Feb, 1927] PROGRESS OF AGRICULTURAL EXPERIMENTS 



33 



times and the eleventh, which was a treatment of ten tons of stable 

 manure per acre, was repeated 32 times. There were, therefore, four 

 plots under a given treatment on the land which had been cultivated 

 two years but not manured; four similar plots on the land newly 

 broken in 1926 and fertilized with stable manure; and four on the land 

 newly broken in 1926 but not fertilized with stable manure. Five of 

 the treatments used contained nitrogen in an amount equivalent to 



Table XVII — Effect of phosphorus and other fertilizers on yield and size of head in Danish 



Ballhead cabbage 



that applied in ten tons of stable manure; the treatment known as the 

 check. In addition, there were two acid i)hospliate and one muriate of 

 potash series. The results are given in Table XVIII. 



The land that was cultivated two years yielded 27,774 pounds per 

 acre; the land cultivated one year, 22,214 per acre, or an increase for 

 the former area of 25.4 per cent. On the old land the yield on the 

 manured part was at the rate of 25,685 pounds per acre and on the 

 unmanured i)art 19,853 or an increase of 79.7 per cent due to manure. 

 On the new land the yield on the manured portion was 25,862 and on 

 the unmanured portion 18,564, an increase of 39.3 per cent. A narrow 

 ridge of lighter soil which yielded higher than the rest of the field ran 

 through the unmanured half and partially accounts for the higher 

 yield, as well as for the very high yields of the plots receiving 2000 

 lbs. of acid phosjihate and the mixed fertilizer plots in the new unma- 

 nured land. The very low yield of the Leuna Salt Peter plot is due 

 to the wet location of two plots of the series. 



Where 20 tons of manure per acre had been applied, acid phosphate 

 increased the yields ap]iroximately as much as an additional 10 tons 

 of manure, but in the absence of manure, especially in the new land, 

 the yields of cabbage were higher on the acid phosphate plots than in 

 the extra manure plots. 



In the presence of some manure the quickly available chemical 

 sources of nitrogen yielded as high or better than the same amount of 



