Robertson, Andrew

2019-02-15T14:18:49Z

2019-02-15T14:18:49Z

1932

1. The effect of the growing plant on the acidity of the soil has been studied by means of dish and pot experiments. 2. The growing plant had the effect of raising the pH of the soil in all cases. 3. The various effects of carbon dioxide on a number of soils have been studied. 4. The passage of carbon dioxide through the moist soils raised their pH values in a manner similar to that of the growing plant. 5. The passage of carbon dioxide through suspensions of various soils in water increased the acidity. The extent of the change depended on the degree of saturation and the buffer capacity of the soil. 6. Leaching three soils with a saturated carbonic acid solution increased the acidity of approximately the first half inch, and lowered that of the second half inch, of soil. 7. Measurements of the seasonal variation of pH value, and conductivity and calcium content of a water extract of the fertile soil B were made. 8. The pH value of the soil was at a maximum after heavy rainfall and at the time of minimum conductivity and calcium content in the soil extract i.e. with a minimum concentration of electrolytes in the soil solution /and vice versa. 9. The effect of lime on the soil and on the plant was observed. 10. The pH value, conductivity and calcium content of the water extract increased with liming soil B. 11. The changes in yield, calcium and sulphur content of the crops grown on the limed soil were insignificant. 12. Liming the infertile soil W in pots increased the pH value of the soil and the crop yield. The yield increased up to 8 times that for the untreated soil as also did the calcium content. The sulphur content of the plants rose slightly with the smallest addition and then fell with larger applications of lime to the soil. 13. Liming soil W in the field caused a ten -fold increase in both yield and calcium content with a decrease in sulphur content of the crop. 14. The effect of sulphur on the soil and plant was observed. 15. The conductivity and calcium content of the soil extract were more than doubled by the addition of sulphur. 16. The calcium and sulphur contents of the growing plants were increased considerably by the sulphur treatment of the soil.

http://hdl.handle.net/1842/33720

The University of Edinburgh

Annexe Thesis Digitisation Project 2019 Block 22

The ionic exchange between plant and soil: with special reference to hydrogen, calcium and sulphur

Thesis or Dissertation

Doctoral

PhD Doctor of Philosophy