A study in soil cultivation. The effects of varying soil consolidation on growth and development of rain-grown cotton

• Published in: The Journal of agricultural science 1937-10, Vol.27 (4), p.511-540
• Main Author: Heath, O. V. S.
• Format: Article
• Language: English
• ISSN: 0021-8596; 1469-5146
• DOI: 10.1017/S0021859600050425

1. Experiments were carried out in four seasons at Barberton, South Africa, occupying approximately 2¼ acres of ground. Three soil treatments were used, viz. Normal (N), Compressed (C) and Grubbed (loosened) (G). 2. Measures of consolidation of the soil were made with a specially designed apparatus, and large differences established (pp. 516–520). 3. Estimations of water content and nitrate content were carried out. No great differences were found (pp. 520–524). 4. Fortnightly samples of the plants were taken, from which numerical data were collected designed to estimate morphological development (primary data, pp. 526–529). 5. Derived data on net assimilation rate, relative leaf-growth rate and efficiency index were calculated (pp. 529–533). 6. Growth in total dry weight was found to conform approximately with an exponential law up to the time of flowering. Up to this stage also net assimilation rate was found to remain constant. 7. Growth differences between treatments were related to variation in net assimilation rate only (p. 531). 8. The results were analysed statistically. Significant results alone are emphasized. 9. In all respects growth and development on the consolidated soil was more rapid than that on the grubbed soil, normal being generally intermediate. 10. The results are discussed with reference to the question of nitrogen supply, water supply and aeration of the soil.