Fertilisers are basically sources of plant nutrients, whose cycling is stimulated through the soil and the plant, and they are designed to help rectify deficiencies in essential minerals in the soil. Some fertilisers, such as those based on rock minerals, are soil conditioners which are designed to modify the properties of soil, especially their cation exchange capacities, acidity, and phosphorus fixation capacities, so that water and plant nutrients are made more readily available to the growing plant.
Water soluble phosphatic fertilisers, such as superphosphate and diammonium phosphate, under the action of rain or irrigated water are dissolved in the soil, and the elements are held in the soil to be absorbed by plants. However, the phosphorus in the dissolved phosphate anions can form chemical bonds with aluminium or iron atoms to form oxides or oxyhydroxides in highly weathered soils. Consequently, phosphorus can be ‘locked’ onto the solid part of the soil, effectively removing it from soil solutions. The phosphorus that was applied through fertiliser will no longer be available in the liquid phase and cannot be taken up by the plant roots (Coventry, 2001). Phosphorus that is absorbed or converted to insoluble forms in the soil via applied fertiliser is known as fixation.
The widespread phosphate fixation problem exposes land managers to the risk of not gaining the full agronomic benefits of fertiliser application. Consequently, many managers are prone to over fertilising by applying additional fertiliser than what stays in the soil solution to be absorbed by plants. Overapplication of fertiliser not only adds unnecessary costs to the farming enterprise, but it can also cause pollution of sensitive riparian or wetland environments by leaching.
The primary producers of food must not only increase soil nutrient concentrations but also improve the structure of the soil and reduce soil losses to increase soil productivity, food production and food security. The foundation for survival and food security is healthy soil, which is why soil regeneration practices should utilise products that are sustainable and do not negatively impact the environment.
The use of naturally occurring rock mineral fertilisers such as NatraMin Blends are increasingly being used in agriculture as an alternative source of nutrients to chemical fertilisers. Compared to soluble fertilisers, which provide only nitrogen, phosphorus, and potassium and rarely calcium, magnesium, sulphur, and trace minerals, rock mineral fertilisers have a large array of macro and micro minerals.
Rock Mineral Research
Investigations into the benefits of using rock minerals have been around for a long time. Pot trials on sugarcane growing in basaltic soils of Hawaii were undertaken by McGeorge (1924) and it was reported that the higher soluble silica contents in the soil increased the availability of phosphorus to the cane and that the sucrose obtained from the cane also had higher phosphorus content (McGeorge, 1924).
Major improvements in sugar cane yields resulting from applications of between 100 t/ha and 400 t/ha of crushed basalt to the poor, highly weathered soils of Mauritius were reported by Parish and Feillafe (1958) on a review of previous research undertaken in the early 1950’s. They found that the tonnage of sugarcane increased significantly, and the sucrose content was still substantial after eight years.
Harley and Gilkes (2000) recommended the use of rock dust as a slow-release fertiliser for several reasons, including:
- it is not readily leached from the soil
- it is acceptable to ‘organic’ farmers
- in developing countries it is affordable
- stockpiles of quarry or mining by-products can be reduced
According to VanStraaten (2006), multi-nutrient silicate rock fertilisers can also provide numerous advantages. These include:
- they provide a wide range of macro and micro minerals
- their properties enable them to raise soil pH
- they can be used as slow-release fertilizers in acidic soils that lack nutrients
- their application does not have a detrimental effect on the environment
- their availability and affordability make them a good choice
Scientific Research Into The Benefits Of NatraMin
At the University of Queensland, Dr Bernard Wehr and associates conducted a replicated trial that examined the effects of NatraMin Cal-S on soil properties and plant growth in 2017. Results showed that NatraMin Cal-S increased the soil’s plant available water content (PAWC) significantly over soil with no amendment applied (Control). Using NatraMin Cal-S resulted in an increase of up to 13.1% PAWC in soils, which was achieved by increasing the water content at field capacity (7.3% increase) or by increasing the capacity of the soil to hold water.
In these same trials, NatraMin Cal-S resulted in a 26.26% increase in dry shoot biomass (yield) over the control with an even more pronounced difference under the soil surface, where dry root biomass increased by more than 39% in NatraMin Cal-S treated soil. In addition to improving the health of the current plant, root growth also improves the health of the soil over time.
Furthermore, an analysis of data captured during the trial suggests that NatraMin appears to stabilise soil organic carbon, reducing the release of CO2 into the atmosphere, providing additional environmental benefits over using synthetic fertilisers in high quantities.
Maintaining and increasing soil organic carbon has been related to a variety of agronomic benefits, including increased soil health and fertility. “The major finding of this (UQ) study is that NatraMin Cal-S has the ability to stabilise soil organic carbon by slowing its rate of degradation,” Choong (2017) stated. As a result, farmers can use NatraMin Cal-S as a long-term approach to prevent soil organic carbon depletion and maintain soil health.
NatraMin appeared to have an impact on soil pH, especially in acidic soils. This is even more noteworthy when examined in conjunction with the reduced CO2 emissions discovered from the soil respiration trials, because unlike traditional compounds like Lime (Calcium Carbonate) which release CO2 when used to increase soil pH, silica-based products like NatraMin can improve pH without releasing CO2.
Additional trials conducted by AgSolutions in 2019 at The University of Queensland Gatton Dairy Research Unit investigating pasture production and dry matter utilisation revealed impressive results, with NatraMin treated pasture yielding a 19.4% increase in kilograms of dry matter per hectare and a 53.7% increase in total pasture utilisation over untreated pasture.
Healthy plants require soils with a proper balance of nutrients to develop, so soil health is extremely important. Plants with an acceptable balance of nutrients are required for herbivores to graze, and herbivores with an appropriate balance of nutrients for predators to devour, are both necessary for healthy herbivores and carnivores. As a result, the healthy if all land creatures are linked to the health of the soil!
Using NatraMin Mineral Fertiliser and Soil Conditioners, combined with soil management practices that focus on improving organic matter, repairing/preventing erosion, and improving soil structure issues via various soil amelioration methods, will be reflected in the ability of the land to produce nutritious, sustainable products with little negative environmental impacts.
By Shannon Godwin (BAppSc GDTL)