Covering exposed roots and improving soil health – an alternative approach
More than 60 people attended the MPC field day on September 8th 2011 at Lance Emery’s farm. The focus of the day was on the work Lance has undertaken to improve his orchards sustainability by using green waste mulch and compost to cover exposed roots. This has improved soil health, provided erosion control and given a good orchard harvesting surface.
This day featured demonstrations of a steam weeder, an alternative to herbicide use, and three different machines available for spreading mulch and compost.
The Field Day started with a demonstration of steam weeding by Karen Muir from Weedtechnics. (www.weedtechnics.com).
Steam weeding causes plant cells to rupture and die. It is a contact control method that only kills the parts of the plants it contacts. Therefore to get good control, it is best to target young weeds and initially frequent applications are necessary.
The steam for the applicator is generated by a diesel powered boiler. The boiler demonstrated uses 9.0L of diesel /hour. Travel speed is determined by the height of the growth being sprayed, with the initial application applied at approximately 1.5km/hr. Once into a program, this can be increased to 6km/hr.
Delivery of the steam for weeding can be carried out manually using a steam lance or mechanically with a circular applicator or a combination of fixed lance and circular applicator (see photos below and over the page).
The circular applicator is designed to allow it to revolve around tree trunks and thus completely eradicate all weeds and grass from between the trunk area.
The steam has an immediate effect on the appearance of the grass and weeds in that they appear blackened by the heating effect of the steam. It was explained that the steam heat has very little effect on the beneficial micro/macro organisms within the soil as the heat from the steam doesn’t penetrate into the soil unless the weeder remains in the one spot for a long period of time.
A section of a tree row with long grass was treated two weeks prior to the field day and the results were viewed on the day. The demonstration area showed the steam weeder had a good result in knocking the grass down. To improve the result, a follow-up application would be ideal. For the best results the weeder needs to be used frequently initially to counter the regrowth of weeds and grass from viable plant systems that remain in the soil.
The steam weeder appears to be a useful method for controlling grass and weeds in a macadamia orchard and with some modification to improve the application system for macadamia orchards could be a valuable tool.
Lance Emery’s story
Lance is an inventive farmer prepared to think outside the square. He’s developed some innovative orchard practices to improve soil health and soil erosion control.
Lance’s results are dramatic – no exposed roots, a fibrous root system that binds the soil and mulch together, a surface that is easy to harvest from and a high microbial diversity in the soil. His orchard practices are a credit to Lance’s hard work, dedication and love of his farm.
No chemical fertilizer
Most people are surprised upon seeing Lance’s healthy trees when he tells them he hasn’t used chemical fertiliser (excluding trace elements and agricultural lime) for nineteen years.
“In 2004 I started to work on a problem in my orchard that resulted from ‘stem flow’ washing the soil out from between the trunks of the trees with-in the tree row. This erosion exposed the trees surface roots and made harvesting difficult with nuts being lost in the trench between the trees and caught under the tree roots” said Lance.
Lance thought he might be able to fill this trench in with recycled organic material and turn the trench into a mound. After searching around for a viable source of material, Lance found a good supply at his local council.
In the first year, Lance spread chicken litter and then the recycled material over the top by hand. After seeing the results of putting this material down, he then purchased a Wallaby Spreader to make spreading easier. The material was not ideal and was difficult to spread with the spreader. To overcome this problem, Lance initially thought of a double conveyor design but was convinced by a machinery manufacturer to install a pair of spinners to the end of the spreaders conveyor system. This allowed him to place the material exactly where he wanted it along the trunk line of the trees. The draw back was that it was a slow process. Today Lance is still working on modifications to the spreader, to make it run faster.
There was an unexpected benefit from the placement of the mulch down the tree row, with the mulch material acting as a barrier to water movement sideways, slowing surface water runoff on side slopes. Mobile silt was caught by the mounds and actually built up on the tree row. From this work Lance now has a mound down his tree rows which was described by someone as a “hard sponge” – you can squeeze the material but when you try to pull it apart it won’t separate easily due to the large number of roots in it.
Lance now uses annual applications of about 20.0kg of chicken litter and 15 kg mulch per tree which continues to create a low mound of rich dark soil across the tree root system. When the surface is disturbed, surface feeder roots become very obvious. This soil abounds with life and earth worms are very easy to find.
Trees continually fed with nutrients
Lance has found since starting this system his orchard production has stabilised. “I can now expect no more than about a 5.0t variation in my crop from one season to the next and I think it is because my trees are continually being fed with nutrients from the decomposing mulch and chicken litter and they don’t get stressed easily”.
Husk is used in areas of the orchard where the trees look like they may need a bit extra nutrition or on individual trees that are not doing as well as others.
Diversion drains a key part
The installation of diversion drains throughout the orchard has also been a major part of Lance’s work to overcome soil erosion. These drains serve 2 purposes – to carry the bulk of the surface water away from a tree block – and to stop water entering another block in the orchard. These drains have helped prevent damage from occurring when there are heavy rainfall events.
Limb removal is carried out across the farm to allow the regrowth of grass on the orchard floor to reduce soil erosion. In the oldest block of trees, they have now regrown to a point that the grass has retreated to all but the best lit areas in the block.
As a result, Lance is now preparing to remove every second tree in every second row of this block. He has prepared for this operation by experimenting with ringbarking the trees that he intends to remove, hoping that they might crop well once more before loosing their leaves. Lance see the loss of leaves from the trees to be removed as making the trees easier to handle when they are cut down and a bonus to the biomass that will be left behind in the orchard.
There are also many other different ideas and innovations that Lance has undertaken on his farm. All of these have been aimed at improving the farms sustainability, both financially and environmentally. It is a credit to him and something he should be tremendously proud of.