THIRTY-FOURTH FRUIT-GROWERS' COX\'EXTION. 



131 



make profit out of this otherwise detrimental state in the soil. This 

 is only possible, however, in soils free from injurious amounts of alkali 

 whieli would otherwise rise to the surface. 



In some instances hardpan soils have been blasted to grow orchards. 

 Such blasting must, for best success, be done, in hardpan which is not 

 too thick and is underlain by a sandy soil directly underneath. Where 

 such conditions occur, citrus fruits have thrived, and even such trees 

 as the peaeh have done remarkably Avell. "Warning must be given con- 

 cerning the character of hardpan encountered, for in all cases it is 

 necessary to break through into sandier soil below. Where holes are 

 blown into hardpan without breaking through it, such holes are the 

 receptacles for excess water, both in summer and winter, often causing 

 the souring of roots and damage to orchards. 



ALKALI AND FRUITS. 



The relation between fruits and alkali in soils is often very marked, 

 depending greath^ on the character of the alkali. It has been observed 

 in vineyards that the variet\' of grape has little to do with the resistance 

 to alkali, but the texture of the soil exerts considerable influence. 

 Sandy soils containing alkali exert a much more injurious eifect than do 

 heavy or clayey ones. Quantities of alkali have been found in good 

 vineyards on heavy soils which would entirely destroy the same vines 

 in light sandy soil. The color of grapes is often considerably reduced 

 by the presence of alkali. This necessitates changing of varieties on 

 certain soils thus affected, forcing the vineyardist to plant the colorless 

 or white sorts. 



Among the orchard fruits less affected by the presence of alkali than 

 othei-s may be mentioned the fig. olive, pear, and pomegranate. These 

 have all shown a tolerance of alkali considerably in excess of other 

 orchard fruits. The citrus is particularly affected by alkali, especially 

 the chlorides or common salt. The presence of excessive quantities 

 of lime or marl in citrus groves often causes yellowing of the leaves, 

 l)ut as this condition is encountered only in one or two particular soil 

 types, careful selection of soil will avoid this evil. 



SOIL FERTILITY. 



Perhaps the most important, most baffling, and least understood rela- 

 tion between fruits and soils is that of fertility. The almost endless 

 variety of fruits grown in California, the various qualities desired in 

 them, and the great variation in soils render this subject of fertiliza- 

 tion very complex. A fertilizer which will do well on one type of soil 

 will not give the same results on a different one. Different crops show^ 

 corresponding differences in the effect of fertilizers. Out of these con- 

 flicting statements some generalizations may be drawn. It may be 

 generally stated that the soil which is most ideally perfect in physical 

 texture and depth is iLsually the most fertile, containing plant food in 

 the best condition for plants. This may be explained partly by the 

 fact that the ideal soil permits of slow but perfect percolation of water 

 downward and similar rise of soil water upward under the influence 

 of capillary power and heat. Such a passage of water not only distrib- 

 utes the soluble plant foods evenly throughout the upper layers of soil, 



