CLOVER AND BASIC SLAG.

Auckland Star, Volume LVII, Issue 303, 22 December 1926, Page 22

CLOVER AND BASIC SLAG.

STRIKING MANUKIAL EFFECT. I The most striking manurial effect ■which slag has when applied to grass hinds is the luxuriant growth of clover, and more especially white clover, that it produces. In some pastures so marked is the different appearance of the herbage in the dressed and undressed portions, and so sudden the transition, one would almost fancy that the clover had been actually sown on the one portion and withheld on the other. Indeed the view has actually been expressed that slag has the power of raising the spontaneous generation of clover, but the old maxim that nothing comes out of nothing holds 89 true in the realm of agricultrue as anywhere else. Another equally fantastic explanation for the wondrous stimulus given to clover growth by the action of slag is that the lime which it contains by facilitating the decomposition of the husk .of the seed allows in this way the young seedling to emerge. The truth, however, is that in nearly all pastures clover plants are present to some extent, and small and diminutive though they may be, they are nevertheless there, and it only requires a combination of favourable circumstances to ensure their vigorous growth. What Slag Does in Reality. In transforming unfavourable to favourable conditions of growth for the weakened plants lies the chief part of the explanation of the magical effect of slag as a pasture top-dressing. This improved condition, which induces a close undersward of rich succulent ; feeding in pastures is without doubt.- as much due to the indirect influence of its alkaline constituent—lime—as to the direct plant food which slag supplies in the form of phosphates. The lime which it contains not only corrects £he over-acidity of"the soil, thus making the pasture uncongenial for fog, worthless grasses and weeds; it does more, it acts on the insoluble plant food present, both mineral or organic. From the ■ former it unlocks a store of available potash— the plant food -of all others to which clover most quickly responds. The latter it serves to decompose, and thus .to increase the amount of humus-as well as the supply of available nitrates. The effects of slag on a pasture are, therefore, * both direct and indirect. Directly it furnishes phosphates-, the chief effect of- which are evidenced in the increased luxuriance as well as the superior quality of the grasses; indirectly it discourages, such undesirable intruders andmonopolisers as sorrel and other pasture weeds,-and by unlocking the. potash constituents of the soil it gives an immediate stimulus to the spread and development of the clover. -Slag in Conjunction with Kainit. On light soils likely to be deficient, in potash, slag, if employed for the renovation of pasture, should be used in conjunction with a potash manure such as sulphate of potash or kainit. On such soils the use of slag alone may not bring about the "desired luxuriance of grass, but the addition" of potash will ensure the increased value of- the- pasture so treated. Strong loam or heavy clay soils will, however, respond better to application of slag alone, also peaty soils on which there is much undecayed vegetable matter.