Drainage treatments in trial blocks at T&G Global’s Evenden orchard and Bostock’s Red Barn orchard. The narrow window between finishing harvest and the soil becoming too wet to work was longer than anticipated this autumn making the task easier. All earthworks were completed and pasture re-sown. Vehicle access was restricted to allow the pasture to establish and soil to settle.
A range of treatments was included and implemented to compare to the new land shaping approach including Crasborn’s harrow and planter (Figure 2) and Aqualine V-blade, slotting and ripping and rut filling (Figure 3).
GPS Levelling
Land levelling is a proven technique more commonly used in cropping, where soil is moved around to create fall across a field and allow surface water to drain off. Growers use this approach to reduce water lying on the surface and saturating areas of crop which results in reduce yield. Software is used that is specifically designed to minimise and optimise movement of soil. The height of the blade or scoop used to cut and fill soil is controlled by software through the tractor hydraulics. The same principles are being applied to existing orchard rows to create fall along the inter-rows and drain surface water off the block.
The inter-rows were rotary hoed to create a suitable tilth, to allow small volumes of soil to be moved along the inter-row (Figure 4). The elevation profiles indicated that only light shaping would be required to create fall along the inter-rows, where 100mm would be the maximum change in height (cut/fill) necessary.
Hugh Ritchie’s Trimble RTK-GPS base station was set up in the orchard. Patrick Nicolle’s Trimble FMX unit with WM-Drain software was mounted on the T&G and Bostock tractors. A GPS Control Systems Trimble GPS antenna was mounted above Gene Williams’ 2.5m wide levelling blade, see Figure 1. The tractor hydraulics were used to control the blade height.
WM-Drain was used to record the elevation of each section in the orchard. An accurate RTK-GPS elevation profile was recorded by driving along the inter-row and the WM-Drain software used to generate the optimal profile (Figure 5), within specified parameters, such as minimum slope.
Soil was shifted using the blade to cut and fill areas to achieve the optimal profile designed in WM-Drain. Because the tractor hydraulics were not suited to automation without major changes, the blade height was manually controlled using the tractor hydraulics and lowered or raised. Multiple passes (up to six) were required along each row to move soil to create the desired profile. The results of the land levelling are shown in Figures 6 and 7.
Figure 6. Examples of inter-rows after land levelling has been completed
After earthworks the alleyways were re-sown in pasture. Vehicle access has been restricted to allow the pasture to establish and soil to settle. Timing is important to ensure orchardists can access blocks to continue their yearly programme in a timely manner, without damaging the newly formed alleyways.
The Crasborn machine cultivates and pulls soil from outside the wheel tracks using a set of angled discs. Harrows are used to break up and smooth the soil. A levelling bar with raised sections above the wheel tracks is used to further even out the soil. A compressed air seeder is used to sow pasture along the inter-row. Finally, a cambered roller creates a crowned inter-row and compacts the soil surface. The all in one implement (Figure 2) completes the final product (Figure 7) in one pass.
