Journal
REVISTA BRASILEIRA DE CIENCIA DO SOLO
Volume 43, Issue -, Pages -Publisher
SOC BRASILEIRA DE CIENCIA DO SOLO
DOI: 10.1590/18069657rbcs20180166
Keywords
potassium forms; K fertilization; non-exchangeable K; 2:1 clay minerals; X-ray diffraction
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Funding
- Fundacao de Amparo a Pesquisa do Estado do Rio Grande do Sul (FAPERGS)
- Brazilian Council for Scientific and Technological Development (CNPq)
- CNPq (Brasilia/Brazil)
- CAPES (CAPES-COFECUB program) [009/2011, 3504-11-5-Te 761/12]
- CAPES-Brazil [BEX 2353/15-6]
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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.
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