Plantability measures how well the planter was able to distribute the seeds evenly at the planned depth and spacing.
A survey conducted by Aprosoja-MT in partnership with Embrapa indicates that only 58 of the 289 plots evaluated met the ideal seeding standard, meaning that only 20% of the monitored areas operated with the recommended precision. The average loss was 4,785 plants per hectare. This article explains how to assess this uniformity in your crop, what factors compromise it, and which machine and seed adjustments can correct the problem.
What is plantability?
Plantability can be defined as the ability to plant efficiently, ensuring that seeds are distributed evenly in the soil and planted at the proper depth for their development.
This practice aims to maximize plant emergence, reduce planting failures, and prevent unnecessary competition among plants. Good plantability also reduces production costs, as it prevents the waste of seeds and inputs.
In addition, it promotes more efficient use of resources such as electricity, water, and nutrients—factors that directly influence the final result.
Plantability is the ability of the combination of seeder, seed, and soil to place each seed at the spacing and depth specified for the crop.
The result depends on the equipment settings, the physical uniformity of the batch, and the conditions encountered in the field. These factors influence plant emergence and distribution along the row.
Uniform seeding promotes the establishment of the intended plant stand, facilitates management, and reduces losses associated with failed germination and seeds planted too close together.
The assessment should take into account the longitudinal distribution of the plants after emergence. The population per hectare is also important, but it does not, on its own, reveal how the plants are distributed along the row.
How do you assess a field's suitability for planting?
The assessment can be conducted directly in the field, once the crop has emerged. The method described in an Embrapa study uses two rows, each five meters long, per plot.
The criterion based on the ABNT standard considers plant spacings ranging from 0.5 to 1.5 times the average row spacing to be acceptable.
- Less than 0.5 times: indicates double spacing, with plants that are very close together.
- Between 0.5 and 1.5 times: this corresponds to the range considered acceptable.
- Greater than 1.5 times: indicates a distribution failure.
The proportion of acceptable spacing helps determine the accuracy of seeding. The higher this proportion, the closer the result is to the planned distribution.
In the survey conducted by Embrapa in partnership with Aprosoja, only 20% of the 289 plots evaluated showed full precision. The failures resulted in an average loss of 4,785 plants per hectare.
In areas with 50% accuracy, the reduction in plant density ranged from zero to 36,000 plants per hectare. This figure represents the worst-case scenario observed, not the survey average.
To assess the area itself, repeat the measurement at at least three representative points. Include the ends of the area and areas with greater compaction, where operating conditions may vary.
See the Embrapa study on plantability assessment to learn about the methodology and results of the survey.
What factors affect plantability?
Seed distribution is the result of a combination of equipment, seed lot, and environmental conditions. Evaluating these factors together helps identify the source of problems and determine the necessary adjustments.
Seeder Adjustment
Discs, rings, feed tubes, and metering systems must be suitable for the shape and size of the seeds. Adjustments must be made in accordance with the manufacturer’s specifications.
Conduct the check before beginning planting and whenever there is a change in lot, a change in operating conditions, or the identification of distribution errors.
Planting speed
Speed affects how the seed chambers fill and how the seeds are released by the metering unit. Excessive speed can increase the occurrence of missed doses and double doses.
For mechanical disc seeders, Embrapa Soja uses a reference range of 4.5 to 6 km/h. Field studies report an increase in seed failures and double seeding at speeds above 4.5 km/h.
Surveys in Mato Grosso use 5 km/h as the working reference and 5.5 km/h as the tolerable limit. Performance, however, depends on the equipment and operating conditions.
Pneumatic and electric dispensers can operate at higher speeds, provided that the vacuum system, discs, rings, and tubes are in good condition. Conduct tests before setting the operating speed.
Plant test strips at different speeds and compare the distribution after emergence. The results will allow you to choose a planting rate that is compatible with the desired precision.
Soil conditions
Moisture, temperature, soil compaction, and the amount of straw all affect seeding and emergence conditions. Adjustments should take into account the characteristics of each field.
The depth must remain uniform along the entire line. Variations can cause uneven emergence and put some plants at a disadvantage compared to their neighbors.
Seed quality
Size, shape, physical uniformity, and physiological quality influence performance in the planter and seedling establishment.
Batches with a wide range of sizes may require specific adjustments. Selecting the right discs and rings helps ensure that the distribution remains as planned.
Seed Treatment and Distribution in the Furrow
Seed treatment alters physical characteristics of the seed surface, such as weight, shape, roughness, and flowability. These changes can affect the movement of the seeds through the metering system.
When the coating makes the surface sticky or causes an excess of loose powder, distribution may be affected. Therefore, the process must take into account product compatibility and application quality.
In a Unesp test cited in the technical audit, changing the timing of graphite application increased the acceptable spacing rate from 79% to 90% and cut the number of failures in half.
The polymer helps the products adhere to the seed and reduces dust shedding. The result depends on the formulation, the dosage, the equipment, and the application conditions.
Drying agents are used in industrial treatment formulations to aid in the completion of the drying process and to improve the physical properties of the batch. The audit did not identify any independent evaluation that, on its own, substantiates this effect on the distribution.
Graphite can improve flow when applied at the recommended dosage. Excess graphite promotes dust formation and can contaminate the equipment; always follow the dosing device manufacturer’s instructions.
