Soil biology controls nearly all the processes that create soil structure, store nutrients, and make them available to the plants. This includes activity of earthworms, bacteria, fungi, protozoa (single-celled animals) and insects. For these organisms and processes to function, the soil pH levels need to be right.
Soil biology controls nearly all the processes that create soil structure, store nutrients, and make them available to the plants.
pH is a measure of the soil’s acidity: the lower the pH, the higher the acidity. Bacteria, fungi and earthworms within the soil perform best in soil with a pH of 6.0-6.5. At this level, phosphorus – an essential macro-nutrient – is also at maximum availability for the plants (Fig. 8).
For farming at its most profitable, you need the pH as close to this range as possible before adding any further nutrients. Liming to get the pH to the right level before adding fertiliser will improve your soil’s fertility faster than adding nutrients through fertiliser alone.
The availability of nutrients in slow-release fertilisers depend on many factors: soil pH, temperature, pasture performance, biological activity, Anion Storage Capacity (ASC) and, to a lesser extent, soil moisture. Fig. 9 shows the lab release results of uPgrade against the pasture growth curve. The increased levels in the months following application, compared to the spike and drop of superphosphate, shows why slow release fertilisers are more effective for pasture growth.
Soil exchangeable aluminium can have a detrimental effect on root growth if levels build up in the soil, as well as being toxic to animals. While no toxic levels (considered to be more than 3 mg/kg soil) were recorded in the trial, superphosphate tended to increase the soil exchangeable aluminium levels, while uPgrade decreased them (Fig. 11).
Soil exchangeable aluminium usually increases with acidity, so these results are in line with the trends in soil pH change. In soils where aluminium toxicity is already a problem, TerraCare uPgrade should help to improve the situation.
The Pirongia Trial
TerraCare trials undertaken in Pirongia (Waikato) showed that both our slow-release phosphate fertiliser products – uPgrade and rePlenish – grew more pasture than superphosphate at the same application rate of phosphorus.
Reducing the amount of phosphate fertiliser means not only a cost reduction, but also less phosphorus being lost to runoff and leaching.
The Olsen P levels – or the measure of plant-available phosphate in soil – were consistently lower when using rePlenish and uPgrade compared to superphosphate, yet the pasture growth was greater where TerraCare products were applied.
This means that the Olsen P test is not necessarily a true measurement for future pasture growth. So when using TerraCare DCP products, we can reduce the Olsen P levels (as shown in Fig. 2, page 11) to between 10-15 for less intensive farms and 15-20 for high-performing dairy farms.
Healthier farms with the TerraCare Way
There’s so much going on beneath your pasture that you can’t see. Microorganisms working away in the soil, plants reaching out roots to take up vital minerals. All these elements and minerals need to be delicately balanced to ensure that they’re easily available to the plants and microorganisms that need them.
And that’s the science behind TerraCare’s fertilisers – they’re based around testing to enhance your farm’s health.