12 MASS. EXPERIMENT STATION BULLETIN 355 



the plant is high. However, as the lignin increases, there is a tendency for yield, 

 grade index, and crop index to decrease. 



It would seem that those fields which have little lignin residue from the pre- 

 ceding crops would be desirable for a succeeding tobacco crop. 



Rates of Decomposition of Various Bedding Materials. (John Zak and Walter 

 S. Eisenmenger.) The following bedding materials were analyzed for total nit- 

 rogen: southern pine sawdust, southern pine shavings, white pine sawdust, cedar 

 sawdust, hemlock shavings, chestnut sawdust, oak sawdust, birch shavings, 

 peanut hulls, and cacao hulls. Each of the materials was mixed with an equal 

 amount of soil (on a dry basis), and sufficient nitrogen added in each case to bring 

 the total nitrogen up to 1 percent. Determinations for rates of ammonification 

 and nitrification were made every two weeks during a period of fourteen weeks. 

 During the first two weeks of decomposition, maple sawdust had the lowest 

 rate of ammonification, followed in order by birch, cedar, oak, and hemlock. 

 Chestnut sawdust had the highest rate. The rates of ammonification of the 

 different conifers followed rather closely a general curve. There was no evidence 

 of nitrate accumulation until after four weeks, when traces began to be found. 

 Reappearance of nitrates at the end of the experiment was due to the decrease 

 in the amount of cellulose present. 



In another series, the bedding materials were saturated to 90 percent of their 

 water-holding capacity with cattle urine and left to decompose. Determinations 

 of ammonification and nitrification were made once a month. Lignin determina- 

 tions were also made at the beginning and end of the decomposition process to 

 study the comparative changes in the various materials. During the first month, 

 birch shavings had the lowest ammonification rate, followed by hemlock and 

 southern pine. Nitrates did not begin to accumulate until the end of the ex- 

 periment. 



From a study of the lignin accumulation, it was found that cacao hulls decom- 

 pose most readily, followed by birch, oak, chestnut, and peanut hulls. Little 

 lignin accumulation was found when white pine, cedar, and hemlock were used, 

 indicating a slow rate of decay. The following data show the lignin content 

 before and after decomposition expressed in percentages. 



Lignin, Percent 



Percentage 



Original Decomposed Change 



Cacao Hulls 20.83 30.12 44.60 



Birch Shavings 17.57 22.98 30.80 



Oak Sawdust 26.00 30.29 24.19 



Chestnut Sawdust 23.99 29.64 23.55 



Peanut Hulls 28.70 34.09 21.60 



Cedar Sawdust 27.49 30.98 12.69 



Hemlock Sawdust 26.41 29.65 12.27 



White Pine Sawdust 24.22 26.07 7.64 



Southern Pine Sawdust 26.64 24.75 —7.92 



Southern Pine Shavings 26 . 64 24 . 53 —7.92 



Maple Shavings 22.74 17.98 —20.93 



The Use of Nitrogen as an Aid in Decomposing Old Sod. (Karol J. Kucinski, 

 William H. Bender, and Walter S. Eisenmenger.) After the encouraging results 

 obtained last year, the experiment was continued. Calcium cyanamid, at the 

 rates of 100 and 50 pounds of nitrogen per acre, applied to an old sod before 

 plowing in the late fall of 1937 proved to be effective in hastening decomposition, 

 as shown by yields of potatoes, corn, and cabbage. Another area, receiving the 



