OCTOBEB 9, 1908] 



SCIENCE 



493 



After each weighing enough distilled water 

 was added to bring the weight slightly above 

 the optimum. 



The experiment with sample (a) was car- 

 ried on for fourteen days after the baskets 

 were sealed. With the sample (j) the test was 

 conducted for eighteen days. At the end of 

 these periods the green plants were cut off 

 close to the paper disks and weighed. 



The following table gives a summary of 

 the results of these tests. 



SOIL SAMPLE (a) 



SOIL SAMPLE (i) 



In this table a comparison of series I. with 

 IV. and of I. with II. indicates a lack of 

 potassium in the soil. A comparison of II. 

 with IV. and of H. with III. shows but little, 

 if any, deficiency of phosphorus in the soil. 

 A comparison of III. and IV. and of lli. 

 with II. clearly shows a deficiency of nitrogen 

 in the soil. With regard to calcium in the 

 form of lime a comparison of VT. and Vil. 

 indicates that lime alone is of little or no 

 value. It is of interest to note here that the 

 actual application of lime alone to this soil 

 under field conditions did not give any in- 

 crease of crop. But, as is well known, the 

 application of lime alone will give poor re- 

 sults on land deficient in nitrogen and in 

 mineral constituents, especially potassium 

 compounds. A comparison of V. and IV. in- 

 dicates that lime used in conjunction with 

 mineral fertilizers may be of value on this 

 soil. In this table, as well as in the follow- 

 ing one, it is noteworthy that the amount of 

 water transpired keeps pace with the weight 

 of the green plants; that is, the larger the 

 green weight of the plants the greater is the 

 total transpiration. 



In this table a comparison of series I. with 

 IV. and of I. with II. shows a deficiency of 

 the soil in potassium. A comparison of II. 

 with IV. and of II. with III. does not indi- 

 cate a lack of phosphorus ; in fact, it raises the 

 question as to whether or not the acid phos- 

 phate may have done actual harm in the case 

 of III. With regard to nitrogen a compari- 

 son of III. with IV., with H. and with I 

 in turn shows a deficiency of this element. 



On the whole the results of tests with 

 samples (j) agree with the results of those 

 with sample (a). Though from these tests 

 sample (j) would seem to be in a better 

 chemical condition than sample (a), in that 

 (j) responds less readily to treatment with 

 fertilizers than does (a). Compare VII. of 

 Table (a) with the other series of Table (a) 

 and V. of Table (j) with the other series of 

 Table (j). A bit of evidence bearing out this 

 contention is to be found in the statement 

 that soil (j) has actually yielded 40 bushels 

 of com per acre while soil (a) has given but 

 10 to 12 bushels of corn to the acre. 



From all these tests it appears that the soil 

 of the Boydton Institute is deficient mainly 

 in nitrogen and potassium and in humus. As 

 a result of these tests and in view of the diffi- 

 culty of obtaining a sufiicient supply of farm- 

 yard manure at Boydton, the writer has 

 advised the use of green manuring, for this 

 purpose turning under cow peas, or crimson 

 clover, to be stimulated by the application 

 of potassium, in the form of muriate of 

 potash, and small dressings of available phos- 



The president of the Boydton Institute, Mr. 

 John R. Hague, at whose instigation these ex- 

 periments were made, has agreed to conduct 



