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A commercial cotton contamination cleaner developed and used to combat the plastic contamination problem in Chinese cotton was tested to compare its performance at removing typical plastics found in U.S. cotton to that of conventional cotton gin seed cotton cleaners. Seed cotton “spiked” with pieces of shopping bags, single-layer non-tacky round module wrap (RMW), and three-layer RMW of various sizes was introduced into the machines. Overall, the contamination cleaner was more effective at removing plastic contamination than a conventional cotton gin stick machine and inclined cleaner. Increasing the airflow to the contamination cleaner improved plastic removal. Overall capture of plastic across all sizes and types increased from 16 to 48% when airflow was increased from 17,500 to 30,200 m3/hr (10,300 to 17,800 ft3/min). However, seed cotton captured with the plastic also increased from 1.4 to 34 kg (3 to 75 lb) per bale. Shopping bag material and one-layer non-tacky RMW (lighter, pliable) were more effectively removed than three-layer RMW (heavier, stiffer), and smaller plastic pieces were more effectively removed than larger pieces. All the machines tested removed about the same amount of cotton trash (about 13.6 kg or 30 lb per bale).

HighlightsReducing the ginning rate improved fiber quality properties.HVI color, leaf grade, and trash area were improved as the ginning rate is reduced.AFIS gave longer, more uniform, and lower short fiber content results with slower ginning rates.Economic benefits on lower ginning rates are negated by input cost, i.e., labor costs.Abstract. Fiber quality needs to be maintained as ginning rates and saw loadings increase. This study utilized two gin stands, which were each operated at three different Ginning Rate Levels to determine if there were significant differences in fiber quality as a function of ginning rate. As ginning rates were reduced, HVI results for leaf grade, trash area, and color grade, were significantly improved. AFIS measurements showed lower ginning rates resulted in longer fibers with less short fiber. Reducing the ginning rate on average from 7.36 to 4.10 bales/h (48.7 to 27.2 kg/saw/h) increased the lint value by $3.92 per 218 kg bale, yet the increase in lint value may be negated by increased labor and other costs due to the additional processing time per bale. Keywords: Fiber quality, Ginning rate, Short fiber content, Neps, Saw gin capacity.

HighlightsRelationships between seed coat fragments and other seed and fiber properties were examined among cotton genotypes.Genotypes in the study had a broad range of properties that were significantly different among genotypes.Seed coat fragment levels were significantly correlated with cottonseed fragility, fiber-seed attachment force, and ginning energy.Longer, stronger cottons tended to have higher seed coat fragment levels.Abstract. Seed coat fragments (SCF) are difficult to remove from ginned lint. Cotton genotypes vary in SCF levels, but details are lacking regarding the cause of SCF. This study examined ten genotypes with highly variable levels of SCF to find relationships between SCF and cottonseed rupture force, fiber-seed attachment force, and net gin stand energy. Results showed that the attachment force of the fiber to the seed increased significantly with SCF levels, and net gin stand energy consumption increased with SCF levels, suggesting fibers more strongly attached to seed were prone to SCF formation. Cottonseed rupture force was measured, but only one genotype with very low seed rupture force had increased SCF; otherwise, SCF increased with cottonseed rupture force. Unexpectedly, fiber length, strength, and micronaire were significantly correlated with SCF levels, indicating that the longer, stronger, cottons with lower micronaire in the premium range tended to have higher SCF levels. These results show that multiple, otherwise desirable factors may contribute to cotton containing high SCF levels. Keywords: Seed coat fragments, Cottonseed fragility, Cotton attachment force, Gin stand energy, Fiber quality.

