Profundidade de sulco, área de solo mobilizada e força de tração de uma semeadora-adubadora em razão da velocidade de deslocamento

Furrow depth, soil disturbance area and draft force of aseeder-fertilizer at different seeding speeds

Resumos

The aim of this his study was to evaluate the furrow depth, the area of soil disturbance and the draft force required for a precision seeder-fertilizer as a function of seeding speed in a no till system for corn production. The experiment was conducted in a 4³ factorial randomized block design with four replications, consisting of four forward speeds obtained by changing gears and three tractor's engine rotation speeds. During seeding, the operating speed, engine rotation speed and draft force on the drawbar were measured. After seeding, furrow depth and area of soil disturbed were assessed. The results showed that: the furrow depth was influenced by the increase in the operating speed; the area of soil disturbed increased by 41% with increasing operating speed, the average drawbar draft required per seeding line and per area of soil disturbed decreased with increasing speed; and the average drawbar draft per furrow depth increased with the operating speed.

No till system; energy demand; agricultural mechanization

ENGENHARIA AGRÍCOLA

Profundidade de sulco, área de solo mobilizada e força de tração de uma semeadora-adubadora em razão da velocidade de deslocamento

Furrow depth, soil disturbance area and draft force of aseeder-fertilizer at different seeding speeds

João Cleber Modernel da Silveira^I; Haroldo Carlos Fernandes^II; Alcir José Modolo^III; Suedêmio de Lima Silva^IV; Emerson Trogello^V

^IAgricultural Engineer, Doctor Science. Instituto Federal Goiano. Rodovia Sul Goiana, Km 01, Zona Rural, 75901-970, Rio Verde, GO, Brazil. [e-mail]

^IIAgricultural Engineer, Doctor Science. Universidade Federal de Viçosa, Department of Agricultural Engineering. Av. Peter Henry Rolfs, s/n, Campus Universitário , 36570-000 Viçosa, MG, Brazil. [e-mail]

^IIIAgricultural Engineer, Doctor Science. Universidade Tecnológica Federal do Paraná. Via do Conhecimento, Km 01, Caixa Postal 571, 85503-390 Pato Branco, PR, Brazil. [e-mail]

^IVAgricultural Engineer, Doctor Science. Universidade Federal Rural do Semi-Árido, Department of Agricultural and Environmental Engineering. Av. Francisco Mota, 572, Bairro Costa e Silva, 59625-900, Mossoró, RN, Brazil. [e-mail]

^VAgronomist Engineer, Master Science student. Universidade Tecnológica Federal do Paraná. Via do Conhecimento, Km 01, Caixa Postal 571, 85.503-390, Pato Branco, PR, Brazil. [e-mail]

RESUMO

Este trabalho teve por objetivo avaliar a profundidade de sulco, área de solo mobilizada e a força de tração solicitada por uma semeadora-adubadora de precisão em sistema de plantio direto na cultura do milho, em razão da velocidade de deslocamento. O delineamento experimental foi em blocos ao acaso, com quatro repetições em arranjo fatorial 4 x 3, com 12 tratamentos, constituídos de quatro velocidades de deslocamento, obtidas pelos escalonamentos de marchas e de três rotações do motor do trator. Durante a semeadura, monitoraram-se a velocidade de operação, a rotação do motor e a força de tração na barra. Após a semeadura, foram avaliadas a profundidade do sulco e a área mobilizada de solo. Os resultados mostraram que: a profundidade do sulco foi influenciada pelo aumento na velocidade de operação; a área mobilizada de solo aumentou em 41 % com a elevação da velocidade de operação; o requerimento de força na barra de tração, média, por linha de semeadura e por área mobilizada de solo diminuiu com o aumento da velocidade; e a força média na barra de tração por profundidade do sulco aumentou com o incremento da velocidade de operação.

Palavras-chave: Plantio direto, demanda energética, mecanização agrícola.

ABSTRACT

The aim of this his study was to evaluate the furrow depth, the area of soil disturbance and the draft force required for a precision seeder-fertilizer as a function of seeding speed in a no till system for corn production. The experiment was conducted in a 4³ factorial randomized block design with four replications, consisting of four forward speeds obtained by changing gears and three tractor's engine rotation speeds. During seeding, the operating speed, engine rotation speed and draft force on the drawbar were measured. After seeding, furrow depth and area of soil disturbed were assessed. The results showed that: the furrow depth was influenced by the increase in the operating speed; the area of soil disturbed increased by 41% with increasing operating speed, the average drawbar draft required per seeding line and per area of soil disturbed decreased with increasing speed; and the average drawbar draft per furrow depth increased with the operating speed.

