with the pH and soil type information supplied. Follow up petiole analyses will determine whether uptake of that nutrient has been achieved.

In many crops soil applications of trace elements must be made prior to planting and therefore, often the soil test and soil type are the only available means to make a decision on pre plant or early foliar trace element applications.

For more information on Soil Sampling click here