29 JUNE 1929, Page 15

SOUR Gnats.

That eminent band of scientific men, mobilized by the Americans, in their most thorough manner, to investigate the secret of the perfect lawn or golf green, have come to a conclusion that has startled English specialists: The secret, they say, is sourness. If you can eliminate lime (as by repeated applications of sulphate of ammonia) you will create a con- dition in which no weeds can grow but certain of the finer grasses only flourish. It is difficult for those who have been brought up in the cult of lime as the foundation of fertility at once to accept the verdict without qualification. It is possible that what is true of one country is not true of another. For example, in our wetter atmosphere and soil sourness might disastrously encourage moss ; and it is un- doubted that our shortest, finest grasses grow on chalk downs. But golf-green grass is a thing by itself ; and we have all discovered within the last few years that nothing more certainly wipes weeds away from our cricket pitches, tennis lawns, and golf greens with the same efficiency as sulphate of ammonia. Sprinkle it neat on a daisy or plantain and the weed vanishes, while a circle of grass springs up irresistibly round the wound. Spread it broadcast with a treble addition of sand—though the Americans condemn sand too ?--or fine earth and the grasses steadily conquer any plant with a broader leaf.