Seeds of soybeans are very delicate, because their skin is very thin. Therefore, they require a special approach for seedbed preparation.
Peculiarities of preparation soybean seeds
Seed skin damage during handling and planting is one of the main causes of low germination. It has been proved that damage of seed skin reduces moisture level of cotyledons and increases the risk of bacterial and fungal pathogens. Once embryo is damaged, embryonic root tissue can be damaged as well and this can result in worsedevelopment of the root system. In general, if soybean seed is significantly damaged, the overall stand of the crop may be poor the fact that reduces profitability of growing.
Seed damage caused by treating equipment
One of the highest dangers to soybean seeds is treating of large quantities of seeds with auger or conveyor belt type treaters. American scientists have studied the effect of treating equipment on seed germination. The trials were made on the following systems:
seed treaters with a 5.5-meter conveyor with rubber belts.
seed treaters with a 4.8-meter brush auger.
seed treaters with a 4.8-meter steel auger.
seed treaters with a 4.8-meter auger with a plastic cap flighting.
Samples of treated seeds were collected at the discharge sleeves of each treating system. Then they were tested for germination and compared to the control (seeds which were not treated with any one of these systems). The study found that the average germination after treating through all of the above systems was 5.2% lower than in the control batch. It also showed a significant difference in the degree of injury to the seed when the flow rate of seeds was 600 bushels (16.33 tonnes) per hour. Auger with plastic flighting was the least traumatic, seed germination rate being the closest to the control. Treaters with brush and steel augers caused a 7% decrease in germination compared with the control. However the experiment showed that the damage to the seed can be significantly reduced by lowering auger speed from 525 to 370 r / min. However, even under these conditions, treating system using a conveyor belt was the worst: a metal part of the conveyor without a rubber liner at the receiving part of the conveyor highly traumatized seeds. Based on the research results it is recommended to take such measures to reduce seed damage while treating:
– augers must operate at a lower speed and should be constantly filled with
– there should be a plastic or rubber liner on the receiving side of the
conveyor or auger to mitigate the hit when loading seed;
– you need to update the treating equipment or its parts regularly because the worn-out equipment is more traumatic for seeds;
– you should decrease the height of falling of seeds during unloading from the seed auger / conveyor (not higher than 3 meters);
– gently move the bags of seeds. If they are thrown on solid flooring, seed germination may be reduced up to 10%.
Seed germination depends on accuracy of the seed treatment rate
During pre-sowing treatment of seeds loss or damage of seeds can occur when using treating equipment with inaccurate dosing and ineffective applicators. Outdated or inaccurate machinery causes uneven application of liquid products, most of the slurry gets on seeds coming first, and the rest that get into an applicator / auger later, remain almost untreated. As a result, about 20-30% of the seeds receive excess chemicals in excess, about a third of the seeds get the right proportion of protection products and inoculants, and the rest are left without proper protection and become an open target for pests and diseases. A substantial overdose of chemical active ingredients is very toxic to the seeds and has a negative effect on its germination and vigor.
Inoculation is an important technological factor of a profitable soybean growing. There are three types of inoculants presented on the Ukrainian market: dry peat (with planting window of 24 hours); liquid products with also 24 hours before planting application; liquid pre-inoculants containing extender, these are applied up to 90 days before planting.
How to apply inoculants
Dry peat based inoculants:
Option 1. Sprinkle soybean seeds in a thin layer on a hard flat surface covered with a tarp or a plastic wrap. Add dry inoculant to the seeds and slowly mix them with shovels until the peat uniformly covers the seeds.
Option 2: Add the inoculant to the seeds straight into the sowing drill just before sowing. Gently mix by hand until a uniform coating of seeds is attained.
Option 3. The inoculation may be carried out in a concrete mixer.
Seed treatments are applied to dry or if desired to a pre-moistened seeds (2 ml of water per 1 kg of seeds). Inoculation can be carried out with a preliminarily diluted peat inoculant (ratio of water – inoculant being 2:1) the slurry is then applied onto 100-120 kg of soybean seeds. Prepare as many seeds as you are able to sow during the day! Do not keep inoculated seeds over 24 hours!
You can use stationary or mobile auger/conveyor belt/bucket elevator seed treaters with well-calibrated seed flow and dosing systems for inoculation of soybean seeds with liquid inoculants.
Inoculants produced by well known South and North American or British producers are compatible with the majority of pesticides registered in Ukraine, they can be applied sequentially (first pesticides, and 3 days on inoculants). Results of lab tests conducted by the mentioned inoculants producers demonstrate that when properly used inoculants are compatible with chemical treatments such as Cruiser 350 FS (thiamethoxam, 350 g / l), Maxim XL (fludioxonil, 25 g / L metalaxyl-M +, 10 g / l), APRON XL (metalaxyl-M, 350 g / l), Fever (prothioconazole, 300 g / l), Vitavax 200 FF (thyram 200 g / n + carboxin, 200 g / l), Royal Flo (thyram, 480 g / l).
Liquid inoculants that contain extender may be applied to the seeds simultaneously with these pesticides.
Application of the product without the use of pesticides
If the seeds are only inoculated you can avoid adding water or add just a little bit (2-4 L/T) for a better distribution of the active ingredient on the surface of seeds. In this case, the volume of the slurry should not exceed 5-8 l / t. The water should be clean, non-chlorinated!
Applying the product with the use of pesticides
In case of combined treatment of soybean seeds with pesticides and inoculant total slurry volume should not 8-max 10 L/T. In this case, stick to this rule:
Never add not diluted with water pesticides to the bacteria! First water then chemicals.
Mix the working slurry (10 L / T seeds) slowly for 10-20 minutes and apply to seeds. Do not keep a ready solution for more than 2 hours! Do not leave prepared solution until next day!
Measures after inoculation
Do not inoculate or store inoculated seeds in the sun – treat and store the seeds in the shade or under a shelter. If the inoculated seeds are transported on trucks they need to be covered with a damp cloth as protection from direct sunlight and drying off.
Increased rates of inoculant are not harmful to the seeds and can be useful on those soils where soybeans have not been grown before, where pH levels are below 5.5, or where seeds are sown into a dry and cold soil.
How to choose a right treating equipment
Choosing mobile auger type treaters, thus better to give preference to those having a polyethylene fighting or wide screws which ensure a minimum gap between their edge and the wall of the steel pipe in which they are located. On such treaters seeds will not fall into the gap and, accordingly, will not get damaged. Applicators must be a cone-type with cross-spraying of liquid products. It is better to choose seed treaters with two tanks (one – for chemicals another for inoculants) for a simultaneous treatment & inoculation with liquid inoculant; with individual pump systems, so that the slurries of pesticides and bacteria get onto the seeds through two nozzles, without mixing them. Such equipment is common in Canada and has recently appeared on the Ukrainian market.
Following these guidelines on how to minimise seed damage and how to use your chemical and biological products efficiently, you will not only ensure optimal germination of your soybeans, but also guarantee a 100% pest control of your harvest!