Dissertação/Tese CRESCIMENTO, NUTRIÇÃO DE PLANTAS DE MILHO E CARACTERÍSTICAS QUÍMICAS DO SOLO ADUBADO COM COMPOSTO ORG NICO ADICIONADO OU NÃO DE ENXOFRE ELEMENTAR OU SULFATO DE AMÔNIO - PPGPV

AVALIAÇÃO DO COMPOSTO ORGÂNICO ACIDIFICADO COM ENXOFRE ELEMENTAR OU SULFATO DE AMÔNIO NO CRESCIMENTO DE PLANTAS DE MILHO

Organic compost is an organic fertilizer that can improve soil quality and reduce the use of chemical fertilizers. However, the release of hydroxyls during the composting process raises the pH of the compost and consequently the soil, which can limit the amounts to be applied to the soil. This study aimed to evaluate whether the previous addition of elemental sulfur or ammonium sulfate to the organic compost allows the application of higher doses of compost to the soil and, thus, increase soil fertility and the growth and nutrition of corn plants. Independent and identical experiments were carried out in pots in a greenhouse with samples of a Rhodic Hapludox (LVd) and Typic Quartzipsamment (NQ). The treatments were arranged in a 4 x 3 factorial scheme and an additional treatment, being the fertilization of the corn plants with doses 4, 8, 6 and 32 kg m-3 of the compost previously acidified with 16 g dm-3 elemental sulfur (CO +S0), and 8 g dm-3 ammonium sulfate (CO+SA) and, of the compost without acidification (CO), plus the control treatment without addition of fertilization (control). The maximum pH in the LVd was 6.7 at the dose of 26 kg m-3 of CO, 2.2 units higher than the pH of the control soil (pH = 4.5). In NQ, the three fertilizers, on average, increased the pH from 5.0 to 5.8 at the dose of 20 kg m-3. Fertilizing the two soils with increasing amounts of the three fertilizers increased the soil nutrients concentrations (P, K, Ca, Mg, Fe, Zn and Mn). Organic fertilizers provided higher levels of Ca and Mg in both soils, higher availability of K in NQ and higher availability of Zn, Mn and Fe in LVd. Regarding the growth of maize plants fertilized with organic fertilizers, height, collar diameter, shoot and root dry mass were higher in the LVd fertilized with CO+S0 and in the NQ fertilized with CO+SA. In both soils, in general, in relation to the control, the use of organic fertilizers increased the foliar concentrations of P, K, Ca and Mg and did not influence the concentrations of Mn and Zn. The addition of S0 or SA was more efficient to reduce the pH elevation in LVd than in NQ. The addition of S0 or SA to the compost did not allow the application of higher doses of compost in the two soils.