166 MASS. EXPERIMENT STATION BULLETIN 162. 



2L The fact that increases in crops, even on the dissolved phosphates, 

 account for only a very small proportion of the total phosphoric acid ap- 

 phed — less than 10 pounds out of 216 per plot — indicates that the 

 favorable effects were due chiefly to indirect causes. 



22. The dissolved phosphates greatly stimulate early root and top de- 

 velopment. Tlus action is of great importance in enabhng the crop to 

 draw more largely upon the soil both for water and food, and in enabhng 

 some crops to resist insect injury. 



23. Dissolved phosphates are reported to favor tillering (stoohng), and 

 this means a thicker growth of grains, grasses and millets. 



24. Dissolved phosphates favor early and perfect ripening, and are 

 therefore much to be preferred where earliness is desirable and in case of 

 crops liable to autumn frost injury. 



25. Dissolved phosphates, chiefly through the activity of the calcium 

 sulfate which they contain may somewhat increase the availabiUty of soil 

 potash. 



26. The use of dissolved phosphates has been shown to be favorable to 

 nitrification, and to larger gain in atmospheric nitrogen acquired through 

 the activity of soil bacteria. 



27. Finally no injurious secondary effects are known to be associated 

 with any reasonable use of dissolved phosphates. Our experiments indi- 

 cate that they do not increase the necessity for the use of lime. 



Massachusetts farmers, gardeners and orchardists are advised against 

 the general use of raw rock phosphates. In so far as they are needed in 

 our agriculture the phosphates employed should be the more soluble and 

 available kinds, such as acid phosphate (dissolved rock), dissolved bone, 

 basic slag meal and bone meals. The dissolved forms are advised for a 

 quick start and early maturity. The mixed fertilizers upon our markets 

 usually contain a large proportion of phosphoric acid cliiefly in soluble 

 and available forms. The station bulletins show their character. Those 

 high-grade fertihzers with a large proportion of water-soluble phosphoric 

 acid will be most favorable to a quick start and early maturity. 



Natural rock phosphates are unadapted to the conditions of our agri- 

 culture, and their use will, with most of our crops and on most soils, give 

 highly unsatisfactory results. What is needed in our agriculture is fre- 

 quent (in case of many of our hoed crops, annual) applications of dis- 

 solved or quickly available phosphates. 



Rel.\tive Phosphate Needs of Different Crops. 



Our experiments indicate the use of phosphates to be especially neces- 

 sary with all cruciferous crops (cabbage, turnip, cauUflower, Brussels 

 sprouts, rape, etc.). 



The onion also, especially if inchned to production of scalUons, needs 

 heavy apphcations of available phosphates. 



For crucifers and onions in connection with materials supplying nitro- 

 gen and potash, 1,000 pounds per acre of a good acid phosphate, or an 



