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Putaruru Press, Volume VII, Issue 311, 24 October 1929, Page 1

Of the important plant food constituents taken from an acre of soil it is estimated that an average crop of man gels will remove 1201 b. of nitrogen, 3001 b. of potash, o3lb. of phosphoric acid, and 421 b. of lime. The above figures are only approximate, as so very mtich depends on the mecli.anical nature of the soil; clay soils, for instance, usually contain potash and nitrogen, but generally require phosphoric acid and lime. To liberate much of tho potash and nitrogen locked up in these retentive clay soils, it is found necessary to give periodical dressings of lime or chalk. Chalky soils contain a large proportion of phosphoric acid, but very little potash, and are benefited largely by green manuring, or the application of farm-yard manure, which will be the means .of introducing humus or organic matter. This is equally important in the case of light, sandy soils, which, although poor in potash and lime, generally produce early crops if liberally manured and limed. One ton of farmyard manure of average quality will contain about 121 b of nitrogen, 51b. or Gib. of phosphoric acid, and about 141 b. of potash; thus it is evident that this manure cannot be economicaly applied to all classes of plants, although it may suit plants of the cabbage tribe fairly well.