Seed Conditioning Thomas G Chastain CSS 460/560 Seed Production
Seed Conditioning Seed conditioning prepares harvested seed for marketing. Contaminants such as inert matter, other crop seeds, and weed seeds need to be removed prior to marketing. Seed can also be size-graded for precision planting. Tall fescue seed
Seed Conditioning Seed conditioning in Oregon is typically performed in growerowned plants unlike in many seed producing regions, where seed conditioning plants are owned by seed companies or controlled by cooperatives. Seed conditioning warehouse
Seed Conditioning Reasons for Seed conditioning: 1. Remove weeds and other contaminants from harvested seed. Harvested seed is known as combine-run seed prior to cleaning and the harvested weight of the seed is known as dirt weight. 2. Upgrade seed quality by removing broken, shriveled, or light seed. 3. Size-grade for better plantability. 4. Apply seed treatments, seed pelleting and coating, inoculation with Rhizobium, and scarification. Combine augering harvested seed into truck
Seed Conditioning Basic steps in seed conditioning Receiving Bulk Storage Pre-cleaning Cleaning Seed Treating Bulk bins and elevators (Townsend Seeds photo) Storage Bagging
Seed Conditioning Seed conditioning of perennial ryegrass removes 10 to 20 % of the initial harvested weight of seed in the form of inert straw, nonviable flower parts, weed seeds, and good crop seed. Typical cleaning costs are $4 to $5 per 100 lbs seed. Re-cleaning to remove annual bluegrass seed contamination costs the producer 75% of the original costs plus the additional loss of crop seed. The grower may lose another 7 to 10 % of the good crop seed in the re-cleaning process. Kentucky bluegrass seed contaminated with ergot sclerotia and stems
Seed Conditioning Separation of crop seed from contaminants is based on differences in physical properties among the desired seed and the contaminants. The choice of seed conditioning machine depends on the kind of crop seed and the type of contaminants that are present
Seed Conditioning Principles of Seed Separation Characteristic Size Width/thickness Length Shape Surface Texture Color Specific Gravity Electrical conductivity Affinity for Liquid Weight Machine Air-screen Size grader Indent disc or cylinder Spiral separator Dodder or roll mill Color sorter Gravity Table Electrostatic separator Magnetic or buckhorn Aspirator Color sorter (Dahlman Seed Company photo)
Air-Screen Cleaner Separation of crop seed from contaminants based on size. This is the primary seed cleaner in most conditioning warehouses. The air-screen cleaner has a higher capacity compared to other types of cleaners. Some warehouses may have more than one airscreen cleaner. Adjustments on this machine include rate of feed, air flow, and screen size and type. Air-screen cleaner (AT Ferrell photo)
Air-Screen Cleaner Round hole screen Oblong hole screen Triangle hole screen Wire mesh screen Screens are made of perforated sheet metal or steel wire mesh. Perforated metal screens come in a range of sizes and shapes of holes including round holes, oblong holes, and triangular holes. Round hole screens are often designated by a single number such as 10. This means the screen is 10/64 ths of an inch in diameter. Others are fractions of an inch in diameter. Wire screens are measured in the number of openings per inch in each direction.
Air-Screen Cleaner Air-screen cleaners may can have 1-4 shoes, each containing 1-3 screen decks. Stems, weed seeds, other crop seeds and contaminants that do not pass through the perforations in the screen are called scalpings. Small contaminants are called fines. Top Shoe Bottom Shoe Hopper Fan Clean Seed
Length Separator Indent Cylinder Short seed are raised in the pockets in the cylinder wall into the trough while longer seed are rejected. A machine with intermediate capacity. Adjustments on this machine include rate of feed, pocket size (cylinder), position of the separating edge (trough), and speed of rotation. Cross-section of indent cylinder A. Cylinder wall B. Trough C. Separating edge D. Auger conveyor Short Seed Long Seed
Length Separator Indent Disc Like the indent cylinder, short seed are lifted in the pockets of the disc while longer seed are rejected and left behind. Short contaminants may also be lifted from good long seed. Seed moves through the openings in the spokes of the disc acts like an auger in moving seed. Modern discs can be broken down for quicker replacement of discs on the shaft. Diagram of indent disc showing principle of separation (top) Individual disc (lower left) and inside of indent disc separator showing multiple discs on shaft (lower right)
Length Separator Indent Disc Disc pockets have different shapes on the lifting edge. R pockets (rice) have a flat lifting edge and will tend to lift flat, short seed. V pockets (vetch) have a round lifting edge and will lift short, round seed. More than one size and shape of disc pocket can be used in the machine. Adjustments on this machine include rate of feed, pocket size and shape of lifting edge, position of the tailings gate, and speed of rotation. R Pocket V Pocket Leading edge Lifting edge Leading edge Lifting edge
Gravity Table The gravity table separates seed from contaminants on the basis of specific gravity. Heavy seed move up the inclined table in a fluidized bed of air passing through the deck with each thrust of the deck. Light seed do not move up the deck and exit at a lower position. Adjustments on this machine include rate of feed, air flow through the deck, deck elevation and angle, and rate of deck thrust. Seed Direction of deck thrust Heavy Light Light
Gravity Table Hopper Light Heavy Bank of commercial gravity tables in a vegetable seed conditioning plant
Surface Texture Separator Roll Mill The roll mill separates seed from contaminants on the basis of surface texture. Also known as a dodder mill. Smooth seed such as alfalfa move down between two inclined textured rolls moving in opposite directions. Rough seed such as dodder catch on the rolls and are deflected by the metal shield away from the smooth seed. Adjustments on this machine include rate of feed, speed of rotation of the rolls, incline of the rolls, and distance of metal shield from rolls. Diagram showing principle of separation in roll mill (top), alfalfa seed (lower left), dodder seed (lower right)
Grass Seed Conditioning Scalper Debearder Air-screen cleaner Air-screen cleaner Disc and/or Cylinder Separator Seed Treater Gravity Table Bagging Machine Air-screen cleaners in grass seed conditioning warehouse
Carrot Seed Conditioning Debearder Scalper Air-screen cleaner Indent Disc Separator Carrot seed Gravity Table Air-screen cleaner Indent Cylinder Separator Seed Treater
Cucurbit Seed Conditioning Crushed Fruit Ferment Crushed Fruit Water Remove Gelatinous Pulp Rotary Dryer Rotary dryer Air-screen cleaner Gravity Table Packaging