Development of a Non-inverter Peanut Digger Shaker

A new digger prevents climate damages, and reduces the amount of peanut losses
August 22, 2014
Development of a Non-inverter Peanut Digger Shaker (Enlarge)


A unique non inverter peanuts digger shaker was designed and developed by the institute of agricultural engineering, ARO and commercially manufactured by an Israeli workshop company "Agromond" Ltd. The machine uproots the peanut plants; gently raise them from the ground, shake and clean them from dirt and organized them in a uniform windrow were the peanuts are on ground surface and the foliage cover them and protect them from climate damage. In comparison with an old peanuts digger, the new digger prevents climate damages because of the unique windrow structure. Field tests showed that the new digger also reduced the amount of peanuts losses at a higher work capacity.



Peanuts are grown in all soil types, 2 or 3 rows on high 1.93 m wide bed with nearly 9,000 plants per dunam (0.1 Hectare). During growth, plants stems are extended and their vines are connected which produce a rug of vegetation. The peanuts yield is harvested in two stages. At the first stage the plants are uprooted and placed on the ground for drying. After 7 to10 days the dry plants are threshed and the peanuts are harvested and send to the peanuts packinghouse. In Israel as in other countries, peanuts are uprooted using different kind of digging machines. In all of them, the uprooting system is based on penetrating the ground beneath the plants, cutting the roots, pulling the plants by their vines, shaking and cleaning them while being elevated and finally drop on the ground to build a windrow. The penetration and uprooting are made by stationary blades or rotating square rods. Pulling and elevating the plant are made by different conveyors like bar conveyor with cleats or a pair of belts or chain. The uprooting operation causes peanuts losses and usually the ripen peanuts are left in the ground. The amount of peanuts losses depend on the plant age and their health (Sanders and Bett, 1995, McNeill, 1996). The diggers drop the plants from a high level and use different accessories for building the windrows. They produce disorderly structure windrows or organized windrows were all plants are upside down with peanuts facing the sky or in a "sandwich" structure were the peanuts are in-between the foliage. In all types of windrows the plants are separated from each other, which cause peanuts losses and pickup harvesting difficulties. Comparison of peanut losses of three types of peanuts digger working in sandy and loess soils (Kashti Y. et al. 1995), showed that, peanuts losses could reached as high as 50 kg per dunam which is nearly 8% of the yield.

In Israel most of peanut fields are located at the western "Negev" that produces more than 70% of exported yield. In this area the microclimate during peanuts harvesting season are characterized in high sun radiation and dew. Most of the "Negev" peanuts grower uses an old peanuts digger shaker that produces non uniform and disorderly windrows.

Part of the plants in these windrow are partly upside-down or fully upside-down which exposed the peanuts to sun radiation and dew. Dew encouraged germination of fungi on peanuts shells and sun radiation blacken them. Israeli peanuts are exported in shell where white and larger peanuts are classified as high quality peanuts and get a higher price. Black and dark shell peanuts are not exported and sold at local market. The income from them is reduced by 60% in comparison to the exported peanut price. It is estimated that in this growing area, climate damages can affect 10% of the yield.

The objective of this research was to develop a peanuts uprooting system and to design and construct a new peanuts digger in order to prevent climate damages and reduce peanuts losses.


Development of the uprooting method

At the first stage of the research a field observations study on the old and common peanuts digger used in western Negev (Fig. 1) was made in order to test the uprooting work and to find why the plants in windrow are upside down or unorganized and what are the causes for peanuts losses. During the field observation it was noticed that the plants left the conveyor late at a high level when they were almost upside down. Furthermore, it was noticed that the machine raised the plants from ground to the conveyor by pulling the foliage. It was assumed that these pulling forces caused the peanuts losses.

The conclusions from these filed observation were: 1. it is necessary to cancel plant pulling forces in order to prevent peanuts losses; 2. conveying the uprooted plants back to the ground from low level directly (without any accessories) in order to prevent the plants upside down phenomenon; 3. using the leaf and vines to cover the fruit to prevent climate damages.



