Use biology to reduce NPK inputs
Although many growers assume that most of their nitrogen requirements come from a bag, this is not the case. A large percentage of the nitrogen utilised in crop production is supplied by biology and if we acknowledge and understand this fact, then we can work to optimise this natural supply. Similarly, the release and delivery of phosphate and potassium is a biological process. If we introduce and/or nurture these creatures, it can seriously reduce NPK inputs. Nitrogen-fixing organisms can be introduced whilst the success or failure of these inoculums is often determined by the presence of molybdenum in the soil. If you don’t have 0.5ppm of molybdenum in your soil, you may struggle to achieve significant nitrogen-fixation. Molybdenum is required for bacteria to build nitrogenase, the enzyme required to convert atmospheric nitrogen gas into ammonium nitrogen in the soil.
Another way you can reduce nitrogen inputs is by ensuring that you have a fully functioning nitrogen recycling system. Protozoa play a big role here. Bacteria have a carbon to nitrogen ratio of 5:1 which means that their body contains almost 17% nitrogen. There can be two and a half tonnes of bacteria per hectare in a good soil and this equates to over a tonne of urea locked up in their bodies and not available to the plant. Protozoa eat 10,000 bacteria a day and recycle their nitrogen to make it plant available. Many soils lack protozoa but they can be inexpensively reintroduced using lucerne teas. For some reason, all three forms of protozoa are found in large numbers on lucerne (assuming that they have not been killed off with pesticides used to kill lucerne flea). They can be easily multiplied and introduced to restore nitrogen recycling and they have an added bonus of firing up your earthworm populations. Protozoa is a favourite food source for these dynamic fertiliser machines.
Phosphate solubilising organisms can be introduced with inoculums like Nutri-Life BAM™ or Nutri-Life Bio-P™ and their numbers can be boosted with simple additives like wood vinegar, humic or fulvic acid. Another highly productive strategy involves stubble digestion programs. Cellulose-digesting fungi release organic acids that can release locked up phosphorous in your soils. Soil-life testing reveals the decimation of these creatures through tillage, fungicides, herbicides, nematicides, acidic phosphates and high salt fertilisers. It is a simple, inexpensive process to brew up these organisms and apply them to crop residues to speed the breakdown of organic matter. Not only do you build carbon (for which you will soon be paid carbon credits) but you have also improved your fungi to bacteria ratio and now have a soil full of fungi that solubilise phosphate, protect from disease and promote plant growth with their unique exudates.
There are also inoculums available that can solubilise potassium and they are particularly productive in clay soils where potassium can become trapped in the clay platelets. In these soils the small potassium molecule can be set free by organisms that fancy potassium. If you are brewing compost teas, you can encourage these brews to become potassium generating by combining a little potassium sulfate as a food source during the brewing process. This encourages the multiplication of potassium solubilising organisms that are present in all compost teas, as they now have a food source specific to them.
The bottom line here is that we need to reduce our reliance on NPK inputs as they are destined to dramatically increase in price in line with peak oil and peak phosphate. BHP have recently been trying to buy up the world’s largest potassium producer because it is good for business. They know that this non renewable resource will rise and rise in price as population and demand for food increases. The message for primary producers is to work more closely with a natural system to reduce your requirement for these increasingly expensive inputs.