Fluid Fertilisers are the way forward
By Dr Bert Quin
Fluid fertilisers are defined in New Zealand as high-solids products containing only 10-20% water (just enough to allow them to be kept agitated and spread through specialised equipment). Unlike what are commercially defined as ‘fpa’ (fine particle application) in which all ingredients are finely ground regardless of benefit and cost, each individual ingredient in fluid fertilisers is present in a range of particle sizes to suit that nutrient.
The main factors deciding the particle size range chosen for each nutrient are (a) whether it is possible and intended for some or all of that nutrient to be taken up through the leaves, as in a foliar fertiliser, and (b) what sizing will allow passage of the particular ingredient through the plant canopy to the soil, with as many individual particles as possible, with a totally even spread, to optimise nutrient uptake.
‘Liquid’ fertilisers got a deservedly bad name in New Zealand beginning in the 1980s, because of blatantly dishonest and misleading claims that the tiny amounts of nutrient being applied per hectare at the rates recommended by the seller would maintain production. Typically, these products were applying less than one kg/ha of the key nutrients, and trivial amounts of trace elements. They made huge profits for their suppliers, but cost farmers dearly. Several such companies added growth promotants and ‘greening’ agents to their products, to create an impressive but fleeting visual benefit.
This type of con has arisen again recently, but wrapped in a more sophisticated, single-invoice ‘package’ of on-farm ‘advice’ and application. Nutrient application rates remain massively below maintenance requirements.
Unfortunately, this has distracted attention from the enormous benefits of true fluid fertilisers, as described above. Fluid fertilisers have all the advantages of sold fertilisers – relatively low cost products designed to maintain and improve soil fertility and plant growth – but avoid their disadvantages of dust, segregation of components during handling, transport and spreading, and entry of nutrients into waterways.
In addition, fluid fertilisers offer a combination of important advantages – extremely accurate placement (thereby allowing deposition of nutients into waterways to be avoided), extremely even coverage of much smaller-sized particles than granules, optimising both leaf and root uptake, and the easy addition of both solid and liquid additives, additional nutrients, seed and insecticide. In particular, the additives can include cutting-edge products that greatly increase both P and N efficiency and reduce losses.
For all these reasons, I believe that ‘fluids’ are the way to go. The water content is simply the carrier, the means to ensure that the nutrients and additives required to optimise productivity on each given farm can be applied in the most cost-effective manner, in any terrain, in any weather.