Fig. 1. The old peanuts digger at work


Developing the new non inverter peanuts digger shaker

Based on the conclusions drawn from field observation study, a tractor mounted new digger shaker was designed (Fig. 2) and constructed (Fig. 3). The tractor rides on a growing bad and pulls the digger. The digger continually uproot the plants, gently raise them while shaking them to clean from dirt and prepare a non invert, uniform and organized windrow. Two rotating square rod bars (1) dig and penetrate the ground beneath the plant, a first conveyor (2) mounted in moderate inclination with strong round rod bars, penetrate the ground too, gently raise the soil and plants and convey them to a double inclined square hollow structure bars conveyor (3) that shake them free of soil and convey the uprooted plants back to the ground where the peanuts are placed on the ground while the foliage cover them. Two closed vertical cylinders (4) are mounted behind the digger on two parallelograms with hydraulic reduced weight system, are rotated from ground, which reduces the width of the windrow to a size that is suitable for the pickup harvester. In front of the digger there is a depth control mechanism (5) that continually keeps the desired uprooting depth in order to prevent peanuts losses.

Fig. 2. Isometric view of new non inverter peanuts digger


Fig. 3. New non inverter peanuts digger in field


Field test and results

In the peanuts harvesting season of 2009, the new non inverter peanuts digger shaker was tested in comparison to the commonly used old digger at two farms in the western Negev area, uprooting peanuts grown in commercial fields. The comparison includes measurement of uprooting capacity, peanuts losses inside and on the ground and observation of climate damages present in the windrows. The first test (test 1) was conducted in loess soil while the second test (test 2) was performed in sandy soil. Each test has two treatments; uprooting plants with the new and the old digger from adjacent plots of growing beds. In both tests 1 and 2, peanuts losses inside and on the ground were collected by hands from 10 m long bed for10 times. Furthermore, in test 2, peanuts losses were harvested from both treatments plots by special harvester machine, which collect both inside and on the ground losses.

Both test showed that the new digger proved to produce a better windrow size and shape and all fruit were covered by their foliage (Fig. 4) in comparison with the windrows produced with the commonly used digger (Fig. 5). During all drying days of peanuts uprooted by the new digger no fungi on peanuts shell was observed.

Peanuts losses collected by hands from test 1 and 2 are showed in figures .6 and 7 respectively. Figure 8 shows the mechanically harvested peanuts losses from test 2. From these figures it can be seen that the total peanuts losses caused by the new digger was dramatically lower than that of the common old digger.



Fig. 4. Windrow produced by non inverter peanuts digger




Fig 5. Windrow produced by old peanuts digger




Fig 6. Test 1 peanut losses



Fig 7. Test 2 peanut losses



Fig 8. Test 2 mechanical harvested peanut losses




A new type of tractor mounted peanuts digger shaker was designed and constructed. The digger is a non inverter peanuts plant digger type, which produces uniform and organized windrows where the peanuts on ground are covered by their foliage.

Field tests showed that the new digger totally prevents climate damages and produce much less peanuts lose, even at a 15% higher field output.

The machine is a US patent pending no. PCT/IL2011/000134 and it is commercially manufactured by an Israeli work shop company.



The authors wish to thanks Mr. A. Vaza from Agricultural Extension Services, Kibuz Nirim and Moshvey Hanegev Organization for their corporation in this research.



Sanders, T. H.; Bett, K. L. 1995. Effect of harvest date on maturity, maturity distribution, and flavor of florunner peanuts. Peanut Sci. 22, 124-129.

Mc Neil, K.L. and Sanders, T.H. 1996. Pod and seed relation to maturity and in-shell quality potential in Virginia-type peanuts. Peanut Sci. 23, 133-137.

Kashti, Y., Nir, I., Barlev, E., Vaza, A. 1995. Testing of bars, belts and chain peanuts digger, Institute of Agricultural Engineering, ARO.




Y. Kashti, I. Sagi, F. Geoola, A. Levi, R. Brikman - The Institute of Agricultural Engineering 


(Published in ISRAEL AGRICULTURE, 2012)


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