SHELL LAND DRESSING.

New Zealand Herald, Volume LX, Issue 18499, 8 September 1923, Page 16

SHELL LAND DRESSING.

FERTILISING VALUE. It is noteworthy that in Cornwall, England, it has long" been customary to dress .the land with sea.sand, which contains a large proportion of calcium' carbonate, derived from tho shells of . marine molluscs. In this district the- wind carries inland tho sand from tho beach and piles it up into 1 dunes,, covering vast areas. Largo quantities of this sand have been us(id for agricultural purposes for many centuries. At one time Tit was considered that the sand had no value, but it has been used in increasing quantities during tne last twenty years, its low price .causing it to be preferred to lime. 'Hie sand is applied alone, or more • often, mixed with straw, dung or some other natural fertiliser, usuallv at the rate of 5 to 7£ tons per aero, although sometimes twice tho amount is used. As the calcium carbonate content of the Sand ranges from 2 to 84 per cent., its calcium oxide percentage varies • from 4.5 to :47 per cent. The sand contains no other substance of agricultural value, sodium chloride being present only m negligible quantities. As the sand can be obtained for almost nothing, the cost of tho lime it contains depends entirely on transport. Slaked lime is much more available than limestono or sand while ground limestone, being . a . little finer than this sand, is slightly more readily assimilated by plants. The relative prices of the different substances vary according to the locality- ' : Numerous experiments have been made in England to determine the manorial vi.lue of sea sand. In 1920 three meadows w;re fertilised respectively with the three forms of lime associated with phosphates, potassium and ammonium sulphate. All three meadows ; did well, but the one manured with sand was superior to the others. In other experiments the plots to which lime had been applied were distinguished by the clover growth and the,small number .oi weeds present, whereas the other plots were, infested .with weeds. The plot that hitd received sand (4.06 tons at £1 12s) was equal or'superior. to the others, to which respectively 2.03 tons of ground limestone at £3 10s, and i ton slacked lime at £1 l;is had been applied. The prices of the stind and of the slacked lime were thus tl'out equal, but eight times more of the sJind were required. '. ' ;;