ANNUAL REPORT, 1941 33 



This system allowed for drainage of the soils and also the actual determination 

 of the pH of the soils in place. The soils were limed at a rate of from 125 to 1000 

 pounds of calcium carbonate per acre-inch, based on previously determined vol- 

 ume weights of the soils as they were found in the field. 



The reactions of the so'ls of each series, variously limed, were determined at 

 regular intervals. The soils were wetted with distilled water and allowed to stand 

 overnight to permit drainage of the excess water and the removal of nitrates 

 that may have accumulated as a result of bacterial action. The pH values were 

 determined in duplicate samples of soil dampened with water and with saturated 

 potassium chloride. The pH values obtained with the use of potassium chloride 

 were considerably lower than those obtained with water. The amount of lower- 

 ing of the pH value due to the presence of the salt showed a relationship to the 

 exchangeable hydrogen content of the soil. The indications are that, in general, 

 soils of higher exchange capacity require greater quantities of lime for neutraliza- 

 tion than do soils of low exchange capacity at the same initial reaction. The 

 data obtained have not been sufficient to establish any quantitative relationship 

 between the exchange capacity, the initial reaction, and the lime requirement. 



Similar experiments set up under field conditions in the localities from which 

 the soils were obtained gave results parallel to those found in the laboratory, 

 except with the two soils which had received a large quantity of commercial 

 fertilizer for growing onions. It is believed that fertilizer produced a lowering 

 effect on the reaction similar to that observed when potassium chloride was 

 added to the soil under laboratory conditions. 



Soils having higher base exchange capacities than those obtained originally 

 for these tests have been secured and will be tested in a similar manner. 



The Effect of Orchard Mulches on the Plant Nutrient Elements in the Soil. 

 (Dale H. Sieling and J. K. Shaw.) The objectives of this experiment are to in- 

 vestigate the influence of mulching on the accumulation and movement of nutrient 

 cations and of phosphates in an orchard soil and to study the effects of mulching 

 on the trees. 



Six mature Mcintosh apple trees which had been fertilized with complete 

 fertilizer for the past ten years and had been cultivated during that time were 

 selected for this study. Three separate plots consisting of two trees each were 

 treated as follows: Plot 1 received an application of 290 pounds of hay per 1600 

 square feet and will be mulched from time to time with hay of known mineral 

 composition; Plot 2 received Fiberglass wool of 2-3 inches in thickness; and 

 Plot 3 was left fallow and will be cultivated in the usual manner. 



Soil samples were taken at two systematically located positions under each 

 tree before mulching was started. At each sampling location four samples were 

 taken at specified depths so that any movement of mineral nutrients resulting 

 from mulching might be detected when further samples are obtained and analyzed. 



The samples of soil were stored in sealed glass jars to prevent loss of moisture 

 and the subsequent fixing of potassium and other mineral nutrients. After the 

 moisture in the soil had been determined, samples were extracted by the neutral 

 ammonium acetate method and the extracts were analyzed for the exchangeable 

 ions: hydrogen, calcium, magnesium, and potassium. 



From the analysis it has been observed that the base saturation of this soil 

 was very low and conversely the hydrogen saturation was very high. In one 

 surface sample the base saturation was as low as 5.2 percent. The amount of 

 exchangeable potassium in the surface soils ranged from 100 to 200 pounds of 

 pocassium per acre for a 6-inch depth. This amount of potassium is usually 

 considered adequate for good crop production but may become a limiting factor 

 as the other elements are increased since the subsurface soils contain a much 

 smaller amount of this element. The exchangeable calcium was exceptionally 



