An important step in corn cultivation is desiccation, which, due to resource efficiency and the tall height of plants, is best performed using DJI AGRAS series agro-drones. The starting point for corn desiccation is typically the beginning of physiological maturity, marked by the formation of the "black layer" (blacklayer). The appearance of the black layer on corn kernels depends on the FAO hybrid and can occur within a moisture range of 36–28%. A fully formed black layer indicates physiological maturity and complete detachment of the seed from the cob. Corn desiccation is generally recommended when seed moisture is 35–40%, provided that vegetative green leaves are still present.
Using desiccants on corn has become increasingly important due to reduced grain drying costs, timely harvesting, and soil preparation. Drying costs are one of the main expenses in corn production.
Gas is a key component in the elevator service cost. Lowering corn grain moisture by 1% per ton requires approximately 1.3–1.5 m³ of gas. In fall 2022, the cost of drying corn with gas ranged from 200 to 350 UAH per ton per 1% of moisture, depending on the elevator. In 2023, corn drying costs are expected to remain at a similar level. In 2022, grain moisture levels were high, often exceeding 30% due to various factors. A similar high moisture level is expected in 2023.
Drying 1% of corn grain moisture at an external elevator in 2022 ranged from 200 to 300 UAH. Drying corn from 30% to 14% moisture requires removing 16% moisture. The calculation: 16% × 250 UAH = 4,000 UAH per ton. At a yield of 8 t/ha, the drying cost per hectare is: 8 × 4,000 = 32,000 UAH/ha. For 10,000 hectares, the total drying cost amounts to 320,000,000 UAH or $8 million (at an exchange rate of 40 UAH/USD).
At a corn price of $119.7 per ton (4,786 UAH/ton) in September 2023, with a yield of 8 t/ha, the total revenue per hectare is $957.6 (at an exchange rate of 40 UAH/USD). Out of this, $800/ha or 84% of costs is spent on drying grain with a 30% bunker moisture content. This presents a huge opportunity for cost optimization using DJI AGRAS drone desiccation, reducing drying expenses and improving corn production efficiency.
Corn drying costs are not limited to natural gas expenses. Additional logistics costs, including transportation, handling, wages, electricity, and machinery depreciation, must also be considered. A grain truck carries 30 tons of corn, of which approximately 4 tons is water that needs to be evaporated at the elevator dryer to achieve the standard 14% moisture content. Reducing moisture levels before transportation leads to lower costs.
Some companies plan corn harvesting until late December, facing grain quality issues due to high moisture content. This leads to fusarium development on cobs, which may force some grain to be processed for ethanol instead of regular sale. Unharvested fields left untreated in autumn result in reduced yields of at least 10–15% in the following year due to delayed spring tillage. Additional risks include snowfall, leading to significant financial losses and missed commercial opportunities. All of this underscores the importance of corn desiccation with DJI AGRAS drones, which significantly reduces drying costs and enhances the profitability of corn cultivation.
Delaying harvesting beyond November 1st is not advisable because drying efficiency decreases at temperatures below +1.5 – 4.5°C. Heating the air in a dryer to +100°C is significantly easier when the outside temperature is +10°C rather than 0°C or -5°C. It is also essential to understand that corn should not be overdried, as it is prone to increased kernel cracking. Corn with internal cracks is more likely to break during transportation from the grain dryer to the silo and later during loading onto trucks or railcars. This can lead to excessive grain fragmentation, causing the foreign material content to exceed the acceptable 2% limit. The maximum heating temperature for corn in moving layers of shaft dryers should not exceed +50°C, with the drying agent temperature limited to +130°C (if the corn is intended for processing) or +110°C (for long-term storage). Heating corn above +60°C leads to fat oxidation, degrading essential vitamins and bioactive compounds, which ultimately reduces grain quality and nutritional value.
The question of “how to reduce costs on post-harvest corn drying” has always been relevant, but the sharp rise in gas prices in recent years has drastically shifted attitudes toward its solution and the importance of fuel savings at grain elevators. Previously, corn desiccation with DJI AGRAS drones was viewed as a cost-saving measure, but now it has become a necessity.
