1919] Pendleton: A Stiidy of Soil Types t89 



necessary because of the fact that it was desired to grow two crops a year on the 



soils. The winter crops will not do well in summer, and vice versa, even though 

 the summers in Berkeley are relatively cool, and though the greenhouse was 

 whitewashed during the summer months. 



The seed was obtained in most cases from the Division of Agronomy of the 

 Department of Agriculture of the University of California. Such varieties as 

 were not available from this source were obtained from the commercial seed 

 houses in San Francisco. 



Usually the seed was planted directly in the pots, using sufficient seed to be 

 sure that enough would germinate and grow to give the desired number of plants 

 per pot, usually six. After the plants were well established, ami before there was 

 any crowding in the pots, the plants were thinned. In some cases an insufficient 

 number of plants germinated to give the desired number per pot. Difficulty was 

 found in getting the soy beans and cowpeas to germinate, especially in the 

 heavier soils. This was overcome by sprouting the seeds in an incubator ami 

 planting them when the radicle was half an inch long or more. An excellent stand 

 was thus obtained. 



No actual measurements of the height of the plants, or the length of leaves 

 were made in the greenhouse work. But photographs were taken, and in these 

 photographs the attempt was made to secure representative records of the entire 

 series, without photographing the crop in every pot. The usual procedure in the 

 Altamont and Diablo series was to photograph tA\o pots out of each set of tripli- 

 cates, an attempt being made to select average, representative pots. In the large 

 Hanford series one representative pot of each set of triplicates in each crop 

 series was photographed, and three representative sets of triplicates were also 

 photographed. Thus some of the pots appear twice, and allow of comparisons. 



If any doubt be entertained as to the relative weights of the crops in the pots 

 photographed as compared with those not so recorded, the relative weights of the 

 crops may be easily obtained by referring to the tables of dry weights. In prac- 

 tically every case the pot label can be read from the photograph. The method of 

 labeling is exemplified as follows : 



6 Soil sample no. 6 (Diablo clay adobe from Danville). 

 W Wheat, first crop. 

 2 Pot 2 of the triplicate set first planted to wheat. 



CP Cowpeas, second crop. 



During the growth of the crops, notes were taken as to the relative growths and 

 the general conditions of the plants. 



When the crop had ceased growing it was harvested, whether or not it was 

 mature in the sense of having set and developed seed. The plaids from a given 

 pot were put in a paper bag, labeled, and placed in the drying oven for 24 hours. 

 The plants were weighed when dry and cool. If any mature seed was produced 

 it Avas weighed separately. 



Between the first and second crops the soil was allowed to rest from two to 

 three weeks or longer. Each pot was emptied and the soil passed through a 

 quarter inch screen before replacing in the pot. This broke up the lumps and 

 removed most of the roots. The roots were not saved. The weight of the roots 

 would have been interesting, but their recovery, especially from the heavy soils, 

 would have involved careful washing, and the loss of much of the soil. It was 

 thought that some washing would be necessary, even in the 1 fan ford series, in 

 order that the resulting figures might be at all accurate. 



