Pasture renovation - basics

This is the first in a series of four articles on pasture renovation by Dr Deric Charlton.

What is pasture renovation?

It’s a way of making pastures more productive, and there are several techniques you can use. We farm pastures intensively and they sometimes “run out”, losing their vigorous, most nutritious plants because of pest attack, disease, drought or mismanagement. Resowing them with a suitable seeds mixture rejuvenates the forage feed supply.

How much of the farm should you do each year?

Don’t take on more than you can handle. Some farmers don’t do any as their pastures are producing well because they manage them well. Other farmers may renovate 10-30% of their farms each year so their pastures are ten years old at most. For cost-benefits, see the section on Costs at the end.

When to do it?

Early autumn is best in North Island - when enough soil moisture has been replaced by rain, but before the soil temperature falls under 10 degrees C. Perennial ryegrass stops growing well below 6 degrees C. It’s important that new plants are well established before winter.

Spring sowing is best in South Island, after winter frosts have passed. Autumn-sown plants can be killed by frost heave. However, chicory grows best following spring sowing, and it can also be done in summer-moist North Island areas. But slugs will feed on emerging seedlings - and populations can reach one million per ha! That doesn’t leave much for the livestock.

Why do pastures need renovating?

• Some pastures don’t need renovating - they have been managed well and can remain productive for many years. Some British pastures haven’t been sown in the past millennium!
• Pastures can “run out” or become generally unproductive and reasons may not be obvious.
• The paddock has low soil fertility, and it’s not worth improving it, unless you have new productive pasture to make good use of it.
• To gain benefits from the latest pasture species and cultivars on the market.
• Unpalatable weeds have taken over and any remaining useful grasses and clovers are struggling.
• Treading damage (pugging) during winter may have killed off the productive grasses and clovers, and also caused damaged soil structure.
• Pests, such as grass grub, porina caterpillar, black beetle, clover root weevil, slugs and clover flea have killed off the valuable grasses and clovers.
• The grasses are infected with endophyte fungus (that grows inside the plant) and cause serious ryegrass staggers in livestock.
• Livestock grazing the paddock suffer seriously from pasture-related disorders, including facial eczema, zearalenone and pneumonia.
• The paddock needs levelling and/or draining.

Which method to use?

This is based on questions such as:

• How bad is the paddock?
• How steep is the paddock?
• Can it be rescued with minimal action?
• How much money can you afford?
• Do you want a long-term or a short-term fix?

Remember - “Well begun is half done.” Traditional gardeners sow three seeds - one for the weather, one for the bugs, and one for themselves. Farmers should sow at least three seeds, and maybe more if you’re sowing in hill country!