Soil Testing

Better nutrient + pH management = profit.

Soil testing is an important aspect of pasture and vineyard management. It allows you to determine your fertiliser requirements for the coming season. You can only manage what you can measure!

Until recently soil testing has been conducted by sampling the top 10cm of soil at different locations within a soil type. This method provides an accurate test for broadacre soil, as pasture plant feeder roots are concentrated within this depth.

Grapevines have a much deeper root system and therefore sampling the nutrients in the top 10cm of the soil does not provide an accurate picture of the nutrients available to vines. It is for this reason that we now adapt sampling for soil testing in vineyards, which includes analysis of the soil at depth.

Analysing both the surface soil and subsoil is also important in measuring soil acidity and estimating the potential requirement for lime. Lime requirement depends on the pH of the soil, as well as the soil texture. For example if a sandy soil and clay soil both have a pH of 4.5, the clay would require more lime than sand to raise the pH to 5.5. This is due to clay having a much higher surface area than sand.

Clay is made up of many small particles whereas sand has fewer, and larger particles. The lime displaces the hydrogen ions on soil particles as it moves down the profile, causing the pH to increase (becoming more neutral). It is for this reason that more lime is needed to coat all the clay particles compared with the sand. It is possible to determine the quantity of lime needed on your soil using CSBP NUlogic soil analysis.

Brooke Anderson

Agronomy Solutions