Mechanized planting: comparative study of the use of GNSS systems

An essential factor for the farmer to remain competitive in the market is the improvement of agricultural activity, through the use of efficient systems such as the adoption of precision agriculture techniques and the use of satellite guidance systems, GNSS (Global Navigation Satellite Systems). 

GNSS is a set of technologies that involve positioning and navigation systems using satellites. The use of an autopilot guided by a GNSS signal offers resources to improve the operation, with potential cost reduction in the implementation of new crops based on the correct arrangement of plants on the ground. 

Thus, these associated technologies work on crop mapping, planting alignment, reducing trampling and increasing the operational performance of machines, among others.

A study carried out by researchers from the Federal University of Paraná compared four different groups of systems associated with mechanized potato planting, evaluating their area utilization rates and determining which was the most efficient.

Comparing GNSS Systems

The study was carried out at the Canguiri Experimental Farm (FEC), belonging to the Federal University of Paraná, located in the municipality of Pinhais (PR). The tractor used was a New Holland brand, model T7.260 LAR FPS – Full Powershift, with hydraulic pilot IntelliSteer System, maximum engine power of 241 hp and rotation of 1.000 rpm for sowing. For the experiment, the four-row Watanabe planter was used in the four tests.

In tests carried out without manual control of the machine, the AFS Guide hydraulic autopilot, from the Case IH brand, was used. This system comes integrated with an AFS 372 receiving antenna, AFS Pro 700 monitor, and the option of the RTK precision system. The RTK receiver used in the test was the Trimble TDL 450h with 14 selectable channels, configurable power in 2, up to 35W; waterproof (IP67).

Sowing was carried out in four moments, which are represented by the acronyms: MM, MBL, PaSC and PaRTK. The MM test (manual marker) was carried out with a manual pilot and without the aid of satellite location equipment, just the reference line marker. The MBL test (manual light bars) was developed with a manual pilot and with the aid of the light bar for direction. The PaSC (autopilot without correction) trial used autopilot but not correction software. Finally, in the PaRTK test (RTK autopilot), the use of the autopilot was associated with the RTK system, which is the GPS receiver with the correction signal.

The experimental design used was randomized blocks, with five replications. PLM Office software was used to plan the rows at the Mapping & Records level. From the area chosen in the field (25,6m x 111,45m), maps of the work area were made in the software and parallel rows were created, spaced 0,80m apart.

Area utilization index 

In Table 1, the utilization values ​​indicate that the treatments with the automatic pilot obtained higher rates of area utilization than the treatments that used the manual pilot.

There was no significant difference between the sample groups, explained by the small size of the area covered (2.853m²). 

It is known that the appropriate spacing for planting babata is 0,80m between rows and 0,35m between plants. The equidistance between plants during sowing is extremely important, as the lack of space causes intraspecific competition, which can harm the development of the crop. Furthermore, this misalignment creates difficulties for subsequent operations, as it can cause seeds positioned adjacent to the transit lines to be trampled. Therefore, the parallelism shown in the PaRTK group (Figure 1D) is the most appropriate for the plantation to have better productive performance. The non-uniformity of the planting lines was evident in the MM (Figure 1A) and MBL (Figure 1B) groups, which led to a reduction in adequate spacing between the lines. 

In Figure 1 (A and B) they are the result of the MM and MBL groups, respectively. Images C and D were obtained from the experiment of the PaSC and PaRTK groups. The arrows indicate some points where a lack of equidistance between the lines was observed.

The planning was to reach a total of 3.566,628 linear meters. PaRTK was the group that showed the best area utilization index (IAA) with 3.569,644 linear meters covered, when compared to the others, followed by PaSC, with 3.569,664 linear meters. The MM (3.570,572 linear meters) and MBL (3.571,040 linear meters) groups achieved more meters covered, when compared to the control group in terms of the total distance covered, and to the other groups that used the autopilot system.

The PaRTK group was the one that obtained the best operational utilization rate, due to the ease with which the work could be carried out and the results observed by the operator. The main gains in using autopilot were in relation to the increase in working hours and the reduction of the workforce involved in the operation. 

In planting with the MM and MBL control groups, there was a lower operator utilization rate, as they required greater physical and psychological performance from the operator, making him more susceptible to errors even with the help of GNSS.

*Per Maíra Laskoski, Julio Soczki, Guilherme Luis Parize, Leonardo Leonidas Kamiecik, Thiago da Silva Xavier e Samir Paulo Jasper, from the Federal University of Paraná