HighlightsCotton gin saws 0.91 and 1.14 mm thick were compared.Thicker saws had approximately 10% lower processing rate at full motor load.Thicker saws used about 35% more energy to gin the same amount of lint.Abstract. Most cotton fiber (lint) is separated from the seed by gin saw teeth that pull the lint between metal bars (ribs). These ribs are spaced close enough to each other that the seeds cannot pass with the lint. Cotton gin saws are available in three thicknesses, 0.9144, 0.9398, and 1.143 mm (0.036, 0.037, and 0.045 in.). No data from controlled experiments has been published which compares the effect of saw thickness on the economically important performance measures gin processing rate and energy consumption. Two shafts were prepared by installing, at the proper spacing, 406 mm (16 in.) diameter saws of 0.9144 and 1.143 mm thickness for testing on a reduced-width (46-saw) Continental Double Eagle gin stand with constant rib spacing at the USDA-ARS Southwestern Cotton Ginning Research Laboratory in Las Cruces, New Mexico. Energy consumption was recorded for target processing rates 4.88 and 6.08 g saw-1 s-1 using pre-cleaned seed cotton grown in New Mexico, Texas, and Mississippi in a randomized complete block experiment with five replicates. On this equipment we found that the thicker saws averaged 90% (4.69 g saw-1 s-1) the processing rate of the thinner saws (5.21 g saw-1 s-1). Net ginning energy of the 1.143 mm gin saws was 26.5 W-h kg-1 compared to 19.7 W-h kg-1 for the 0.914 mm saws, or about 35% more energy. Results were consistent for cottons from all three regions. Thicker saws are less likely to break under harsh conditions at the ends of the gin stand and are still recommend for use there, but there appears to be no advantage with regard to processing rate or energy use to installing thicker saws across the full width of the gin stand if rib spacing remains unchanged. Keywords: Cotton gin, Energy use, Gin saw thickness, Processing rate.

HighlightsWe compared 0.91 to 1.14 mm thick gin saws by ginning seed cotton from three regions.The gap between the saw and rib was 0.914 mm for the thin saws and 0.800 mm for the thick ones.Response variables were tested using a sequentially reduced (backwards regression) model.Lint “turnout”, lint value, and seed damage did not appear to be significantly different due to saw thickness.Abstract. Over 95% of U.S. cotton post-harvest processing is done using saw gins. Gin saws have long been supplied in three thicknesses. We quantified the effect of saw thickness on lint turnout, lint value, and seed damage, variables that determine producer returns. Saw cylinders stacked with 0.9144 and 1.143 mm (0.036 and 0.045 in.) thick saws, the thinnest and thickest available, were operated in laboratory conditions on three cotton growths (cultivars and production practices) from Mississippi, New Mexico, and Texas in an experiment with five replicates. Fiber quality from samples obtained after lint cleaning was measured using High Volume Instruments (HVI). HVI results were combined with Commodity Credit Corporation Marketing Assistance Loan premium and discount tables to calculate fiber value. Seed damage was estimated after germination using Association of Official Seed Analysts rules. A backwards regression approach in JMP reduced each response variable’s model until only significant controlled and uncontrolled variables remained. Tested variables included: growth and saw thickness and their interaction; processing rate; processing energy; test duration; foreign matter content; moisture content; and ambient humidity and temperature. There was no significant difference in fiber value due to saw thickness. Seed quality differences were insignificant. Differences in lint turnout due to saw thickness also were statistically insignificant. Saw thickness selection may be based on other considerations. Keywords: Cotton gin, Cottonseed, Fiber quality, Gin saw, Saw gin

Highlights Principal component analysis found the impact of controlled and uncontrolled drying system variables. Cotton gin fuel use can be minimized by avoiding excessive drying and minimizing conveying air. Post-harvest processors should minimize the length of, and insulate, the duct from the burner to the mix point. Abstract. Fuel price volatility and variable incoming cotton moisture levels make drying costs unpredictable, threatening cotton gin profitability. One means for managing this risk is improving fuel use efficiency. Fuel use audits were conducted in 26 commercial cotton gins over three seasons to elucidate industry best practices. Material flow and changes in moisture content were used to estimate beneficial drying energy. Airflow and temperature data were used to estimate fuel consumption. The ratio of these quantities, defined as fuel use efficiency, was included with twelve other variables in a multivariate statistical analysis. Principal component analysis identified two controlled variables that inversely correlated to fuel use efficiency: the length of the duct between the burner and the seed cotton mix point, and the volume of conveying air per unit mass of seed cotton. Minimizing these two variables could reduce the cost of fuel energy, provided that the air volume is sufficient to maintain material flow, drying, and gin processing rate even when receiving very wet cotton. Keywords: Drying, Energy conservation, Fuel consumption, Postharvest processing, Principal component analysis.

Automation provides key benefits to production plants: increased speed of production, improved quality control, enhanced worker safety, and reduced production costs. Numerous types of systems use automated control throughout the world; in cotton gins, there are a few main systems that rely on some form of control: material flow, fire suppression, dryer temperature, press operation, and moisture restoration systems. This chapter provides an overview of control systems in general along with key examples of control systems in use in U.S. cotton gins.