The decision to conduct corn desiccation becomes even more challenging in non-homogeneous (heterogeneous) fields, particularly those with depressions ("bowls") and significant soil variations, common in the Polissia region. Desiccation promotes uniform and accelerated moisture loss and grain ripening. Drying the crop significantly simplifies the harvesting process for combine harvesters. Drier biomass is easier and more effectively chopped, ensuring even field distribution, which improves soil preparation for the next season.
Glyphosate-based desiccants are most commonly used for corn desiccation. They systemically penetrate the lower, often green stem, making it easier to cut with combine blades and improving threshing efficiency. There are also frequent cases of corn desiccation using contact-action desiccants with diquat as the active ingredient. These products effectively dry the green corn leaves, which significantly influences seed moisture reduction.
The start of desiccation can be determined by observing the drying of upper leaves, which serves as a signal of physiological maturity. This stage may occur at different times depending on the hybrid and typically follows one of three patterns: Drying of the first leaf, followed by the beginning of the second leaf drying. Drying of the first and second leaves, followed by the beginning of the third leaf drying. Drying of the first, second, and third leaves.
It is crucial to understand that desiccation efficiency can be affected by high humidity levels and low temperatures (especially at night when temperatures drop to +5°C). Intense moisture loss from corn kernels almost entirely stops when the average daily air temperature drops to +5 – 6°C, combined with relative humidity rising to 80 – 90%. Such weather conditions usually begin in early November. When these conditions occur, postponing corn harvest is no longer practical, as grain moisture will not significantly decrease and will not reach the desired standard level.
The table below presents the economic efficiency of DJI AGRAS drone desiccation on corn at a yield of 10 t/ha with an initial moisture content of 30%, where desiccation reduces grain moisture by 6%. Moisture reduction through desiccation can exceed 6%, reaching up to 20%, depending on weather conditions, hybrid FAO, and desiccation timing. The drying cost per 1% of corn moisture is approximately 250 UAH per ton. However, the actual drying cost may be significantly higher than 250 UAH per 1% per ton, depending on elevator location, gas prices, and contract agreements. Through drone desiccation, farmers can significantly reduce corn drying costs by decreasing grain moisture by at least 6%, leading to estimated savings of approximately 1,359,837.5 UAH per 100 hectares.
One of the weed and pest control systems for corn is presented in the table below, where the third treatment is carried out using a DJI AGRAS drone against the European corn borer during the tasseling-flowering period with a tank mix of insecticides: Karatel Plus 0.2 + Coragen 0.12, as well as desiccation with Helios Extra 2.5 L/ha when seed moisture reaches 35%. All crop protection treatments in this protection system can be performed using a DJI AGRAS drone. A key feature of this protection system is the application of GromNext together with pre-emergence herbicides, without pre-sowing cultivation, targeting actively growing weeds at a height of up to 10–15 cm. If weeds overgrow, the GromNext dose increases to 2.5 L/ha. The optimal growth stage of corn for post-emergence herbicide application is the 3–5 leaf stage. At this stage: Broadleaf weeds should be no more than 4 leaves. Grass weeds should be between the 2-leaf stage for annual monocots and the end of tillering, as well as perennial grasses up to 10–15 cm in height. A mandatory measure in this system is corn desiccation using a DJI AGRAS drone at physiological maturity when seed moisture reaches 35%.
It is crucial to apply post-emergence herbicides on corn in the 2–4 leaf stage, while the growing point remains underground, and before the onset of June heat at the end of May. Temperature conditions also influence the herbicide breakdown within the plant and its phytotoxicity on crops. The corn ear initiation occurs at the 2–3 leaf stage, while its formation takes place after the 5-leaf stage. The number of kernel rows is genetically determined from the beginning. However, row length and the number of ears develop between the 6-leaf stage and tassel emergence. Stress during these critical phases leads to a shorter ear length, while stress after pollination results in reduced grain filling.
