• Important factors that affect seed germination and emergence include
• the viability of the seed (percentage germination under laboratory conditions)
• soil temperature
• availability of soil moisture to the seeds
• soil aeration and' the resistance of the soil to seedling emergence
• These are influenced by the soil type, the physical condition of the soil, depth of sowing / planting, the intimacy of contact between the seed and the soil, the degree of compaction of the soil above the seeds and formation of surface crust after sowing.
• Final field emergency stand is also influenced by pre-emergence, physical losses by birds and the post emergence losses due to diseases; insects and adverse environmental conditions.
• It should be apparent that sowing equipment can not control all the factors involved in the emergence.
• Sowing is the art of placing the seed in the properly prepared bed, at optimum depth, at uniform spacing so that the recommended seed rate is maintained.
• Most of the crops under optimum irrigation condition are sown on flat surfaces.
• Under too low or too high rainfall conditions, the sowing is done in furrows or on ridges and the root crops are generally sown on ridges.
• The different methods of sowing are (i) Broad casting, ii) Dibbling, iii) Seed dropping behind the plough, iv) Drilling, v) Hill dropping, vi) Check rowing and vii) Transplanting.

Broad casting

• is the scattering of the seeds on the field surface after broadcasting, they are covered by manipulating the soil.
• In this case, the intercultural operations can be carried out only with hand tools.
• Millets, upland paddy and other rain fed crops are boradcasted.
• This is the method broadly adopted for nursery raising in the low land rice cultivation.

• is the process of placing the seeds in holes at definite depth made in seed bed and covering them.
• The and tool used is called dibbler which has many conical projections made in a frame.
• This is adopted for small plots and is generally used for vegetable crops.

• behind the plough in the furrow made by the indigenous plough is a common method used in most of the dry land areas.
• A man or woman following the plough drops the seed by hand and the seed is covered when the next furrow is opened.

• means dropping the seeds in the furrow through send tubes. Metering of seed may either be done manually or mechanically.
• The accuracy of depth of placement, spacing and amount of seed sown are much higher than the other methods.
• The rear covered is also more.
• The only disadvantage is that seeds may sometimes get damaged and get clogged during operation Drilling can be done either manually (behind the country plough) or by tractor drawn seed drills.

Hill dropping

• In hill dropping the seeds are sown in lines as in drilling and seed dropping in line is also controlled.
• Unlike drilling the seeds are dropped at a fixed spacing and not in a continuous stream.
• In hill dropping, plant spacing in a row is also maintained.

• is the method in which the spacing between the rows is the same as that between the plants.
• This makes it possible to do inter culture in both directions.

Transplanting

• of seedlings is commonly done for paddy vegetable crops and flower plants.
• Due to the better care given to the plants in the nursery stage, transplanted seedlings given more yield.
• This is a labour intensive and time consuming operation.
• Transplatner is the machine used for this purpose.

Components and functions of seed drill

• The functions of a seed drill are
• to carry adequate quantum if seeds
• to open a furrow of uniform depth
• to meter the seeds
• to cover and deposit the seed in the furrow properly
• to cover the seeds and compact the soil around the seed.

• In the case of manually metered seed drills, a funnel is attached near the handle and the seed is conveyed in seed tubes and dropped below the shoe and then covered by the soil.
• In case of mechanically metered seed drills, the components are i) frame ii) seed box iii) seed metering mechanism iv) furrow open v) covering device and vi) transport wheels.
• The frame is usually made of angle iron with suitable braces and brackets and should be strong enough to withstand all types of loads in working condition.
• The seed box is made of M.S. or G.I. sheet with a cover and should be of sufficient capacity.
• A small agitator may be provided to prevent clogging in it.
• Seed metering mechanism allows the flow of seed into the seed tube at predetermined interval and normally draws power from the land wheel through gears.
• The furrow opener opens a uniform depth of furrow in front of the seed tube.
• The covering device moves behind the furrow opener and immediately collects the soil and covers the seeds.
• The transport wheel helps in easy conveyance of the seed drill and the rotary power is drawn to run the seed metering mechanism, through a clutch arrangement.

Seed metering mechanisms

Fluted feed type

• The fluted feed roller has longitudinal grooves throughout its periphery, which rotates with the axle over which it is mounted and throws the grains out on the adjustable gate, from where it falls into the grain tube.
• The fluted roller is mounted at the bottom and can be shifted sideways. As the length of the roller exposed is more, the amount of seed dropped increases. The feed rate can be controlled by positioning the bottom plate.

Cup Feed Mechanism

• In this type, the seed box is of two sections, viz., seed storage box end feed box.
  In the feed box, a disc with no. of cups fixed in the periphery is fixed on a spindle, which receives power from the land wheel through appropriate gears or chain drive.
• The cups may have two faces one with larger groove and the other with smaller ones.
• The seed will be carried by the individual cups when spindle rotates and dropped into the funnel of the seed tube by gravity.
• The seed rate is governed by the speed of rotation of the disc.

