1894.] PUBLIC DOCUMENT — Xo. 33. 255 



ents of plant food by raising vegetables consuming them in 

 different proportions. 



5. Wherever the quality of a crop controls its economical 

 and commercial value, it seems advisable that care should be 

 taken to secure the exclusion of an accumulation of soluble 

 saline substances not called for by the crop. This circum- 

 stance deserves particular attention in cultivation under 

 glass, where the body of soil is limited, and the removal of 

 such substances by percolation to the lower layers offers but 

 little chance of relief. In our experiment above described 

 this view of the question of supplying plant food in the 

 greenhouse has guided us in selecting a series of concen- 

 trated chemical manures, which for the above reason are now 

 recommended for patronage. 



6. There are, for obvious reasons, no unfailing receipts 

 for a general fertilizer mixture best adapted to all kinds of 

 soil for the production of field and garden crops, yet there 

 are certain relative proportions of the essential articles of 

 plant food which seem to recommend themselves for the rais- 

 ing of vegetables for the market. A mixture containing the 

 proportion of twenty-four per cent, potassium oxide, twelve 

 per cent, phosphoric acid and twelve per cent, nitrogen 

 deserves a careful trial. In some cases it has been found 

 advisable to add nitrogen at different times in small quanti- 

 ties in the form of nitrate of soda. This should be added 

 at different stages of growth, and has been found desirable 

 in the case of cabbages, turnips, cucumbers, onions, lettuce, 

 asparagus, strawberries, grapes, fruit trees, etc. Peas, beans 

 and all leguminous crops need no such addition, for after 

 reaching a certain size they are qualified, by bacterial action 

 upon their roots, to benefit by the elementary nitrogen of the 

 atmosphere in sufficient amounts to secure success. 



7. A regular periodical addition of a moderate amount 

 of organic animal and vegetable refuse matter, as barn-yard 

 manure and vegetable compost, may form an efficient part of 

 the system of manuring adopted. 



8. It has been found advantageous, in starting the culti- 

 vation of garden vegetables and orchards upon new lands, 

 to enrich the lower layers of the soil by deep ploughing, 

 together with the addition of a liberal supply of natural and 

 commercial phosphates (South Carolina, Florida or odorless 



