Table 1. Average Yields (Grams) of Three Successive Crops: Bark-soil, 

 Peat-soil Mixtures, and Soil Controls 



* Mean of yields significantly greater than controls at the 1 percent level. 

 t Mean of yield significantly greater than controls at the 5 percent level. 

 t Control not significantly greater at the 1 percent level. 



Three successive crops were grown in these mixtures in the following 

 order: (a) cabbage, one plant per pail; (b) radish, four plants per pail; 

 and (c) field corn (Kingscrost) , two plants per pail. About midway in the 

 growth of the cabbage, a nutrient solution was supplied to correct defici- 

 encies. Subsequent crops received fertilizer when soil tests indicated their 

 need. Between the radish and corn crops the mixtures and soils were allowed 

 to remain fallow for 6 months. 



The yield results appear in Table 1. There are several noteworthy points. 

 (1) Cabbage was the only crop showing yields significantly greater for 

 bark than for the soil controls; two of those yields were for old softwood 

 bark and one for old hardwood bark. The generally more advanced state 

 of decomposition and finer texture of these old barks compared to new bark 

 was probably largely responsible for this. Yields for plants in peat-soil 

 mixtures were close to that for the control. (2) With increasing concentra- 

 tion of organic matter, the growth of cabbage was consistently poorer. (3) 

 At the 30 percent concentration and above, except for the old softwood 

 bark, there was no advantage in the use of bark or peat. (4) In the new 

 barks, growth was very poor at the 30 and 50 percent levels of concentration. 



With the radish crop all yields in bark or peat mixtures were much lower 

 than the controls. However, the plants in the peat mixtures at the two higher 

 proportions of 30 and 50 percent yielded much better than those in the 

 corresponding proportions of any of the bark mixtures. 



With the corn crop, growth in all the cultures was very uniform. Statistical 

 analysis showed no significant variations from the controls. The decay of 



