What generates losses in cotton harvesters

When the operator increases the speed of movement of the cotton picker, he consequently increases the possibility of leaving product in the field.

Cotton is one of the most cultivated plant species in the world and is currently produced in more than 60 countries, with emphasis on China, India, the United States, Pakistan and Brazil, which are the largest producers, respectively. Brazil is the third exporting country and the first in rainfed cotton productivity. Domestic demand is also promising, being the fifth largest consumer of cotton in the world (Abrapa, 2012).

In the survey carried out by the National Supply Company (Conab, 2016) for the 2016/17 harvest, the area cultivated with cotton in Brazil is more than 950 thousand hectares and points to a reduction in the planted area of ​​2,5% in the 2015 season. /16, when compared to the previous exercise.

The state of Mato Grosso is the largest Brazilian producer of cotton, responsible for 57,6% of the production of the species in seeds in the 2015/16 harvest, where the majority of cotton farmers plant second-crop cotton, due to the high volumes of rainfall during the first cotton sowing period (Conab, 2015).

According to the sixth Conab survey (2016), in Mato Grosso cotton will register an increase in the planted area this year, reaching 2,7% in relation to last season, driven by the increase in planting in the western region of the state. Productivity expectations will be within the historical average of 4.100kg/ha for long-cycle cotton (first harvest) and 3.951kg/ha for dense cotton (second harvest).

The cost of producing cotton crops increases every year due to high input costs and the use of late-cycle cultivars, which require cultural treatments for periods longer than 200 days in many cases. An alternative to avoid the increase in production costs would be the use of high-technology seeds, which can increase productivity by around 50%, and reduce losses during mechanized harvesting (Ferreira, 2007).

A very important step within the cotton production process is harvesting and, when carried out inappropriately, it can cause quantitative and qualitative losses in the final product (Eleutério, 2001).

The cotton plant has indeterminate growth, and depending on the environment and management adopted, plants can be obtained with architecture that favors harvesting, increasing productivity (Oosterhuis, 1999). Still according to the author, other factors can influence losses during harvest, such as ripening point, harvesting conditions, machine settings, harvesting speed, plant size, type of machine, type of soil, variety and climatic factors. . According to Vieira et al (2001) the maximum acceptable loss in cotton harvesting is 10%, with an ideal range between 6% and 8%.

During mechanized harvesting, quantitative losses occur in the order of 15% to 17%, while during manual harvesting these losses do not exceed, on average, 5%. When it comes to qualitative losses, mechanized harvesting reaches 35%, and manual harvesting reaches 5% (Embrapa, 2006).

To evaluate losses in the mechanized harvesting system, a group of researchers from the Federal University of Mato Grosso carried out work with the objective of diagnosing losses in cotton harvesting as a function of the harvester's travel speed in the 2012/2013 and 2013/ harvests. 2014.

THE EXPERIMENT

The experiment was conducted in the 2012/13 and 2013/2014 harvests, in the production field at Fazenda Aeroporto, located in the municipality of Sinop (MT). The Köppen classification for the region is an Aw climate, tropical savannah, proper, with summer rain and dry winter, characterized by average temperatures of 24°C, with average annual rainfall of 2.500mm.

The assessment of losses in mechanized cotton harvesting took place in the months of July 2013 and July 2014, with a John Deere cotton picker, model 9996, with 257,43kW (350hp) engine power, platform with six lines of harvesting unit, and which used the picker harvesting system. The traveling speeds of the evaluated machine were two, 1,14m/s and 1,36m/s (4,1km/h and 4,9km/h) and the cultivated varieties were FM 951LL and FM 975WS, sown at a spacing of 0,73 .0,76m and XNUMXm, respectively.

The FM 951LL and FM 975WS cultivars belong to Bayer Cropscience, with an intermediate to late cycle, ranging from 150 to 190 days, with medium/high plant size and a fiber yield of 39% to 40% (Bayer Cropscience, 2014).

