dust accumulations from the air or in washings from the surrounding higher lands. This decay is hastened by drainage, so that in the course of time there may be developed over these deep peat marshes a surface layer approaching the black marsh or muck type which permits the sweet grasses to grow and changes the marsh from one class into the other. It is clear, however, that before such accumulations can take place either some inwash from adjacent regions must occur or else a large subsidence of the surface must result from the loss of organic matter, so that tile laid at four feet might in time come to be very close to the surface. But the formation of a more fertile layer over the top, leaving the matter of subsidence out of the question, must necessarily require a long time unless hastened by methods involving considerable expense.

The black marsh or muck type of swamp soil, containing much clay and sand, with a smaller per cent of organic matter, such as is represented by the analysis given in the first table, although much richer inherently

than the peat types, is yet relatively deficient in potash and phosphoric acid when compared with the best types of upland soils so that, aside from having less available depth, because they require underdrainage, they will necessarily require the addition of these fertilizers more persistently than the best class of soils will, and the statement applies with increased force to reclaimed peat soils after they have been brought to the productive stage. Both types are therefore best adapted to intensive types of culture, where the character of the crop grown warrants high fertilization.

Neither of these types of soil are as a class well suited to the growth of alfalfa or of the clovers generally. Alfalfa does best, and the clovers, too, on deep, open, well-drained soils rich in lime. This, however, is to be said, so far as the need of these soils themselves is concerned, they are so inherently rich in nitrogen that for a long time there would be less need of clovers in the rotation to keep up the nitrogen supply.

CHAPTER XII

'AGRICULTURE OF THREE
ANCIENT NATIONS

HE attention and effort which have for

THE

centuries been devoted to the maintenance of soil fertility in China, Korea and Japan are probably greater than in any other part of the world, and the efficiency of these efforts is measured by the dense populations these countries have maintained and are still maintaining largely from the products of their soil. Probably nothing can give a safer measure of the maintenance capacity of the farms and farmers of a nation than the number of people they feed per unit area of cultivated field, and it is doubtful if there is a better place to study this problem than in China and Japan at the present time.

We were most of all interested in methods of tillage, of fertilization, and crop rotation.

We wanted to learn by seeing how it is today possible, after 20, 30 and perhaps 40 centuries, for their farmers to provide means of maintenance for such dense populations as now are living in these three countries. During the long maintenance of dense populations the people of these nations have grown into practices of economy and habits of industry the equal of which few people of western nations have attained or are likely to appreciate. While we may never adopt the details of any of the methods of these people, it is worth our while to study carefully some of those they have practiced so long and found eminently satisfactory under their conditions, because of the fundamental principles involved, and because they they may suggest modifications of some of our practices or adaptations of theirs which may be helpful to us.

One of the most fundamental differences between our cultural methods and practices and those of the Far East is found in the fact that there, as nearly as possible, every day in the year the soil, the climate and

the people are crowding growth. In nearly all parts of the densely populated sections two, three and sometimes even four crops are taken from the same field each year. This is made possible partly by their more favorable geographic position. Southernmost China has the latitude of Cuba, while to the north, Mukden, and northern Honshu in Japan, are only in the latitude of New York, Chicago and northern California. The United States lie mainly between 50 and 30 degrees of latitude while China, Korea and the densely populated portions of Japan lie between 40 and 20 degrees, nearly 700 miles farther south, giving them longer and warmer seasons.

But this is not the only cause of their longer growing season. The almost universal practice of planting nearly all crops in rows and in hills in the row permits one crop to be planted, germinated and often hoed before another crop has been removed from the field, thus utilizing for growth all of the time we consume in removing the harvest and in fitting the ground for the