Making Use of Farm Information

Making Use of Farm Information.

17th August 2011
Peter Burton

A farmer recently provided a set of test results of soil taken from his property. The Olsen P figures, the only measure of phosphorus reported, ranged from 35 – 70 with the median being 44.
 
With the Confidence Interval of 5 ± 2 for the Olsen test, the area with a test figure of 35 may contain no less phosphorus than that the area with test figure of 70. 
 
If we add to that information the fact that all areas had received much the same amount of phosphorus over the last twenty years, then the median result of 44 may be a more relevant figure.  Historic soil test results and accurate phosphorus input during the time between the tests also helps make sense of test results.
 
If Resin P and Total P tests are also conducted there are more pieces to add to the jigsaw.   The reason for the tests being taken is also important.  Is it to ascertain whether present phosphorus levels are sufficient for maximum production, or to check that recent inputs have been sufficient to maintain available phosphorus levels?
 
What this all means is that for test results to provide maximum value they need interpretation, and all relevant historical information helps with that interpretation.
 
An examination of the physical structure of the soil relevant to the test results will add a different dimension of significant value.  Soil structure has an important bearing on not only the test result but also the speed at which nutrient is being cycled and therefore the total amount of pasture grown in that area.
 
Digging a 20 – 25cm cube provides a wealth of information that helps with decision-making when it comes to the next fertiliser expenditure.
 
Graham Shepherd’s Visual Soil Assessment (VSA) provides extremely valuable measures particularly when photos are taken at the same time.  The VSA is accepted internationally as a provider of valuable, relevant, and easily understood data.  Local body authorities and other organisations with genuine environmental interests promote it here.
 
We have conducted numerous VSAs over the last 4 years with individual farmers and farmer groups.  Without exception the 2 hours doing the first assessment has provided unique, fascinating, and valuable data.  Subsequent assessments usually take less time. 
 
To know whether a soil nutrient programme is delivering value both in the short and longer term a number of measures need to be taken.  As soil, plant and animal health are all connected and interdependent the overall health of any farming operation can quite quickly be ascertained.
 
This time of the year all pastoral farming operations are under considerable pressure and if there are weaknesses in any area they will manifest themselves in animal health and performance.
 
Where there is a steadily increasing number of animals requiring treatment for calcium/magnesium deficiencies there is likely to be a lack of plant available magnesium with a leaf analysis showing a level of less than 0.22%.
 
This means there is also likely to be calving difficulties as inadequate magnesium reduces the ability of muscles to stretch.  When animals are slow to recover after birthing feed intake will also be down limiting milk production.  With every animal exhibiting magnesium deficiency symptoms there is likely to be a number of other animals performing at less than optimum. 
 
There may be other visual signs of magnesium deficiency.  Highly obvious urine patches may be due to lack of magnesium as magnesium is involved with nitrogen availability in the soil. Left untreated a lack of magnesium will impact on the physical structure of the soil, reducing the quantity of total pasture production.
 
An application of DoloZest will rapidly increase plant available magnesium, with a subsequent improvement in animal performance and temperament, along with a lift in total pasture production throughout the remainder of the season.

For more information on VSA and soil testing call 0800 843 809.