Ready, Set, Go!

Reduce digging losses with proper setup and field checks.

• By Amanda Huber •

digging peanutsOnce the decision to dig has been made and equipment is readied and pulled into the field, a quick field test is needed to put the final adjustments into place.

Clemson University agricultural engineer Kendall Kirk says that producers should synchronize the speed of their digger’s shaker chain, or conveyor belt, to their ground speed. If driving 2 mph, for example, the conveyor belt should be set to a speed of around 2 mph.

“Slower speeds should be used where digging losses are more likely, such as with larger pods, suboptimal maturity, heavier soils and drier soils,” Kirk says. “Driving too slowly will reduce your ability to dig on a timely basis; driving too fast can cause higher yield losses.”

Vine Growth Affects Speeds

Research conducted in 2016 by Kirk and others at Clemson found that digging losses for 80% to 110% of conveyor speed as a percent of travel speed were similar in both Amadas and KMC diggers in Virginia-type peanuts. Digging losses increased by 100 to 200 pounds per acre when conveyor speed was equal to 120% of travel speed.

In 2017, it was found that optimum conveyor speeds of 85% for both equipment brands in Virginias, with significant reductions in yield at higher conveyor speeds tested of 100%, 115% and 130%. Similar tests in runner-type peanuts suggested that optimum conveyor speeds for the KMC digger were 100% to 115%, with at least a 350 pounds per-acre loss in yield digging at 70%, 85% or 130%.

Kirk says the results suggest that lagging the conveyor slightly in excessive vine growth of Virginia-type peanuts, particularly, may be beneficial.

Field Testing Conveyor Speed

According to Kirk, a simple way to set the conveyor speed to match ground speed is to adjust it until the inverted windrow falls slightly, about 2 feet, down field from where the plants were growing. This can be assessed by placing a flag outside of the digger path at the beginning of a row and observing the location of the end of the windrow relative to the flag.

The check works best if the digger is engaged at full operating speed prior to entering into the peanuts. If the end of the windrow is several feet farther into the field than the flag, then the conveyor speed is lagging. If the end of the windrow is equal in position to or behind the flag, then the conveyor is faster than the ground speed.

Look For An Even, Smooth Vine Flow

Producers’ best resource in digger set up and operation is the owner’s manual that comes with the equipment.

The KMC operation guide offers the following guidelines on set up and operating speed.

“Adjust hydraulic speed to match with miles per hour of the tractor or as needed to allow for even and smooth flow of peanut vines up the conveyor. Make a partial pass in the field, then turn off machine and tractor or have someone following from behind to monitor machine performance.

“Check to be sure minimal peanut loss is found on the surface or down in the ground. Look at the inverted windrow to ensure that the tap roots are standing straight up in the air and not leaning to one side after inverting. If peanut vines are not inverting with the tap root up, adjust the vine rods to make a tighter windrow, and be sure that the cutting coulters are deep enough to fully cut the peanut vines.”

KMC says the proper speed of the conveyor can be adjusted by using the provided rear shaft tachometer readout and adjusting the hydraulic flow so that the readout shows 2.9 for a 3 mph tractor speed. The tachometer is programmed from the factory to give the correct readout for the speed relationship of 3 mph tractor speed, the normal operating speed.

Daily Checks For Machinery

Each day of digging should begin with a careful examination of the equipment. Amadas’ operator manual advises inspecting the following digger parts.

“The conveyor belt assembly, drive chain and conveyor rods are a part of the digger-inverter that needs to be checked daily.

Inspect conveyor rods for damage. Check for bent pins or rods. Repair or replace as needed.

“Inspect the conveyor belts’ tension and tracking. The belts should have approximately 2¼ inches of sag. Inspect the conveyor drive chain daily for signs of wear. Make sure the chain is properly aligned and with the correct amount of tension. Repair or replace a damaged chain as needed.

“Inspect the inverter drive chains daily for signs of wear. Make sure the chains are properly aligned and have the correct amount of tension. Repair or replace a damaged chain as needed.

“Inspect inverter rods daily for visible damage. Adjust rods if out of alignment. Replace or repair rods as needed.

“Scrapers are located at the bottom of each conveyor belt. Make sure each scraper is securely in place. Keep scrapers free from debris to ensure proper conveyor operation. As the scraper blades wear, it is important to adjust the placement of the scrapers to keep them close to the front idlers (1/16 inches) to prevent soil build up.

“Excessive build up on the front idlers will over-tension the conveyor belt and cause premature wear. Note that an excessively worn blade may be flipped so that the other side can be used.”

See the operator’s manual for additional daily and weekly checks.

Conveyor Speed Calculator

Current models of Amadas and KMC diggers provide an interface with a digital readout of the conveyor speed in miles per hour so that hydraulic flow rate can be easily adjusted to match conveyor speed to travel speed.

In absence of a digital readout, Clemson University’s precision ag team created a conveyor speed calculator. Through simple calculations and set up, producers can use this method to set conveyor speed relative to ground speed. The tool can be found at

Reduce pod loss and add to the bottom line with careful setup and testing of harvesting equipment.

Good Agricultural Practices At Harvest

• Inspect and adjust digger and sharpen blades. Set the blades with a slight pitch to cut the taproot just below the pods.

• Ensure uniform, fluffy, well-aerated windrows. Pods should not touch the ground.

• Carefully adjust combine for your field conditions. Read your operator’s manual for specific adjustments. Proper combine adjustment and speed will reduce pickup losses, percent of loose-shelled kernels, hull damage and foreign material. Excessive dirt and trash blown into the basket during combining will cause airflow restrictions during the curing process and may result in uneven drying and mold development.

• Combine efficiency depends upon several variables including windrow condition, cylinder speed, forward travel speed, internal adjustments and modifications for large-seeded peanuts. Impact and mechanical injury during harvest is largely associated with fast moving parts of the picking cylinder.

• Speed can be the enemy of peanut quality. Fast-moving combine parts may damage a high percentage of hulls and kernels. Both visible and non-visible damage opens the door to insect and mold infestations.

• Read more of the U.S. peanut industry’s Good Agricultural Practices on the American Peanut Council website at