STATE BOARD OF AGRICULTURE. 



Chemical. 



Tho iiiiiieral coustitiieiits studied were those that were of some use to 

 thc'plaiit as K, PO^, Oa, (Mg in later determinations) and N in the forms 

 of ammonia, nitrite and nitrates. The results are given both as parts 

 per million (p.p.m.) of the solution and of oven dried soil. As the soil 

 varied in moisture content, the latter puts the results on a more com- 

 parable basis. 



The above nutrients were determined by the method as found in Bul- 

 letin 31, Bureau of Soils, for colorimetric work. Finding it difficult to 

 obtain good results for calcium by this method, gravimetric determina- 

 tions of calcium and magnesium were then made according to Bulletin 

 107, (pp. 15-16) Bureau of Chemistry. The phosphoric acid (PO4) with 

 a few exceptions is not high. Most of the results lie between one and 

 five parts per million on oven dried soil. The potash (K) has a wider 

 variance than that of j^hosphoric acid. The calcium and magnesium 

 vary considerably in the different soils, due to the treatment and reac- 

 tion of the soil. 



The nitrogen varies, but this is to be expected since it is a more 

 changeable quantity. The solutions from the same soil extracted at the 

 same time, one from a snmll cylinder and tlie other from the larger one, 

 agree fairly well in most of the cases in total nitrogen (sum of the dif- 

 ferent kinds), whereas they may vary in the ammoniacal nitrate or nitrate 

 nitrogen. This is due probably to denitrification taking place in the cylin- 

 ders during the extractions. This was noted in an extraction of a sandy 

 soil. No. 32 of B. No nitrite was found in the solution from the small 

 cjdinder and only a trace in tlie larger one, but the portions that came 

 Avith oil afterAvards showed marked amount of nitrogen present as nit- 

 rite. This led to the analyzing o"f successive portions. 



TABLE VIII.— NITROGEN DETERMINATION OF DIFFERENT PORTIONS OF THE SAME 



SOIL. 



Amount of N. in various portions of extractions of a sandy soil. 



I Small cylinder. 

 II Large cylinder. 



