14 



had been devoted to the growing of a particular crop for two 

 years in succession. All had been fertilized and treated alike 

 in every respect and all had been tested in advance as to the 

 uniformity of the soil by growing the same crops in rows 

 across all of the plots. When onions were grown the third 

 year, the yields ranged from 12 bushels to 412 bushels, ac- 

 cording to the crop which had preceded. The poorest onions 

 follow^ed mangels, cabbages, buckwheat, and turnips; they 

 were better following onions than they were following potatoes; 

 but the best crop of all was secured on the area which had 

 been devoted to redtop the previous two years. The other 

 grasses, clovers, corn, and cereals seemed to be better crops to 

 precede the onions than buckwheat or some of the root crops. 

 This is merely suggestive of the fact that we ought to study 

 carefully the effect of crops upon those which follow, so that 

 we may plant in the best order of rotation. 



Beets cannot b6 grown successfully on very acid soils unless 

 lime is used, yet liming the same soil might prove injurious to 

 radishes. Carrots and all types of turnips respond well to 

 liming on acid soils. 



Peppers and eggplants are both greatly helped by lime if 

 they are grown on very acid soil. The fertilizer used for these 

 plants should be rich in nitrogen, moderately rich in phosphoric 

 acid, and should contain a considerable quantity of potash. 



Cabbage, cauliflower, kale, Brussels sprouts, and similar plants 

 are all greatly helped by liming on very acid soils. On account 

 of their extensive leaf growth, they require fertilizers not only 

 containing high percentages of nitrogen but also of potash. 

 Some of these plants have a particularly low feeding power 

 for phosphoric acid; hence the fertilizer should contain a high 

 percentage of this ingredient in available form. 



Lettuce, spinach, and upland cress are among those crops 

 which are most sensitive to acidity; consequently on very acid 

 soils it is of the utmost importance that the land be limed 

 heavily before one attempts to grow them. In this respect 

 they are like onions and beets. 



These crops require a fertilizer with a high percentage of 

 nitrogen, a fair percentage of available phosphoric acid, and a 

 moderate to high percentage of potash. In the case of spinach 



