Without such indicative thresholds, no degree of confidence can be placed in the work of breeders and physiologists. Based on my experience, aluminum appears as exchangeable cation when the pH (H2O) falls below the level of 5.5 and it becomes dominant (> 60% ECEC) at pH
According to our long term experimental data in Lithuania, mobile or available Al is a critical issue in combination with depressed pH at >10 mg kg−1 (or >1 meq kg−1). Also we found that relations between soil pH and soil sorption properties are not stable in limed soils.
Al is important for tea (Camellia sinensis ) in thesub-tropical area. Tea only can grow in the soil with the low pH, most of them can grow well if pH
You can find some information about tea and soil fertility in my early work. It is in Chinese , but with the English abstract and the tiltles of table and figures.
Characteristics of soil fertility in the tea-Chinese tallow tree ecosystem in southern Anhui
https://www.researchgate.net/publication/231315964_Characteristics_of_soil_fertility_in_the_tea-Chinese_tallow_tree_ecosystem_in_southern_Anhui?ev=prf_pub
Article Characteristics of soil fertility in the tea-Chinese tallow ...
Thank you Sir. What about the ability of tea to absorb Al-P complexes formed in acid soils?
Tea have quite high ability to absorb Al-P complexes in the acidic soil. As you know, P deficiency is quite often in the acidic soil. Since 60s', phosphorus was in introduced in to southern of China, including tea garden. There are many long term experiments about tea, Phosphate and Al study. The paper I mentioned to you is my work for my master degree and I do not have papers in my hand about these data and I am sure that you can dig it out ....
Here are some examples in English
Stimulatory Effects of Aluminum on Tea Plants Grown under Low and High Phosphorus Supply
DOI:10.1080/00380768.1985.10557443
Effect of Organic Acids on Aluminum Toxicity in Subsoils
doi:10.2136/sssaj1986.03615995005000010006x
I just remind you that tea is also rich in F and the availability or toxicity of Al is related to F in the soil and it is one of the reasons why the soil ph become low and low....
In general, Al saturation above 25-30 % (% of CEC) in soil is implicated for its toxicity to plants. In some Indian classical soil science literature, Al saturation level of
Growth of most crop species are stimulated by low Al-saturation up to 10-30%. Above growth begins to decrease. Above 50 or 60% of Al-saturation toxic effects really deplete growth. But tea growth is stimulated up to more than this toxic level.
Dr Luc, I'm hugely interested to know as to why Al saturation upto 30% stimulates plant growth. It is certainly not an essential element for crop species. what beneficial effect it might have on crop nutrition? any comments please!
Dr Manoj, Al and Phosphorus form Al-P ion pairs in acid soils. The stimulative effect is due to P absorption with Al. But if Al concentrations becomes to high toxic effects are prevailing on P absorption effect.
About stimulating effects at low Al soil levels:
- Bertand, R et H. Agulhon; 1912. C.R. VIIème Cong. Intern. Chim. Apll., New-York, 15, 37.
- Cerighelli, R.;1955. Cultures tropicales. I. Plantes vivrières, 6-171. Ed. Baillière et Fils, Paris.
- Hacket, C.; 1962. Stimulative effects of aluminium on plant growth. Nature, London, 195: 471-472.
- Mc Leod, L.B. and L.F. Jackson; 1965. Effect of concentration of the aluminium ion on root developpement and establishment of legume seedlings. Can. J. Soil Sci., 45 (2): 221-234.
Specially for tea and plant Al accumulators:
- Sivasubramaniam, S. and O. Talibudeen; 1971. Effect of aluminium on growth of tea (Camelia sinensis) and its uptake of potassium and phosphorus. J. Sci. Fd Agric., 22: 325-329.
- Chenery, E.M.;1955. A preliminary study of aluminium and the tea bush. Plant Soil 6: 174-200.
- Evrard, C., J. Roels, P. Remy, G. Tshitenge et H. Pollack; 1967. Détection par activation neutronique d'accumulateurs d'aluminium dans la flore congolaise. Atomic energy review 5 (3): 119-125.
Thank you Dr Luc, your reply is really very informative and useful.
Dr. Kumar - In Brazil, one of our methods for lime recomendations is based on plant tolerance to Al toxicity. We use the relative value of Al3+ saturation in the CEC at soil pH (effective CEC). Thus, for corn and sorghum values of 15 - 20 %, rice 25 %, cotton 10 %, pasture 20 - 30 %, etc.
Thanks Dr Antonio. these are really useful information. Most of the soils in our region (northeast India) is having Al saturation over 30%. By the way, could you please refer to some citable references containing these information.
Regards
Very interesting question Luc. i am enclosing some PDFs for ready references , but could see hardly any literature relating the relative aluminium tolerance limits of different crops...
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