The Abrasem Best Practices Guide provides guidance on application, coating quality, flowability, handling, and planting of treated seeds.
It’s worth noting, however, that when done properly, the treatment does not impair distribution. A study by the Federal University of Santa Maria cited in the audit indicates that polymer and graphite, when applied correctly, do not reduce the quality of distribution.
Laborsan operates CTIS, its Center for Seed Technology and Innovation, which is dedicated to the development and evaluation of formulations, including flow and distribution tests.
Soybeans: What Changes When It's Time to Plant?
Soybeans are more forgiving than corn because they have high phenotypic plasticity and compensate for deficiencies by branching. But this compensation is limited, and it costs days in the growing cycle.
The critical factor for soybeans is seed size. The disc and ring are selected based on the sieve, so a batch with widely varying sieve sizes throws this pair off.
That is why the physical uniformity of the lot carries almost as much weight as germination in the report. Seeds of the same size pass through the disc in a predictable manner.
Soil moisture and temperature on planting day make all the difference. Cold or dry soil delays emergence and widens the gap between the first and last plants in the row.
Plants that emerge three or four days late are unlikely to catch up with their neighbors and end up being overrun.
Corn: What Changes When It's Time to Plant?
Corn has a lower compensatory capacity compared to soybeans. Neighboring plants can utilize some of the available resources, but they recover only a portion of the yield that would have been produced by the missing plant.
Ultimately, every 1% defect rate in the crop translates to about a 0.77% loss in productivity, according to a study by Embrapa Corn and Sorghum in collaboration with UFSJ. This is the opposite of soybeans, which more than make up for it.
Both factors play a role, albeit in different ways. The final output is what the survey measures most consistently: a failure that brings down the production line directly reduces productivity.
The isolated effect of irregular spacing—with the population remaining constant—is smaller and is still debated in the literature. In the field, these two factors go hand in hand, because spacing irregularities worsen both at the same time.
Depth is also a more critical factor. Variations within the same row cause plants to emerge on different days, and the one that emerges later becomes a dominated plant.
Disc, vacuum, and speed settings must be checked on a field-by-field basis, not just once per harvest. Soil, crop residue, and moisture levels affect the seeder’s performance throughout the day.
A quick check of seeding accuracy after emergence shows, in just a few minutes, whether the day's settings were correct.
Learn more about corn plantability to gain a deeper understanding of crop-specific planting rate and spacing calculations.
Embedded technology and real-time monitoring
Monitoring systems can record seed distribution during operation and indicate omissions, overlaps, and variations between rows, depending on the equipment's capabilities.
This data helps the operator identify deviations and verify whether the adjustments are producing the expected results. The reading should take into account the conditions of each field.
Monitoring works best when integrated with field inspections. A post-emergence review allows you to compare the machine's records with the actual crop stand.
Refer to Embrapa's technical guidelines on seeding equipment to supplement your assessment of the operation.
How does a crop benefit from uniform planting?
A uniform distribution promotes the establishment of the target population and reduces losses associated with failures and duplicates. The final outcome depends on the crop, the environment, and the management practices used.
Field evaluation makes it possible to identify problems early on and make adjustments to the planter, the speed, and the seed variety used.
The quality of the treatment also plays a role in this result. Smoothness, uniform coverage, and precise dosage all contribute to the seed’s performance during operation.
Measuring, adjusting, and verifying the emergence turns regulation into an evidence-based decision. Monitoring should be part of the planting routine for each field.
FAQ – Frequently Asked Questions About Plantability
What is plantability?
Plantability is the ability of the combination of machine, seed, and soil to place each seed at the planned spacing and depth. The closer the actual spacing is to the theoretical spacing, the greater the precision of the distribution. The assessment is made after emergence by comparing the distance between plants to the average row spacing.
How can you tell if the planting is even?
Measure the distance between plants in two five-meter rows once the crop has emerged. Spacing between 0.5 and 1.5 times the average is considered acceptable according to the ABNT criterion based on Kurachi. Below that, there are doubles; above that, gaps. The proportion of acceptable spacing indicates the precision of the seeding.
What is the ideal planting speed?
The speed depends on the metering system and operating conditions. For mechanical discs, the reference range cited by Embrapa Soja is 4.5 to 6 km/h. Higher speeds can increase the number of misses and doubles. Pneumatic meters require inspection of the vacuum system, discs, rings, and tubes.
What are planting gaps and doubles?
A gap is the empty space in a row when the distance between plants exceeds 1.5 times the average. A double occurs when two plants are too close together, with a spacing of less than 0.5 times the average. In corn, every 1% gap in plant stand can result in a yield loss of about 0.77%.
Does seed treatment affect plantability?
Yes, and the method used matters more than the treatment itself. In a test conducted by Unesp, simply changing the timing of graphite application increased the acceptable spacing rate from 79% to 90%. In contrast, a properly performed polymer treatment does not reduce the quality of distribution, according to a study by UFSM.
What is the difference between plantability and plant population?
Plant density refers to the number of plants per hectare. Planting pattern refers to how they are distributed along the row. Two crops can have the same plant density but very different yields, because one has plants spaced evenly while the other has gaps and double plants.
