A slice of lime, anyone?

What is not rain, not sunshine, not bugs and not fertiliser but makes a Gippy milkmaid’s grass grow?

The great pyramid of Gippsland

The great pyramid of Gippsland

Lime! This is the first 30 tonne load of a 210 tonne order I placed the other day. High in calcium, lime helps to balance the natural acidity of our soils. Why does it matter? You can read all about it on a DEPI acid soil factsheet but here are the basics:

  • a low pH binds up the soil’s nutrients, making them less available to the plants
  • there’s a greater risk of manganese toxicity in acidic waterlogged soils
  • the nitrogen-fixing organisms in the soil suffer
  • plant roots become stunted in acidic conditions, making them more vulnerable to dry spells and root-eating pests
  • aluminium becomes more soluble and affects plant growth

Some of our paddocks are fine but others are desperately low, both in calcium and pH. Last year’s finances were just too tight to do much about it but, with a better milk price this year, I’m making up for lost ground.

It will take years to see any impact. In three applications over the last seven years, for example, we’ve spread a total of 7.5 tonnes/ha of lime on the paddock around the house because it’s one of the most acidic on the farm. Despite such a heavy dose of lime, we’ve only managed to lift the pH from 4.0 (that’s in CaCl2, not water, for the aficionados)  to 4.5, which still qualifies it as highly acidic.

Just goes to show that Giza wasn’t built in a day.

A beautiful set of numbers

What does a farmer do when the kids are sick with gastro and it’s raining? Paperwork. Although I detest the oceans of sheets that flood my desk, the one batch that carries the same anticipation as a Christmas present is my annual set of soil tests.

Soil test results

The beautiful set of numbers that are the river flats

 
These geeky looking sheets let me know what type of fertiliser to spread and where. Now, once upon a time, the farm’s fertiliser order was pretty basic (3 in 1 on one side of the road and 2 in 1 on the other) and it shows. Some paddocks had luxury levels of phosphorous and a shortfall of potassium, while most had miserably low pH results. Accordingly, we are now spending less on phosphorous and more on potassium and lime (both standard calcium and dolomitic).

The rotten thing about acidic soils associated with high aluminium levels, as ours have been, is that they make many of the nutrients unavailable for the plants.

Getting the nutrient levels right with the help of soil testing and observing the signs of nutrient deficiencies has led to a massive reduction in the volume of inorganic nutrients we apply to the paddocks. This has saved our family tens of thousands of dollars and boosted the growth of our pastures while lowering the risk of leaching into waterways. A big win for the sustainability of the farm.