It’s spring and cropping time is upon us. But it isn’t always straight forward to get the crop sown and growing.
If it’s pouring down and paddocks are wet, as they sometimes can be in spring, applied nutrients like urea are at risk of leaching. If it’s dry, as can also be the case, nitrogen can volatilise before the newly-germinated seedlings are able to make use of them. That’s wasted nutrient and money.
Wastage can also occur from machinery damage to new seedlings when the post-germination or side-dressing is made.
However, this wastage need not occur if a polymer-coated urea (PCU) is used in the cropping fertiliser.
Damage like this to new crops wastes money
Nutrients that stay put
We’ve already described the advantages of using PCU at times when nitrogen is required. It’s perfect for building a winter feed wedge, and for boosting summer pasture quality.
But it’s also ideal for providing the nitrogen needed for heavy feeder crops like maize and brassicas due to the protective coating around the urea granules that enables the nutrients to stay put.
When it’s wet, nitrifying bacteria transform urea into plant friendly nitrate very quickly. The problem with this is that the rate of nitrification is usually faster than plant growth rates. So newly-germinated maize or brassica seedlings cannot use all of the nutrient that has been applied. Therefore, there’s a high probability the nutrients are leached away and wasted.
With PCU, the protective coating reduces wastage even if it is very wet. This is because the nutrient is released gradually through the semi-permeable coating in a controlled pattern, much more in line with the needs of the growing seedlings.
Notably, PCU is used in extremely wet environments around the world such as wet-field rice-growing regions to reduce nutrient loss and increase yields.
Nutrients that improve yields
In the academic journal Molecules, a very recent review of controlled release fertilisers (CRF) such as PCU states that “The current evidence shows that CRFs can improve yield, crop quality, nutrient recovery, and nitrogen-use efficiency …” (Siudak et al., 2026: 22).
This is very encouraging in our search for tools to increase production while reducing environmental harm.
Avoiding nutrient wastage while increasing yields is an important ethos for us at Fertco, and one reason why we’ve been using PCU very successfully in our Fertco 2-step Maize Programme and our Fertco Smart Brassica Base.
But there’s another reason why PCU is perfect in cropping blends. And that’s to do with the number of fertiliser dressings required for maize and brassica crops.
No need for side dressings
Typically, maize requires three dressings: a base dressing, applied before planting, a second dressing applied at sowing time, and a third dressing, applied around the time the young maize seedlings are at the 4-leaf stage.
Brassica crops are usually given two dressings: a base dressing prior to planting, and a side-dressing just before the young plants reach the canopy-closure stage.
However, with a PCU in the cropping programme, there is no need for a post-germination side dressing; the nutrients can be applied in the base dressing and remain in the PCU granule until gradually released in a steady but predictable pattern based on soil temperature.
Machinery damage avoided
Apart from a reduction in fertiliser spreading costs, being able to forgo the side dressing removes the risk of machinery damage to newly germinated plants, either from tyre damage or knifing if the side dressing is buried.
Also avoided are hassles around spreader availability which can be especially awkward if the weather is very wet.
Establishing a crop requires significant investment. But including PCU in our Fertco cropping mixes is proving to be an effective means of helping our customers reduce wastage in time and money.
This article was published in the Coast & Country News.
