Farm advice: Soil chemical and physical testing

Soils will continue to change over time; that’s why regular soil testing is crucial to the continued health and success of your farm

Soil testing will showcase the mineral imbalances that may be affecting the health of your crops or livestock.

Macroporosity is a measure of the proportion of large pores in the soil that provide the air supply to roots and microbes. A 10% decrease in pasture production for every one percent decrease in microporosity below the critical level of 10%. It’s the best soil physical field calibrated test for New Zealand and was developed by AgResearch in the late 1990s. 

Treading damage can cost loss in pasture production.

When soil structure has damaged the infiltration, rate decreases and pores that are required for aeration and drainage are destroyed.

Other issues are ~80% decrease in worm populations, increased runoff of water, sediment, faecal coliforms, phosphate and other nutrients, plus increased greenhouse gases.

An ASC test (Anion Storage Capacity), previously known as P Retention, is a measure used to define the phosphorus (P) immobilisation potential of soil. This will test the ability of the soil to hold on to phosphate and sulphur.  An ASC test must be included with every sampled area to determine its level. This is particularly valuable information when bearing in mind the use of phosphorus and sulphur fertilisers.  Low ASC soils have minimal
P binding sites.

Once you have all the testing done and have all the accurate information on what needs to go on your soil, the next step is to develop a fertiliser programme specific to each area or paddock. Fine particle or slow-release fertiliser is a great choice.

Fine particle fertiliser has improved fertiliser use efficiency with lower spread rates required to get the most out of it. Featuring a rapid uptake of needed nutrients, fine particle fertiliser deficiencies can be rectified quickly due to the excellent foliar nutrient uptake.

With efficient application, the proportion of nutrients can be varied. Not only that, it also has reduced environmental impact.

You may not be able to change your soil type or the climate, but you can control the amount and type of phosphorus and sulphur that are applied to vulnerable areas.  

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