2.4.4 (i) Drilling

Precision drills are now almost universal in use and are essential for the "drilling to a stand" technique.  A precision drill is defined as one which selects and deposits seed at predetermined distances.  Common features of precision drills are: land wheel drive, minimum seed drop, boat shaped coulters and flat rollers (Rose 1972).  In the U.K. the "Stanhay" pinched rubber belt drill is used, but disc types are popular elsewhere (Hull & Jaggard 1971).  Ten or twelve row machines are necessary to compensate for slow forward speed of precision drills, but the N.I.A.E. have a test drill accurate at 11 km/hr (Hayward 1978).  Munday (1977) has shown that no commercial drill sows perfectly.  Doubles, singles or multiple misses and inconsistent spacings are always observed, but the seed can confound the drill performance when doubles are due to pellets with extra embryos and misses due to dead or empty ones.  However, better drills that reduce the amount of seed roll and that are more accurately space-calibrated are required for "drilling to a stand".

Beet seeds should not be sown below 3.8 cm due to the small perispermic reserves.  Early sowing should be shallow (< 2 cm) for good emergence.  If sown later then 3 cm is better as the surface dries out (Hull & Jaggard 1971, Hibbert et al 1975).

Alternative drilling techniques such as fluid drilling of pre-chitted seed (Longden et al 1979, Currah 1978) have as yet unsolved technical problems and cannot be used for fast and even emergence in sugar beet.

(ii) "Drilling to a stand"

Drilling to a stand" is only successful with precision drills, good emergence and relatively weed free fields.  In the U.K. 12 - 15 cm spacing in 50 cm rows is commonly used to achieve 74,000/ha but Fletcher (1974) has shown that no universally recommended spacing) is possible as localised factors are involved.  The technique works best for April sowing when compensatory growth is adequate to make up for irregular spacing.  Neeb and Winner (1970) cited by Hull and Jaggard (1971) deliberately mixed good and dead seed to encourage irregular spacing and reduce population and still found a linear relation between population and yield up to 80,000/ha.  However, Thomson (1956) cited by Hull and Jaggard (1971) also deliberately obtained an irregular stand by random hand-singling and found 0.5 t/ha less from an irregular stand than from a similar regular, hand-singled stand.  Knott, Parker & Mundy (1976) found that with "drilling to a stand" irregularity effects were worse with low populations, made with wide rows and spacing, and at the same time found 70,000/ha was optimal for a fen soil, but only 50-56,000 for a silt.



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[Introduction & Contents]     [Chapter One]     [Chapter Two]     [Chapter Three]     [Chapter Four]     [Chapter Five]     [Chapter Six]     [Chapter Seven]

[2.4]     [2.4.1]     [2.4.2]     [2.4.3]     [2.4.4]     [2.4.5]     [2.4.6]     [2.4.7]     [2.4.8]