Are Crop Spraying Drones an Option?

Koringfokus Magazine · July-Aug 2022

Improved operational efficiency and application quality are key selection factors in the choice of an ideal drone for winter grain crop spraying against pesticides or herbicides, without compromising on the reduction of input costs and the impact on the environment.

Technology is a dynamic partner to be included in a grain production plan and team. However, it is developing at such a rate that farmers need to clearly distinguish between the pros and cons of a professional spraying drone as an asset, compared to using it as a contracted service. Agriculture spraying drones can replace the traditional pesticide or herbicide sprayers. Nowadays remote-control copters are also used for fertilisation and to sow seed. To apply granular fertilisers or sow seeds, the spray tank is replaced, enabling applicators multitask. Overberg producer, Dirk Human, says drone and precision technology need to support improved precision and accuracy in spray applications.

“As a management tool a drone is essential to increase precision application without overdosing or underdosing on plant foliage in avoiding too many chemicals.”

Human says alien control in the protected wetland areas of the Nuwejaars Marshland near Elim would benefit from the less-polluted GPS precision spraying by drones compared to conventional options.
It is not true that crop spraying drones will always be more cost-effective than traditional crop spraying by fixed wing aircraft or mechanical equipment. Calculations for contracting drone crop spray services, or for buying it as a farm asset or an intended contractor business, needs to be done carefully, says Pieter Boshoff from Clarens Chemicals in the Eastern Free State.

Improved efficacy in crop spraying

Introducing the most recent crop spraying drone option to grain producers, Tim Wise, CEO of PACSys Precision Agriculture Systems, says they have been in the spray drone business for six years now, striving to improve the efficiency of crop spraying.

“We are an approved training organisation (ATO). We do not supply drones without guiding private owners and contractors to obtain accredited training for remotely piloted aircraft (RPA) operator licenses and professional support,” says Wise. “When we started out, the technology was not ideal
to do mega crop spraying on e.g. wheat, maize, canola and fodder crops. As KZN based sugar cane farmers, our focus with drone introduction was in areas where steep mountainous slopes require precision piloting and equipment. To improve results, save on the long term and remain environment friendly, the crop spraying DJI Agras T30 (with a 30-litre payload) has been a massive leap forward for the drone crop spraying industry,” says Wise.

He confirms that spraying accuracy is better than with aerial application;

“Since drone calibration and GPS controlled systems allow for persistent predetermined flight lines for centimetre precision. With the spray nozzles being directly under the propellers as the driving force, efficacy of contact insecticides will benefit from enhanced penetration.”

Licensing and requirements

Company level licences, drone level licenses from Civil Aviation and pilot level licenses are essentials in the drone crop spraying business. In South Africa, drone regulation is done by the South African Civil Aviation Authority (SACAA) and all flights are registered. In accordance with Part 101.02.4(1) of the Civil Aviation Regulations, 2011, no remotely piloted aircraft (RPA) shall be operated within the Republic, unless such RPA has been issued with a certificate of registration by the director.

Prior to making an application with SACAA, aspiring remotely piloted aircraft operators will be required to obtain aviation training at an approved training organisation. Previous experience is recognised by SACAA for a person who has held a pilot license; a military qualification equivalent to a license and rating; an air traffic control license or a military qualification equivalent to an air traffic control license or previous commercial air unmanned aircraft operations experience. The remotely piloted aircraft training course is provided by SACAA approved training organisations that have basic remotely piloted aircraft training on their operators’ certificate. In addition, pesticide and herbicide operators need to adhere to the Department of Agriculture, Land Reform and Rural Development (DALRRD) regulations and work under supervision of a registered pest control applicator for at least six months.

It is possible

The DJI factory where the crop spraying DJI Agras T30 is manufactured, is situated in what is widely considered as China’s Silicon Valley. Here they benefit from direct access to the suppliers, raw materials, and a young, creative talent pool to develop and manufacture precision drones for industrial, agricultural, security, land-mapping, construction, landscape, equipment and structure surveillances. While the next generation 40-litre capacity spraying drone is almost ready to leave the DJI headquarter factory in Shenzhen to reach South Africa by December 2022, Wise focused on the 30-litre version. Should farmers consider purchasing a drone for own, shared or contractual services with one or more licensed operators, a new 30-litre payload will cost about R350 000 which include training and support, says Wise. Pre-owned drones are also available. also available. Legally qualified remotely piloted aircraft operators are responsible for the handling of all spray and safety procedures. With the market valuation retailing value of the drone in mind, some owners would prefer to take out asset finance. In that case drone insurance will be required to assist them with cover, should the drone be damaged, stolen or cause damage. An insurance house pointed out that accidents do happen.

“There are definite risks involved flying over crops with a DJI Agras T30’s with take-off weight being about 76 kg when at full capacity. Liability risk should be considered for potential crop loss due to fire, since the machine is powered by lithium batteries. Third-party liability insurance will be needed to cover losses potentially caused by the drone.” Wise confirms that drone assisted crop spraying in South Africa is currently done at about R250/ha.

“However, there are numerous factors impacting on the actual cost on each farm or even each unique grain block. Such variables include land size, topography, season length and the history of previous
business with clients.”

Spray drone batteries require regular recharging during spraying. Batteries need to be replaced after every 1 000 battery charge cycles. Spray contractors calculate labour, skills, accreditation of staff and transport cost to be invoiced, says Wise. Wise noted that tractors could usually do 10-15 years before write-off replacement, compared a replacement expectation of about 3 years in the case of a farmer-owned drone and as little as 12-18 months should it belong to a contractor who needs to keep up with the competition with new technology being released about once a year, with 30%-40% greater efficiency.

What to expect

When the contractor arrives at the farm to render drone crop spraying service, they would usually turn up with a 650-litre mix-ing unit, one or more fully equipped and well-maintained spray drones and at least a 32 kVA generator for battery charging, says Boshoff.

Landowners provide all required chemicals or fertilisers. Drone crop spraying takes place during day and night sessions. On average the DJI Agras T30 drone can cover about 80 hectares on a fair-weather day at 10 ha/hour. Farm surveillance with the spraying drones equipped with sensors and high resolution multispectral or hyperspectral cameras is useful to pro-actively monitor and control weeds and pest outbreaks on the land. Regular routine flights across precision allocated and numbered production blocks also expose irrigation and fertiliser shortages.

Considering the cost and application efficacy of natural or chemical pesticides, herbicides, water or liquid fertilizers by drone crop spraying, grain producers need to consider various realities when considering a precision agriculture spraying drone as an asset. These include cost, insurance, modular part replacements, convenience, stability and reliability. Other key considerations are accuracy and penetration, professional training, after-sales support, the drone’s ability to offer more night spraying hours and the benefit of short notice availability by drone spraying contractors, saving money should a pest or weed crisis arise. Producers need to note that all applications for relevant licensing must be submitted to the SACAA for company, drone and operator registration. Pest control operator certifications are done by DALRRD, as is the case with arial, mechanical or hand crop spraying in South Africa.

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