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A project is exploring how pastoral farmers can get the most from fertigation.
With new limits on nitrogen (N) fertiliser coming into play, some pastoral farmers are looking at how to reduce N fertiliser use, while making the most of every kilogram (kg) of N applied.
A MPI Sustainable Farming Fund (SFF) project is investigating how to maximise the benefits of N application through fertigation (applying fertiliser together with irrigation water) for irrigated pastoral farms.
In New Zealand, fertigation has mainly been used in horticulture, viticulture and a few large-scale arable operations, while overseas, it’s used in arable and horticultural cropping systems. At low application rates itis known to distribute N more uniformly than granular fertiliser application.
But beyond that, its potential to help New Zealand pastoral farmers reduce their environmental footprint while maintaining farm viability and sustainability is still being investigated.
Recent trials have explored ways of maximising fertigation’s offer to irrigated pastoral farms. In Year 1 of the SFF project, fertigation did not result in an increase of dry matter (DM) across different N treatments.
In the first trial, solid urea fertiliser was applied and irrigated either immediately or two days later, or was fertigated (dissolved in water and applied with irrigation) onto perennial ryegrass/white clover pastures. Over eight months, seven harvests were taken, with each of the three treatments producing similar amounts of DM.
A second trial, looking at the frequency of N application, focused on the DM produced from N fertigated once a month compared to weekly applications, also on perennial ryegrass/white clover pastures. An identical total amount of N was applied in both cases – 25 kg N per hectare (kg N/ha) once a month or 6.25 kg N/ha per week. Both approaches produced similar amounts of DM.
Year 2 of the project will replicate the Year 1 trials, while taking into account environmental considerations, as well as the agronomic benefits considered in Year 1. Fertigation could allow farmers to apply N at the optimum time, when it’s most needed by the pasture and when environmental risks are lowest. As it allows smaller amounts of N to be applied more often, it could help to reduce losses and environmental impacts and, by matching N application to demand, improve the effectiveness to the pasture and profitability. This could have significant implications for ‘shoulder’ season N management.
This fertigation SFF project has begun with small plot trials at Lincoln University as well as on-farm monitoring at Pāmu’s Waimakariri Dairy Unit. Ballance Agri-Nutrients is collaborating with Irrigation NZ, the Ministry for Primary Industries, Pāmu Farms of New Zealand and others on the project.
Article supplied by Ballance Agri-Nutrients.