Good farming practice dictates that nutrients removed from the farm via meat, milk or plant products must be replaced. However, for organic farmers and growers in NZ, this hasn’t always been an easy task due to a shortage of organically-certified fertilisers.
But with the value of the organic sector recently reported at over NZ$1.1 billion, and expectations that both domestic and export markets will continue to grow, the need for fertilisers aligned with organic agriculture and horticulture principles is more important than ever.
Fortunately, thanks to scientific and technological advancements, the range of organically-certified fertilisers continues to increase. So whether you already have organic certification, are transitioning to organic certification, or wanting to integrate organic practices into your operation, sourcing organic fertilisers needn’t be an issue.
Organic NPK
Organic fertilisers are those derived solely from natural sources. They must contain the nutrients that plants need to grow like the macronutrients nitrogen (N), phosphorus (P), or potassium (K).
For organic producers, natural sources of BioGro certified nitrogen can be found in products like Phosta N, a plant-based fertiliser with 10% N, recovered from the fermentation of vegetable matter. Another great source of nitrogen is a product called Protamin N13, a by-product of the leather industry with 13% N.
BioGro certified phosphorus can be found in RPR (reactive phosphate rock), or guano, sourced from the natural deposits of seabirds.
BioGro approved potassium choices are sulphate of potash (SOP), mined from underground salt deposits, or Phosta K, a by-product of the sugarcane industry.
Apart from N, P, or K, these products often come with extra benefits which fit perfectly into an organic system.
Extra benefits
One example of this is Protamin N13. It contains hydrolised proteins and amino acids which have a biostimulant effect on soil microbes, improving nutrient uptake and healthy plant growth. The granules are also high in organic carbon which improves soil health.
Phosta K is another example. It’s not just a source of chloride-free potassium. It also contains plant-available forms of nitrogen, phosphorus, sulphur, magnesium, and calcium. Likewise, Phosta N delivers more than simply nitrogen. It has phosphates (P) and calcium too.
Another characteristic these fertilisers possess is their reduced solubility.
Reduced solubility
Fertilisers with reduced solubility release their nutrients gradually, so losses to the environment are avoided and plants get the nutrients they need as they grow. Protamin N13, Phosta K, Phosta N, guano, and RPR all deliver their nutrients much like this, albeit at different rates with some being slower than others.
BioGro S and Mg
An often overlooked but vital secondary element required by plants for healthy growth is sulphur (S). Fortunately, a BioGro certified source is available: elemental sulphur prills. Elemental sulphur is yet another fertiliser that releases its nutrients gradually.
A further source of natural sulphur can be found in Kieserite, although this fertiliser is usually applied as a BioGro certified source of magnesium (Mg). Magnesium is essential for photosynthesis and therefore strong plant growth, so needs to be applied where soil Mg reserves are low.
BioGro sources of traces
Micronutrient or trace element deficiencies in NZ soils are well documented. Some have serious consequences for plants and animals. Just as with NPK and secondary nutrients like S and Mg, the trace element content of the soil will fall over time where animal and plant products are removed. So organic farmers and growers need access to natural sources of trace elements.
Nowadays, this is possible. At Fertco, we can provide natural BioGro certified sources of boron, cobalt, copper, iron, manganese, molybdenum, selenium, and zinc, so most deficiencies can be dealt with.
With the wide range of BioGro certified fertilisers like the aforementioned, nutrient deficiencies are one less thing for organic farmers and growers to worry about. As always, the best place to start is with a soil test.
This article was published in the Coast & Country News.
