SoiLSj Fertilizers and Irrigation 143 



Soils and Crop Changes. 



Peas and sivcct peas do not grow well continuously in the same 

 ground. I know this practically in my experience, but in no book have 

 I ever found zvhy they do not grozv. 



There are two very gfood reasons why some classes of plants can- 

 not be well grown continuously in the same piece of ground. One is 

 the depletion of available plant food, the other the formation of in- 

 jurious compounds by the plants, or the gradual increase of fungoid, 

 bacterial or animate pests in the soil, which finally become abundant 

 enough to seriously hinder growth. DifTerent plants take the plant 

 foods, as nitrogen, lime, potash, phosphates, etc., in different propor- 

 tion. More important, perhaps, is the fact that the root acids that 

 extract these foods are of different types and strength. Thus before 

 many seasons it may happen that most of the plant food of one or 

 more kinds may be nearly exhausted as far as that kind of plant is 

 concerned that has grown there continually, while there would be 

 plenty of easily available food for plants with a different kind of root 

 system and different root acids, etc. This is one reason why rotation 

 of crops is so good; it gives a combination of root acids and root sys- 

 tems to the soil during a term of years, and it also frees the soil from 

 one certain kind of organism because it cannot survive the absence 

 of the particular plants on which it thrives. 



Summer-Fallow Before Fruit Planting. 



/ recently bought a ranch at Sheridan, Placer county, and was 

 intending to put lo acres to peaches and 50 acres to ivhcat or barley, 

 but the residents tell me that the land must be summer-fallowed before 

 I can do anything. The soil is a red loam and has not been plowed 

 for six years. 



Your local advisers are probably right as to the necessity for sum- 

 mer-fallowing in order to conserve moisture from a previous year's 

 rainfall and to get the land otherwise into good condition. There 

 might be such a generous rainfall that an excellent crop might come 

 without summer-fallowing, and the results will depend upon the rain- 

 fall. If it should be small in amount, you might not recover your seed. 

 By the same sign you might not get much growth on your fruit trees, 

 but you could help them by constant cultivation and by using the 

 water-wagon if the season should be very dry. Therefore, you are 

 likely to do better with trees than with grain without summer-fallow- 

 ing, although even for trees it is a decided advantage to have more 

 moisture stored in the subsoil and the surface soil pulverized by more 

 tillage. 



Defects in Soil Moisture. 



/ have apricot trees thai appear to be almost dead; all but a very 

 fezv small green leaves are gone, and they look bad, still I think they 

 might be saved if I only knew what to do. 



