Mitigation of ammonia and greenhouse gases emissions from urea coated with oil shale residues in a silvopastoral system.

The objective of this work was to investigate the viability of using retorted oil shale as urea coating (U + ROS) in the decrease of N losses by ammonia (NH3-N) volatilization. The experiment was carried out in a silvopastoral system with a randomized block design with split-plots. The main treatments consisted of spatial arrangements of the trees, while the subdivision of the plots constituted the surface application of common urea (U) and retorted oil shale-coated urea (U + ROS) for the pasture. In addition to NH3 measurements, fluxes of N2O and CH4 in the soil were determined, as well as soil moisture and contents of mineral N (0-5 cm). Independently of tree spacing, the use of ROS along with urea (U + ROS) showed a mean decrease of 15.9% in the accumulated NH3 volatilization and 24.1% in the peaks of emission, although it was not significantly different from the U treatment (P < 0.10). In addition, it did not increase significantly the N2O and CH4 emissions, evidencing a potential to decrease N losses by ammonia volatilization, with no impact on greenhouse gases emissions from the soil.

Produção de morangos a partir de fertilizantes alternativos em pré-plantio / Pre-planting fertilization effects on strawberry fruit yield

O trabalho teve como objetivo avaliar doses de fertilizantes alternativos na adubação de pré-plantio quanto à produção de frutos de morangueiro. Os tratamentos foram baseados em doses de adubação NPK (kg ha-1) recomendada para a cultura do morangueiro em que as doses de torta de mamona (TM), fosforita alvorada (FA) e cloreto de potássio (KCl) variaram de acordo com a recomendação da análise de solo. Os tratamentos foram dispostos em delineamento em blocos casualizados em parcelas subdivididas, sendo as cultivares dispostas na parcela e as adubações na subparcela. Foi utilizado um esquema fatorial 2x4, em que o fator cultivar apresentou dois níveis: 'Camarosa' e 'Camino Real', e o fator adubação de pré-plantio, quatro níveis. As avaliações realizadas foram produção de frutos por planta, massa seca da parte aérea e índice de clorofila. A cultivar 'Camarosa' apresentou maior número e massa de frutos por planta e maior massa seca da parte aérea. A cultivar 'Camino Real' apresentou maior massa média por fruto e maior índice de clorofila. Com relação às doses de adubação de pré-plantio que propiciaram maior número e massa de frutos por planta, foram 1.937kg ha-1 e 1.713kg ha-1 de adubo, respectivamente.

The study aimed to evaluate the doses of alternative fertilizer pre-planting fertilization on strawberries yield. The treatments were based on doses of NPK (kg ha-1) recommended for strawberry culture in which the doses of castor bean (TM), phosphorite dawn (FA) and potassium chloride (KCl) varied according to the recommendation of the soil analysis. The treatments were arranged in randomized blocks design at split plots with cultivars in the plot and fertilization in the sub-plot. It was used a factorial 2x4 arrangement, in which the cultivar factor had two levels: 'Camarosa' and 'Camino Real', and the pre-planting fertilizer factor with four levels. The evaluations were fruit yield per plant, shoot dry mass and chlorophyll content. 'Camarosa' cultivar showed a greater number and weight of fruits per plant and higher dry mass shoots. Cultivar 'Camino Real' had the largest average per fruit and increased chlorophyll content. Regarding the fertilization rates of pre-planting, which fostered a greater number and weight of fruits per plant, it was 1937kg ha-1 and 1713kg ha-1 of fertilizer, respectively.