-\s^> 



Bulletin 275. 



of the soil, which permitted most of the moisture to pass to the bottom 

 of the pot, leaving the upper soil somewhat too dry for good results. 

 After standing a few weeks the soil became more compact and the 

 moisture distribution better. 



As was observed by most of the experimenters upon this subject, 

 plants made a poor growth in the freshly steamed soil and the seed 

 germinated less well. Both of these phenomena may in part be accounted 

 for by the moisture conditions just described, but the effect on growth 

 was too marked to be attributed entirely to that cause. After a certain 

 period, differing in length with different soils, the plants began to 

 improve and were eventually much more luxuriant than those on the 

 unheated soils. The sandy loam was the first to recover, the clay 

 next and the silt loam the last. 



Table IV shows the weight and nitrogen content of the wheat crops 

 (entire plants) removed from Soils 1 and 2 after growing three months, 

 and at maturity after growing seven months. 



Table IV. — Showing the Change ix Larger Yield from Soil 2 to Soil i 

 WITH Increase in Length of Growing Period 



On examining this table it may be seen that at the end of three 

 months the crops on the two unsteamed soils are about the same, as was 

 also their nitrogen contents. At the same time the crop on steamed Soil 

 No. 2 is considerably larger than that on steamed Soil No. i, while 

 the percentage of nitrogen is higher in the smaller crop. Glancing at 

 the records of the crops harvested at the end of seven months it will 

 be seen that while there is little difference between the crops on the 

 two unsteamed soils it is quite noticeable that the order of yield in the 



