8. Fertilizer sources of plant food. 



a. Nitrogen. — Nitrate of soda is the most quickly available source 

 of nitrogen and may also help reduce the necessity for potash. Sulfate of 

 ammonia and cyanamid are good sources of nitrogen, the latter the cheap- 

 est; while organic materials such as tankage and cottonseed, though high, 

 may be necessary in connection with those already named. 



b. Phosphoric acid. — Acid phosphate whether by itself or in 

 mixed fertilizers is the most quickly available and generally best adapted to 

 the needs of our agriculture, since basic slag meal cannot be obtained. Fine 

 ground rock phosphates cannot be advised, but the phosphoric acid in fine 

 ground bone and tankage is valuable though much slower in action than 

 that in acid phosphate. 



c. Potash. — ^It should be remembered that there are no thoroughly 

 satisfactory potash substitutes. Fine ground feldspar cannot be recom- 

 mended. Wood ashes of different kinds are at present the only important 

 available source of potash, although the vegetable ammoniates such as 

 cottonseed meal and castor pomace contain a moderate amount of that 

 element. 



d. Mixed fertilizers both with and without potash will be offered, 

 but the maximum of that element will probably be 1 per cent. It is not 

 thought that these goods in the quantity in which they can generally be em- 

 ployed will furnish sufficient potash to be of much value to the crop, while it 

 will necessarily add materially to the cost of the fertilizer. The mixed ferti- 

 lizers on the market are most of them practically ammoniated superphos- 

 phates, supplying nitrogen and phosphoric acid in varying proportions and 

 combinations. 



9. Suggestions for different crops. 



a. For grasslands where clover is not particularly desired, for this 

 year, materials furnishing nitrogen chiefly or exclusively; nitrate of soda, 

 sulfate of ammonia and cyanamid being among the best. A combination of 

 the first and third has sometimes given exceptionally good results. Quantity 

 of this mixture or any of the single materials, 100 to 200 pounds per acre. 

 If phosphoric acid also is deemed necessary, a highly nitrogenized com- 

 mercial brand may be desirable. 



b. Top-dressing clover and alfalfa. — Wood ashes if obtainable are 

 probably best under the peculiar conditions now existing. 



c. Corn. — Use manure and 300 to 500 pounds of a fertilizer carry- 

 ing 2i to 3 per cent of nitrogen and about 10 per cent available phosphoric 

 acid. 



d. Potatoes, root crops and vegetables. — Use some manure if avail- 

 able and in connection with it 500 to 600 pounds of a mixed fertilizer con- 

 taining about 2h per cent nitrogen and 8 per cent phosphoric acid. If ma 

 nure is not available and the soil is strongly acid, broadcast 800 to 1000 

 pounds of wood ashes and use 1000 to 2000 pounds of mixed fertilizer con- 

 taining about 4 to 4i per cent nitrogen and 8 to 10 per cent phosphoric acid, 

 or a mixture of chemicals which will furnish equivalent plant food. 



e. Oats, barley and spring top-dressing winter grain. — Except on 

 soils made rich by heavy applications to previous crops, 300 to 400 pounds 

 per acre of mixed fertilizer containing about 4 to 5 per cent nitrogen and 8 

 to 10 per cent phosphoric arid, or a mixture of chemicals made up chiefly of 

 nitrate of soda and acid phosphate, supplying about 100 pounds of the 

 former to 200 of the latter. 



f. Orchards. — Chief dependence this year should be placed upon 

 tilage where practicable. A little nitrate of soda may be useful on the 

 poorer soils and where orchards stand in grass. 



Bulletin 162 on Phosphates in Massachusetts Agriculture, Circulars 

 on Green Manuring, on the use of Lime and on the Selection of Fer- 

 tilizers for our leading crops will be sent on application. Address, 

 Experiment Station, Amherst, Mass. 