• The mechanism normal has arms with jaws, which will pick the large, size seeds like potato or seedlings for transplanting (like paddy) and place it in the seed bed.
• The potato planter has radially projecting arms fixed on the land wheel, whereas in the transplanter the jaws are fixed on a horizontal arm.

• Some of the bullock drawn seed drills has this mechanism.
• The brush will receive power from the land wheel and rotate at the bottom of the seed box.
• The holes in the seed box bottom will be opened and closed by the brush in the predetermined pattern and allows the seed to pass through at regular intervals.

Furrow openers

• Furrow opener is that part of the seed drill which opens a uniform furrow to place the seed at appropriate depth.
• The different types of furrow openers are (a) shoe type, (b) hoe type, (c) single disc type and (d) double disc type.
• The shoe type furrow opener, works better in the poorly prepared seed bed.
• They are made of two curved runners with their cutting edges on the ground and meeting at the share point.
• The hoe type of furrow opener, is having a single or double point shovel.
• The seed tube is fixed behind the shovel.
• The disc type is favoured where the seed bed consists considerable plant residues.
• The single disc opener has a small disc, with little disc angle, which shifts the soil to one side.
• The seed is dropped behind the disc.
• In the double disc type, the two discs are placed closer and opens furrow, in which the seed is dropped in between the discs precisely.

Furrow closer

• This component of the seed drill is attached at the rear side to close the furrow after the placement of seed.
• It may be a lengthy plank, drag chain roller or press wheel or miniature bund former.
• This process helps in driving the air present near the seed and allows required moisture migration for germination of seed.

• There will be two wheels fixed one on either side of the main axle or one each on two cut half axle.
• The wheel rim may be flat one or provided with lugs.
• The wheel may not have any rim and directly run on the sturdy spokes.
• Any one of these wheels or both may supply power to the seed metering mechanism through a chain or gear drive.
• Usually a clutch will be provided to engage or disengage the power transmission to seed metering device.

  Broad casting device

• Broad casting technique is adopted for the small grain crops.
• A broad casting device will have a hollow cylindrical seed box with no holes drilled on its surface so that one seed can pass through at a time.
• The cylinder will be fixed on an axle with necessary covers and mounted on separate land wheels.
• The unit can be pulled by a handle.
• In operation the seed box is filled with 80% of its total volume with the seeds and the cylinder is rolling when it is pulled and seeds squeeze through the holes freely and drop on the seedbed.
• After completing the broadcasting, the seedbed has to be given a light harrowing by means of a blade harrow or plank, so that a thin layer of soil covers the seed.

• This is animal drawn hand metered seed drill commonly used in Andhra Pradesh and in northern districts of Tamil Nadu.
• This normally has a sturdy beam and handle made of karuvelam or babul wood.
• Number of tynes, usually 3 to 12 Nos, are fixed in the horizontal beam to make furrows.
• Bamboo sticks are used as seed tubes.
• The tubes are pierced into the tynes.
• The top end is fixed below the seed bowl.
• Usually each seed bowl will have three to four seed tubes.
• There are two pole shafts attached to the beam.
• The seed drill is attached with the yoke and drawn.
• The depth of the furrow is controlled by the operator handling the implement.
• The second individual, usually woman labour, carries the seed and drops it in the bowl uniformly so that the seeds are distributed evenly.
• The rate of sowing of the seeds depends on the efficiency of the individual dropping the seeds in the bowl.
• This seed drill cannot be used for mixed cropping directly.
• If desired, two seed drills should be used simultaneously to sow the different crops, or some of the seed tube can be blocked and the sowing done by the third individual walking behind the seed drill.

• This is a bullock drawn seed drill suitable for sowing groundnut pulses, maize, sorghum, etc.
• The unit has tree furrow openers and a seed box.
• This has a cup feed type seed metering mechanism.
• The entire unit is mounted on a pair of spoke type ground wheel.
• Drive for the seed metering mechanism is taken from the ground wheel, through clutch and sprocket-chain.
• The furrow opener is of shoe type.
• Bar type furrow closer trailing behind the seed drill covers the sees sown.
• A vertical clevis is provided to attach the pole shaft depending upon the height of the animals.
• A handle is provided to control the movement of the machine.
• The seed drill is capable of covering 1 to 1.5 ha in a day of 8 hours.

• The unit consists of 7 sets of seed dropping systems actuated by a common ground wheel.
• It can be mounted over a tractor and used.
• Two numbers of furrow forming channels are fitted at both the edges of the body frame which form the furrows.
• The furrows serve as a water conserving media for subsequent utilization of the rain water by the crop.
• The rotors are edge-drop seed plates which can be changed depending upon the seed type.
• Since individual seed hoppers are provided, mixed cropping is also possible with this unit.

• The seed cum fertilizer drill consists of two components for seed metering and fertilizer metering systems.
• The two systems have been designed in such a way as to place the fertilizer in a continuous, strip in the furrow at the bottom followed by seed placement 2.5 cm above the fertilizer line.
• The furrow closers provided at the rear gives the compaction for proper germination of seeds.
• The implement saves nearly Rs.68.75 per hectare when compared the conventional practice.