Survey of Pinto Bean Harvest Losses in Northeast North Dakota
June 18, 2008
By Terry Gregoire, extension area cropping system specialist; Scott Knoke,
Benson county extension; Lionel Olson, Grand Forks county extension; Bill Hodous, Ramsey county extension; and Terry Lykken, Towner county extension.
Pinto bean production has become a stable feature of crop production in northeast North Dakota. It is estimated that 328,000 acres of pinto beans were planted in nine counties in 2007. Due to prostrate growth habit, the majority of pinto beans are harvested by first cutting the beans and windrowing or directly picking up the cut beans from the row after cutting.
In recent years, there has been an increased interest in harvesting pinto beans without underground cutting. Grower desire to not undercut plus several technical innovations have both assisted and accelerated the interest in direct harvest. No-tillers are concerned about soil erosion yet would like to include pinto beans in the rotation. However, they need to avoid the tillage and residue loss that accompanies the cutting operation. In addition, growers would like to reduce harvest cost by not purchasing or leasing specialized cutting machinery and also reduce time devoted to the underground cutting operation.
Technology developments have also encouraged less undercutting. A few varieties of pinto beans have been recently released that have an upright architecture (type II A) similar to black beans. This offers promise of much reduced harvest loss due to higher pod set than traditional prostrate growth pinto beans. Innovations in reel designs such as air assisted reels, rake reels and brush guards for combines and swathers have increased the efficiency of picking up dry bean vines and reducing shatter loss from above ground cutting. Ground rollers that press rocks into the ground have become common. Using this practice greatly reduces the risk of stones and rocks getting into the combine and allows closer cutting to ground surface.
Despite recent innovations growers are reluctant to change harvest techniques primarily due to unacceptable harvest losses that generally accompany dry bean harvest without underground cutting. The losses have been estimated by growers but numbers are highly variable and generally disseminated by coffee shop talk with no documentation. Growers are left with very few facts to help them in making decisions about harvest methods.
Survey Plan and Methods
A survey of dry bean fields was conducted following the 2006 and 2007 harvest to obtain harvest loss data from randomly chosen fields in Ramsey, Benson, Towner and Grand Forks counties. Data obtained was intended to help answer the following question. What is the difference in seed loss after combine harvest, if any, between underground cutting and above ground cutting techniques? Eighteen dry bean fields were randomly surveyed in Towner, Ramsey and Benson counties following combining harvest in 2006 and twenty two in 2007 for a total of 40 fields. Twenty one fields were undercut and 19 were direct cut without undercutting roots. A metal hoop of 1.23 sq ft was randomly tossed either behind the combine on the harvested residue pattern or in between the combine residue pattern. Five sampling locations were selected in both areas for a total of ten samples. Beans were counted as shelled or those left in a pod. Pounds per acre were calculated based on 1600 seeds per lb for pinto beans. The area represented by each sample varied among fields and was estimated by measuring the residue distribution width behind the combine. This distance was used to calculate losses directly behind the combine and the remaining width used to calculate losses between the residue swaths.
Several methods are currently used to underground cut/swath/pickup dry beans. All these techniques were grouped together in this study. There are also several methods to cut dry beans above ground. Swathing, flex head or floating header bars, etc. were all grouped together as direct cut for the purposes of this survey.
Average harvest losses were similar for both years and higher for direct cut methods (Table 2) than undercut methods (Table 1) due to a larger seed and pod loss measured in the area between combine harvest swaths. Losses behind the combine were similar for the two methods. This would indicate that direct methods have a tendency to shatter more in the cutting and gathering operation compared to undercut. The range of losses was also greater for direct cut methods than undercut methods.
However, the data does show that losses for both methods can be lowered when techniques are used to reduce losses. Total losses for the best three undercut fields averaged 24 lbs/acre in 2006 and 53 lbs/acre in 2007 while the average loss for the worst three was 218 lbs/acre in 2006 and 194 in 2007. Direct cut beans averaged 129 lbs/acre loss for the best three fields in 2006 and 112 in 2007 while the worst three averaged 347 lbs/ acre in 2006 and 384 in 2007.
Regardless of harvest methods, it appears that approximately 200-250 lbs per acre could be saved if the best harvest techniques that were applicable are used. Some techniques used by growers in direct cut systems to reduce harvest losses include:
1) rollers to submerge rocks.
2) upright bean architecture.
3) timely cutting when pods are tough at correct maturity or following dew or rain events.
4) appropriate modifications to sickle guards and keeping sickle blades sharp.
5) improved reel design for swathers and combine headers that reduce shatter losses.
6) establishing uniform and dense populations; using desiccation to reduce maturity differences and allow more harvest volume.
7) Cutting at an angle to the row.