Performance of the tractor and seeder together

The development of a crop begins with the deposition of seeds in the soil, their germination and emergence of seedlings. Therefore, the sowing process must provide optimal conditions for its development, taking into account all the parameters that may vary according to the tractor-seeder set and its specific settings.

In mechanized sowing operations, operational performance is generally related to the tractor-seeder set, and may undergo operational changes depending on different factors such as the actual speed of travel and the soil preparation process, interfering with parameters that may vary in function of the configuration of the tractor-seeder set and its specific adjustments.

The most important parameters for improving the sowing process are the effective and operational capacity of the field, with a possible reduction in the number of mechanized sets depending on the larger area worked in the same period of time of operation in the field. For this, studies on the subject are necessary, with answers on the efficiency in the use of equipment and inputs in a manner concomitant with the sustainable growth of agricultural activity.

The effective and operational field capacity is directly related to the speed of movement of the mechanized set, interfering directly and indirectly in fuel consumption, wheel slippage, traction force and power available in the tractor's drawbar, thus contributing to low field capacity.

One of the aspects of great relevance during sowing, but which is given little attention, is the type of soil preparation. The soil preparation condition with little consolidation can contribute to increased slippage and low speed, reducing the operational capacity of the mechanized set. The use of a scarifier, when compared to the use of a plow plus harrow, may present lower effective and operational field capacity, requiring greater care to obtain favorable efficiency.

With the aim of evaluating the effective and operational field capacity of the tractor-seeder set as a function of soil preparation and gear scheduling, a field experiment was carried out using a Tatu Marchesan seeder-fertilizer, model SDA³ flow continuous line of 15 lines, with a spacing of 0,158m, driven by a 4x2 TDA (auxiliary front-wheel drive) tractor of 88,26kW (120hp) with auxiliary front-wheel drive connected. The tests were carried out in an experimental area belonging to the Department of Agricultural Engineering of the Federal University of Ceará (UFC), located on the Pici Campus, Fortaleza (CE).

In order to achieve the objective, the experimental design was in randomized blocks, in a 2x3 factorial arrangement with four replications, totaling 24 treatments. The treatments consisted of two soil preparations (plow preparation + harrow and scarifier) ​​and three gear levels (L3T - third gear reduced with the multitorque system activated in the turtle position; L3C - third gear reduced with the multitorque system activated in the rabbit, and L4C - reduced fourth gear with the multitorque system activated in the rabbit position), with an engine speed of 2.000rpm.

Each plot was 4,15m wide and 15m long. To prepare the soil, a mounted fixed disc plow was used, a lightweight drag harrow from the Marchesan brand, model GN, Off-set and a scarifier from the Marchesan brand, model AST/Matic 450. The parameters evaluated were: travel speed in km /h(V), effective field capacity in ha/h (Cce) and operational field capacity in ha/h (Cco).

The travel speed was determined by time, measured using a digital stopwatch, activated and deactivated according to the passage of the tractor's front wheels laterally to the stakes that delimited the length of the plots. The effective field capacity was obtained as a function of the working width of the seeder-fertilizer and travel speed and the operational field capacity was obtained as a function of the working width of the seeder-fertilizer, travel speed in km/h and efficiency of operation of the seeder-fertilizer, which is 75%, according to Asae (1997).

The results obtained for travel speed showed that the average values ​​were significant in relation to the prepared soil treatment and gear scaling (Graph 1), with a higher speed developed in the soil prepared with a more harrow plow (6,09km/h) and smaller for scarified soil (5,84km/h). This result may be associated with greater consolidation of conventionally prepared soil, allowing the tractor to develop higher speeds due to more efficient contact between the tire and the soil.

Means followed by the same letter in the columns do not differ from each other using the Tukey test (5%). * - significant; ns - not significant. P1 - preparation: plow plus harrow; P2 - preparation: scarifier. DMS - minimum significant difference. CV - coefficient of variation.