HighlightsExperimental high-capacity seed-cotton reclaimers were evaluated for the growing high-speed roller-ginning industry.The experimental reclaimers minimized the amount of seed-cotton loss compared to the conventional reclaimer, but had more seed loss than a conventional reclaimer.The conventional reclaimer had the lowest combined seed and lint loss when processing Pima cotton.An experimental reclaimer based on a current cotton gin machine had seed and lint losses nearly $10 per cotton bale less than the conventional reclaimer when processing Upland cotton.Abstract. In a roller ginnery, a reclaimer machine removes partially-ginned or unginned seed cotton (carryover) from the mixture of carryover and ginned cottonseed that is expelled from the roller-gin stand during operation and returns the carryover to the gin stand for re-ginning. Conventional seed-cotton reclaimers are marginally adequate in their capacity to handle the increased carryover that high-speed roller ginning produces. Overloading a reclaimer often leads to choke-ups and downtime for the ginnery. The objective of this study was to develop and test high-capacity reclaimers. A modified 3-saw cylinder stick machine and a modified 2-saw cylinder gin-stand feeder were tested and compared to a conventional reclaimer. The saw-cylinders in the modified machines were operated at standard full speed, 1/2 of full speed, and 3/4 of full speed. Both Pima and Upland cotton were included in this study because there is a sizable amount of roller-ginned Upland cotton. Results showed that the experimental reclaimers reclaimed more carryover than the conventional reclaimer. An effective reclaimer will 1) reclaim carryover without also capturing residual seed that will likely be removed with cotton trash when returned to the gin stand feeder (seed loss) and 2) allow seed to pass through to the seed storage while minimizing the amount of residual carryover that escapes with the seed (carryover loss). The experimental reclaimers minimized the amount of residual carryover loss, but they had more residual seed loss than the conventional reclaimer. Increasing the saw-cylinder speeds of the experimental reclaimers decreased the residual seed loss but increased the residual carryover loss. Estimates of the value of the lost seed and of the lint on the lost carryover revealed that the conventional reclaimer had the lowest combined loss of $3.56 per bale when processing Pima cotton and the experimental 2-saw feeder with saw-cylinders operating at full speed had the lowest combined loss of $6.89 per bale when processing Upland cotton. The results suggest that losses of lint and seed may be further reduced by using a combination in series of different types of reclaimers to take advantage of each of their respective best features. Keywords: Cotton ginning, Roller ginning, Seed-cotton reclaimer.

A comprehensive gin maintenance program is critical to optimizing the efficiency of a ginning system and affects labor, energy, and maintenance costs; safety, downtime, daily throughput, fiber properties, and customer satisfaction. A comprehensive gin maintenance program includes a sound maintenance philosophy, downtime and repair documentation and guidelines, a dormant season repair program, ginning season preventive maintenance, and a ginning season repair program. Implementing a comprehensive gin maintenance program in dormant and ginning seasons will minimize the frequency and length of downtime. This will maximize throughput, reducing energy and labor costs per bale, benefitting both the gin’s customers and its owners. Example downtime, inspection, repair and preventive maintenance reports are provided.

There is a need to develop cotton ginning methods that better preserve length uniformity, a fiber characteristic that is critical with newer, more efficient air-jet spinning technology. This report summarizes results of harvesting and ginning studies within the past fifteen years that included High Volume Instrument (HVI) fiber length uniformity index (uniformity). The studies concluded that cultivar was an important determining factor and some production practices, such as early defoliation and stripper harvesting, could also reduce uniformity. Uniformity was not adversely affected by seed cotton cleaning machinery (cylinder cleaners and stick machines). Saw ginning reduced uniformity more than did roller ginning, from 0.8 to 2.0%. Uniformity was negatively affected by the saw-type lint cleaner, from 0.4 to 1.1% per stage. Moisture restoration before lint cleaning partially mitigated (0.5%) lint cleaning’s decrease in uniformity. Studies reviewed in this report suggest that most of the decrease in uniformity occurs at the saw-type lint cleaner feed bar. Although uniformity was not affected by lint cleaner grid bars, faster lint cleaner saw cylinder speeds did reduce uniformity. Roller gin-type lint cleaners reduced uniformity 0.2 to 0.8%, which was less than the reduction caused by saw-type lint cleaners.

