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Calibrating the bean planter before planting helps ensure the desired plant population, uniform seed distribution, and proper planting depth. Correct adjustment also reduces waste and emergence problems, making calibration an important pre-planting step in different regions and growing seasons.
Before entering the field, the producer needs to organize seeds, fertilizers, and other inputs, as well as check soil conditions such as moisture, straw cover, and leveling. In this process, calibrating the planter acts as a link between crop planning and the execution of sowing.
Bean cultivation is sensitive to gaps, excessive plant density per meter, and variations in planting depth. Because the seeds are relatively small, changes in the metering device, discs, spring pressure, or working speed can lead to plantless spaces, double seeds, and uneven emergence.
Uneven depth can also exacerbate problems in soils with a lot of straw or moisture differences. Furthermore, an uneven stand can hinder subsequent operations such as spraying and harvesting, while excess seed increases planting costs.
Therefore, before calibration, it is necessary to check the mechanical condition of the machine. Cleaning the seed and fertilizer boxes helps to remove dust, remnants of previous crops, and foreign materials.
It is also important to check for excessive rust or dents and to inspect the condition of hoses, seed delivery tubes, bearings, and joints.
Seeding discs should be inspected for oval holes, broken parts, or other wear. The model used must be compatible with the size and shape of the seeds in the batch to be planted, especially when there are cultivars with larger or more elongated grains.
The metering system, whether mechanical or pneumatic, also requires attention. Excessive clearances can lead to failures or the dropping of two or more seeds close together.
The furrow openers, cutting discs, compaction wheels, and covering wheels should also be inspected. Wear on the furrow openers can alter the depth and formation of the furrow, while the cutting discs need to be in proper condition to cut the crop residue without causing clogging in no-till planting systems.
Compacting and covering wheels must ensure seed coverage and good contact between soil and seed. The transmission also needs to be checked, including chains and gears, with lubrication and replacement of heavily worn components.
Another important point is the working speed. The producer must respect the range indicated by the manufacturer to maintain the accuracy of the bean seed dosage.
Before adjusting the machine, it is also necessary to define the desired population. This planning considers the type of bean, the production system, the productive potential of the soil, the fertility level, the spacing between rows, and the available equipment.
The calculation must take into account the technical recommendations for the cultivar and the production environment. The germination rate indicated in the seed report and the vigor of the seed lot also need to be considered to estimate the quantity of seeds required and to compensate for any losses during emergence.
Based on the desired plant population, row spacing, and total row length per hectare, it's possible to determine the number of seeds per meter of row. This number should serve as a reference for the practical adjustment of the planter.
In mechanical machines, the initial adjustment should follow the table provided by the manufacturer, considering the gear combination or pulley adjustment indicated for the beans.
In pneumatic systems, it is necessary to select the disc appropriate to the seed size and adjust the vacuum and application rate to achieve the planned quantity. This initial adjustment still needs to be confirmed by bench testing.
The bench test allows you to verify if the theoretical settings correspond to the machine's operation. To perform it, the planter must be safely suspended, allowing the drive wheels to rotate without the machine moving.
The boxes should be partially filled with the same batch that will be used in the field. Whenever possible, the seeds should be in the same treatment condition planned for planting, since products such as inoculants, fungicides, and insecticides can alter the seed flow.
Next, you need to determine the number of revolutions of the drive wheel corresponding to a known travel distance, such as 50 or 100 meters. The machine's manual usually provides this ratio.
Containers can be positioned under the seed outlets of the selected rows. After the wheel has rotated the defined number of times, the collected seeds should be counted and related to the simulated length.
The result allows you to check how many seeds are being distributed per meter of row. The measurement should be compared with the previously defined target.
If the quantity is higher than desired, the rate should be reduced by adjusting the transmission or metering device. If it is lower, the rate should be increased. The test needs to be repeated until the result is close to the target and shows acceptable variation between the lines.
During this evaluation, it is also important to observe the occurrence of doubles and skips. Systems that provide good singulation are especially important for bean sowing.
Calibration doesn't end with the quantity of seeds. The sowing depth also needs to be checked, as it directly influences plant emergence.
The appropriate depth depends on the soil type, moisture, and the presence of mulch. The goal is to allow good contact between the soil and the seed without causing excessive burial.
The initial adjustment of depth limiters should follow the manufacturer's instructions. In very loose or sandy soils, excessive depths can hinder emergence.
In clayey soils with straw cover, sowing a slightly deeper seed, as long as it's within the recommended range, can help maintain moisture close to the seeds.
After the bench adjustment, it is necessary to perform a test in a small area of the field. The machine should operate at a speed close to that which will be used during planting.
After sowing a small strip, it is necessary to interrupt the operation and carefully dig up several points in the rows to check the actual depth of the seeds using a ruler or tape measure.
The assessment should consider the uniformity of depth between and along the rows. If the seeds are too shallow, they may be more exposed to desiccation or predators. If they are too deep, emergence may be slower and more uneven.
In this case, the adjustment of the limiting wheels, the spring pressure, and other components must be adjusted before repeating the test.
Compacting and covering wheels also need to be adapted to soil conditions. The pressure must be sufficient to keep the soil firm around the seed, but without causing excessive compaction on the surface.
In the case of heavy rainfall, surface compaction can promote crust formation. Conversely, in moist soils, it is necessary to reduce pressure to prevent waterlogging and problems with soil structure.
Planting speed also affects the quality of distribution. Very high speeds can increase gaps, doubles, and variations in depth.
In areas with steeper slopes or uneven ground, a lower speed can help maintain machine stability. On level terrain, work should be done within the range indicated by the manufacturer, without exceeding the limit that would compromise dosage accuracy.
During the field test, the producer should observe furrow formation, seed drop, and coverage. Excessive vibrations or seeds jumping within the furrow are signs that the speed may need to be reduced.
Seed treatment also interferes with calibration. Fungicides, insecticides, and inoculants can modify the roughness and friction of seeds, altering their behavior in seed metering devices.
For this reason, calibration should be performed with the seeds already treated and in the same condition in which they will be used for planting. It is also necessary to avoid excess graphite or other dry powders, which can promote slippage or clogging.
Treated seeds must be thoroughly mixed before being placed in the planter box. Clumping can cause uneven flow and compromise distribution.
If bench or field tests identify problems, it is necessary to check for the presence of clumped seeds, excess dust, or friction in the conduit tubes.
Machine inspection, population calculation, bench test, depth check, and speed evaluation form a set of procedures to prepare the planter before its final entry into the field.
Calibration should be redone whenever there is a change in cultivar, seed lot, or working conditions. The machine model also affects the settings, so specific values for gears, depth, and population should not be generalized across equipment.
During testing, safety must also be a priority. Adjustments should not be made while the machine is in motion or with unprotected rotating components.
When lifting the planter for bench testing, it is necessary to use sturdy and suitable stands or supports. The tractor must be switched off and the parking brake engaged before any intervention.
The use of appropriate personal protective equipment, such as gloves, goggles, ear protection, and boots, is also part of the precautions during operation.
Calibrating a bean planter before planting, therefore, requires planning and attention to mechanical and agronomic details. The procedure aims to transform the planned population into a uniform seed distribution, with adequate depth and better conditions for emergence.
When performed according to the characteristics of the cultivar, the seed lot, the machine, and the soil and climate conditions, adjustment contributes to a more homogeneous stand and can reduce waste and planting costs.
