How to get better performance from seeders

Efficiently distributing seeds in the soil depends on several factors, among which the choice of furrowing disc is essential. To do this, it is necessary to carefully analyze the conditions and characteristics of each situation and make the choice that best meets each need.

The basic function of seeders is to distribute a certain quantity of seeds in the soil, whether prepared according to a conventional or direct cultivation system or any other conservation practice, in a pre-determined arrangement. To perform this function in the desired way, seeder-fertilizers must open and shape a furrow in the soil; dose and distribute the amount of seeds and fertilizers; cover the furrow and lightly press the soil around the seeds, aiming to remove air pockets, which harm the germination process.

Furrowers are responsible for opening the furrow for the deposition of seed and fertilizer in the soil. Furrowers can be of the hoe, machete or disc type, the last two being the most used. Hoe furrowers are preferably used on soils without stumps, roots or crop residues, as a lot of plugging can occur in these conditions. Behind the furrowing hoe is the tube that carries fertilizers or seeds, so that they are deposited in the furrows after they are opened.

Machete or rod furrowers, popularly known as “botinha” have the advantages of being able to place fertilizer and seed at greater depths. Disc furrowers have been the most used, as they work more efficiently on soils with crop residues or in inadequate soil preparation conditions. Disc furrowers can be single discs or double discs offset. Lag discs have an advantage over simple discs in that they better model the groove.

Several studies state that the use of furrowing rods increases traction force requirements, fuel consumption (hourly and specific) and the slip rate of the mechanized tractor-seeder set, in relation to the double disc type furrow opening system. . However, there are also reports showing that the rod promotes greater soil mobilization.

Given the importance of verifying the behavior of furrowers, a team of researchers carried out research work at the Federal University of Viçosa that aimed to evaluate the variables displacement speed, force, power required for traction of the seeder-fertilizer and wheel slippage tractor engines in the no-till system. To carry out the tests, the seeder-fertilizer was assembled with just one planting line positioned in the center of the chassis.

Two planting line assembly configurations were evaluated. The first was called version “A” and was composed of the following mechanisms: straw cutting disc, double disc lag in the fertilizer deposition system, double disc lag in the seed deposition system and covering and depth control wheels. The second was called version “B”. In it, the outdated double disc-type furrowing mechanism used in the fertilizer deposition system was replaced by a machete-type one with a removable tip and individual adjustment of depth and angle of attack.

Two agricultural tractors were used, one manufactured by Massey Ferguson and the other by John Deere. The two assembly configurations of the seeder-fertilizer planting line, versions “A” and “B”, were tested under the same operating conditions, that is, with the same gears and engine shaft rotations.

Because the seeder-fertilizer is a mounted coupling implement, it was necessary to make a train to install the load cell between the tractors, and thus be able to measure the force required to pull the seeder-fertilizer. In the scheme presented in Figure 1, tractor 1 represents the tractor manufactured by Massey Ferguson, which, in this second stage of the tests, was used as a source of power to drive the mechanized set formed by tractor 2, which represents the one manufactured by John Deere, which kept its gear in neutral position.

The mechanized set consisting of the Massey Ferguson tractor and the seeder-fertilizer were evaluated at five different travel speeds, obtained by varying the gear and rotation of the engine shaft, as shown in Table 1. The speeds were obtained by the relationship between the length of the experimental unit (20 m) and the time taken to travel the unit, measured by a stopwatch.

In addition to the speed, the force required (kN) by the seeder-fertilizer (Figure 2), power required for traction of the seeder-fertilizer (kW) (Figure 3) and slippage of the driving wheels (decimal) (Figure 4) were determined.

To obtain data exclusively on the force required by the seeder-fertilizer, it was necessary to calculate the force required for traction of the mechanized assembly subtracted from the force of resistance to displacement offered by tractor 2. This force was then multiplied by the average displacement speeds and obtained - the power required for traction of the seeder-fertilizer.

Using the disc furrower, configuration “A”, in fertilizer deposition, the average travel speeds did not affect the force required for traction of the seeder-fertilizer. In configuration “B”, machete furrower, the speed influenced the traction force and the lowest travel speed (3,68 km/h) had the lowest traction force per planting line (4,311 kN). The power required for traction of the seeder-fertilizer was influenced by the travel speed of the mechanized set, in the two assembly configurations of the planting line (“A” and “B”). At the time of the tests, it was also evident that at identical travel speeds, the lowest power values ​​were associated with configuration “A”, indicating, for the experimental conditions, that the configuration equipped with the double disc type furrowing mechanism was out of phase in the system. of fertilizer deposition required less power to pull the seeder-fertilizer than configuration “B”, where the machete-type furrowing mechanism was mounted.

Slippage of the driving wheels of the tractor used as a power source was observed in both assembly configurations of the planting line. The values, in decimal, were obtained under two different conditions. In the first, the seeder-fertilizer was attached to the tractor and kept in the transport position. This condition was considered “no load” (N_VSC). In the second, considered “with load” (N_vcc), the active elements that equipped the planting line were placed and maintained in operation. After the start of the test, the number of turns made by the driving wheels around its axis was measured. With the values ​​in hand, slippage was determined using the relationship below: 

The slipping of the tractor's driving wheels is not influenced by the average travel speeds with the seeder-fertilizer operating in settings “A” and “B” (Figure 4). However, the values ​​of the variable under study in the two planting line assembly configurations (“A” and “B”) were different and the value of configuration “B” was greater than that obtained for configuration “A”. This indicates that the driving wheels of the tractor assembled with the seeder-fertilizer equipped with the machete-type furrowing mechanism slipped more than the driving wheels of the tractor assembled with the seeder-fertilizer equipped with the lagged double disc. This fact was expected and can be explained based on the greater requirement for traction force and power presented by the seeder-fertilizer mounted in configuration “B”, whose machete-type furrowing mechanism operates at greater depth and mobilizes a greater volume of soil.

It is worth noting that even though we observe the strong influence exerted by the machete-type furrowing mechanism in relation to many parameters, targets of research in Brazil, we cannot infer which is the best furrower. It is necessary to analyze the conditions and characteristics of each situation, such as tractor power, number of seeder-fertilizer lines, soil moisture, type and mass of vegetation cover, soil texture, soil surface conditions, soil resistance to penetration , soil water content, among others.

Haroldo Carlos Fernandes, UFV; Paula Cristina Natalino Rinaldi, UFRRJ; Jefferson Machado Fontes, UFV

Article published in issue 155 of Cultivar Máquinas.