Successful data acquisition on mobile platforms, such as tractors, requires the provision of protection for the sensitive electronics, as these platforms are inherently rife with electrical transients that have sufficient energy to cause damage to unprotected instrumentation. Unfortunately, though there are many protection options for industrial applications (i.e., those installed at 120VAC), off-the-shelf products for mobile protection are extremely limited and, after a survey, were determined to provide insufficient protection. The objective of this study was to identify the requirements for the protection of mobile platform instrumentation and equipment, and/or identify circuits that can perform this function. A literature review of electrical transients typical to automotive electronics was performed and circuit simulations were performed using open source software. Off-the-shelf circuit components were tested, via simulation, in various configurations until a design emerged that provided adequate protection from all surge classes. To ensure protection of valuable data, one of the design criteria was to ensure the circuit would continue to supply power to the personal computer (PC), and electronics, even during a load-dump event. The circuit was also designed to provide protection from electrical fast transients and electrostatic discharges. The reported circuit is capable of protecting a computer and data acquisition electronics installed on 12 VDC mobile equipment. This simple, inexpensive design meets Automotive Electronics Council requirements and uses readily available components without a specially fabricated circuit board.

New mexico pod–type green chile (Capsicum annuum) is one of New Mexico’s leading horticultural commodities. Cultivated acreage of green chile in New Mexico is threatened because of the high cost and insufficiently available labor for hand harvest. Therefore, mechanization is necessary to sustain the industry. Successful mechanization depends on harvester design coupled with plant architecture that optimizes harvest yield and quality. Harvested green fruit must be whole, unbroken, and unblemished for fresh and processed markets, so harvester design and plant architecture must maximize yield while minimizing fruit damage. In two trials conducted at the New Mexico State University Agricultural Science Center in Los Lunas, six cultivars (AZ-1904, Machete, PHB-205, E9, PDJ.7, and RK3-35) were evaluated for plant architecture and harvest efficiency with a double, open-helix mechanical harvester with two counter-rotating heads. Cultivars were direct seeded on 17 Apr. 2015 and 14 Apr. 2016 and managed according to standard production practices. Plant architecture traits, plant width, plant height, height to first primary branch, distance between first primary branch and first node, basal stem diameter, and number of basal branches were measured before harvest. Mechanical harvest yield components, which included marketable fruit, broken fruit, ground fall losses, unharvested fruit remaining on branches, and nonpod plant material, were assessed after once-over destructive harvests on 2 Sept. 2015 and 31 Aug. 2016. Fruit width, fruit length, and pericarp thickness were measured from a representative sample of 10 marketable fruit. In 2015, ‘AZ-1904’ and ‘PDJ.7’ had significantly (P ≤ 0.05) more marketable yield than ‘Machete’ that had the least marketable yield. No statistically significant differences were found in marketable yield in 2016. When both years were combined, ‘PDJ.7’ had significantly more nonpod plant material harvested and the plants were taller than all other cultivars. We found mechanical harvest performance to be significantly affected by plant height, with shorter plants yielding less marketable fruit. Despite differences in fruit wall thickness, no significant differences were measured in broken fruit. In 2015, ‘AZ-1904’ had significantly less basal branches per plant, reducing obstruction for the picking mechanism. Harvest efficiencies (marketable harvested fruit yield as a percentage of total plot yields) ranged from 64.6% to 39.3% during this 2-year trial, with the highest harvesting cultivars PDJ.7 and AZ-1904. In the future, all new mexico pod–type green chile breeding efforts for mechanical harvest must incorporate desirable plant architecture traits to increase harvest efficiencies.

Cotton post-harvest processing research requires moisture content determination for seed cotton, cottonseed, and lint. Methods for determining moisture content have changed and are no longer consistent between laboratories. This research compared standard procedures documented in 1972 and those currently practiced for finding moisture content by oven drying, and quantified the variability. Seed cotton from four modern cultivars (ranging from 9.4% to 36.8% foreign matter), lint, and cottonseed were brought from dry conditions, blended, and then stored for more than 30 days in a controlled environment (21°C, 65% RH) to reach uniform moisture content. Additionally, 150 seed cotton samples were placed in plastic zipper bags and sent by air freight to a distant location and back or stored on-site. Drying baskets (652 cm3) were loaded, in random order, with 25, 35, 50, 71, and 100 g seed cotton or 10, 14, 20, 28, and 40 g lint. Cottonseed was placed in 45 cm3 aluminum cups (10 g) or 800 cm3 aluminum baskets (50 g). Wet weights were determined in the controlled environment. After drying, replicated sets of seed cotton, lint, and cottonseed samples were weighed inside a drying oven and then outside the oven while still hot. Some samples were dried for twice the recommended duration. Sample location in the ovens was tracked. Weighing hot seed cotton samples outside the oven after drying increased apparent moisture content by approximately 0.5% due to air buoyancy; weighing lint samples outside the oven increased apparent moisture content by 1%. Smaller differences in apparent seed cotton moisture content were found when halving or doubling the amount of material in drying baskets or doubling the drying duration. Foreign matter had a minor influence on apparent moisture content. Storage for three days and shipping by air freight in plastic zipper bags did not measurably change the apparent moisture content of seed cotton. Sample location within the drying oven made no difference. Current practices are satisfactory if dry weight location is taken into consideration. Measurement uncertainty has decreased compared to 50 years ago, but the recommended minimum number of samples per treatment was increased slightly for greater statistical power. Keywords: Cotton lint, Cottonseed, Moisture content, Oven drying, Seed cotton.

