Comparison of harvesters with draper and conventional platforms

Evaluation shows that draper platforms make it possible to work at higher speeds than operating with conventional platforms and also reduce the level of product losses in the field.

Mato Grosso is the largest soy producing state in the country, with soy grown in large areas, requiring machines capable of supporting this production system. Mechanized grain harvesting is one of the most complex mechanized operations and is one of the most important steps in agriculture due to its high added value, with high-cost operations, as its adequate execution contributes to the return on investments made throughout the production cycle of a crop.

The need to adopt mechanized grain harvesting was due to the increase in the world population and the need to produce more food. The harvesting process must be carried out when the crop reaches its physiological maturity point, this way the producer will have better quality grains and make it easier to harvest this material in the field.

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As harvesting machines became important, mainly for soybeans cultivated on a large scale and with the aim of reducing the time of the crop in the field after the harvest point, some standards were sought within the projects of new machines, such as increasing operational capacity, reduction of grain losses, adaptation to terrain and crop conditions, implementation of technology and reliability.

On this topic, research has been reported in the United States since the 60s with the aim of reducing these limiting factors. In Brazil, during this period there was almost nothing in terms of research and industry, and from the 2000s onwards there was a real revolution in these machines, adopting all available technology.

Currently, the market offers harvesters with high operational capacity and models that allow this variable to be considerably increased by increasing the platform width (machine working width), increasing the grain tank, promoting fewer stops for unloading, and reducing grain unloading time. The reduction in losses was achieved through better adaptation of the platforms to the conditions of the terrain, crop and cutting height, better threshing and cleaning systems such as axial systems. The increase in engine power also allows for greater speed and better functioning of the systems, achieving reliability. All this with lower fuel consumption.

These machines also feature an increase in microprocessed systems, that is, on-board electronics, with autopilot, GPS system and use in Precision Agriculture for production mapping that transforms harvesting into one of the most automated operations in the agricultural system.

Within this concept, the platforms, considered one of the systems that cause the greatest grain losses inside the machine, have seen a surprising advance in the new models, with a considerable increase in size, control and adaptation systems, gaining flexibility to adjust to the terrain and environmental conditions. cutting height, among others.

In general, the platform model considered conventional presents a power system composed of a helical conductor, with a worm also called “snail”. Conveyor belt platforms with rubber, known as draper, promote better feeding through greater loading capacity of harvested mass per unit of time, lower platform weight with a greater stability system and adaptation of cutting height and terrain undulations. These characteristics provide a lower number of stops due to bushings, speed stability, as it would maintain constant power supply, greater flexibility in terms of cutting height, lower losses compared to conventional platforms and consequently better performance.

Optimizing harvester performance is an important factor, as we are talking about machines with high operating costs. In cases like this, it is necessary for producers to have a tool that allows them to estimate the performance of the harvesters, helping to choose the correct capacity and also to choose the machinery required to transport the crop.

Machines with draper platforms have a higher acquisition cost than those with conventional platforms, so it is important to base them on research within real working conditions. Some research that carried out a comparative evaluation of the two platform models observed that the harvester with a conventional platform presented a performance of around 5ha/h, while the machine with a draper conveyor belt type platform presented a performance of around 6ha/h and also a smaller amount. of losses per hectare.

For the conditions of Mato Grosso, with large areas of soybeans and a short harvest period, machines with draper platforms can be a great option in a scenario that requires high yield combined with cost control and rationalization of mechanization and investments.

COMPARATIVE

With the aim of evaluating harvesters with draper platforms and conventional platforms operating at different travel speeds, researchers from the State University of Mato Grosso carried out two experiments in the commercial area of ​​the Tamboril farm, in the municipality of Pontes e Lacerda (MT). The climate in the region, according to the Köppen classification, is tropical, hot and humid, with a dry winter (Aw), with an average annual temperature of 24,5°C and an average rainfall of 1.527mm per year.

The soybean cultivar harvested was Codetec 246, with a population of 220 thousand plants per hectare. All cultural treatments were carried out according to the needs of the culture. Due to the farm's planning, the grains were harvested with moisture above the recommended level, 18%, with the ideal harvest range being 12% to 14%, drying after harvest.

In the first experiment, a randomized block experimental design (DIC) was used, using a Massey Ferguson 9790 machine, year 2014, with a 35-foot platform, operating at three different speeds: 5km/h, 6km/h and 7km/h and speed of 670rpm axial rotor. Three replications were carried out for each treatment, in plots measuring 50 meters long and ten meters wide. The natural losses caused by the natural fall of the pods were evaluated. The losses at harvest time, caused by the cutting platform and internal mechanisms such as the separation and cleaning system, were also evaluated, thus obtaining the total losses.

The results of this experiment, presented in Figure 1, show that no losses above the recommended level were observed at any of the speeds evaluated, which would be 60kg/ha, a result considered quite satisfactory.

In the second experiment, a randomized block design (DBC) was used in a 2x4 factorial scheme, with four replications for each treatment, with the treatments consisting of two harvesters of different brands and cutting platforms (Table 1), operating at four speeds. different displacements (4km/h, 5km/h, 6km/h and 7km/h), and axial rotor speed of 700rpm. Each plot was 50m long and 10m wide. The total losses of soybeans caused by the machines and the theoretical operational capacity of the machines studied were evaluated.

The highest averages caused were found with the harvester working at a speed of 7km/h, with an average loss of 81,28kg/ha. On the other hand, the lowest average losses occurred when the harvester operated at a speed of 4km/h, obtaining an average loss of 50,17kg/ha. With an increase in the machine's travel speed, there is a greater amount of losses, both on the platform and in total.

Loss levels (Figure 2) during harvest were above the acceptable limit of 60kg/ha, however, this fact may have occurred due to high humidity and pre-harvest management. It can be seen in Figure 2 that when using a speed of 5km/h, the machine with a draper platform presents a reduction in total loss of 35,52% when compared to the platform with a helical conductor. The decrease in total losses when comparing the two types of platforms is similar to what other researchers found.

In the comparison, a theoretical estimate of the operational capacity of the machines evaluated was also carried out (Figure 3). The harvester with the conveyor belt system had a greater operational capacity than the platform with a helical conductor, as it has a 1,5 meter larger platform. This advantage, combined with the conveyor belt system, will enhance the process, thus reducing the time it takes to harvest the material in the field.

The machine with the draper platform at a speed of 4km/h presented an operational capacity of 0,5ha/h more than the one with a conventional platform, and at the highest speed of 7km/h it presented a performance of 0,9ha/h greater than the conventional platform.

In the state of Mato Grosso, with extensive soybean areas and a narrow harvest window and where producers usually harvest at speeds of up to 7km/h, the machine with a draper platform becomes an advantage. In addition to ensuring that the producer obtains a performance gain of 0,9ha/h, it is also possible to reduce their total losses by 12,93%, reaching 60ha/day, with better adaptation to the terrain conditions.

Therefore, when choosing to purchase a machine for harvesting soybeans, the producer must pay attention to the type of platform he wishes to purchase, taking into account acquisition costs, operational costs and gains from increased yield and reduced harvest losses.

Erick Marinho Samogim, Taniele Carvalho de Oliveira, Zulema Netto Figueiredo, Unemat

Article published in issue 172 of Cultivar Máquina