http://www.agric.nsw.gov.au/reader/nuts-berries/dpi331.htm
Well, we had to do this dot point by ourselves so I sort of bullshitted my way through it. I did Macadamia orchards in northern NSW. And I actually had three program/strategies because I thought it'd make up for the fact that it was really bullshit. Actually I was annoyed, when we were given the dot point to do as an in-class task I assumed she wanted at least a page, and most of our class handed up a paragraph. But.. meh. I can't be bothered to summarise it.
But when I handed it my teacher claimed it was a Band 6 answer.. which I have some serious doubts about.. but I'll put what I wrote up, and I'll give you the website where the information came from and you can make up your own mind.
Hope it helps!
Macadamia orchards in NSW inhabit over 6000ha of land. Most of the orchards are grown on krasnozem soil in high-rainfall areas of over 1400mm per year. However, the area's high rainfall increases the potential for erosion and nutrient leaching from soil. Factors such as heavy rain, loss of organic matter and movement of machinery used to crop the orchards all contribute to soil erosion to reduce the soil's ability to absorb rainfall and withstand erosion as well as to destroy the surface soil structure. It also contributes to the reduction of plant root growth, which in turn affects erosion. It is in places like these that farming and cropping is a vicious cycle. It is apparent when erosion has taken place as the fine roots of the trees are exposed to sloping sites.
However, three programs have been implemented to reduce the amount of soil erosion at these sites:
1. Controlling run off water,
2. Mulching, and;
3. Growing groundcovers
Run-off water at these sites is a major cause of erosion. Heavy rainfall allows water to trun down the tree trunk and along the tree-row, removing soil as it does and so exposing tree roots. This pathway for water often becomes a drainage channel if the rain continues on, and this increases the erosion. Runoff also carries away fallen nuts before they can be harvested. To combat this, contour or diversion banks are usually made, however due to the heavy rainfall nature of the area, new systems have to be made. In this case it is to run the tree rows directly downhill, as well as any associated drainage. This way drainage systems can be connected with natural water courses and diverted away from the orchards. Although established drainage systems that run downhill decrease the chance of water finding/creating its own drainage system, it is possible that the runoff, which most likely contains dirty and pesticides, will runoff into natural streams/rivers which in turn affects that body of water's ecosystem with the increased chance of algae growth. Erosion has been reduced, yes, but at what cost?
Mulching is not only used to reduce erosion, but improve the tree's health and crop growth. In fact, some farmers use the trees own leaf litter and prunings to mulch the trees. This protects the usually bare soil from the impact of heavy rain. Mulch also allows for the absorbtion of water, as heavy rainfall sometimes creates problems by simply removing top soil by hard hitting water-drops. Mulching is an effective system to reduce soil erosion, as prunings from trees and leaf litter can be used making it economically sound. But it it possible to admit that mulching only reduces a small amount of erosion, and by itself is probably not an effective enough measure. But combined with other methods, it can contribute greatly to the reduction of soil erosion.
Growing groundcovers is also used to reduce soil erosion. By growing such groundcovers, it stabilises the orchard floor thereby allowing usually bare soil to be kept together by the growth of the groundcover (sweet smothergrass and amarillo peanut have been used) It also reduces the amount of nutrient loss in runoff, as the soil where the groundcover is growing absorbs much of this runoff. Growing groundcovers is much like mulching, alone it may reduce the amount of erosion by a little, but combined with other methods used to combat erosion, it contributes greatly to reducing the problem. Growing groundcovers is an innovative measure that can be used to soak up runoff, increase soil stability and protect soil from heavy rainfall.
All these methods combined together to the reduction of soil erosion in macadamia orchards in northern NSW. It is proof that farmers are examining new methods to combat soil erosion on their farms.
