19201 SOILS FERTILIZERS. 815 



on upland soil a comparison was made of acid phosphate and proiind rock phos- 

 phate oil a three-year rotation of oats; clover and timothy meadow; and 

 potatoes, rutaba?;as, and corn. The phosphates were applied with and without 

 manure. It was found that the application of 10 tons of manure once in 3 

 years produced an average increase of 94.8 bu. of potatoes, 7.3 bu. of oats, and 

 0.43 tons of hay. The addition of either acid or rock pho.sphate along with the 

 manure failed to produce a distinct increase in yield, and the same phosphates 

 when applied without manure showed little or no effect even with rutabagas. 



In a rate-of-manuring experiment stable manure was applied at the rates of 

 5, 10, and 20 tons per acre just before plowing for the cultivated crop. In this 

 experiment potatoes proved to be the most satisfactory cultivated crop, the 

 increase being especially marked with all three rates of manuring. The greatest 

 return per ton of manure applied was obtained from the lowest rate, but the 

 increased cost of application more than offset this gain. Each ton of manure 

 at the 5-ton rate gave an increase of 10.5 bu. of {lotatoes, 1.4 bu. of oats, and 88 

 lbs. of hay. At the 10-ton rate the increases were 9.6 bu. of potatoes, 0.5 bu. 

 of oats, and 92 lbs. of hay. At the 20-ton rate the increases were 5.8 bu. of 

 potatoes, 0.5 bu. of oats, and 53 lbs. of hay. 



In an experiment on the value of peat as a fertilizer six A-acre plats 

 received applications of peat just before plowing for the cultivated crop. The 

 yields of corn, rutabagas, and potatoes so far obtained are not considered to be 

 satisfactory evidence of the value of peat. 



Further experiments on peat soil cropped to a 3-year rotation of grain, clover, 

 and timothy meadow, and a cultivated crop, and receiving 10 tons of manure 

 once in a rotation, showed that the peat soil did not produce crops equal to those 

 produced by adjoining mineral soil. Marked increases in crops were obtained 

 through the use of ground limestone, and there was a marked decrease in weeds. 

 Where lime was not applied the legumes, such as clover and alfalfa, were en- 

 tirely absent. 



Manure v. commercial fertilizers for Maryland soils, A. G. McCaix {Rpt. 

 Md. Agr. Soc, 4 {1919), pp. 187-194). — Field experiments on ten of the im- 

 portant soil types of Maryland, conducted at the Maryland Experiment Station 

 to obtain information regarding the use of stable manure and commercial fer- 

 tilizers in the State, are reported. 



On a reddish brown shale loam soil, part of which had been cleared for from 

 40 to 50 years and part for only about 5 years, it was found that for the old 

 land organic matter is the limiting factor. Until this is supplied no combina- 

 tion of fertilizer elements is likely to bring about maximum production. On the 

 other hand, it was found that phosphorus alone may be used with good results 

 on the new land. 



Experiments on an old, worn, silt-loam soil, with a tight clay subsoil, showed 

 that for soils of this type good results will follow the use of stable manure, 

 reinforced with phosphorus, or the use of several different commercial fertilizer 

 mixtures. 



Experiments on a silt-loam soil indicated the great need for organic matter. 

 Neither a complete fertilizer nor phosphorus alone or in combination with 

 potash gave increases in the yield of wheat and grass comparable with those 

 produced with the use of manure alone or reinforced with floats or with acid 

 phosphate. A complete fertilizer gave the largest increase in tomatoes, but 

 manui'e alone and in combination with phosphorus gave the largest increase 

 in the corn crop. 



The occurrence and nature of the plant growth-promoting substances in 

 various organic manurial composts, F. .\. Mockekidgf. (Biochcni. Jour., 14 

 {1920), No. S-4, pp. 432-450). — A number of experiments conducted at King's 



