​Evaluation of a self-propelled forage harvester for corn crops

Evaluation with a self-propelled forage harvester for corn cultivation, carried out in the southwest region of Mato Grosso, shows that it is possible to harvest more than 6,5 hectares per hour while maintaining the quality of the harvested product. 

The state of Mato Grosso is the largest producer of beef cattle in Brazil and the practice of confinement in the final process is becoming increasingly common among livestock farmers, making supplementary feeding of the animals necessary for this. One of the main sources of dietary supplementation for cattle is silage. However, to guarantee a return in productivity, it is essential to supply superior quality forage. There are several factors that affect the final quality of the product, ranging from harvest management to the type of harvesting machine adjustment and silage processing.

Self-propelled forage harvesters stand out for their work capacity, versatility and incorporation of technological innovations, as well as high uniformity in relation to the size of the chopped material. However, they have a high acquisition cost, which makes them viable only for large properties and/or in the form of service provision, a fact that is becoming an option in the southwest region of Mato Grosso, where there are a large number of properties that grow corn for silage. and do not wish to purchase a machine to be used only for harvesting corn, so they opt for an outsourced service.

The operational capacity of forage harvesting is one of the factors that make it attractive and needs to be measured together with the capacity of vehicles to transport the material, as these machines require a fleet of trucks or transloaders to work in parallel to the machine. Other considerations that must be observed are the cost of repairs and maintenance, manufacturer support and ease of operation.

The JD 7830 forage harvester with 352 Kw of power, according to the manufacturer, has some features such as the IVLOC TM transmission system (variable cutting width), which offers an adjustment in particle size, from the operator's cabin. The flow of matter, inside the machine, is optimized to obtain constant processing, also featuring a metal detector system.

The harvester's cutting cylinder with 48 segmented blades cuts the forage with efficiency and precision, and can be easily sharpened from the operating cabin. The machine has stainless steel feed rollers that rotate following the perimeter of the cylinder with radial cutting, maintaining control of the material layer and providing excellent feed quality compared to conventional cutting systems.

The grain processor is a system that crushes corn grains and consists of two large diameter grooved rollers (107 teeth), made of hardened steel. The crushing can be increased or decreased by the operator's command and the spacing between the rolls is read on the cabin column monitor. It is also possible to install or remove the grain processor to adapt it for harvesting other crops.

The platforms used are the Kemper rotary platforms with 6, 8 and 10 lines, in this case the one used in the study was the 8 lines one. With a cutting width of 4,5 to 7,5 meters, it guarantees a short and quick transit of the material, allowing you to harvest corn, sorghum and other upright crops regardless of the direction of the cut or the spacing between rows. The ends of the platforms can be folded, allowing a total transport width of 2,95 m, ensuring safe movement on public roads.

For the cutting and processing of forage plants, ensiling machines must be prepared and adjusted to ensure uniformity of the mince and the quality of the silage. However, most forage harvesters do not perform their work correctly, as they operate with inadequate settings or a lack of technical support. These facts cause uneven chopping, which is not ideal for the crop, resulting in low quality silage and even low feed yield for the animals.

Studies to identify the real characteristics of these machines are of fundamental importance, as they influence the final quality of the product and must be carried out with the aim of not only informing the producer, but also optimizing the production system.

To this end, a study was carried out with the objective of evaluating the JD 7380 forage harvester for corn cultivation (zea mays L.), observing the harvest cut adjustment ranges. The study was carried out at Fazenda Ressaca – Grupo Nelore Grendene, in Cáceres (MT). The farm adopts the beef cattle production system, semi-confinement, with a large part of the production, the animals are kept on pasture and only at the end of fattening are they taken to the confinement. This property produces corn as fodder, ensiled in trench silos.

The design was in randomized blocks in a 2x2 factorial scheme with speeds of 7 km/h (V₁) and 9 km/h (V₂₎ and cutting size settings (particles) of 10mm (R₁) and 14mm (R₂), respectively. As it was a harvest in the farm area, the choice of speeds and cutting size adjustments occurred depending on the work and the demands of the property, being V₁ and the R₁ the one that was being used in the harvest and the V₂ and R₂ adjusted for the study.

The silage was collected using a plastic bucket measuring approximately 2 liters, which was removed from the collection truck. A sample was also taken to determine the dry mass of the silage, checked in an oven at 60 ºC for 72 hours.

Once collected, they were dried in the shade and subsequently subjected to a set of sieves, measuring 25x25 cm, adapted to the methodology mentioned by Lammers et al. (1996), described by Jobim et al (2007) and Schlosser et al (2010). This adaptation was carried out to classify the fragments into particles larger than 0,75” (19,1 mm), between 0,75 and 0,31” (19,1 to 7,9 mm) and particles smaller than 0,31 ” (7,9mm). The methodology consisted of weighing 250 grams of dry forage sample, placing it on the upper sieve and starting systematic agitation. The shaking was carried out on a flat and smooth surface, and consisted of eight series of five vigorous shakes (after every five shakes the set of sieves is rotated 90º), totaling 40 movements.

The results showed that for the average percentage values ​​retained in each of the sieve meshes for each treatment (Figure 01), the granulometric distribution of the chopped corn was retained on the sieve greater than 15mm (64%), followed by particles less than 9 mm (29%) and particle sizes between 9 mm and 15 mm (7%). In relation to the average size of the particles retained in each sieves, there was no significant difference, however, when comparing the percentages retained in each sieve, there is a difference between the treatments, as the particles retained in the sieve smaller than 9 mm are different from each other, due to regulation.

As for the average particle sizes, when using a setting of 10 mm, an average of 14,2 mm was obtained and the increase in speed did not significantly influence the particle size, when adjusted to 14 mm, an average size of 16,3 mm and also showed no significant difference.

Research indicates that particles below 8mm should be between 45% and 65, but the study did not use a setting below 10mm as it is not used on the farm. More studies are needed to confirm the results, however all the technology involved in harvesting with this machine also leads to other types of studies since within the data obtained it is possible to infer that using the maximum speed tested, of 9km/h, up to 6,7 hectares per hour can be harvested without interfering with the average particle size.

In this sense, other aspects related to operational capacity, the need for transshipments working in parallel with the machine, which are currently limiting for increasing the machine's working speed, as well as other actions related to harvest mapping and precision agriculture technology, could be used with the aim of improving the quality of silage and obtaining food with greater digestibility for cattle, promoting better efficiency in the use of machines in beef and dairy farming.

Paulo Cesar Lima Silva, Jane MB Vanini, Zulema Netto Figueiredo, Eder Pedroza Isquierdo, Mariana Ferreira de Oliveira, UNEMAT – Cáceres – MT

Article published in issue 155 of Cultivar Máquinas.