408 University of California Publications in Agricultural Sciences [Vol.3 



Calcium 



The Diablo, Altamont, and Hanford soils were analyzed for their 

 calcium in the A horizon only, while the A, B, and C horizons of the 

 San Joaquin sandy loam were analyzed (tables 22, 23, and figs. 15-18). 



Diablo clay adobe. — There is much divergence in the amounts of 

 CaO in this type, varying from 0.36% to 2.05%, with the average 

 of 1.23%. 



Altamont clay loam. — In this type there is a little greater varia- 

 tion than in the Diablo samples, with a range of from 0.78% to 5.64%, 

 averaging 2.44% CaO. In both this soil and in the Diablo the wide 

 variation in the lime content is undoubtedly due to the nature of the 

 parent rock, since the soils are residual. 



San Joaquin sanely loam. — In the CaO content there is no uni- 

 formity among the samples. The A samples of this type contain from 

 0.47% to 2.98%, with an average of 1.65%. It would seem that the 

 materials from which the soils were derived were of varying composi- 

 tion. For from the present climatic conditions soil no. 25 is the one 

 subject to the least leaching, and yet has the least CaO content. The 

 B and C percentages follow the surface very closely — sufficiently so 

 to necessitate no particular explanation. The range of variation in 

 the B horizon is from 0.11% to 2.42%, and the average is 1.42%. 

 The C samples vary from 0.17% to 2.81%, with the average of 1.52%. 



Hanford fine sandy loam. — The A samples of this type contain 

 from 2.56% CaO to 4.69%, with 3.33% as the average. The varia- 

 tions are not so marked among the series of this type as in the cases 

 of the other three soils. The absolute range is nearly as great, but 

 the relative variation is less. 



Even though there are differences between the average CaO con- 

 tent in the several types, the wide variation in the amount found in 

 the several samples of a given type, and the overlapping of these 

 amounts from the different types entirely preclude any statement 

 that as regards the calcium content the soils of any one type are 

 closely similar to one another, or that one type has a higher or lower 

 lime content than another. 



