Effects of certain fertilizer and manurial treatments on the cation exchange properties and organic matter content of dunmore silt loam

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Virginia Agricultural and Mechanical College and Polytechnic Institute


An investigation of the pH, organic matter content, and cation exchange properties of the soil of the 26-year-old rotation and continuously cropped plots at Blacksburg, Virginia was carried out. Individual soil samples were taken of the eight sub-plots which represent each plot. After the chemical work had been completed, the data obtained were analyzed statistically. As a result of this investigation, the following conclusions are considered worthy of mention:

Fertilizer and cropping practices which tended to increase crop yields also tended to increase soil organic matter and cation exchange capacity.

There was a significant, positive correlation between organic matter content and cation exchange capacity of the soil. The organic fraction seemed to be of greater importance than the mineral fraction in contributing to the cation exchange capacity of this soil.

Superphosphate, rock phosphate, muriate of potash and farm manure had or no effect on soil reaction.

Ammonium sulphate caused a reduction of the pH and exchangeable calcium and magnesium and an increase in exchangeable hydrogen. The application of this fertilizer decreased exchangeable calcium but had no influence on the pH.

Of the total potassium applied as muriate of potash, an average of 15 percent remained as exchangeable potassium in the upper six inches of soil.

Where farm manure was applied, exchangeable calcium, magnesium, potassium, and cation exchange capacity were increased significantly.

Examination of the samples and crop yield data from the check plots indicated considerable soil variation.