To estimate the variables, a template measuring 0,5 meters wide and 3,8 meters long was used. A plot was selected that represents the property as a whole. In this plot, plants contained within the template were sampled at five random points.

The sampling to survey losses was divided into two stages, the first consisted of collecting data relating to the estimate of Pre-Harvest Losses (PPC), before mechanized harvesting, and the second stage was carried out after mechanized harvesting through the collection of Total Loss (PT) estimate data.

To determine pre-harvest losses, all the material that was lying on the ground inside the template was manually collected. To determine total losses, all the material that was inside the same template used to determine pre-harvest losses and that remained in the soil and on the plant after passing through the harvester was manually collected.

To determine productivity, all bolls present on all plants contained in the space delimited by the template were manually collected, before the harvester passed, that is, without post-harvest losses, thus representing maximum productivity.

The duly identified material upon arrival at the laboratory underwent a cleaning process, was weighed and the humidity of the samples was determined. Moisture was determined by the gravimetric method, and the samples were removed for this purpose, weighed wet and dried in a forced air oven at 70ºC, until constant weight (Ferronate et al.

The simple random sampling method was used (Vale et al, 2009) to be able to infer the population about the variables studied. The treatments consisted of two travel speeds: 1,14m/s and 1,36m/s (4,1km/h and 4,9km/h). For each treatment, 16 replications were used, totaling 48 experimental plots. The total area used in the experiment was 2,94ha, in each evaluation. The results obtained from the losses were subjected to analysis of variance using the “F” test and the means were compared using the Tukey test at a significance level of 5% probability, using the statistical application Saeg 9.0 (Ribeiro Júnior, 2001 ).

RESULTS OBTAINED

The seed cotton productivity results came from the manual harvest carried out in each plot, before the harvester passed through. The average water content in seed cotton at the time of harvest was 6,8% and 7,9%, in the 2012/2013 and 2013/2014 harvests, respectively. (Figure 1)

Productivity values ​​differed significantly between cultivars. Cultivar FM 951LL had a higher yield than FM 975WS.

Comparing numerically the productivity of these two crops with the average for the state of Mato Grosso in the 2012/13 harvest, presented by Conab (2014), it is noted that the property presented a real productivity higher than the state average, which was 3.915kg/ha in the 2012/13 harvest. In the 2013/2014 harvest, it presented a productivity below the state average, which was 3.934kg/ha (Conab, 2015).

When manually harvesting to obtain productivity, pre-harvest losses were evaluated (Figures 2A and 2B).

In the 2012/2013 harvest, pre-harvest losses were greater, however, it was not relevant to negatively affect the crop's real productivity indices.

The pre-harvest losses found in the 2012/2013 and 2013/2014 harvests (Figure 2B) are in line with the results found by Belot et al (2002) for the state of Mato Grosso, which is between 0,50% and 4,79%.

Total loss increased with increasing travel speed, observing statistical differences between speeds in the two harvests (Figures 3A and 3B).

In the 2012/2013 harvest, with the increase in speed from 4,1km/h to 4,9km/h, there was an increase of 12,11% in total loss. In the 2013/2014 harvest, the increase in speed from 4,1km/h to 4,9km/h resulted in an increase of 19,23% in losses. In percentage points, the total loss was greater in the 2013/2014 harvest due to the speed of harvest.

The high loss rates (11,9%) were probably due to inadequate adjustments of the harvesting and shredding mechanisms or the plant compression plates on the harvesting drums, which must be checked and adjusted so that the spindles harvest as much seed cotton as possible.

Based on data obtained in the field, it is possible to state that higher speed resulted in greater total loss. Even so, the total losses found in this work are within the limit considered acceptable for mechanized cotton harvesting.

 

Gabriela de Faria Veiga Viotto, Welington Gonzaga do Vale, Diego Augusto Fiorese, Solenir Ruffato, Geraldo do Amaral Gravina, Adailton Nogueira da Silva Júnior, UFMT

Article published in issue 169 of Cultivar Máquinas