ERT 453 – DESIGN OF MACHINE SYSTEM IN BIOSYSTEM LECTURE 7 >> CROP PLANTING
CO 1 Ability to ANALYZE(C4) specialized components and EVALUATE (C6) mechanized systems for production, handling and processing of biological materials. TOPIC OUTLINE Seed drills, planting machines, implements for inter-cultivations. SESSION 2012/2013 COURSE OUTCOME
SESSION 2012/2013 introduction
SESSION 2012/2013 introduction
Seeders and planters are essential for the reproduction of crops. Their function is metering and placing in the soil of seeds or plants or of part thereof. Thus, seeders are used for generative reproduction, whereas planters aid in vegetative propagation. However, in some parts of the world, the term planter is used for a seeder. SESSION 2012/2013 introduction
Both seeders and planters, • Used as solo machines, or • Combinations with preceding soil cultivating machines. • In some cases, combinations with fertilizing equipment also are common. SESSION 2012/2013 introduction Generative reproduction of crop Corn, beans, sunflower Vegetative reproduction of crop Potato, paddy rice
SESSION 2012/2013 examples Row Planter The containers at the top hold the seeds to be planted. This is pulled across the field that the farmer wants to plant Seed Drill This is pulled by a tractor. It is used to plant grains and vegetable seeds. This can make different kinds of ditches that the seeds go in depending on what kind of soil there is.
One way to measure the capacity of a set of machinery is by the number of work days required to complete field operations. • This depends on: • number of crop acres, • machinery operations performed, • size of the machinery in use, and • availability of labor. SESSION 2012/2013 How Large Should Machinery Be?
The number of seeds that need to be planted per meter or foot of row length depends entirely on the plant population and row widths that have been chosen according to recommendations. • The main concern is deciding whether single or multiple seeding should be used. • In single seed planting, mechanical planters drop seeds out one at a time along the row. . SESSION 2012/2013 SEED POPULATION
Small farmers who hand plant their crops usually use multiple seed planting (hill planting), sowing several seeds per hole and spacing the holes rather far apart. • This reduces time and labor and also may improve seedling emergence under crusty soil conditions, but it may lower yields somewhat because of inefficient use of space and increased competition between the plants within a hill for sunlight, water, and nutrients. SESSION 2012/2013 SEED POPULATION
To calculate a seeding rate. SESSION 2012/2013 SEED POPULATION Seeding Rate Desired Plant Population % Germination x % Pure Seed x % Live Seed Emergence
For example, let’s say a grower wants to establish a stand of 170,000 plants per acre using a 7.5-inch row drill. The seed tag indicates that the seed has a 92 percent germination rate and is 98 percent pure live seed. Assuming a 10 percent loss in germination due to a clay soil that crusts, what seeding rate will achieve the goal stand?. SESSION 2012/2013 SEED POPULATION
SESSION 2012/2013 seeders
Generally comprise one or several hoppers, which contain: • The seeds of metering parts, and • Equipment for seed placement in the soil. • The metering either aims at equidistant spacing of the seeds or restricted to feeding a stream of seeds into a conveying tube. • The former case can be defined as precision seeding, whereas for the latter case, the term bulk seeding might be appropriate. • Since in most cases the seeds are placed in row, the definitions of precision drilling as well as bulk drilling make sense. SESSION 2012/2013 seeders
Precision drilling is used mainly for rather widely spaced crops such as corns, beans, sugar beets and sunflower. With closely spaced crops, precision drilling is too expensive and therefore bulk drilling is common. SESSION 2012/2013 seeders
SESSION 2012/2013 Conditions for seeding methods
The mean area per seed with drilled crops is • The product of row-spacing and the average seed distance within the row. • Row-spacing varies widely with crops, climatic conditions and production technology. • Precision-drilling of crops occurs mainly with row-spacing between 25 cm and 90 cm. SESSION 2012/2013 Seed-spacing and seeding-depth
Since in humid areas the water supply allows generally for higher seed and crop densities, row spacing in these areas is closer than in dry regions. Furthermore, mechanical weed control and harvesting methods often require minimum row spacings. SESSION 2012/2013 Seed-spacing and seeding-depth
Seed spacing within the row always is a fraction of row spacing, though under ceteris paribus conditions, equal spacing within and between the rows would promote high yield. However, realizing a given seed area by narrower row spacing associated with wider seed distances in the row increases the investment for precision seeding as well as for row-crop harvesting. This is because the number of seeding and row-crop harvesting units increases for a given working width. SESSION 2012/2013 Seed-spacing and seeding-depth
With bulk drilling, the row spacing varies between 8 cm and 25 cm. Narrow spacing are common especially with grass, clover, alfalfa, small grain seeds in humid area. Here again average seed spacing within the row always is a fraction of row spacing. SESSION 2012/2013 Seed-spacing and seeding-depth
Seeding depth needed depends very much on: • Seed size, and • Water content of the soil (soil moisture). • The larger the seeds and the dryer the soil, the deeper the seeds should placed to ensure emergence, and vice versa. SESSION 2012/2013 Seed-spacing and seeding-depth
Metering of the seeds – consists of two functions: • Singling of the seeds • Transporting them to the furrow. • In many cases, singling of the seeds is accomplished purely in a mechanical way, however sometimes the singling process is supported by airflow. • Accordingly, mechanical as well as air-assisted precision drills must be dealt with. SESSION 2012/2013 Precision drilling
SESSION 2012/2013 Mechanical precision drilling Singling method
SESSION 2012/2013 • These shape & dimensions of the holes/cups depend on the seed. • Too large or too small dimensions promote doubles or skips, respectively. • Besides that, it is important that the seeds get to the furrow in the original sequence. A long, free falling distance from the delivery point to the furrow is detrimental; it deteriorates an originally even seed sequence. This especially applies to small seeds. • In this respect, the orientation of the metering disk is relevant. • Falling height decrease.
