Parched pastures and potassium

Red clover

Gorgeous feed like this can be more water use efficient with potassium

Despite the last few days of searing heat, we still have some nice pasture on hand. It won’t last forever but I am hoping that we can make the spring pastures stretch longer into summer with some judicious fertiliser choices.

I’ve bitten the bullet this year and invested in soil testing for each and every paddock on the farm. It’s shown that our fertiliser regime is working but we still have a way to go in some cases. The main issues we must address are potassium and pH.

Potassium (K) allows plants to use water more efficiently, making them more resilient to both waterlogging and drought. Some of our paddocks only have half the potassium levels they should, especially the rises that dry off first, so I’m hoping that regular applications of potash will allow us to make much better use of those paddocks.

Unfortunately, potassium is readily leached from the soil, so even my extra doses (70kg of MOP behind the cows throughout autumn/winter/spring) simply maintained rather than make a significant improvement in K levels last year.

For a neat technical explanation of the role of potassium in agriculture, see this: Potassium in Agriculture.

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.