Hydrochar (CH) of sugarcane by-products has a slow release of carbon and nutrients to highlight potassium, and initial studies have shown an improvement in the properties of the plant and soil indicating that it has the potential to be used as a conditioner of the soil, however it is necessary to use fertilizers. It is worth mentioning that potassium is one of the strategic minerals for maintaining agricultural productivity. In view of the above, this work has as main objective to evaluate if in a stressful situation (addition of fertilizer N and P without addition of K) there will be a greater release of K from hydro char during tomato growth compared to the system that receives fertilizer (NPK) . For this, pots containing soil and / or sand for tomato planting will be set up, with a control containing only sand (C) and another only argisol (CArg), a system containing sand and NPK fertilizer (ANPK), another sand and the addition of 10 t ha-1 of hydrothermal coal and NPK fertilizer (ACHNPK) and another containing another sand and addition of 10 t ha-1 of hydrothermal coal and NPK fertilizer (ACHNP) another system containing a system containing Argisol and NPK fertilizer (ArgNPK), another argisole and addition of 10 t ha-1 of hydrothermal coal and NPK fertilizer (ArgCHNPK) and another containing another argisol and addition of 10 t ha-1 of hydrochar and NP fertilizer (ArgCHNP). These pots will be kept in a plant growth chamber for 30 days, maintaining a photoperiod of 16 h day and 8 h night. At the beginning and end of the experiment, dry mass of the root and aerial part, length of the root and aerial part, as well as quantification of potassium in the soil and in the plant will be determined. Scanning electron microscopy (SEM) images of the root and shoot will be obtained in order to verify better rooting or development in the presence of CH. The end of this experiment is expected to have resulted in inferring whether hydrochar can be used as a fertilizer to release potassium in a situation of scarcity of the element.
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