At times we get asked the question: How long will my Prescription Blend last in the soil and will I require a blend next year? Unfortunately, there isn’t an easy answer to this question; it is really site specific. What it comes down to is how ‘completely’ the initial blend balances and amends the soil, and how much nutrient is lost each year (i.e., crop removal, leaching losses etc). For instance, in horticultural situations, the full soil balancing requirement for calcium and magnesium is normally recommended as a single treatment. We expect calcium and magnesium will remain balanced for an extended period of time (i.e., more than 5 years), as crop removal of these elements will not normally significantly affect soil levels. In addition, the products we generally recommend for calcium and magnesium are not prone to leaching. Even after this 5 year period, calcium and magnesium requirements (for soil balancing purposes) should remain minimal.
On the other hand, in some instances it is not possible to completely supply the calculated requirement due to rate restraints. For example, a soil shows very low zinc levels (e.g., 0.1 ppm); our maximum recommended annual application of zinc sulfate monohydrate is 25 kg/ha (to avoid plant toxicity and damage to soil biology). This input provides 3.8 ppm of zinc. The application will therefore not be sufficient to reach the ideal minimum level for zinc (5 ppm), although it is certainly a good step in the right direction. The same can be applicable for any element. Subsequently, it would be ideal to evaluate soil levels of these elements 10 months after the initial blend to ascertain if further inputs would be beneficial.
As a side note, in areas with high rainfall or very light soils with low nutrient holding capacity, we suggest splitting the recommended soil amendment into two (or more) applications to reduce loss through leaching/runoff.
We are also often asked how long it will take until chemical NPK and pesticide inputs can be reduced. This largely depends on the time taken to fully balance and incorporate sufficient amendments into the soil (i.e., slow acting humates, phosphates and basalt rock minerals). This can take quite a period of time (e.g., two or more prescription blend treatments) for growers who have a history of heavy chemical usage, as their soils are often unbalanced with low carbon and poor microbial activity. Conversely, providing you are starting with a high organic matter, soil reliance on NPK and pesticides inputs can be significantly reduced within one season. Organic matter is one of the hardest, and most important, soil properties to build as it governs overall soil fertility. Organic matter is responsible for the structural integrity of fine textured soils, and it is the home base for beneficial soil biology. As such, it is responsible for recycling and solubilising soil nutrients, and for fixing atmospheric nitrogen. Building soil organic matter is really the key to reducing dependence on synthetic NPK forms and stop-gap pesticide use. So, in that regard, if you have good organic matter levels you are one big step in front of growers with low carbon.
Biological systems are dependent on so many different interlacing factors, and actual requirements will vary from season to season. For this reason we monitor plant nutrient levels throughout the season with regular laboratory leaf analyses. We want to catch any problems early before they can seriously impact yield and profitability.
Nutrition Farming® (soil mineral balancing, microbial/biology balancing and precision nutrition throughout the season) has the potential to be more economically viable than conventional farming. Again, this will obviously depend on the soil’s starting point and current fertilising/farming practices. We work with numerous growers who, after applying prescription blends, have not needed to add soil amendments for the last few years and have significantly reduced pesticide requirements. Their input costs have reduced and the quality of their produce is achieving premiums that they previously thought weren’t possible. An example of this is our local strawberry growers who have been applying Prescription Blends. Balancing the soil has improved plant availability of the full-spectrum of nutrients; plant growth last season was so good that the fertigation program needed to be cut back to avoid over-vigorating the plants. Ultimately, our approach gives growers more long-term financial security; it is not possible to predict future inputs costs but we do know in which direction they will be trending.