New Zealand’s two main fertiliser companies – Ballance Agri-Nutrients and Ravensdown – produce a variety of solid superphosphate fertilisers, usually granulated.
Superphosphate contains phosphorus, sulfur and calcium. Potassic superphosphate has potash blended in. For sulfur-deficient regions, elemental sulfur is added – with or without potash.
Other elements that may be added are:
- trace elements such as molybdenum, copper and boron for plant growth
- selenium, copper, cobalt or sodium for animal growth.
When extra nitrogen is required, ammonium sulfate (but not urea) is blended with superphosphate. Mono-ammonium and diammonium phosphate are blended with granular ammonium sulfate and potash, to form fertilisers with different nutrient combinations for use on a variety of pastoral, arable or fodder crops. The more expensive compounds imported from Europe are used on high-value export and domestic horticultural crops, and on export vegetables.
Ravensdown Fertiliser owns (wholly or jointly) several quarries that extract lime, used as a soil conditioner. It also supplies animal health supplements such as magnesium, calcium and sodium, as well as trace elements, agrochemicals and anthelmintics (for internal parasites).
Ballance Agri-Nutrients sells mostly through the farm-servicing agencies such as Wrightsons PGG, Farmlands and RD 1, whereas Ravensdown and Summit Quinphos deal directly with their farmer customers.
To supply fertiliser throughout the country, the companies maintain a network of stores. These hold stockpiles of the main product lines for local farmers, or use local carriers to take them to the farm. The companies also transport products from ports or manufacturing works to their clients, ensuring there is a consistent supply around the country.
Ballance and Ravensdown own aerial topdressing companies (SuperAir and Wanganui Aero Work respectively) and Ravensdown has several joint ventures with companies that spread fertiliser from trucks.
All three companies employ graduates in agriculture, horticulture or resource management, or ex-agricultural servicing personnel as their sales staff. These field officers or technical sales representatives are the main link between the farmer or grower and the company.
Field officers advise farmers on soil, plant and animal nutrients. To create fertiliser programmes, they use soil, plant and animal tissue tests, historical information about nutrient use, data about the farms and productivity, and farmers’ business goals. Computerised models are used, with digitised farm-mapping tools to help create and document fertiliser recommendations. GPS (global positioning system) records show the path of the aircraft or trucks applying the fertiliser.
Effect on the environment
Public concern is increasing over the decline in water quality as a result of pollution from soil loss, nutrient runoff and leaching from mostly animal excreta. The companies need to be aware of the impact of fertilisers on water quality, and to develop nutrient management plans that allow farmers to gain the desired level of productivity while minimising nutrient loss to surface and ground water.