Choosing a Producer Seed Treating System
Most current products are water-base liquid solutions with high polymer and drying agent content. These are needed to stick the product onto the seed, and dry quickly so it stays attached. Think of them as quick drying latex paint.
Just like field spraying, seed-treating crop benefit is determined by the effectiveness of the product, and how well it's applied.
Producer Seed Treating System Components.
When choosing a seed treating system, ask the following questions to check for applicator effectiveness.
1. How is the product applied?
Originally seed treating was done with gravity drippers, but they lack any means of accurate control, so are poor at delivering accurate rates or uniformity. New treating products are designed to stick where placed, so don't work well with drip type application, which initially places all the product on about 10 % of the seed.
Flat fan spray nozzles are used, but are notorious for plugging with chemical and dust residues. They can plug partially or completely, eliminating any reliable pressure to flow rate relationship. Flow rate is thus highly uncertain. Most flat fan units are not calibrated, so users must try to field calibrate or guess at flow volumes.
Some applicators use 2 nozzles, hoping a bad application can be improved by spraying twice. Unfortunately, reducing the nozzle opening by half makes plugging occur even more quickly.
Controlled droplet Hollow cone nozzles are a 2-part center hole types, used for application of liquid fertilizers and similar products where droplet size control and plugging resistance is required. This makes them a reliable applicator for producer systems.
Spinning Disc applicators are available, but usually not in producer systems due to their higher cost and maintenance requirements.
Higher value producer treating systems should have reliable applicators that resist plugging. They should also be flow calibrated with the chemical, for ease of use and accurate application.
2. Is the seed rate controlled?
Seed flow rates to the chemical applicator must be stabilized, to apply a predictable rate of chemical. This can be done with augers, conveyors, metering rolls or restrictor plates. In many producer-treating setups, it is not controlled at all. This pretty well eliminates any rate accuracy.
Higher value producer treating systems will have some means of controlling the seed rate, and hopefully indicate what that rate is.
3. Where is the product applied?
Seed treating can be applied in augers, conveyors, bean ladders, restrictor gates, custom units, or dumped onto the seed in the seed drill.
Crop benefits from treating are a direct result of how uniformly the seed is treated.
Dumping liquids into an auger or conveyor isn't much use for crop protection. Operating them at half of full capacity exposes more seed to the spray, but still hits only about 1/5 - 1/3 of the seeds with 100 % of the chemical.
The top seeds get a 500 % rate; the bottom ones none. 80 % of the seed is improperly treated. That means only 20 % of the benefit gets to the crop. Not much field help.
Spraying with uncalibrated flat fan nozzles into augers conveyors is a bit better, but not much. It requires field calibration to set each rate, and flat fans plug quickly with dust and chemical residues. Flat fan nozzles are designed to overlap, so most have a flow variance of 30 % from the center of the pattern to the outer edge. The treated seed gets the same variance.
Flat fan spraying into bean ladders yield similar reliability and uniformity problems. Ladders are good velocity arresters, but poor as grain spreaders.
Spraying into augers with calibrated hollow cone nozzles allows accurate rate application; you just can't get it uniformly applied.
Calibrated hollow cone nozzle applicators provide the best application accuracy and reliability, when applying with a one auger treating system.
4. Improved uniformity of product onto the seed yields better field benefit.
To get all the benefit from your seed treatment, you must treat all the seed.
Treating all the seed uniformly requires changing the seed flow pattern before the chemical is applied. Some treaters do this by changing the seed flow into a thin stream; others by spreading it out into an air curtain. Anything that opens up the seed flow to chemical application will usually help, provided it doesn't mechanically hurt the seed by the change.
The only effective seed re-distributor treaters currently on the market for producers are the Flexicoil air seeder unit and the Graham G3. They both deliver over 85 % primary application accuracy.
The Flexicoil on the go unit puts the seed onto a spiral with a thin curtain of chemical. It is quite effective, but has issues with plugging and complexity. It is no longer being sold, but still has many units in service.
The Graham G3 is a high-speed applicator, used in both producer and commercial applicator systems. It comes pre-calibrated for accurate pressure delivery of chemical, and operates at high throughput speed (1200 to 1500 bu. per hour). It is used in conjunction with a seed flow control unit like the TX7 transfer auger, or a restrictor control cone if hung from a gravity discharge bin.
5. Cost - Benefits of Producer seed treaters.
Seed treaters are used to deliver crop production benefits via the seed. Their value to a producer is determined by how well they do this.
Like a field spraying operation; good seed treating products will fail with bad application.
Each producer must decide how much to invest in an applicator, vs. how much field benefit he expects from the product. (see chart)
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