Does Ferralsol Clay Mineralogy Maintain Potassium Long-Term Supply to Plants?
ABSTRACT Ferralsols ( Latossolos ) should contain few or no 2:1 clay minerals and have low potassium (K) contents, and consequently low levels of non-exchangeable K forms are expected. The aim of this study was to evaluate how the clay mineralogy of a Ferralsol affects the soil K dynamics in response to K fertilization during cropping and whether the clay mineralogy was altered due to successive crops and K fertilization. A tropical Brazilian Ferralsol under field conditions was sampled (0.00-0.20 m) in contrasting K fertilization plots: no K application (control plot) and 3,200 kg ha-1 applied K2O fertilizer. These two treatments were submitted at eight different crop cycles, performed in pots under greenhouse conditions, and fertilized with 0, 30, and 90 mg kg-1 K2O before each crop cycle. The biomass K, exchangeable K, non-exchangeable K, and structural K contents were determined after each crop cycle. At the end of the experiment, the presence of 2:1 clay minerals with hydroxy-aluminum interlayered in the soil clay fraction was verified, which ensured K adsorption in a form available to plants when K fertilizer was added. Cropping without K fertilization resulted in limited crop yields and exhausted the exchangeable and non-exchangeable K soil reserves. The previous K fertilization history influenced the soil K reserve and its availability to plants in the Ferralsol studied. The crops without K addition decreased the proportion of 2:1 hydroxy-Al interlayer minerals in the soil in relation to the kaolinite clay minerals.
| Main Authors: | , , , , |
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| Format: | Digital revista |
| Language: | English |
| Published: |
Sociedade Brasileira de Ciência do Solo
2019
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| Online Access: | http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832019000100512 |
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