William Mayfield, National Program Leader, CSREES, USDA 

Stripper harvesting Mid-South and Southeastern cotton seems to come in cycles. Those of us who have experienced a few cycles are tempted to think that the interest will fade away like it did before. To do so would be a mistake because of improvements in cotton production technology.

In an article published in 1978, I indicated that the two factors limiting the production of narrow row, stripper harvested cotton in the Mid-South and Southeast were: (1) reliable weed control technology, and (2) technology to control plant size. Today, both of these technologies are well established. Thus, ultra narrow row (UNR) cotton deserves a thorough scientific and economic evaluation.

Agronomic results, both from controlled experiments and on-farm experiences in the last few years, have shown increased yields, especially on marginal cotton soils. However, very little attention has been paid to ginning, marketing, and textile utility. Currently, research is focused on these areas so a complete evaluation will be possible soon.

Stripper harvesting is attractive to producers because it is less expensive than picking. The initial cost of the machine is about half the cost of spindle pickers and maintenance is much less. When the capacity of strippers is considered, the total costs per acre for stripping is about half the cost of picking, a potential savings of as much as $30-40 per acre. Strippers also get a higher percentage of the crop off the stalk. Excellent management of pickers can produce harvesting efficiencies of 95 percent or a little better. Average picking efficiencies are probably 90-92 percent of the crop, while strippers can get 97-99 percent. Generally, stripper harvesting efficiencies run about 5 percent higher than picker efficiencies. However, part of the difference in efficiency is low quality cotton. The spindle picker drops hard locks, and damaged locks which the stripper will put into the basket, lowering the average quality of stripped cotton.

Stripped cotton contains much more foreign material per bale than spindle picked cotton. Typical stripped cotton will contain about 700 pounds of foreign material while spindle picked will contain 100 to 150 pounds. A field cleaner on the stripper would be expected to remove about half of the foreign material, leaving about 350 pounds, three times the trash in spindle picked cotton.

Field cleaners are gin stick machines modified to handle the very high volumes they must handle in good yielding fields. The effectiveness of these cleaners is highly dependent on the moisture of the cotton, and they will choke if moisture is too high. Thus, the number of hours which strippers with field cleaners can operate during a day is somewhat less than a spindle picker.

Annually 1/4 to 1/3 of the U.S. crop is harvested with strippers, mostly with brush type strippers in 30-40 inch rows. Generally, the cotton produced on the Texas High Plains and in most of Oklahoma is stripped. Gins in this area are equipped to handle the extra plant material and ginning charges are higher to cover the additional costs. In recent years, some producers have purchased strippers equipped with field cleaners which reduce the foreign material content in the seed cotton. Ginning charges are generally based on seed cotton weight in that area, so the charges for ginning are reduced on field cleaned cotton. Because gins in the traditional machine picked areas are not equipped to handle the extra volume of trash, and all the producers in a gin community will not be using strippers, a field cleaner should be used on UNR cotton produced in traditional machine picked areas.

Harvesting Equipment
Currently, the headers used for UNR cotton have been salvaged from Allis Chalmers machines which are about 20 years old. These old headers have been mounted onto new strippers and sometimes painted to match the stripper. In many cases, these old AC strippers have been reconditioned and are being used. Finger stripper technology has not improved in at least two decades, but some manufacturers are now looking at improvements and several are offering updated headers.

Ginning UNR Cotton
In order to properly gin URN cotton, the ginning system should include more seed cotton drying and cleaning equipment to handle the extra foreign material (Figure 9-4, Ginners Handbook). In general, gins for picker cotton would need an additional stick machine or an additional combination burr and stick machine as the first cleaner. The second stage of lint cleaning is more likely to be needed for stripped cotton. Also, the trash handling system would need to be of higher capacity.

The more aggressive gin cleaning necessary to remove the increased foreign matter may slightly lower the fiber quality, but the differences in certain quality factors may not be detectable. Seed cotton cleaners do not cause much quality damage, but any cleaning has the potential to increase neps or short fibers slightly.

There are several potential problems for picker gins processing stripped cotton. Without the extra machinery in the system to handle the trash in the seed cotton, unsatisfactory levels of trash in the lint and excessive quality reduction due to bark are likely. Trash conveyors, pneumatic conveying lines, trash augers, and trash disposal systems will be overloaded. Increased trash content puts an extra load on the drying system, forcing a reduced processing rate. Too much trash will make it to the feeder where the feeder trash auger will be overloaded. More trash will accumulate in the roll box of the gin stand where it is chewed up by the gin saws, increasing the bark content of the lint and the trash content of the cottonseed. The high trash contents increase the repair and maintenance costs, contributing to higher ginning costs.

For gins that are not properly equipped, the only way to handle UNR cotton is to reduce the processing rate to match the capacity of the system bottleneck (driers, seed cotton cleaners, or trash handling system). This can cause very serious cost increases for the gin because the hourly cost of operating a particular gin is basically constant regardless of the processing rate. For example, a thirty-bale per hour gin requires no more energy or labor to process thirty bales per hour than to process twenty bales per hour.

Summary
Ultra narrow row cotton is a very hot topic among cotton producers who are struggling to find ways to reduce their costs so they can produce cotton at current prices. Controlled experiments and producer experiences have shown significant yield increased with UNR cotton, especially on marginal land. The reduced cost of stripper harvesting is widely known and somewhat exaggerated.

In order for UNR to be successful, several challenges must be met.

• Harvesting equipment must be improved
  
• Gins must be equipped to handle the extra foreign material. This is not a technology problem but an economic problem, especially if only a small part of a gin’s volume is stripped.
  
• The textile industry must determine the fair utility value of UNR cotton.
  
• The marketing system must relay the fair value to the producer.

Stripper harvested, narrow row cotton production systems have been tried many times, but the complete package of production technology has never before been available. UNR cotton seems to offer an alternative for some producers which can compete with other crops such as corn and soybeans. Thus, we should give UNR cotton a thorough, unbiased, scientific, and economic evaluation.