Trees on farm

There are many options for tree species and locations to plant trees. However, it is essential to ensure you are planting the right tree species in the right place and are maintaining the planting to maximise the benefits to your farm. This page provides guidance and issues to consider when planting trees on a dairy farm. For further information, see Canopy – a government website with links to further planting resources and funding opportunities for on-farm planting.

General planting guide

Planting location

When considering tree planting, it is vital to take a holistic farm approach. Think about the future farm landscape, the additional benefits the plantings could provide, their role in wind management, potential shade issues in winter, and integration with riparian management planning. Some areas where it is common to plant trees are:

• Paddock boundaries
• Edge of races
• Corners in a pivot irrigated paddock
• Hard to farm areas e.g. ungrazed, dry, steep sidings and embankments
• Steep grazed or marginal areas
• In flat paddocks and paddock edges
• Gullies and areas carrying sudden deluges of water
• Edges of critical source areas, like low-lying swales (ephemeral channels)
• Loose or poorly consolidated soils (ash, sand)

Tree species

Different species of trees have different purposes, and knowing which tree to plant is critical for success.

Evergreens include most conifers, eucalypts, and native species. They create good shade in summer but in some areas can cause issues with winter shading and frost retention.

Deciduous trees with heavy leaf fall can create work in autumn if planted too close to buildings, gutters, and drains.

Make sure you are selecting trees that are not harmful to livestock or companion animals – check with your vet if you are unsure.

Some trees are also eligible for earning carbon credits under the New Zealand Emissions Trading Scheme (ETS), providing specific criteria are met.

See below for selecting species for shade and shelter, soil erosion and land stability, and pollination.

Preparation for planting

Good site preparation is essential for successful plantings, including spraying of existing vegetation prior to planting. On compacted soils, ripping may be needed.

Measure the planting area and order trees from a reputable nursery well in advance.

Be careful not to drain established wetlands – wet areas can be managed by choosing distinct species. If you are unsure, ask your regional council.

Establishing plantings

Planting is usually a winter activity, but depending on the species, some sites may be better planted in autumn or spring.

Large ‘standard’ trees may need staking at planting to prevent collapse.

Release spraying is recommended as long as necessary to establish the trees. Alternatively, weed mats or mulch can be used for individual trees or small-scale plantings.

Standard trees especially may benefit from irrigation. On dry sites, pipes should be installed in their root zone at planting.

Control problem weeds like gorse and blackberry. Spot-spraying planting sites to remove competing vegetation is also important.

Pests like rabbits, hares, deer, goats, and possums can all spell disaster for young trees. Try to minimise their numbers before planting and keep them low after that.

The Trees That Count website has extra resources that specifically address how to plan and establish plantings, so they have the best chance of success.

Fencing off plantings

Fencing off and/or protecting plantings to exclude stock is crucial for successful establishment, even with fast-growing exotics. Trees need protection from browsing or rubbing by livestock. Some trees are also toxic to livestock, e.g., acorns from oak trees can cause sickness in cattle, and macrocarpa needles can cause abortions.

Lines of trees can be fenced off, either temporarily or permanently. Electric fencing can keep belts narrow and you can lift the bottom wire of the fence once the trees are established to allow grazing underneath.

Individual trees need protection with hot wires or robust individual tree guards, especially if pests like rabbits and hares are a threat.

Tree pruning and maintenance

Pruning some species (removing all lower branches) means shade moves further into the paddock. This discourages livestock from camping at the base of trees, reducing the risks of soil compaction, pugging, and leachate loss from pasture.

Pruning dual-purpose shade/shelter belts requires careful thought. Reducing lower branches can cause the wind to speed up at stock height.

Interplanting shade belts with a row of low-stature trees (flax, pittosporums, coprosmas) can balance shelter with shade.

Shade and shelter

Suitable trees planted in the right place will provide excellent shade and shelter for livestock.

Trees planted for shade intercept solar radiation, reducing ambient temperatures by up to 10 degrees Celsius in summer. Contrary to opinion, providing shade does not result in animals spending less time grazing.

Also think about how the amount of shade changes depending on the time of year/day. The higher the sun is in the sky, the less the area of shade. At higher latitudes, e.g. Northland, the angle of the sun will be greater than at lower latitudes e.g. Southland – and the amount of shade created will be less, and vice versa.

Providing shade for as many animals as possible will help prevent large groups from gathering under too few trees as this can lead to high nutrient loading, soil compaction, and pasture loss.

The table below shows the length of shadow created by a selection of mature trees when the sun is at 70° - an angle that represents a mid-New Zealand location in mid-summer, in the middle of the day, and so is an estimate of the minimum length of shade created.