Deep cryogenic treatment (DCT) has been known since the 1930s to improve hardness, fatigue resistance, and wear resistance of steel. While the effect of DCT on wear properties has been well documented, there is no consensus regarding the causal mechanisms, nor a widely accepted quantitative description of them. DCT transforms retained austenite into martensite and triggers the precipitation of fine carbides, among other things. We observed that DCT had a negligible effect on Young's modulus and the yield limit of high carbon spring steel. The observed microstructural changes (presence of specific dendritic inhomogeneities typical for inclusions of austenitic phase in non-treated specimens and homogeneous microstructure of treated ones) can serve for qualitative purposes only. However, we found that DCT led to a decrease in steel electrical resistivity which can be explained by noticeable differences between the resistivities of the martensitic and austenitic phases. We propose a micromechanical model for electrical resistivity which allows monitoring of the content of retained austenite and postulate that it can be used for other materials as well. We also observed increased resistivity after mechanical loading of the specimens, correlating with increased dislocation density caused by loading. This quantity can be used to assess the average dislocation density.

In agriculture, manure and cotton gin waste are major environmental liabilities. Likewise, grass is an important organic component of municipal waste. These wastes were combined and used as substrates in a two-phase, pilot-scale anaerobic digester to evaluate the potential for biogas (methane) production, waste minimisation, and the digestate value as soil amendment. The anaerobic digestion process did not show signs of inhibition. Biogas production increased during the first 2 weeks of operation, when chemical oxygen demand and volatile fatty acid concentrations and the organic loading rate to the system were high. Chemical oxygen demand from the anaerobic columns remained relatively steady after the first week of operation, even at high organic loading rates. The experiment lasted about 1 month and produced 96.5 m3 of biogas (68 m3 of CH4) per tonne of waste. In terms of chemical oxygen demand to methane conversion efficiency, the system generated 62% of the theoretical methane production; the chemical oxygen demand/volatile solids degradation rate was 62%, compared with the theoretical 66%. The results showed that co-digestion and subsequent digestate composting resulted in about 60% and 75% mass and volume reductions, respectively. Digestate analysis showed that it can be used as a high nutrient content soil amendment. The digestate met Class A faecal coliform standards (highest quality) established in the United States for biosolids. Digestion and subsequent composting concentrated the digestate nitrogen, phosphorus, and potassium content by 37%, 24%, and 317%, respectively. Multi-substrate co-digestion is a practical alternative for agricultural waste management, minimisation of landfill disposal, and it also results in the production of valuable products.

Gins have become more energy efficient. However, energy costs account for 25% of the total variable costs of ginning, including seasonal labor, increasing from 15% in 1994. Recent studies found that average electricity use at gins is approximately 35 kWh per bale, down from 53 kWh per bale reported in 1980. However, gins must continue to increase efficiency to remain profitable and consumers are increasingly concerned with the sustainability of textile products. This paper reviews recent research on energy use and conservation in cotton gins and offers suggestions on ways for gin managers to reduce energy use based on this research. Gins should focus on maximizing their ginning rate and sustaining this rate as much as possible during the ginning season. Increased ginning rates will reduce per-bale costs of not only electricity and fuel, but labor as well. Maintaining consistent material flow through the gin, matching equipment capacities, and minimizing downtime allows gins to produce more bales per shift. More than half the electricity at gins is used for material handling, primarily by the large centrifugal fans used to convey materials. The cost of conveying materials should be considered when designing or updating gins. Gins should use only the volume of air necessary for consistent conveying and adequate drying and need to eliminate unnecessary friction losses in conveying systems. To reduce fuel use, dryer control systems should be used to avoid excessive drying of cotton. Insulating drying systems might be economically feasible, particularly from the burner to the mixpoint. Gins also should consider strategies to reduce the prices paid for electricity and fuel.