Soil herbicides should be used in fields where annual weeds are predominant. Proper preparation of the field surface with minimal plant residues is a necessary condition when working with soil herbicides. The application of post-emergence herbicides in corn crops should be planned from the 2-3 true leaf stage and not postponed to later stages (5th, 6th, or 7th leaf).
When using plant protection products, it is essential to strictly follow the application regulations. The optimal air temperature for herbicides is 17-18°C (or at least between +8-10°C and +25°C), for fungicides between +12°C and +20°C, and for insecticides between +15°C and +25°C. Post-emergence herbicides should be applied at earlier weed development stages (seedlings, 2-4 true leaves for annual weeds, and the rosette stage for perennial weeds).
It is not advisable to spray corn that is under stress from drought, frost, pest damage, etc. When applying soil and then post-emergence herbicides in corn fields in May, there may be frosts down to 0 to -1°C, a return of cold weather after a warm period, and sharp temperature fluctuations. Depending on the herbicide, the application of soil treatments should be stopped when the air temperature drops below 8°C, and post-emergence spraying should be halted if the temperature falls below 10°C.
DJI AGRAS series drones are the most popular among farmers for field spraying and desiccation. These drones are the best-selling unmanned aerial vehicles in Ukraine. The leading agricultural drone is the DJI AGRAS T30. The DJI AGRAS T30 spraying drone, due to its numerous power units with propellers, eliminates droplet drift and trailing compared to drones with only two motors and propellers. The propellers, arranged in a circular pattern around the drone, direct the droplets straight onto the plants, preventing the solution from being blown away—an important advantage in ensuring high-quality spraying compared to other agricultural drones on the market. It features eight electromagnetic valves, which differentiate the spraying zones and prevent wind drift. The foldable arm design reduces the drone’s size by 80% when collapsed, making transportation and storage more convenient. The DJI AGRAS T30 is equipped with the highest-quality battery (BAX501-29000mAh-51.8V) with a capacity of 29,000mAh and a warranty of 1,000 cycles or 12 months, surpassing other drone batteries in terms of charging cycles. DJI AGRAS drones lead the market in quality, experience fewer breakdowns, and require significantly lower repair costs. AGRONIX is the #1 team in Ukraine for applying crop protection products with agricultural drones, as well as for selling and servicing DJI AGRAS drones. This is confirmed by customer reviews and the professional support provided to farmers by the company’s specialists.
The use of DJI AGRAS T30 agricultural drones in crop production technology offers several advantages over ground-based self-propelled sprayers: High productivity – Two agricultural drones can effectively replace one ground sprayer. In an 8-hour workday, two drones can cover 100-200 hectares, with a spraying capacity of 12.5-25 hectares per hour. Fine droplet application and ultra-low volume spraying – Reduces water consumption for preparing and applying the working solution by 40 times, from 200 liters per hectare to just 5 liters per hectare. Precise application timing – Operating at a flight height of 1.5-5 meters, drones enable treatments to be carried out during biologically optimal periods, ensuring proper fertilization even in challenging weather conditions. No soil compaction – Eliminates yield losses of at least 20% caused by soil compaction from heavy machinery. No crop damage – Unlike ground sprayers, drones prevent 5-10% of crop losses caused by wheels running over plants. Efficient field coverage – Two drones can fully handle all spraying needs for farms of 2,000-4,000 hectares. Cost-effectiveness – A DJI AGRAS T30 drone (without additional equipment) is 30 times cheaper than a self-propelled sprayer, which costs $230,000–250,000. Fuel efficiency – Drones consume 8 times less fuel per hectare than self-propelled sprayers. While a ground sprayer uses 1 liter of fuel per hectare, charging agricultural drone batteries requires only 3 liters of fuel per 25 hectares. This results in a fuel cost of just 5-6 UAH per hectare for drones, compared to 50-60 UAH per hectare for self-propelled sprayers.
