With the picking and ginning season underway, Cotton Ginners are sharing timely advice with growers to help achieve the best fibre quality and financial return.

Ginners say the way cotton is picked has a significant impact on both fibre and seed quality, with the quality of ginned cotton directly linked to the condition of the seed cotton before it enters the gin.

Regardless of the picking method used, ginners highlight the importance of correct machine setup and adjustment, well-trained operators, and careful timing of nutrient application, defoliation and picking. These factors all influence the amount of trash and moisture in the seed cotton—and ultimately, the final result.

Ginners recommend cotton growers consider the following quality considerations to ensure the best results for all:

Quality Considerations

1. Moisture

Increased moisture results in microbial/bacterial action which leads to colour degradation (spotting) and discoloration which affects the colour grade, with the fibre becoming yellower and less bright with trash adhering to the lint. Other fibre properties such as micronaire, length, strength and elongation can also be affected.

Seed cotton moisture also has a significant influence on seed quality, with an increase in moisture content resulting in a decrease in germination and vigour, due to an increase in free fatty acid content and aflatoxin level. Increased moisture content also leads to increased mechanical damage to the seed, resulting in an increase in the quantity and weight of seed coat fragments and mote.

Furthermore, during ginning, increased moisture also leads to increased gas usage, reduction in production, blockages, and the possibility of fires.

It is commonly accepted that seed cotton can be harvested with moisture levels of ≤12% without compromising the quality of the fibre and seed. It must be remembered that up to 2% moisture is added to seed cotton by the spindles to keep them clean and to enhance the adherence of the fibre to the spindle and allow for its removal by the doffer.

2. Module Staging

To avoid variability in fibre quality and processing performance modules should be staged, transported, and ginned in the sequence that they were harvested.

When transporting modules through harvested rows, the module should be carried high enough to minimise contact with those rows to prevent drag and tearing of underside of wrap.

Modules should be staged on well drained areas of bare soil, such as turn-rows. If the soil is wet, wheel slip by the truck can cause the loading chains to tear the plastic wrap.

Do not allow module ends to touch, as this will cause water to enter the modules rather than to run off down the ends. The modules should be aligned so that the centrelines are within a +/- 13 cm band. Gaps between modules also allow ventilation.

3. Contamination

Plastic contaminants can cause major problems, and it is essential to prevent plastic wrap making its way into cotton bales. The first step to address the problem of contamination, is to prevent/avoid or minimise the contamination entering the production process, particularly during growing and harvesting, through appropriate farm management and associated practices, for example:

• All workers should be made aware of the consequences of contamination and must be provided with the tools to clean up and isolate rubbish, for example provide garbage bins in which all waste is thrown and use only white cleaning rags.
• Where practical remove plastic and other contaminating debris from the field prior to harvest.
• Take into consideration the duration of storage (both on farm and at the gin), mode (flat bed or specialty trailers) and distance of transportation, when choosing the type and manufacturer of wrap. This being especially important as the quality of the round module wrap plays an important role in preserving fibre quality and minimising contamination.
• Repair any significant wrap tears in the field prior to loading on module truck to prevent further wrap damage and ginning problems.
• Loose outer tails must be secured with 3M™ Hi-strength 90 spray adhesive or lint bale repair tape.
• Tag modules and notify the ginner of potential issues caused by malfunctions during harvesting.

The Australian Cotton Ginners Association encourages growers to discuss their requirements with their ginner and even be present when their cotton is being processed.

Prepared by René van der Sluijs, CottonInfo Fibre Quality Technical Lead and current Treasurer of the Australian Cotton Ginners Association.