The objective of this article is to review the literature and describe the current technology used by U.S. cotton gins for seed cotton unloading. Unloading systems supply the gin with raw material. Their essential functions are 1) to remove non-cotton materials such as protective covers used during transport and storage and large foreign objects such as dirt clods and rocks; 2) to break apart modules, which are compacted for transport and storage, so seed cotton is in small, loose clumps that can be dried more easily and cleaned; 3) to remove green bolls and some soil; and 4) to supply the gin with a steady, controlled flow that can be interrupted if there is a problem. Changes in the way harvested cotton is packaged in the field have resulted in significant changes in unloading systems in recent years. Current recommendations and best practices are presented.

Emission abatement cyclone performance is improved by increasing collection effectiveness or decreasing energy consumption. The object of this study was to quantify the pressure drop and fine particulate (PM2.5) collection of 1D3D cyclones (H = 4Dc, h = 1Dc) at inlet velocities from 8 to 18 m s− 1 (Stk = 0.7–1.5) using heterogeneous particulate as a test material at inlet concentrations from 3 to 75 g m− 3. Cyclone exhaust was passed through filters. Laser diffraction particle size distribution analysis was used to estimate PM2.5 emissions. Response surface models showed a strong correlation between cyclone pressure loss (Euler number) and inlet velocity and predicted a 46% reduction in pressure loss for a 25% reduction in inlet velocity (Stokes number). The model for PM2.5 emissions was less definitive and, surprisingly, predicted a 31% decrease in PM2.5 emissions when operating 25% below the design inlet velocity. Operating below the design inlet velocity (at a lower Stokes number) to reduce pressure losses (Euler number) would reduce both the financial and the environmental cost of procuring electricity. The unexpected co-benefit suggested by these trials was that emission abatement may improve at the same time, though other empirical trials have shown emissions to be independent of inlet velocity and Stokes number.

Fuel cost increases and consumption variability threaten gin profitability. Twenty-three U.S. cotton gins were audited to elucidate drying system components, layouts and process control strategies that made better use of fuel. Seed cotton samples were obtained before and after each drying system and the difference in their respective moisture contents was used to quantify drying. Air flow and temperature were measured to estimate fuel consumption in each drying system. The ratio of drying to heating energy indicated fuel use efficiency. For the commercial gins analyzed so far fuel use efficiency ranged from 3 to 38 percent. First stage systems averaged 21% and second stage systems averaged 9%. From the limited data available it was not possible to separate fuel use efficiency differences by specific dryer types. Gins with duct insulation made better use of dryer fuel, and the improvement was proportional to the fraction of duct length insulated. Fuel use efficiency also improved with burner proximity to mix point.

Growers and field scouts need assistance in surveying cotton (Gossypium hirsutum L.) fields subjected to thermal defoliation to reap the benefits provided by this nonchemical defoliation method. A study was conducted to evaluate broadband spectral data subjected to unsupervised classification for surveying cotton plots subjected to thermal defoliation. Ground-based reflectance measurements of thermally treated and non-treated cotton canopies were collected at two study Sites (Site 1 and Site 2) with a handheld hyperspectral spectroradiometer. The hyperspectral data were merged into eight broad spectral bands: coastal blue (400–450 nm), blue (450–510 nm), green (510–580 nm), yellow (585–625 nm), red (630– 690 nm), red-edge (705–745 nm), near-infrared (770–895 nm), and panchromatic (450–800 nm). Also, a broadband normalized difference vegetation index (NDVI) was created with the red (630–690 nm) and near-infrared bands (770–895 nm). For each study Site, two datasets were analyzed: (1) two-class case (thermally treated cotton observations and non-treated cotton observations) and (2) five-class case (thermally treated cotton observations and non-treated cotton observations and three additional classes created with the weighted average of the thermally treated cotton observations and non-treated cotton observations). The clustering algorithm referred to as CLUES (CLUstEring based on local Shrinking) was employed to automatically group the data into clusters without the user selecting the number of clusters. Cluster validation was determined with the average silhouette width; also accuracy was assessed with contingency matrixes. Clustering analysis worked well in dividing the data into appropriate groups, with the best cluster structure occurring for the NDVI. User’s and producer’s accuracies for the NDVI were greater than 86%, indicating an excellent classification. Findings support future endeavors to assess airborne and satellite-borne systems equipped with sensors sensitive to the wavelengths deemed useful in this study and unsupervised classification techniques that automatically determines the numbers of clusters to evaluate thermal defoliation of cotton fields. Published by Elsevier B.V.