Watching fertility levels in soil closely vital for success

While fertiliser prices are currently very high (world supply demand issues) to not address any soil deficiencies locks one into a commonly much less profitable livestock business.

There are lots of factors to consider when making pasture fertiliser decisions, either with choosing fertiliser type and rate, as well as possibly ignoring the fertiliser option.

Soil testing, via nationally accredited laboratories, interpreted by someone who really understands soil test information (if you are not confident to do so) is important for assessing likely benefit from them.

Over the last 50 years a lot of research has added to practical confidence in properly undertaken and assessed soil tests.

An example of how important correcting soil deficiencies is our own case, a central west predominately light soil property with carrying rate before any fertiliser had been applied rated around 2.0 DSE/ha (dry sheep equivalent).

And enterprises would need to be chosen that don't rely on good quality feed.

Despite being relatively conservative our average stocking rate over the last 12 years has been 7.0 to 9.0 DSE/ha. Enterprise choice is fattening steers and that only works if feed is of good quality most of the time.

While a multitude of factors go into making a good farm business, such as pasture species choice and grazing management, none has been more important than correcting soil sulphur and phosphorus deficiency.

With gross margins, including taking out fertiliser costs, around $50/DSE, allowing carrying capacity to gradually recede makes no sense at all.

An important part of a pasture fertiliser program is to monitor soil fertility build-up.

Again using our example starting level for sulphur and phosphorus was low. Single superphosphate was annually at 100 kg/ha for the first eight years. In that time phosphorus and sulphur levels rose to above requirements for fertiliser.

Our program changed to missing two years (based on soil test data), applying again in 2021, and we will probably be able to miss 2022 (depending on soil test results).

Without sulphur and phosphorus correction legumes fail to thrive and soil nitrogen also is a major problem.

Low soil nitrogen results in poor grass quality, especially low protein and digestible energy, as well as poor grass production.

That goes for both native and introduced grasses.

Also read: As yields grow so does the loss of nutrients

As has been shown with cereals soil phosphorus is important for grass pasture quality and yield. Its correction is also important for a good response from nitrogen fertiliser applied to grass pastures.

Research data is limited for grass responsiveness to sulphur deficiency correction, as they use less than legumes. However, generally sulphur deficiency can be corrected relatively easily for minimal cost increase by choosing products that contain good quantities of both phosphorus and sulphur.

Soil testing of every pasture paddock, and different soil types within a paddock, while ideal, can be expensive and time consuming.

A sensible compromise is test soil areas within some paddocks that probably well represent what might be typical for the property.

Even as few as five or so soil tests can provide lots of useful information.

A given soil sample sent for analysis is best if it contains subsamples from at least 10 to 20 cores from over a visually uniform area (all mixed together).

In my view don't be frightened to use agribusiness soil testing services, provided they have national accreditation.

Also NSW DPI have a nationally accredited laboratory.

These are generally handled direct or via Local Land Services officers. Interpretation of soil test data is more commonly where errors of can occur.

An old friend of mine many years ago told me that while fertiliser is expensive, he would have many years previously gone broke if he hadn't used it.

There is no subject more critical to grazing businesses than sensibly addressing soil deficiencies.

Next week: Small farms can be as profitable as big ones.

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