An improved design for a zero-tillage experimental plot drill

Abstract Adoption of conservation farming practices such as zero tillage when planting field research plots is essential to the replication of on-farm practices. The problem is that most drill options fail to meet expectations as they are not built to the scale required, compromise the need for uniformity of plant emergence within plot areas, lack portability, or have been designed and equipped in a manner that is not relevant to farm-scale seeder technologies and practices. Agronomists and Technicians at Agriculture and Agri-Food Canada engaged with engineering expertise to design and build two prototype drills that are now in full operation.

ation 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 57.8 and 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 pack- aged 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 sixrow 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 Con-serva 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-offdriven 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(Collier et al. , 2021(Collier et al. , 2022a(Collier et al. , 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 pro-totype 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.

Fig. 1 .
Fig. 1.Overview of two prototype plot drills designed and built by AAFC-Lethbridge Research and Development Centre, highlighting the hitch, frame, openers, and interface to tractor operator's software and GPS guidance systems.

Fig. 2 .
Fig. 2. Overview of two prototype plot drills designed and built by AAFC-Lethbridge Research and Development Centre, highlighting the material hydraulic metering system and air delivery components.