Establish Shelter for Soil Conservation

Control of wind erosion is most effective when the establishment of shelter is undertaken in tandem with other sustainable land use practices such as minimum tillage and stubble mulching.

Typical Nutrient loss if 1cm of topsoil is eroded
Total N	350kg/ha
Total P	90kg/ha
Total K	1000kg/ha
Total S	60kg/ha
Total Magnesium	650kg/ha
Total Calcium	1050kg/ha
1 cm soil loss = 100 tonnes per ha

Shelter reduces wind speed and the risk of erosion.
Shelter reduces stress on stock and crops, improves irrigation efficiency and can provide a future timber source.

Four factors need to be considered when planning the establishment of shelter.

Orientation:	Windbreaks should be sited across the eroding wind for maximum effectiveness.
Permeability	To avoid causing damaging turbulence it is important that shelter filters the wind. This is achieved by planting at pre-determined spacings (e.g. 3m in a 2 row design) and pruning. A 50% porosity is optimum. Research shows that where wind velocity is halved the eroding energy is reduced by approximately 7/8
Length	The longer the windbreak the better the protection. Short (e.g. <200m) plantings have a disproportionate 'edge' effect where wind slips around the ends reducing the area of protection.
Height	Tall (30 m) shelter gives the most economic protection as the area protected is directly related to the height of the windbreak. Protection from wind extends for a distance 10-15 x tree height,

Wherever possible windbreaks should be sited to run with the lines of the land - the swales, terraces, valleys etc.

Shelter belts should not suddenly stop and start - plantings should link with other plantings, such as copses or woodlots.

Deciduous or open evergreen hardwoods are less harmful than conifers to areas with special values.

Remnant native area should be valued and extended. The use of local native flora may be incorporated into shelter design on some sites.

For more information on this subject contact Customer Services for a copy of our pamphlet "Establish Shelter for soil Conservation in Canterbury."