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Pasture renovation after major flooding events requires a careful and strategic approach. The page provides guidelines on how to handle different types of damage to your pastures, from lightly silted to completely dead, due to being underwater. Key steps include taking time to clear debris and unwanted material, selecting appropriate planting methods, planning for weed management, and applying the necessary fertilisers. Considerations like the species of grass to plant, soil aeration, nitrogen management, and animal health are also highlighted. Following these guidelines will help you restore the productive ability of your land quickly and effectively.
While a speedy recovery is important don't do a rush job as they usually get poor results. Do the job once and do it properly.
Previous experiences from major flooding events (e.g. Cyclone Bola, Manawatu, Waimana) provide the following guidelines on the approach to pasture renovation.
Pastures will be in a variety of damaged states from being lightly silted to being dead from having been under water for weeks. An assessment should be made, as the method used to get pasture growing again will vary depending on the type of damage. The type of pasture damage that can be expected and a summary of management practises to overcome these problems are outlined below.
Species: There will be a desire to get bulk feed quickly by sowing an annual ryegrass providing that perennial is undersown or regrassing carried out in the autumn. Some of the new hybrid and perennial species will establish with similar vigour but will persist for much longer.
Establishment: Aeration of the soil is essential especially where the land has been under water for some time. Ripping, drilling and conventional cultivation will give the best results.
Fertiliser: Much of the silt that covers your farm will have come from steeper hill country and will be of lower fertility. Capital fertiliser may be required. Sulphur is essential and with silting greater than 100mm additional phosphate will be required in the spring mix.
Nitrogen: Flooding causes a short-term deficit of nitrogen and sulphur in the soil. The rotting pasture also uses up nitrogen. Apply SOA or urea with sulphur either at the time of sowing or one week after the pasture has germinated at 150kgs/ha 50% urea; 50% SOA. Nitrogen is a key to getting pastures established and must continue to be applied at rates of 30-40kgs N/ha.
Remember, land is a remarkably resilient resource. Time and some strategic inputs will restore the productive ability of land remarkably quickly.