Key words: No till system, energy demand, agricultural mechanization.

INTRODUCTION

The energy consumption on the implementation of any crop, cultural practices and grain harvesting is crucial for the farmer. Optimizing field operations and, thus, lowering energy consumption by the correct use of farm machinery, increases profitability at the end of each season. However, because of direct seeding systems, seed drills had their manufacturing process changed, making them robust, heavy and with soil-engaging components capable of breaking compacted soil layers caused by equipment traffic on the field, and hence newer seeders require tractors to have more traction power to pull them.

Cepik et al. (2010) discuss that farmers should consider the use of shank-type furrow openers for fertilizer application in compacted soils or compaction-prone areas. In direct seeding, nutrients tend to concentrate on the soil surface. Shank furrow openers allow fertilizer placement at greater depths, which can induce roots to grow deeper into the soil and, thereby, reduce compaction effects on plant growth. However, some studies have shown that the use of shank openers, instead of double discs, increases the furrow depth and the area of soil disturbance (Mion & Benez, 2008), the draft force required and fuel consumption (Silva, 2003).

The draft force required for the operation of large grain seeders (precision seeders) in the horizontal travel direction, including the machine's rolling resistance, in a good seedbed, ranges from 0.9 kN ± 25% per line, for seeding only, and 3.4 kN ± 35% per line, for seeding, fertilizer and herbicide application (ASAE, 1999).

Silveira et al. (2005), working with two seeding depths and different operating speeds, found that increasing the speed from 5.24 to 7.09 km h^-1, the draft force increased by 12.08 and 3.70% at the seeding depths of 1.97 and 2.68 cm, respectively. Furlani et al. (2008), studying the performance of a precision seeder-fertilizer as a function of type of tillage, forward speeds and tire inflation pressure, also observed that seeding at 3.4 km h-1 had lower draft and drawbar power requirements compared with the operating speed of 6.0 km h^-1.

Collins & Fowler (1996), studying planters with double disks and knife-type of furrow openers in a clay soil, recorded draft forces of 0.20 and 1.12 kN per line, respectively. These authors found that for speeds between 6.0 and 10.0 km h^-1 the drawbar draft force increased by 4% for each km h^-1 increase in speed and 20% for each centimeter increase in seeding depth, regardless of the type of furrow opener.

A study on energy demand in corn seeding, at different speeds and soil management systems (no till and chisel plowing), showed that the drawbar draft was not influenced by the soil preparation, but, while at the two lower speeds (4.4 and 6.1 km h^-1) the draft forces were similar, at the highest speed (8.1 km h^-1), the difference was significant (Mahl et al., 2004).

Modolo et al. (2005) found that the draft force required by a precision seeder fertilizer varied with the number of seed lines and the distribution of lines in the machine. The average drawbar draft force increased by 131.9% with the increase in the number of seed lines from one to five.

This study aimed to evaluate the furrow depth, the area of soil disturbed and the draft force of a precision seeder fertilizer as a function of seeding speed in a no till system for corn production.

MATERIAL AND METHODS

The experiment was conducted at the Experimental Field of Assis Gurgacz Foundation, Cascavel-PR, from September to November, 2006. The soil is classified as a heavy clay textured Oxisol (6.8% sand, 17.8% silt, and 75.4% clay). The area is located between coordinates 24º56'30" South latitude and 53º30'28" West longitude, average altitude of 760 m and slope between 0 and 3%. The experiment was arranged in a 4³ factorial randomized block design with four replications: 12 treatments consisting of four forward speeds (3.5, 4.0, 5.5, and 7.0 km h^-1) obtained by changing gears and three tractor's engine rotation speeds (1500, 1900 and 2100 rpm), totaling 48 experimental units.

The experiments were performed with a Tatu Marchesan PST³ trailing seeder fertilizer machine with six seed lines, BR 8.1 perforated horizontal plate seed metering devices (1 1 x 8 mm), with 28 slotted holes, 4.3 mm plain AM000 ring, 20" disc coulter, double discs for seed distribution, shank-type furrow openers (knives) for fertilizer and aligned dual-angled presswheels.

The tractor used to pull the planter was a FORD 7630, 4x2, with front wheel assist (FWA), 75.8 kW (103 hp) engine power at 2100 rpm and mass of 3580 kg without ballast and 6196 kg with maximum ballast. During the test, the tractor was equipped with maximum ballast, i.e., front ballast on tires and wheels.

