An improved design for a zero-tillage experimental plot drill

A major challenge presented to researchers working in the discipline of agronomy and conducting hypothesis-driven field experiments is the scale-up of promising innovations so adoption on-farm achieves the same level of success observed at experimental scale. A problem spanning generations is ensuring planting practices during field experimentation accurately simulate commercial-scale planting equipment (Smith and Bergen 1962). This was less concerning in eras that pre-date the adoption of minimum or zero tillage, but with over 75% of Prairie crop lands now practicing conservation farming using “no-till” air drills (Hamel and Saindon 2017), the challenge to replicate these practices at a small scale in field experimentation has been daunting. This is further exacerbated by the concomitant conversion of summer fallow cropping systems to continuous cropping systems as few plot-scale drills were capable of achieving proper and uniform seed-soil contact due to compacted soil and crop residue clearance issues. While some manufacturers such as SeedMaster and Vale Industries (Conserva Pak^™) produced smaller scale versions for use by the research community, the units would require larger horsepower tractors, appreciable areas of land to accommodate extra-large experimental plots, wider inter-plots, and ∼15 m ranges to separate blocks. Thus, the general drawback is that they remain designed and applied to larger scale field plots, or, cannot be configured to precisely meter, distribute and place small quantities of seed in the seed row. The latter can be a critical shortcoming as seed or fertilizer innovations initially have low quantities of material for field experimentation. Conversely, designs configured to handle small quantities of seed generally are not capable of operating without a pre-plant tillage operation and are often configured with seed delivery systems and seed openers not normally used on commercial seeders, ie., gravity feed. The latter prevents research trial scale and establishment to reflect producer practices, which may compromise the relevancy of research findings to modern-day farming. For agronomy field research to simulate on-farm soil and plant responses better, a small-scale seeder was designed to meet these needs by utilizing processes from large-scale field applications and adopting and configuring them to small-scale plot processes.

Design plans commenced in September 2014 and were completed on 29 October, with emphasis on the design and fabrication of a unique frame compatible with two ranks of commercial-style openers configured with a three-point hitch that would also facilitate ease of maneuverability and portability (loading and unloading on a trailer). Multiple ranks of openers are an important feature as all commercial air drills are configured in this manner; however, several plot seeder frame designs mount all openers on a single rank to reduce cost. The problem is that this sacrifices relevance to commercial field scenarios where the fore and aft positions of openers can create unique furrow conditions. A product box and seed delivery design were also conceptualized with the capability to conduct variable rate seed and fertilizer metering in small quantities applied to a field research plot scale using zero-tillage technology. The product box consisted of two internal compartments with capacities of 57.8and 59.2 L, respectively. Guard rows that would flank each side of the plot to minimize interplot competition effects were integrated with product boxes (2) with a capacity of 7.4 L each. When using small material quantities typically packaged in envelopes corresponding to a specific treatment or experimental unit, the main product box was bypassed using a belt cone distributer and splitter assembly manufactured by ALMACO (Gen2 BCTS, ALMACO, Nevada, IA, USA), which was mounted behind the product box in front of the operator seat (Fig. 1). This provided the capability to “split” up to a six-row experimental unit configuration. As product boxes were not pressurized, venturis, an air box for flow equilibrium, and product collection manifolds (original design by the AgTech Centre) were required to direct the product to either the seed boot or side shoot of the opener. Metering and air delivery utilized commercial components to ensure proper simulation and consisted of a Valmar^TM air product delivery system (Valmar Air Inc., Elie, MB, Canada; Fig. 1), a Raven^TM hydraulic seed calibration and product control system (Raven Industries Inc., Sioux Falls, SD, USA), including Agtron^TM material blockage sensors (Agtron Enterprises Inc., Saskatoon, SK, Canada; Fig. 2), and Morris^TM seed cups (Morris Industries Ltd, Saskatoon, SK, Canada; Fig. 2). The design utilized Conserva Pak^TM knife openers (8) (Model CP129, Vale Industries Ltd., Indian Head, SK, Canada) spaced at 24 cm apart (Fig. 1). The drill was interfaced with a field computer to precisely control rates modulated by GPS-controlled ground speed. This allowed the system to operate with variable metering rates pre-programmed through Farm Works Software^® (Trimble^® Agriculture) and transferred to the field computer.

Safety considerations were integral to the operator platform design as per AAFC Job Safety Analysis (JSA) guidelines. Features included installation of checker plate steel platform installed over the entire machine to facilitate access to all components. Handrails were fabricated and installed around the entire perimeter of drill platform. Lastly, a high-back comfort seat was mounted at the rear for operator of seed and fertilizer cone distributor.

Design revisions, fabrication, and mock-up of the first prototype were completed on 26 October 2015 (Figs. 1 and 2). Further modifications were needed during diagnostic checks as hydraulic flow to operate both hydraulic rams for frame operation and the motors used for seed distribution was inadequate (Fig. 2).

The technical team removed the fan hydraulic system from the tractor’s hydraulic system and added a power-take-off-driven hydraulic pump and reservoir tank mounted to the platform deck. This change increased the hydraulic flow from the tractor to the rams and the motors that govern the materials boxes and the cone metering system. When mock-up and quality assurance work was completed, the drill was disassembled for painting before final reassembly and performance diagnostics—all of which were completed by spring 2016. The drill was first used in conjunction with a newly conceptualized seeding system for wheat—“ultra-early wheat”, and was first detailed in interim and final reports for that project (Beres et al. 2018). It was further described in the subsequent studies and publications of ultra-early wheat seeding systems (Collier et al. 2020b, 2021, 2022a, 2022b).

A second was designed in 2016 to further augment commercial field simulation where air drills are equipped with low disturbance, zero-till disc-style openers (Fig. 1). The prototype was equipped with Pillar Lasers disc openers (Pillar Lasers Inc., Warman, SK, Canada), which are operated with two hydraulic rams and an improved frame to wheel linkage system to decrease the imbalance when the drill is lifted up and down during field operations (Fig. 1). A similar style of improved maneuverability was retro-fitted to the first drill, which also alleviated stress of the front supports of the drill (inversely mounted due to space issues). To facilitate fertilizer research capabilities, a liquid fertilizer kit was installed on both drills, further adding to the flexibility and uniqueness of both prototypes. Additional improvements also included three independent product boxes (115 L capacity each) in addition to the two 17.5 L capacity boxes for outside guard rows. Final drawings were completed in December 2016 and component procurement and fabrication commenced shortly afterward. The technical team performed the first mock-up of the drill in April 2017, and it was sent off to be painted once quality assurance checks were completed. Final assembly was completed in mid-May and in time for the first seeding by this drill in May 2017.

The designs of both drills utilize commercially available technologies to allow for direct seeding on a scale and configuration compatible with agricultural field experiments. The result is optimal plant uniformity required for research, but in a seeding system that reflects “real-world” planting practices. Thus, it maintains relevance to commercial air drills and seeding technologies used on-farm but at a scale compatible with crop breeding adaptation trialing and agronomy field experimentation.

The authors declare no competing interests; an invention disclosure process was conducted for the drills, which was approved with Invention Disclosure “#17546_Zero-Till Plot Seeder”. This equipment did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. All design plans and drawings (see Supplemental S.1) may be available by contacting the corresponding author.