DAIRY 101 NITROGEN LEGISLATION
Molybdenum is required by all plants to turn the nitrate they have absorbed into amino acids and proteins.
All change for nitrogen rules Story and photos by: Karen Trebilcock
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uly 1 marked the start of the Government’s new rules on nitrogen. Under the Essential Freshwater package, the amount of synthetic nitrogen fertiliser applied to pastoral land is now capped at 190kg/ha/year as a permitted activity (requiring no resource consent). The cap applies to the average amount of fertiliser applied across a farm but also to every hectare of pasture and cannot be offset by non-grazed land. You can apply more nitrogen on forage crops but only if you offset it by applying lower amounts on pasture. The cap does not apply to arable or horticultural crops. The changes have been a long time coming and many dairy farmers already use way less nitrogen than the cap. However, for those who have become reliant on nitrogen, not just to fill feed gaps but for year-round production, there must be a change in farming practices or get ready to apply for costly consents. And changing from high-N to low-N use is not just a matter of using less nitrogen fertiliser. Nitrogen-fixing clover needs time
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to re-establish, as much as two to three years, and pasture growth will suffer until that happens. Strategic use of nitrogen fertiliser has always been important but now more than ever. Apply it only when the soil temperatures are between 6C and 16C which is when pastures will be actively growing. N is only taken up by growing plants and if not utilised quickly it leaches through soils or is lost into the atmosphere. Little and often, especially in high rainfall areas, is best. If there are no growing plants don’t apply it, waiting for seed strike and then putting it on is the best option. Don’t put it on areas in a paddock that you know are already high – where stock camp, gateways and around water troughs. And look at skipping paddocks which are sprayed with effluent. Use coated nitrogen products as they are less likely to be leached or lost to the atmosphere before they’re absorbed by plants. Gibberellic acid (GA) can also be used. It’s not a fertiliser but a growth hormone found in plants. When applied with N, if conditions are right, it can increase the response rate. But there are other things you can do as well and soil and herbage tests are the way to start. Yellowing, slow-growing pasture can be due to lots of reasons – not just a lack of nitrogen.
Dairy Exporter | www.nzfarmlife.co.nz | July 2021