AG 405 corn hybrid sedds, 100% purity and 98% minimum germination, according to company data (Agroceres) were used in the trials. An 8-20-20 NPK fertilizer was used at the recommended rate of 330 kg ha^-1. Crop residue desiccation (rye) was carried out by using 1.8 L ha^-1 glyphosate.

Data on furrow depth was randomly collected by inserting a cm-graded ruler into the furrow and taking 15 readings per seed line. For the area of soil disturbed, we used an aluminum profilometer with vertical cm-graded rulers arranged every 2 cm in the transverse direction. The area of soil disturbed was determined by the equation:

(eq. 1)

Where,

A_m = disturbed area (m²);

P_N = height of the natural soil surface profile at each point of the profilometer (m);

P_S = height of the final soil surface profile at each point of the profilometer (m), after

seeding; and

e = spacing between the vertical rules (m).

A data acquisition system —a Campbell Scientific CR23X datalogger was used to continuously record and store the signals generated by the transducers (load cell, radar and infrared optical sensor) installed on the motor-mechanized assembly.

The drawbar draft required to pull the seeder-fertilizer, the travel speed and the rotation of the motor shaft were recorded. The drawbar draft required was recorded by a SODMEX N400 load cell, with 2.156 mVV^-1 sensitivity, coupled between the tractor and the seeder. The pin that holds the drawbar was removed so that it was free and all the draft force required by the seeder was applied to the load cell. The average draft force was determined by equation 2.

where:

F_m = average draft force (kN); F_i = instant draft force (kgf);

n = number of recorded data, and 0.0098 = conversion factor for kN.

The travel speed was recorded by a DICKEY -john Radar Velocity Sensor - DjRVS, with errors of less than ± 3% for speeds from 3.2 to 7.08 km h^-1. The rotation of the motor shaft was recorded by an infrared optical sensor and a 60-toothed gearwheel which gave out 60 pulses per revolution. The wheel was used to determine the rotation of the motor shaft and was coupled to the power take-off (PTO) of the tractor, along with the infrared optical sensor. Using the tractor manufacturer's catalog, we determined the transmission ratio between the rotation of the motor shaft and the PTO rotation. Knowing the transmission ratio and the number of pulses generated by the toothed gearwheel attached to the PTO, we determined the rotation of the tractor power take-off (PTO) and, therefore, the rotation of the engine.

The results were examined by the analysis of variance, and when the interaction between the factors operating speed and engine rotation was significant, the regression analysis was performed. The statistical analysis was performed using the software SAEG 9.1 (UFV, 2007).

RESULTS AND DISCUSSION

The average biomass in the experimental area was 2.41 ton ha^-1. The average water content and density of the soil at a depth of 0-0.10 m were 0.32 kg kg^-1 and 1.05 Mg m^-3, respectively, and, from 0.10 to 0.20 m, the mean values were 0.26 kg kg^-1 and 1.11 Mg m^-3. The highest value recorded for soil resistance to penetration (MPa) in the experimental area was 1.36 MPa at a depth of 0-0.10 m, measured by a PNT-2000 penetrometer.

Because the t-test (P>0.05) showed that only the regression coefficient of the variable operating speed was significant, we removed the variable engine speed from the regression model, generating equations using only the variable operating speed.

Furrow depth for fertilizer placement

Figure 1 shows the results of regression analysis between furrow depth for fertilizer placement and operating speed, with both showing linear trend. The coefficient of determination of the regression analysis between the furrow depth for fertilizer and the operating speed of the mechanized assembly was 0.94, meaning, therefore, that 94% of the variation in furrow depth was explained by the change in speed, with the remainder owing to other factors inherent to operating speed.

The shank opener operated at the proper depth (0.10 m), showing little variation. At the highest speed (V4), the furrow depth was the shallowest (0.0929 m), while at the slowest speed (V1), the furrow depth was the deepest (0.1114 m). Deeper furrows at lower speeds were also reported by Casão Junior et al. (2000) and Mahl et al. (2004).

The decrease in furrow depth for fertilizer deposition with the increase in operating speed can be attributed to knife-type openers. These openers tend to move closer to the surface, even when adjusted to place the fertilizer to predetermined depths. Soil roughness, soil moisture and resistance to penetration, among other factors, may affect this variable.

Area of soil disturbed

Figure 2 shows the results of regression analysis between area of soil disturbed and operating speed. The fitted model, considering the different speeds, showed a linear trend with determination coefficient of 0.92. We recorded for each km h^-1 increase in the operating speed of the mechanized assembly an increase of 0.0008 m² in the area of soil disturbed, which was lower at 3.5 km h-1 (0.0069 m²) and higher at 7.0 km h^-1 (0.0097 m²).

