Unlocking soil’s full potential

Beneath the surface
with David Law
Forward Farming

For the past 18 months, we have regularly reported the physical changes occurring on our Whakatane Total Replacement Therapy demonstration farm, Wyndlea.

Clover has multiplied, pasture is lush and even, and synthetic nitrogen use has been reduced from 180 units/N to 35 units/N per ha.

No mean feat there, but when you start to see those changes reflected on the balance sheet you know you’re really picking up steam.

‘Free’ fert

In our work, we see thousands of dollars of nutrients such as potassium (K) and phosphate (P) locked up in the soil. Farmers are recommended to add more and more, at great cost, when soil tests reflect inadequate levels of these nutrients.

However, a balanced soil – with the addition of calcium, magnesium and boron, where required – has the power to unlock these nutrients in the soil, effectively getting these valuable fertilisers for ‘free’.

At Wyndlea, three areas of the farm are soil tested annually.

A recent analysis has shown that from 2019 to 2021, potassium levels have risen from 3.28 per cent to 8.45 per cent on the effluent block (nutrient BS); 3.65 per cent to 6.65 per cent on the front block; and 2.73 per cent to 4.49 per cent on the back block.

The only potassium added to the farm in that period was nine tonnes in 2019.

That equates to a massive 52 tonnes of potassium unlocked from Wyndlea’s soil, which, at $1,040/tonne, is the equivalent of $54,000 of potassium sulphate.

Similarly, phosphate levels in the soil have increased, and at an extra 52.46kg/ha, or 4.73 tonnes, equates to $9,450 of phosphate.

Major savings

But we’re not finished yet. In that same period, synthetic nitrogen was reduced from 180 units/N to 35 units/N per hectare per year at Wyndlea, equating to 135 units or 26.4 tonnes less urea applied per season – or 57.8 tonnes less ammonium sulphate.

With a reduction in fertiliser cost of $9,000 in that period ($100/ha), total nutrient and fertiliser savings for Wyndlea since 2019 is $72,450.

Not bad for 18 months into a full farm system overhaul.

Instead of paying for potassium sulphate, phosphate and urea, Wyndlea is paying down debt.

It is evident here that Total Replacement Therapy is unlocking the nutrients in the soil, increasing potassium and phosphate availability without adding any.

Calcium, sulphur and boron are the most frequently used minerals at Wyndlea – the cheapest fertiliser you can buy.

A watchful eye

But we continue to do annual soil testing at Wyndlea, because if you aren’t keeping an eye on nutrient levels, you run the risk of milking your farm dry of minerals.

We now have 22 farmers on the Total Replacement Therapy programme, and we are seeing consistent changes occurring when farmers follow the eight-step procedure.

We also understand the importance of supporting farmers through a transition period, so our team is right alongside the farmer to ensure they are getting the most out of their programme.

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