Introduction Over the past few decades, I have observed the development of increasingly divergent views of the roles of both calcium as a nutrient, and lime in itself, in New Zealand agriculture. Many of these newer views are lacking in scientific verification, but nevertheless are likely to be reflecting a great number of anecdotal observations, … Read more
Superphosphate New Zealand’s soils are by and large not naturally fertile, simply because of the low levels of some key nutrients – phosphorus (P) in particular – in the volcanic and sedimentary rocks they have been formed from. Single superphosphate (SSP), made by reacting finely ground phosphate rock with concentrated sulphuric acid, was first produced … Read more
Gibberelic acid or GA (also called gibberellin) is a naturally-occuring plant growth stimulant that, when temperature and soil moisture conditions are right, kick-starts plant growth and cell elongation in particular. It has traditionally had niche usage in horticulture, and vineyards especially. Research with Different Application Rates Early research on pasture demonstrated that pasture … Read more
16. What actually is an RPR? The stated knowledge in 2019. Updated from the original version of 2016 The expression ‘RPR’, or reactive phosphate rock describes a phosphate rock that – with certain provisos like soil pH of 6 or less, and an annual minimum of 800mm rainfall and/or irrigation – will adequately … Read more
15. ‘Dicalcic’ vs Reactive Phosphate Rock (RPR), elemental S and Fine Lime (updated September 2019) What exactly are you getting for your money? Dicalcic Super Dicalcic (aka lime-reverted superphosphate) has been around a long time. When properly made, the water-soluble P component in super, called monocalcium phosphate or MCP, is fully converted after … Read more
The increasing interest in humic acid reflects growing concern that some soils are becoming less biologically active, and growing interest in what can be done to reactivate them. Soils can contain less than one percent to over 10% organic matter. It is the soil’s organic matter, and humic acid in particular, that gives soil … Read more
Suspension fertilisers In most overseas countries, this term is used specifically to refer to a fluid made by mixing high-quality fertiliser ingredients, previously finely ground to below 100 microns (0.1mm), with 40-60% water by weight. Because most ingredients used are quite soluble in water, a saturated solution is formed, with the rest remaining in … Read more
Grazed pastures comprise over 80% of NZ’s agricultural land When these pastures were converted from native forests, bush and tussock, sown with ryegrass and rhizobia-treated clover seed, and fed with P, S and trace elements, soil organic matter levels (and of course the organic carbon, nitrogen and sulphur they contained) were observed to increase steadily, … Read more
The beginnings Introduced ryegrass/clover pasture started to become the mainstay of the New Zealand economy following the decline in gold exports. The original soils, both of sedimentary and volcanic origin, were recognized as being phosphate (P) deficient early on. Application of phosphate rock had mixed success, partly because the large differences in agronomic efficiencies of … Read more
There is a simple answer to this question. They are equally important. Simply throwing manufactured fertilisers on poorly-managed soil does not automatically guarantee large increases in production, unless all the ‘building blocks’ are there. With the post-World War 2 oversowing of poor-quality, unfertilised pastures with lime and superphosphate, pasture production typically trended upwards for … Read more