so
ation may be carried on with advantage j for both combine, bydifferent means, to promote the same end.
Fifthly, In winter, the water is generally more muddy, at leastimmediately after harvest, or a sudden thaw, than in spring.The frost, too, in this season, becomes a powerful engine in ourhands to rend asunder the vegetable matter on the surface, andreduce it to a soil; especially if the water be occasionally, oroften removed, and let on at that season of the year.
But all these advantages combined, are not to be compared■with,
Lastly, Summer flooding of waste land. The peculiar advan-tages which this season presents, are obvious.
The heat of the sun, combined with water, must promote theputrid fermentation of the vegetable matter on the surface ofwaste land. Without moisture, and a certain degree of heat,that process can neither commence, nor be completed. Hence,in warm and moist climates, no waste nor mossy land exists;although the marshes are composed of similar materials, and al-most of the same plants as in colder climates. In Greece , E-gypt, Demerara, and the East and West Indies , no moss orwaste land appears on the surface of low-lying valleys ; and ifthe mosses and wastes of Great Britain , were translated to thebanks of the Oronooko, the Nile, or the Ganges , the formerwould soon be converted into rich meadows, and the latter intoluxuriant pasture. If, on the contrary, the cold of winter wereto continue all the year round, as in some parts of Siberia , theputrid fermentation of all vegetable matter on the surface of theearth, would be arrested and at a stand. The general heat ofour summers operates, therefore, partially, in improving ourmosses and waste lands, even without the aid of art.
But if we flood any waste land often, and lay it dry againduring the heat of summer, we have it in our power, by thismeans, greatly to expedite this process; for this alternation ofmoisture and drought, heat and cold, must promote it withgreater rapidity. Besides, the transition from heat to cold inthis case, is greater in summer than in winter. When land isflooded in the latter season, the temperature of the soil is only afew degrees above the freezing point; and when the water is letoff, the transition is neither very great nor rapid. Whereas, inthe former, especially in the warm months of July and August,the temperature of the air at noon is sometimes above 70, whilethat of the soil, when flooded, seldom exceeds 50 degrees. Thissudden and great rise of temperature, must tend greatly to pro-mote the putrid fermentation of the vegetable matter on the sur-face, and reduce it to a soil; and by repeating this transition'often at that season, by means of alternately flooding and layingthe surface dry, we have it thus in our power to expedite thisprocess.