Thousands of square miles in Lower Bengal annually receive a top-dressing of virgin soil from the Himalayas, - a system of natural manuring which renders elaborate tillage a waste of labour, and defies the utmost power of over-cropping to exhaust its fertility.
Gypsum, or sulphate of lime, applied as a top-dressing at the rate of 2 to 3 cwt.
It appears that with soils which are not rich in humus or not deficient in lime, calcium cyanamide is almost as good, nitrogen for nitrogen, as ammonium sulphate or sodium nitrate; but it is of doubtful value with peaty soils or soils containing little lime, nor is it usefully available as a top-dressing or for storing.
In the broad river basins the inundations deposit annually a fresh top-dressing of silt, thus superseding the necessity of manures.
Per acre as a top-dressing in moist weather.
The plant grows freely in good garden soil, preferring a deep welldrained loam, and is all the better for a top-dressing of manure as it approaches the flowering stage.