Choosing tree species for shade

Species choice will depend on many factors, including the site, type of planting and any co-benefits you are hoping to gain. In general, the best shade species are:

• Fast-growing
• Tall and broad
• Wind firm
• Without brittle branches

As a general guide, the taller the trees and the broader their crowns, the better. Trees with broad crowns provide significantly more shade than narrow trees for any given tree height.

Soil erosion and land stability

While all trees require some maintenance over their lifetime (pruning, thinning), trees are often an economical and sustainable solution for tackling soil erosion in the long term.

Areas on-farm best suited to soil conservation planting include:

• Gullies and areas carrying sudden deluges of water, edges of critical source areas like low-lying swales (ephemeral channels).
• Marginal hill country or steep lowland slopes ('too steep for the fert truck'). Here, consider reverting to forestry crops, tea trees (manuka, kanuka), or reversion to bush over the marginal production.
• Tunnel gullies where gullying collapses the soil surface, leaving holes connected by a tunnel (tomos). The Poplar and Willow research trust provides more resources for planting out erosion-prone hill country.
• Loose or poorly consolidated soils (ash, sand). Even in rolling, productive country (<15°), sheet erosion and mass earth flows can occur (slips, slumps). If fruitful, planting spaced trees and restricting grazing is good management, while retiring land from grazing to production forestry offers an alternative.

The Farm Forestry Association has in-depth resources on production forestry for pastoral properties.

How trees conserve soil

Trees improve land stability by binding soils with their roots, covering the ground with litter, preventing repeated drying/wetting or cracking, intercepting rainfall, and slowing runoff. For this reason, riparian planting often involves deep-rooted trees that can bind and reinforce banks, preventing them from slumping into waterways.

Effectiveness in controlling erosion will depend on the tree species, growth rate, age and spacing. The best soil erosion plantings establish quickly and have extensive root systems. On eroded, exposed, drought-prone sites, species choice is limited simply because few species will survive in these conditions. Similarly, only limited species will tolerate very moist land; swampy earth flows are prone to waterlogging and riparian areas that flood regularly.

The closer trees are planted, the sooner a site will be stabilised as roots grow and interconnect. The bigger a tree is, the larger its root system and the more soil it protects. Remember too that where trees and livestock coexist, closely spaced trees will require more regular pruning and maintenance to ensure pasture growth. Different species establish roots at different rates—this can be a crucial factor when rapid soil erosion control is needed.

Planting options

Leaving native vegetation cover on fragile soils and a buffer or riparian margin along waterways is the most effective way to prevent soil erosion before it occurs. However, if erosion is occurring, the table below provides some options to consider.

Pollination

Pollination is crucial to agriculture – 90 percent of the world’s food relies on pollination by bees and insects. Better pollination drives stronger clover growth and more productive grazing.

You likely know that bees collect and transfer pollen grains between male (anther) and female (stigma) plant parts. But did you know that bees practice flower fidelity? Bees tend to concentrate on one specific species of flower at various times of the year, even though, over the years, they are attracted to a large variety.

Flower fidelity makes bees very susceptible to the mix of trees on the farm. A good mix is necessary to support colonies from spring to autumn (hives hibernate through winter). If not, bee numbers can crash, reducing pasture and crop pollination.

Focus on plants that fuel bees through late summer and autumn into early winter. Spring and early summer is often catered for on farm by agricultural and horticultural crops.

Pollen sources in late autumn and early winter are the most valuable; they fuel the colony throughout its hibernation. More fuel for hibernation equals healthier and many more bees ahead of spring pasture and cropping pollination, rewarding you with more production on farm.

You can do two things to help:

• Consider bee-friendly planting options or components whenever planting trees. Trees for Bees has a wide range of in-depth resources to maximise the benefits of your plantings for bees.
• Talk to your local beekeepers about over-wintering on the farm ahead of spring pasture pollination.

Bee-friendly planting

All planting projects, whether riparian, shelter, or erosion control, can benefit bees. Choose what will work for your farm, considering the following:

• Choose plants to flower in spring-autumn. Note what flowering trees are on-farm already and when they flower and try to aim for trees that flower outside these seasons. By focusing on summer or autumn flowering trees, you can encourage greater pollination of spring pastures and crops.
• Bees like both natives and exotics. A mix of both benefits erosion control and can help fill holes in your farm pollen calendar.
• Remember that honeybees on most New Zealand farms are European species. Native bees will also pollinate exotic trees. Diversity is the spice of bee life.
• The nutritive value of some pollen (measured by protein content) is much higher than others.
• Some flowers are better shaped for bees to visit (e.g., land on, gain entry to, access nectar within). Bees are attracted to flowering plants, but inconspicuous flowers like willow catkins are also excellent pollen sources.

The table below is a bee-friendly list but it is only a sampler. Talk to your local beekeeper(s) and nursery, who can provide more detailed choices suited to your soils, climate, and region. As noted above, always aim for a flowering season mix.