AGRICULTURAL EXPERIMENT STATIONS. £69 



fertilizers, in all kinds of dung, urine, ashes, salts, guanos, 

 phosphates, manufacturing refuse, etc., etc. The remarkable 

 quality of the soil to sift, as it were, some of the most valu- 

 able, because most costly fertilizing elements out of manures, 

 retaining them in a form not easily or not largely removed by 

 rain, and yet accessible to the roots of plants — the so-called 

 absorbent or fixing power of soils — has also been elaborately 

 studied. We have thus a pretty complete knowledge of what 

 a crop requires for its growth, what it carries off from the 

 land, what is returned in straw or tops, and where we may 

 look for the most effectual and cheapest restoration of the 

 materials thus removed. The well-instructed farmer is ■ 

 thereby put in possession of the data for keeping accounts 

 between his soil and his crops, so that he can estimate with 

 accuracy what the soil itself can be relied upon to contribute 

 yearly towards their production, and what must be supplied 

 yearly or during each rotation, by means of manures, in order 

 to maintain, to develop, or to increase the fertility of the laud. 

 Dr. Wolff, who conducted the scientific work in the 

 Moeckern station at its beginning, is the author of a valuable 

 series of tables, which are published in a Farmers' Almanac, 

 in Germany, and are largely employed in this kind of reckon- 

 ing. One of these tables gives the quantities of water, 

 nitrogen, potash, lime, phosphoric acid, etc., in 1,000 parts 

 of all the plants and parts of plants which are encountered in 

 German agriculture, including fifteen kinds of hay, twenty of 

 green forage, nine of roots, eleven of leaves and tops of root 

 crops, twenty-nine of meal, bran, oil cake and other manu- 

 factured products and by-products, sixteen sorts of straw, 

 eleven varieties of chaff, twelve kinds of commercial plants, 

 such as flax, hops, grapes, etc., fourteen of litter, like forest 

 leaves, ferns, flags, sedge, etc., thirty-four varieties of grains 

 and seeds, and seventeen kinds of animal matters, milk, 

 cheese, blood, meat, wool, etc., making a total of 188 farm 

 products. 



Another table gives the comi)osition, in 1,000 parts, of 

 twenty-four varieties of stable and domestic manures, forty- 



