SOILS FOR THE ONION. 291 



be not arrested in this way, and, to assure this, moisture 

 must be adequate until satisfactory size is attained. Land 

 naturally moist, or in which a good supply may be re- 

 tained by cultivation, or for which irrigation is available 

 to counteract natural tendency to dryness, is necessary 

 for the full success of the onion as a mature crop. In the 

 winter, if rains are up to the average, very good growth 

 of green onions can be had on land which is too dry in 

 summer to carry the bulb to full-sized maturity. For 

 satisfactory summer finishing of the crop, soils which are 

 prone to dry out must be avoided, unless irrigation is 

 available. How this matter is affected by methods of 

 propagation will appear presently. 



If the needed moisture can be afforded, onions can be 

 well grown on a variety of soils. Quite heavy adobe can 

 be made to do, but it will be at the cost of most thorough 

 cultivation, producing tilth which is difficult and expen- 

 sive to attain on such soil. Every addition of sand or silt 

 to the adobe improves it in this respect, and the ideal soil 

 for the onion is one which is retentive enough under culti- 

 vation to keep the plant roots from a touch of drought, 

 and friable enough to be easy in cultivation and easy also 

 for the expanding bulb to displace as it grows. The bulb 

 should expand on the ground surface, not under it, and it 

 is very difficult to secure this on a clay without baking 

 of the surface, which dries the roots and results in pre- 

 maturity and small size in the bulb. On the other hand, 

 sandy soil is usable only at a cost of frequent irrigation, 

 for it also loses surface moisture in spite of stirring. Be- 

 sides suitable mechanical condition of the soil, it is essen- 

 tial that it shall be rich in plant food. Onions resent a 

 poor soil. Fortunately California has large areas of loam, 

 of mixed peat and sediment, and of alluvial soils, which 

 are so rich that many onion crops can be grown without 

 fertilizing, but in garden work the free use of manure is 

 the secret of quick, tender and large size, both in the 

 green and mature onion. But the use of fresh manure 

 just before planting is not desirable and even well rotted 



