474 INVESTIGATION BY CULTURE EXPERIMENTS 



Plot 204 is divided into four equal parts and the calcium sulfate 

 applied at the rate of 2 tons, 4 tons, 8 tons, and 16 tons per acre, 

 at a cost of $6 per ton. It produced no benefit in 1907. Whether 

 it will assist in the removal of the magnesium carbonate by double 

 decomposition and leaching and thus improve the soil in time, 

 time alone will tell. 



The 400 pounds of potassium sulfate are applied for a three- 

 year rotation at an initial cost of $10. The increase of 66 bush- 

 els of corn produced the first year, at 35 cents a bushel, amounts 

 to more than twice the total cost of the potassium. The manure 

 also gave very excellent results. 



In Table 93 are given all results obtained during six years' 

 experiments on part of theMomence soil experiment field, located 

 in Kankakee County, Illinois, near the Indiana line, on peaty swamp 

 land which contains much decaying peat and coarse sand in the 

 surface and subsurface, with a clayey sand subsoil resting on 

 impure limestone, while the surface, subsurface, and subsoil 

 contain more than half of the normal amounts of total potassium 

 (19,000, 47,000, and 73,000 pounds, respectively, per acre). The 

 soil contains but little alkali. 



After 1902 (when the corn was damaged by water) the land was 

 tile-drained sufficiently well for ordinary years, but in the ex- 

 tremely wet season of 1907 the corn was planted very late, and with 

 the continued wet weather resulted in almost a complete failure. 



Potassium was not applied to plot 102 for 1902 and 1903, and 

 was not applied to plot no for 1904. The untreated check plot 

 101 is naturally somewhat more productive than the other plots. 



These results from the new Manito field and from the Momence 

 field, on abnormal swamp lands, emphasize the fact that, although 

 some principles are well established and can be applied with normal 

 results on normal soils and on some abnormal soils (as the deep peat 

 and sand ridge soils), there are complex problems still unsolved 

 relating to soils and soil fertility. 



These problems may be chemical, physical, or biological, and 

 their solution may require the application of science yet unknown. 

 Thus, some essential element of plant food may be present in 

 abundance but held in unavailable form by chemical combination 

 or physical absorption; or there may exist some still undiscovered 