Increasing the operating speed from 3.5 to 7.0 km h-1 caused a 41% increase in area of soil disturbed per line. This trend was not observed by Silva et al. (2001), when evaluating the performance of a seeder-fertilizer in no-till corn sowing in a clay soil.

Drawbar draft requirement

Observing Figure 3, we notice a clear decreasing line­ar trend for drawbar draft requirement with increasing speed of operation. When the speed increased from 3.5 to 7 km h^-1, the drawbar draft requirement decreased by 9%, which must be considered for purposes of sizing the assembly. This result may be attributed to the lowest furrow depth found at the highest operating speed (Figure 1).

Similarly, reduction in drawbar draft requirement due to increased speed was reported by Furlani et al. (2007) and Santos et al. (2008). Conversely, Bortolotto et al. (2006) found 2.5% increase in drawbar draft when the operating speed increased from 4.7 to 7.2 km h^-1, in a no-till system in an Oxisol. But, Modolo et al. (2004), Trintin et al. (2005) and Furlani et al. (2005) found no effects of increased operating speed on average values of drawbar draft.

Drawbar draft requirement per seeding line

The estimates of regression analysis for drawbar draft required per seeding line as a function of operating speed is shown in Figure 4. The fitted model for the variable showed a decreasing linear trend with increasing speed and determination coefficient of 0.87. For each unit increase in speed of the mechanized assembly, the average draft on the drawbar per seeding line decreased by 0.0533 kN.

The lowest operating speed required the highest draft force per line (2.61 kN), whereas the highest speed required the lowest draft force (2.42 kN), resulting in a reduction of 9.1 %. Bortolotto et al. (2005) evaluated the energy demand of a PST³ Supreme seeder-fertilizer with eight seeding lines at different travel speeds and types of vegetation. These authors found draft force per seeding line equivalent to 1.62, 1.64, and 1.76 kN when working with speeds similar to those used in this work.

Studying the energy demand of a seed drill, Modolo et al. (2005) found a 126.41 % increase in the draft force required when increasing the seeding lines from one to five, with values below those recorded in this work. The draft force requirement per seeding line (kN) recorded in this experiment, for seeding and fertilization operations, are within the range recommended by ASAE (1999).

Drawbar draft requirement per furrow depth

Figure 5 shows the results of regression analysis for drawbar draft required per furrow depth. The coefficient of determination was 0.95. For each km h^-1 increase in the operating speed of the mechanized assembly there was an increase of 0.8146 kN m^-1 on the drawbar draft requirement per furrow depth.

The drawbar draft requirement per furrow depth increased with the operating speed. However, while the depth was reduced with increasing speed, the draft force per furrow depth was increased. These results differ from those reported by Siqueira et al. (2001), in which increasing the operating speed did not increase drawbar draft requirement in relation to furrow depth. But, Mahl et al. (2004) found results similar to our findings when varying the operating speed.

Drawbar draft requirement per area of soil disturbed

In relation to drawbar draft requirement per area of soil disturbed for the factors studied, the linear regression showed significance for operating speed (Figure 6).

The coefficient of determination of this model was 0.91, and 9% of the variation in the drawbar draft requirement per area of soil disturbed could not be explained by the analysis. It was found that for each km h^-1 increase in the operating speed, the draft force per area of soil disturbed decreased by 294.94 kN m^-2.

The average values of the drawbar draft per area of soil disturbed at the tested speeds were 2508, 2360, 1918, and 1475 kN m^-2, from the lowest to the highest speed. These values are below those reported by Mahl et al. (2004), when evaluating the performance of a seeder-fertilizer in a no-till system for corn sowing, and above those obtained by Bortolotto et al. (2005).

CONCLUSION

The average drawbar draft requirement per seeding line and area of soil disturbed decreased with increasing speed, while the average drawbar draft per furrow depth increased with increasing operating speed.

