Reduce yield loss at digging with proper equipment setup and maintenance.
• By Amanda Huber •
From before the first seed is planted until harvest, producers work diligently to provide all the inputs the crop needs and protect it from pests. Digging is carefully planned with the help of Extension and the maturity board. The same preparation should be given to digger setup and maintenance.
Prevent Mechanical Losses
Clemson University agricultural engineer Kendall Kirk says that the majority of peanut losses at digging are from weakened peg strength, disease and over maturity and mechanical actions of the digger. Reducing losses requires digging at the proper time and accurate equipment set up.
On the digger, the top link sets the angle of the digger blades. For clay soils, a more aggressive angle is needed. For sandy soils, set the blades for a less aggressive angle.
If the top link is too short, the soil will be dug too deep causing excessive soil on the blades and pushing the plants. If the top link is left too long, peanuts are dug too shallow and pods are sheared off and left in the soil.
Tractor speed is another factor in digging losses. Driving too fast causes the plants to bunch up, whereas driving too slowly leads to ripping the vines apart. According to his study, the optimal ground speed for digging Virginia peanuts is 2 to 2.5 miles per hour. For each mile per hour above that target speed, digging losses increased 200 pounds per acre.
Kirk also says growers should synchronize the speed of their digger’s shaker chain, or conveyor belt, to their ground speed. If driving 2 miles per hour, for example, the conveyor belt should be set to a speed of around 2 miles per hour. A conveyor belt running about 20% faster than ground speed can result in yield loss of 100 to 200 pounds per acre.
Look For Problems Prior To Operation
Before a speed can be selected, a thorough inspection of the equipment is a must. Inspect the digger-inverter for broken, bent or missing parts before making adjustments. Make sure the front tool bar is level with the tractor.
Stand at the rear of the machine with the implement raised and sight the top of the tool bar with the top of the rear axle. For accuracy, first be sure the rear tractor tires are inflated to the same pressure. If the tool bar is not parallel to the tractor axle, level the digger by adjusting the lift arm.
Next, inspect the blades. A well-adjusted digger will have sharp, flat-running blades set to clip taproots just below the pod zone where the taproot starts branching. Blades should run level, with a slight forward pitch to lift plants into the shaker. This adjustment can be accomplished best on a flat surface.
Excessive pitch of the digger blades may result in soil and pods being carried forward by the blade before being freed by the cutting edge. Such pods are usually lost. Dull blades cause most digging losses because they fail to cleanly cut the taproot and may drag the roots, dislodging pods from the plant.
Forming A Good Windrow
After plants pass over the digger blades, they are transferred onto the shaking conveyer. This should be set at a depth at which it picks up vines with its teeth just clearing the soil. Check the conveyer chain speed and depth. The chain speed should be set to avoid a pileup of vines ahead of the pickup point and allow a smooth flow of vines through the digger-inverter.
In the field, note the shaking action. It should be only enough to remove soil from the vines. More aggressive shaking is needed where soil clings to pods, roots and stems. The amount of shaking can be changed by adjusting knocker wheels up or down.
As vines exit the shaking conveyer, they engage the inversion wheels and rods. These rods are factory set; however, they will change position with use. Adjust the inversion rods before going to the field by placing the digger on a level surface and setting them according to the operator’s manual. Properly inverted peanut plants will form a uniform, well-aerated windrow with few pods touching the soil.
From Midseason To Harvest
• Apply herbicides when weeds are small for maximum control.
• Be timely with inputs, especially fungicides.
• Keep up with irrigation needs, particularly during peak bloom and pod fill.
• Apply gypsum for needed calcium unless lime was used at planting.
• Know the insects likely for the weather conditions and scout often.
• Consider using a weather advisory for leaf spot.
• Maturity can be sped up or delayed depending on conditions.
• Don’t dig based solely on days after planting or before a freeze or frost is forecast.
Factors Effecting Peanut Loss
1. Blade depth too shallow.
2. Dull blades that do not cut cleanly through the taproot. Pods will be lost if the plant is pushed through the soil.
3. Vine cutter springs too loose or coulters too dull.
4. Conveyor pickup running too high above the lifter rods.
5. Tractor RPM or hydraulic flow too fast.
6. Vine flow not synchronized with ground speed and conveyor speed.
7. Inverter not aligned with the row (indicated by tap roots leaning left or right).
For more information on harvesting equipment, consult your equipment owner’s manual or University of Georgia Extension publication “Peanut Digger And Combine Efficiency” at www.ugapeanuts.com.
