Biocarvão e adubação nitrogenada influenciando o crescimento e o estado nutricional de mudas de castanheiras-do-brasil em um latossolo da Amazônia Central

Abstract

Biochar can be used as a soil amendment, contributing to the recovery of degraded areas and increasing the agronomic efficiency of mineral and organic fertilizers. The objective of this research was to evaluate the effect of biochar and nitrogen fertilizer doses on changes in soil fertility, biomass production and nutritional status in Bertholletia excelsa seedlings. The experiment was conducted in a greenhouse for 210 days in 2017. The experimental design was completely randomized (DIC) in a factorial test (2x4) with 4 replicates. The factors were - absence and presence of biochar (0 and 40 t ha-1) and four increasing doses of nitrogen (0, 67,5, 135 and 270 kg ha-1) and consisted of 8 treatments (n = 32). The pyrolysed brazil nut shell was used as a source of bio-fuel at 500ºC. The soil used was a dystrophic Yellow Oxisols from Central Amazonia, removed from the subsurface layer (20-40 cm), under a secondary forest. Seedlings at the age of seven months were used. One month after transplanting, the diameter at 3,0 cm of the soil and the height of the plants were measured. The following parameters were calculated: relative height growth rate, relative diameter growth rate, absolute growth rate in height, absolute diameter growth rate, absolute height growth and Dickson quality index. pH values and nitrogen, phosphorus, potassium and calcium contents increased with the application of biochar. Micronutrient contents increased with increasing doses of N, except for magnesium. Increasing doses of N promoted greater development of the plant in the weight gain of the dry matter area. The biomass increased the dry matter weight of the roots. The quality index of Dickson did not show any significance among the treatments; on the other hand, the values were above 1, emphasizing the benefits of nitrogen fertilization. For the production of Brazil nut tree seedlings, no dose of N was indicated as ideal. Leaf phosphorus concentrations did not increase either because of increasing doses of N or BC. The foliar concentrations of Ca and iron and magnesium micronutrients had their values negatively affected by BC. In general, the various parameters of soil and plants increase in the intervals of 0 to 135 kg ha-1 of N.