With high hay and grain prices continuing to present challenges for supplement feeding, producers are considering the potential for targeted fertiliser application by boosting pasture growth as a main feed source.
This was a key theme in a recent Southern Farming System webinar that asked the question: At what price is there a place for bagged nitrogen in pastures?
At this webinar, Incitec Pivot Fertilisers technical agronomist Lee Menhenett presented information about the nitrogen needs of pasture, how to minimise risk and make the most of an application, while considering potential agronomic and economic returns.
“Very few producers will be able to rely solely on pasture, hay or grain to feed their stock,” Mr Menhenett said.
“To get through any feed gaps, they can supplement their pasture with hay or grain, or use fertiliser to boost their pasture dry matter.
“The whole farm feedbase needs to be considered to identify when pasture growth doesn’t match animal demand.
“This way, producers can supplement their pastures with nitrogen so that they aren’t exposed during periods of high-cost grain or hay supplements.”
Southern Farming Systems’ Lisa Miller encourages producers to compare the return on investment from applying nitrogen to pastures with buying hay or grain.
“Producers need to consider whether they’re expecting a shortfall of available winter feed, and if they are, they need to know how to calculate what the likely responses to nitrogen will be, weighed against the proposed cost of an alternative feed supplement,” Ms Miller said.
“With current fertiliser prices, for example, you will need to get a response of at least 8kg of dry matter for every kilogram of nitrogen applied. The typical response of nitrogen application is between an extra 5kg to 25kg DM/ha for every 1kg of nitrogen applied.”
Mr Menhenett presented webinar participants with a feed cost calculator to demonstrate the ROI for an application of nitrogen using varying input cost scenarios.
“Calculations consider the weight of dry matter, response rate achieved and the input cost,” he said.
“Moisture, pasture composition and density, soil fertility and grazing management, application rate and the product used can all influence the dry matter response and the return on nitrogen application.”
“The best dry matter response will be to applications of between 25kg and 50kg nitrogen/ha. In this range, dry matter will accumulate as nitrogen rate increases.
“However, beyond 50kg nitrogen/ha, there is a tipping point at which a positive economic outcome is unlikely.
“Each individual needs to consider their situation, input costs, response rate and conversion rate, to find that point.”
Mr Menhenett said when it came to nitrogen, there were numerous considerations prior to application to ensure best management practice and economic and environmental outcomes.
“Urea, the most common fertiliser product, is prone to volatilisation in conditions where limited moisture has dissolved but not moved the urea into the soil.”
Ms Miller agreed, and said considerations of timing, pasture species and cultivars were also important as there were variations in seasonal dry matter growth rates.
“If there’s no moisture, there will also be no growth. But on the flip side, apply nitrogen to waterlogged pastures and the fertiliser will be lost as gaseous nitrogen oxide,” she said.
“Additionally, not all pastures will be responsive. Nutrient deficiencies or acidity might hold back growth, or the species may not have the propensity to grow in winter.
“And timing needs to be considered so that the application is made well ahead of when the feed is needed.”
The feed cost calculator is available along with other presentation materials from the webinar on the Southern Farming Systems website.
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