Now is the perfect time to plan your fertiliser programme for autumn. Whether you are maintaining or building soil fertility, phosphates will be needed. But the quantity needed and how well they work will depend on the type of phosphates used.
Using dicalcic phosphate instead of superphosphate has many advantages.
Although superphosphate is still the go-to option for the majority, dicalcic phosphate offers a plethora of benefits that just can’t be ignored. For one thing, unlike superphosphate, it releases its nutrients slowly. For another, it produces a liming effect upon application, the best example being Fertco’s KingPhos with a pH value of 6.5-6.7. Additionally, dicalcic phosphate can be successfully granulated which reduces both financial and environmental wastage.
Slow release of nutrients
Dicalcic phosphates are citric-soluble, not water soluble like superphosphate. While the phosphates in Super are available for plants to use as soon as the phosphates hit the soil, the nutrients in dicalcic phosphate must be broken down by soil bacteria before the plants can use them. However, this is not a problem as these bacteria are widely distributed in soil, and simply part of a natural process.
This difference in solubility gives dicalcic phosphate a major advantage: the nutrients are released more slowly. So plants are able to access the nutrients as they grow, and less is lost to the environment due to run-off, especially under heavy rainfall. The overall result is that the dicalcic phosphate fertiliser is more efficient at converting its nutrients into plant growth.
Another great advantage is that dicalcic fertilisers are seed safe. If superphosphate is applied at sowing time, there is a risk that new seedlings can be ‘burned’ from a sudden excess of phosphate nutrient dissolving next to their roots. But if dicalcic phosphate is used, new seedlings are safer because the nutrient is released slowly. This enables farmers to apply the seed and fertiliser at the same time, saving time and money.
Liming effect
As mentioned above, dicalcic phosphate has a liming effect, so soil acidity is not affected.
Soil acidity is a common problem for pastoral and arable farmers because plant growth and microbial activity naturally increase soil acidity over time so that plant nutrients like trace elements become unavailable to plants. Moreover, the application of Super, with its very acid value around pH 1.7, can add to this problem.
To overcome this issue, lime is frequently applied. However, if a dicalcic phosphate like Fertco’s KingPhos or SeaPhos is used, separate applications of lime can be reduced or may even be unnecessary. As always, a soil test will ensure you only apply what is actually needed.
Granulation benefits
While these benefits on their own justify the use of dicalcic phosphate over superphosphate, there are further advantages when the dicalcic phosphate is a granulated product.
Firstly, the dicalcic phosphate is transformed from a dusty powder, prone to clogging machinery, into free-flowing granules. Handling becomes easier, and most importantly, application is safer. This is particularly relevant for aerial top dressing where a blockage in the aircraft hopper can create a life-threatening situation for the pilot. Ground spreaders appreciate the granulated dicalcic phosphate too because risk of wind drift is reduced.
Secondly, granulated dicalcic phosphate can be more accurately placed during spreading. This results in less wastage since the product can be directed away from raceways, stock camps, and waterways. This not only saves nutrient wastage, but avoids environmental damage.
And lastly, the granulation process produces a consistent product which mixes safely with other fertiliser. This reduces time and application costs.
So when you’re planning your autumn fertiliser programme this year, consider using a granulated dicalcic phosphate like Fertco’s KingPhos or SeaPhos. The advantages are just too good to ignore.
This article was published in the Coast & Country News.
