Tests before tightening help protect farm fertility
Soil tests should be the first step for farmers trying to managing budgets while maintaining pasture productivity.
Ballance Science Extension Manager, Ian Tarbotton, says keeping soils fertile is good insurance with pasture an
essential feed source, but gut instinct or past experience won’t lead to good decisions on what to spend or save.
“Soil tests will show you what you have to work with and they are the best guide to decisions around a fertiliser
budget. The last thing farmers want to do is to compromise future productivity, so understanding what nutrients are
available now is the best basis for decisions on fertiliser budgets.”
Ian says there are three main nutrients to focus on when it comes to soil fertility: phosphorus, sulphur and potassium,
and how they behave in soil provides a clue for application decisions.
“Sulphur is very mobile in the soil, so usually requires annual applications. Potassium can leach too, notably on coarse
textured soils. On the other hand, phosphorus gets stored in the soil, so depending on reserves it may be possible to
defer phosphate fertiliser application. Some nutrients, such as magnesium and calcium, could be supplied directly to
stock as a short-term measure.”
Phosphorus is a key driver of production, so if possible, levels should be kept in the optimum range and testing will
confirm whether levels need attention.
If sedimentary soil is above the optimum Olsen P range of more than 40, then cutting out phosphate maintenance for a
year will not affect production. If the range is more than 30, then half maintenance of phosphate will not lead to
noticeable impacts. “But if the results sit under 25, then full maintenance phosphate as usual is advisable, as
production will be affected at a time when farmers need to maintain it.”
Ian said that if a farmer makes the call to omit or reduce phosphate, maintaining sulphur levels is important. “Cutting
back on sulphur is false economy. It’s the cheapest form of macro-nutrient and we have slow release options available to
sustain the benefit.”
Ian cautioned that another factor to consider when planning when to apply nutrients was the significant drop in the New
Zealand dollar over the last 12 months, and that it was only a matter of time before the price of imported fertilisers
would increase.
“Our team is here to help. Ballance nutrient specialists will factor in farmers goals, soil tests, product options and
pricing to ensure farmers get the best possible return on their nutrient investment.”
ENDS