Main advantages of pneumatic seeders

The great advantage of pneumatic seeders is the possibility of precisely distributing the seeds in the planting line, a feature that demands attention from the operator to be effective.

The search for machines that perform more precise functions is increasingly strong in the agricultural sector. With the advancement of technology, seeders have been increasingly improved, being capable of performing numerous functions, such as dosing and distributing seeds and fertilizers at different spacings and depths.

The type of soil, climate, rainfall rate, amount of organic matter contained in the soil are some factors that affect the final production of the crop. Furthermore, it is assumed that the machine's travel speed will interfere with the longitudinal distribution, deposition depth and density of seeds released into the soil, directly influencing the final stand of the chosen crop.

In order to achieve greater efficiency in the distribution and deposition of seeds and to avoid errors during the sowing process, all components of the machine must be in perfect synchronization and adjusted according to the needs of the crop.

With the increasing production of large grains, such as corn, it becomes increasingly necessary to study the machines that are directly linked to the production of such grains.

Precision seeders are responsible for sowing large grains, where the seeds are deposited individually or in groups, in the row, at regular intervals. In these seeders, the dosing mechanism can select one or several seeds to be deposited in the soil.

Studies indicate that the uniformity of longitudinal seed distribution is one of the characteristics that most contribute to an adequate plant stand and this directly affects the final productivity of the crop.

To evaluate seed deposition from a pneumatic seeder, an experiment was carried out in the experimental area of ​​the Agricultural Engineering Department of the Agricultural Sciences Center of the Federal University of Ceará, Campus do Pici.

The tractor used to drive the pneumatic precision seeder was a Valtra BM, model 120 4x2 TDA (auxiliary front-wheel drive), with an 88.26 kW (120 hp) engine, working at two theoretical speeds: 5 km/h and 8 km/h . The seeder used to conduct the experiment was a Jumil pneumatic seeder, model JM2090EX.00. The seeder was adjusted to distribute seven corn seeds/linear meter at a deposition depth of 5 cm.

The experiment was carried out over a distance of 40 m in length and five replications were carried out for each factor. In the lines, one-meter spaces were randomly selected for evaluation. Data analyzed using Minitab statistical software – version 16, in a completely randomized design.

To evaluate the data, basic descriptive statistics were used where the following parameters were evaluated: mean, standard deviation, coefficient of variance, symmetry and kurtosis. The normality of the data was confirmed by the symmetry and kurtosis coefficients. Then, analysis of variance was used for data that presented normality. Statistical process control (CEP) was used to evaluate normal data and verify process stability.

It can be seen in Table 1 that the pneumatic seeder working at a speed of 5 km/h obtained an average of 16,04 cm and for a speed of 8 km/h the average obtained was 17,45 cm. It is noted that these average values ​​for spacing are above the value at which the seeder was set, indicating that there was an error during the sowing process, such as, for example, the high vibration of the seed in the conductor tube. Furthermore, the speed of 8 km/h showed greater irregularity in spacing, confirming existing studies where the authors state that the higher the speed, the more flaws can be found in the seed distribution.

The speed of 5 km.h presented a coefficient of variation of 34,53% and the speed of 8 km/h had a coefficient of variation of 36,30%. These results were not satisfactory, as the literature states that the maximum acceptable coefficient for pneumatic seeders is 30%. These high values ​​of coefficients of variation obtained in the experiment may have been influenced by the characteristics of the soil, shape and size of the crop used, the variables under analysis, among other factors.

According to Montgomery (1991), the values ​​of the largest symmetry and kurtosis coefficient must be within the range of -2 and 2, thus the data is considered to have a normal distribution. It is possible to verify that the values ​​of the symmetry coefficient of 0,89 for the speed 5 km/h and 0,48 for the speed 8 km/h are within the expected values, showing normality in the process. The same occurred for the kurtosis values ​​of 1,49 for the speed 5 km/h and 0,13 for the speed 8 km/h, which in both cases presented normality.

Based on the above, when presenting normality in the speeds studied, the analysis of variance is considered efficient for all speeds evaluated. Table 2 presents data from the analysis of variance of the seeder spacing at speeds 5 and 8 km/h.

In the analysis of variance, it was observed that there was a significant difference between the average seed spacing of the pneumatic seeder speeds of 5 and 8 km/h at 5% significance.

Based on Table 3, it is noted that there was a statistical difference using the MDS test at 5% significance. This result shows that the speed of 8 km/h presented the closest value to which it was regulated, standing out in relation to the speed of 5 km/h.

Montgomery (2004) recommends the CEP for the evaluation of normal processes to verify the feasibility of meeting such specifications and quality requirements, in addition to determining the problematic points of the process.

Barros (2008) states that if 95% of the points are within the indicated limits, the process is considered to be stable; however, if more than 5% of the samples are outside the specified limit, the process is considered to be unstable, i.e. , with great variability.

When analyzing Graph 1A, it is possible to observe that the process is stable, as only 10 samples are outside the specific control limits and when analyzing Graph 1B, it is verified that only 6 samples are outside the specific control limits , also being classified as stable.

The pneumatic seeder at a speed of 5 km/h showed an average spacing between seeds of 16,05 cm (Graph 3) and at a speed of 8 km/h it showed an average spacing between seeds of 17,45 cm, but it was adjusted to obtain a spacing of 14 cm between seeds.

The reason why some samples were not within the specific control limits could be due to interference in the seed distribution mechanism, slippage of the seeder's driving wheel or due to the seeds.

It can be seen in the control chart that in both cases, the data obtained does not have high variability, showing uniformity, that is, the distribution of corn seeds at both speeds proved to be effective.

Eduardo Santos Cavalcante, Daniel Albiero, Rafaela Paula Melo, Aline Castro Praciano, Deivielison Ximenes Siqueira Macedo, Federal University of Ceará

Article published in issue 163 of Cultivar Máquinas.