The L4C gear (7,63km/h) provided the highest speed, while the 3LT gear (4,56km/h) presented the lowest speed, a situation already expected, considering that the higher the working gear, the higher the values average travel speed (Graph 2). These values ​​can also be attributed to the transmission ratio, which for higher gear ratios allows the development of higher speeds, regardless of the preparation system to which the soil was subjected.

Means followed by the same letter do not differ from each other using the Tukey test (5%). * - significant; ns - not significant. L3T - third gear reduced, turtle position; L3C - third gear reduced, rabbit position; L4C - fourth gear reduced, rabbit position. DMS - minimum significant difference. CV - coefficient of variation.

The effective field capacity (Cce) showed significant results for soil preparation (Graph 3). The soil prepared with a more harrow plow had better performance for these variables, mainly due to the higher speed developed in this type of preparation, which provided a better surface condition with less sliding of the wheels, allowing seeding to be carried out in a shorter space of time in the same area.

Means followed by the same letter in the columns do not differ from each other using the Tukey test (5%). * - significant; ns - not significant. P1 - preparation with plow plus harrow; P2 - preparation with a scarifier. DMS - minimum significant difference. CV - coefficient of variation.

For the scaling of marches, the effective field capacity (Cce) presented mean values ​​with a significant difference, with an increase in field capacity with increasing speed (Graph 4). The highest average value of effective operational capacity was 1,7ha/h in reduced fourth gear, rabbit position (L4C). These results show the need for greater attention on the part of producers, because depending on the type of preparation, sowing may not be carried out within the established time.

Means followed by the same letter do not differ from each other using the Tukey test (5%). * - significant; ns - not significant. L3T - third gear reduced, turtle position; L3C - third gear reduced, rabbit position; L4C - fourth gear reduced, rabbit position. DMS - minimum significant difference. CV - coefficient of variation.

For soil preparation, operational field capacity (Cco) showed significant results (Graph 5). The soil prepared with the use of the more harrow plow was the one that presented the best operational performance, mainly due to the greater speed developed in this type of preparation, providing a better surface condition that was more consolidated, allowing seeding to be carried out in a shorter space of time in areas equivalents.

Means followed by the same letter in the columns do not differ from each other using the Tukey test (5%). * - significant; ns - not significant. P1 - preparation with plow plus harrow; P2 - preparation with a scarifier. DMS - minimum significant difference. CV - coefficient of variation.

For operational field capacity (Cco), gear scaling presented mean values ​​with significant differences (Graph 6), and an increase in field capacity can be seen with the increase in speed provided by gear scaling. The highest average value found for operational field capacity was 1,5ha/h in the fourth reduced gear, rabbit position (L4C), while the lowest value was obtained in the third reduced gear, turtle position (L3T). 

Means followed by the same letter do not differ from each other using the Tukey test (5%). * - significant; ns - not significant. L3T - third gear reduced, turtle position; L3C - third gear reduced, rabbit position; L4C - fourth gear reduced, rabbit position. DMS - minimum significant difference. CV - coefficient of variation.

Through the correlation analysis between the real speed of travel and the effective and operational field capacity (Graph 7) for the two types of soil preparation, it was also possible to verify an increase in the effective and operational field capacity directly proportional to the increase in speed. Based on this information, and that depending on the type of soil preparation there may be a reduction in these parameters, the producer can anticipate and carry out sowing within the expected time. 

Final considerations

Conventional tillage (plow + harrow) provides greater effective and operational field capacity for the tractor-seeder set. The L4C gear (7,63km/h) presents greater effective and operational field capacity. The increase in speed resulted in greater effective and operational field capacity.

Marcelo Queiroz Amorim, Carlos Alessandro Chioderoli, Daniel Albiero, Elivânia Maria Sousa Nascimento and Leonardo de Almeida Monteiro, UFC

Article published in issue 185 of Cultivar Máquinas, June 2018.