Pedosphere 6(2): 129--138, 1996
ISSN 1002-0160/CN 32-1315/P
©1996 Soil Science Society of China
Published by Elsevier B.V. and Science Press
| Assessment of cation exchange membrane method and estimation of potassium critical values |
| SHEN Jian-Bo1, J. J. SCHOENAU2, P. QIAN2 and K. GREER2 |
1 Department of Plant Nutrition, China Agricultural Uheversitg, Beijing 100094(China)
2 Depariment of Soil Science, Universitg of Saskotchewan, S7N 0W0(Canada) |
| ABSTRACT |
| Soil and tissue analyses are usually used in identifying potassium (K) deficiencies and predicting K fertilizer requirements of crops. The critical levels of both soil and fresh leaf tissue at seventh leaf stage were developed and assessed for canola, chickpea and sunflower grown on two Saskatchewan, soils, with six rates of K fertilizer supply, in a growth chamber experiment. The available potassium in soils was determined by two methods: 1) resin strip extraction, and 2) NH4OAC extraction. The potassium in fresh leaves was determined at seventh leaf stage by a simple procedure using a common garlic press and injector to extract the plant sap and testing the sap with a handheld ion selection electrode meter. The results showed significant relationships between the resin strip extractable K and NH4OAC extractable K, and between the plant uptake of total K and the supply of available K in the soils determined by the two methods. Good relationships were also found between the potassium in fresh leaves and the plant uptake of total K for canola, chickpea and sunflower. The resin strip extraction for K was calibrated using common NH4OAC extraction, and recommended for routine analyses because of its simplicity and sensitivity. |
| Key Words: canola, cation exchange membrane, chickpea, potassium critical values, sunflower |
| Citation: Shen, J. B., Schoenau, J. J., Qian, P. and Greer, K. 1996. Assessment of cation exchange membrane method and estimation of potassium critical values. Pedosphere. 6(2): 129-138. |
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