SESSION 2012/2013 • This explains the predominance of vertically oriented metering disk with small vegetable seed and sugarbeet seeds. • However, • Disadvantages of vertical disk with larger seed compared to horizontal disks can be the rather short peripheral sector available for filling. • Therefore, in U.S horizontal disks still are use (such as corn). • Inclined disks normally deliver the seeds at their highest point. • In order to get a low, free-falling height, they often operate with a parallel rotating chamber plate in the background. • The seeds pass from the singling disk into the chambers of the parallel plate, which then delivers them closely above the furrow. • In most cases, precision metering requires devices that remove doubles and triples from the respective cells such as counter-rotating rollers, stationary cutoffs, or bushes. • Despite this, there still is an influence of the peripheral seed disk speed and thus of the travel speed on the singling process.
SESSION 2012/2013 • Speed increase, reduces the percentage of doubles. • However, this advantage of inclined disks is associated with less precise singling on sloped fields. Their use is not recommended on fields with more than 10% slope. • Vertical disk (outside feeding vs inside feeding)
SESSION 2012/2013 • Generally, mechanical precision drilling requires a much closer adaptation in the dimensions of the singling elements to those of the seeds than air-assisted precision drilling. • This applies especially to vertical or horizontal metering disks equipped with cells and slightly less with inclined disks equipped with cupped ﬁngers. • The cell diameters should be about 10% more than the largest diameters of the respective nearly spherical seeds. • There have been attempts to avoid the need of closely adopting the hole or cup dimensions to those of the seeds. A principle used with mechanical precision drilling is as shown in the next slide figure.
SESSION 2012/2013 • The vertical singling disk is equipped with cam-operated fingers. Within the seed supply these pointed fingers move close to the disk and respectively seize the seed. At the highest point, the seeds again pass from the singling disk respectively into the chambers of a parallel plate for delivery closely above the furrow.
SESSION 2012/2013 Air-assisted precision-drilling
SESSION 2012/2013 • Either the suction or the compression by air is used to assist in singling the seeds. • For singling by suction, a vertical disk with suction holes passes through the seed supply. • Excess seeds per hole usually are brushed off. At the highest point the seeds pass to a sectioned wheel, which brings them to the dropping point. • Compressed air is used for singling the seeds within rather large conical cells on the periphery of a disk. • The pointed tips of the conical cells have open access to the atmosphere. The compressed air removes all seeds from the cells except the lowest, which covers the hole at the pointed tip. Thus, each cell keeps one seed and transports it to the dropping point
SESSION 2012/2013 Air-assisted precision drilling needs less precise seed calibration than all purely mechanical methods and therefore is used extensively for irregularly and non-spherically shaped seeds such as corn, sunﬂower, and some bean varieties. Custom operators especially appreciate that the seed disks seldom must be exchanged when moving from farm to farm with different seed varieties during the season. The investment for air-assisted precision drilling, however, is higher because of the PTO-driven blower. The general concept of precision drilling is, that a metering unit is placed on each opener. This method allows for rather small distances from the delivery point to the furrow and thus favors the exact seed placement. However, this concept requires rather troublesome ﬁlling and monitoring of many seed hoppers. In case all openers of a machine are supplied with seeds from a central seed hopper, the supply can be reﬁlled in bulk and monitoring it is facilitated.
SESSION 2012/2013 But this concept of replacing the row of small hoppers and metering units with one central big hopper and one central metering system requires long seed tubes for gravitational and pneumatic seed transport to the openers. An originally even seed sequence deteriorates substantially during this seed transport. Therefore, sometimes a central hopper provides for seed supply to the standard system of a small hoppers and a metering unit for each row. The investment for this method of two fold seed storage is high, yet it allows bulk ﬁlling as well as metering in place.
No metering of the seeds occurs; instead, a stream of seeds is bulk-fed into the conveying tubes. • Done by studded feed rollers, fluted feed roller or by internal run rollers. SESSION 2012/2013 Bulk seedings
SESSION 2012/2013 Long seed tubes are not detrimental to the seed sequence, since no initial even spacing exists. Therefore, instead of individual metering units–as with precision drilling–metering devices on a common drive shaft and a common seed hopper for all rows can be used. This facilitates loading the hopper in bulk. Conveying within the tubes to the openers is either by gravitational forces or in case of air seeders, pneumatically.
