194 POMOLOGY 



This experiment shows the superiority of any of the treat- 

 ments over the untreated plot. The striking point, in the 

 Hght of later investigations, is the absence of an application 

 of quickly available nitrogen for this orchard. The manure 

 has given outstanding results in yield and growth, no doubt 

 due to the supply of nitrogen it carried as well as to the 

 organic matter added to the soil. Brooks states that too 

 much manure was used, for the trees made too heavy a 

 growth and the fruit was green and coarse. This is a com- 

 mon experience when trees are over-fertilized with animal 

 manures. Perhaps the most outstanding result of this ex- 

 periment is the apparent superiority of the low-grade sul- 

 fate of potash, which contains a large amount of magnesia, 

 over the bone-meal-muriate-of-potash treatment. The dif- 

 ferences in the two plots may have been due to the pres- 

 ence of magnesium as the sulfate or chlorid or to the sul- 

 fur itself in the sulfates of potassium and magnesium, but 

 the cause or causes for the difference in behavior have not 

 been clearly established. The effect of wood-ashes, which 

 contain about 1 to 2 per cent of phosphoric acid (P2O5) and 

 4 to 6 per cent of potash (K2O), is of interest since the com- 

 mon recommendation of the older horticulturists was to use 

 wood-ashes for fruit-trees. 



170. The Ohio experiments. — Further light is thrown on 

 this problem by the Ohio experiments in which a mulch is 

 usually included. This work was conducted in the southern 

 part of the state on land low in native fertility, and where 

 the surface soil is very thin, usually supporting a cover of 

 poverty-grass {Danthonia spicata) and weeds. The land 

 washes or erodes badly and hence it is not deemed wise to 

 cultivate it. 



This experiment gave immediate results when nitrogen 

 was used alone or in combination with fertilizers carrying 

 phosphoric acid or potash. The beneficial effects continued 