Recebido para publicação em junho de 2010 e aprovado em maio de 2011

• ASAE - American Society of Agricultural Engineers (1999) Agricultural machinery management. Standards Engineering Practices Data. (ASAE D497.4 JAN98:359-66.
• Bortolotto VC, Pinheiro Neto R & Bortolotto MC (2005) Demanda energética de uma semeadora-adubadora sob diferentes velocidades de deslocamento e tipos de cobertura vegetal no plantio direto da soja. Acta Scientiarum Agronomy, 27:357- 3 62.
• Bortolotto VC, Pinheiro Neto R & Bortolotto MC (2006) Demanda energética de uma semeadora-adubadora para soja sob diferentes velocidades de deslocamento e coberturas do solo. Revista Engenharia Agrícola, 26:122-130.
• Casão Júnior R, Siqueira R, Araujo AG & Ralisch R (2000) Desempenho da semeadora-adubadora MAGNUM 2850 em plantio direto no basalto paranaense. Pesquisa Agropecuária Brasileira, 35:523-553.
• Cepik CTC, Trein CR, Levien R & Conte O (2010) Força de tração e mobilização do solo por hastes sulcadoras de semadoras-adubadoras. Revista Brasileira de Engenharia Agrícola e Ambiental, 14:561-566.
• Collins BA & Fowler DB (1996) Effects of soil characteristics depth, operating speed, and opener design on draft force during direct seeding. Soil & Tillage Research, 39:199-211.
• Furlani CEA, Lopes A & Silva RP (2005) Avaliação de semeadoraadubadora de precisão trabalhando em três sistemas de preparo do solo. Revista Engenharia Agrícola, 25:458-464.
• Furlani CEA, Júnior AP, Lopes A, Silva RP, Grotta DCC & Cortez JW (2007) Desempenho operacional de semeadora-adubadora em diferentes manejos da cobertura e da velocidade. Revista Engenharia Agrícola, 27:456-462.
• Furlani CEA, Silva RP, Filho AC, Cortez JW & Grotta DCC (2008) Semeadora-adubadora: exigências em função do preparo do solo, da pressão de inflação do pneu e da velocidade. Revista Brasileira de Ciência do Solo, 32:345-352.
• Mahl D, Gamero CA, Benez SH, Furlani CEA & Silva ARB (2004) Demanda energética e eficiência da distribuição de sementes de Milho sob variação de velocidade e condição de solo. Revista Engenharia Agrícola, 24:150-157.
• Mion RL & Benez SH (2008) Esforços em ferramentas rompedoras de solo de semeadoras de plantio direto. Ciência e Agrotecnologia, 32:1594-1600.
• Modolo AJ, Silva SL, Silveira JCM & Mercante E (2004) Avaliação do desempenho de duas semeadoras-adubadoras de precisão em diferentes velocidades. Engenharia na Agricultura, 12:298- 306.
• Modolo AJ, Silva SL, Gabriel Filho A, Silveira JCM & Gnoatto E (2005) Demanda energética solicitada por uma semeadoraadubadora de precisão com diferentes unidades de semeadura. Acta Scientiarum Agronomy, 27:473-479.
• Santos AP, Volpato CES & Tourino MCC (2008) Desempenho de três semeadoras-adubadoras de plantio direto para a cultura do milho. Ciência e Agrotecnologia, 32:540-546.
• Silva ARB, Benez SH, Mahl D, Leite MAS, Pontes JRV, Grego CR, Marques JP & Costa AM (2001) Avaliação de uma semeadoraadubadora de plantio direto em função de diferentes mcanismos sulcadores e velocidades de deslocamento. In: 30° Congresso Brasileiro de Engenharia Agrícola, Foz do Iguaçu. Anais, SBEA. p.1-4.
• Silva PRA (2003) Mecanismos sulcadores de semeadora-adubadora na cultura do milho (Zea mays L.) no sistema de plantio direto. Dissertação de Mestrado. Faculdade de Ciências Agronômicas, Universidade Estadual Paulista "Júlio de Mesquita Filho", Botucatu, 84p.
• Silveira JCM, Gabriel FA & Secco D (2005) Demanda de potência e força de tração de uma semeadora na implantação do milho safrinha sob plantio direto. Engenharia na Agricultura, 13:256- 267.
• Siqueira R, Araújo AG, Casão Júnior R & Ralisch R (2001) Desempenho energético de semeadoras-adubadoras de plantio direto na implantação da cultura da soja (Glycine max L.). In: 30° Congresso Brasileiro de Engenharia Agrícola, Foz do Iguaçu. Anais, SBEA. p.1-4.
• Trintin CG, Pinheiro Neto R & Bortolotto VC (2005) Demanda energética solicitada por uma semeadora-adubadora para plantio direto, submetida a três velocidades de operação. Acta Scientiarum. Agronomy, 27:127-131.
• Universidade Federal de Viçosa (2007) SAEG —– Sistema para aná­lises estatísticas, versão 9.1: Fundação Arthur Bernardes.

Datas de Publicação

• Publicação nesta coleção
  25 Jul 2011
• Data do Fascículo
  Jun 2011

Histórico

• Recebido
  Jun 2010
• Aceito
  Maio 2011