SESSION 2012/2013 The air seeders allow for rather independent location of the seed hopper plus metering devices on the one hand and the openers on the other hand. Operating principle of an air-seeder system
SESSION 2012/2013 Thus, with combinations for soil cultivation and seeding the mass of the ﬁlled hopper can be used to load the cultivator tines. And for large machines, the seeds can be metered from a tender wagon, thus saving time for reﬁlling. Seeds can be fed into the air stream separately for each opener tube by the respective metering devices or centrally for all opener tubes by just one metering roller. With central feeding, all seeds initially are injected into a principal blower tube. The seed-air mixture is led upwards and hits a circular deﬂector manifold. The opener tubes emanate from this deﬂector manifold.
SESSION 2012/2013 Injecting the seeds into the air stream with separate feeding as well as with central feeding in most cases is realized with an air pressure below normal in order to achieve suction. For this purpose, the tube cross-section at the injection point is decreased. Adjusting the seed rate is done either by changing the rotational speed or the volume of the feed rollers. In some cases, the volume of the feed rollers is adjusted to the size of the seeds. Normally, the feed rollers are driven via ground contact wheels. In the future, powering by an electric dc motor—as with precision drilling—may be important, since this facilitates the control for site-speciﬁc farming. However, varying the travel speed with this method still requires the input of a speed sensor into the control system.
SESSION 2012/2013 SEED DRILL
In older methods of planting, a field is initially prepared with a plough to expose and break up the topsoil. This produces a series of linear cuts known as furrows. • The field is then seeded by throwing the seeds over the field, a method known as manual broadcasting. Seeds that landed in the furrows had better protection from the elements, and natural erosion or manual raking would preferentially cover them while leaving some exposed. • The result was a field planted roughly in rows, but having a large number of plants outside the furrow lanes. SESSION 2012/2013 SEED DRILLS
Seed drills have many different types of furrow openers, which are designed for different soil types and crop residues (Table 1). A smooth, level seedbed is necessary to ensure that seeds are not planted at depths greater than 10 to 15 mm. Sowing is at the correct depth is when 5% to 10% of the seed is visible on the surface after sowing. SESSION 2012/2013 SEED DRILLS
A good plant stand has 35 to 40 plants established per meter of drill row after permanent water is applied to the field. A benefit of drill seeding is that fertilizer can be applied at the same time as the seed. Manual weeding is much easier in machine-drilled crops than in broadcast crops. SESSION 2012/2013 SEED DRILLS
Table 1. Suitability of furrow openers in different working conditions. SESSION 2012/2013 SEED DRILLS
General purpose drills may be used for sowing all kinds of seeds from the size of beans to that of clover, at various seed rates and depths, and in rows at various distances apart. Most are ‘full width’ machines with a braced frame and a seed box extending across its width. The seed is delivered from this box by feed mechanisms driven by gearing from one or both land wheel. There is a separate metering device for each row. A clutch is included for putting the feed mechanism in and out of gear. The seed passes down seed tubes to the coulters, which cut grooves in the soil. The seed rate is adjusted by alterations of the gearing or of feed mechanism, while the spacing between rows and the depth of sowing are adjusted by the setting of the coulters. SESSION 2012/2013 SEED DRILLS – GENERAL DESIGN OF DRILLS
SESSION 2012/2013 SEED DRILL – FEED mechanisms Studded Roller Feed External (Fluted Roller) Force Feed
SESSION 2012/2013 SEED DRILL – FEED mechanisms Flexible fluted roller force feed, used in conjunction with movable gear cassetles for seed rate regulation (HestairBettinson)
Internal Double-run Force Feed Pneumatic or Jet Drills Single and Double Disc Coulters Wing Coulters. SESSION 2012/2013 SEED DRILL – FEED mechanisms
Internal Double-run Force Feed • It consisted of a feeder with a line of corrugated discs. Seeds are dispersed when the rotation of the wheels push them towards the corrugations and outside a box where it enters tubes. Both sides are used for dispersing the seeds but the course side is best for sowing oats while the fine side is more beneficial for dispersing seeds at a higher rate. • The studded roller feed contains devices that allow calibration and easy maintenance of the drill. Most commonly used in European countries such as England, the studded roller feed is usually used in conjunction with a multi-speed gear box for better sowing. SESSION 2012/2013 SEED DRILL – FEED mechanisms
Pneumatic or Jet Drills • With the use of pneumatics for its feed mechanisms, drills can plant and till seeds with the use of air. Seeds pass through pipes to the coulters with the use of an air-stream. This type of drill is best used for single seed roots and vegetable seeds. • Also known as the shoe coulter in Britain, this type consists of a chilled iron, which embeds grooves into the soil. This works best in moderate conditions and in hard ground as opposed to softer soil because the seeds can be precisely planted. Any other conditions such as poor tilth and the discs are less effective. SESSION 2012/2013 SEED DRILL – FEED mechanisms
Single and Double Disc Coulters • Single disc coulters place seeds individually and it is not always possible to achieve the same depth for each seed placement. With double disc coulters, the seeds are arranged between them and are dispersed at the same rate and depth. High costs are associated with this due to the large number of parts required. SESSION 2012/2013 SEED DRILL – FEED mechanisms