Crop demands for the macronutrient sulfur (S) are similar or greater than those for phosphorous. However, S is often overlooked in the management of crop fertilization. This study aimed to evaluate the effect of sources and doses of S on soybean cultivation under field conditions. A randomized block design, with 4 replications, was used. The treatments were arranged in a factorial scheme with one additional treatment (3 x 5 + 1), totaling 64 experimental units. Sources (elemental sulfur, single superphosphate and agricultural gypsum) and doses (20 kg ha-1, 40 kg ha-1, 60 kg ha-1, 80 kg ha-1 and 100 kg ha-1) of S were used, in addition to one control (without fertilizer). The following parameters were assessed: plant height at flowering, 1,000-seed weight, yield and agronomic efficiency, which were affected by the doses and sources of S; number of pods per plant, only affected by the sources of S; and number of pods with 3 seeds, with no statistical difference for any of the treatments. The highest yield recorded was 1,927 kg ha-1, at the dose of 80 kg ha-1 of S for gypsum, and the greatest agronomic efficiency was observed for the single superphosphate, at the dose of 20 kg ha-1 of S.

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Environmental impacts caused by the addition of rare earth elements (REEs) to agricultural soils are a growing concern. The sedimentary basin of the Gurguéia River is located in one of the last agricultural frontiers in Brazil; nevertheless, data regarding quality reference values (QRVs) for REEs in soils are still scarce. The objective of this study was therefore to determine the natural concentration and establish the QRVs of REEs in soils of Gurguéia watershed, Brazil. Fifty-five composite soil samples were collected at sites under no or minimal anthropic interference. The average REE natural concentrations in soils from the Gurguéia watershed were lower than those found in other regions of Brazil and worldwide, following the order (mg kg -1 ): Ce (14.01) > Nd (6.19) > La (5.52) > Pr (2.51) > Sm (1.45) > Gd (0.93) > Dy (0.63) > Er (0.42) > Yb (0.39) > Tb (0.28) > Eu (0.26) > Lu (0.20). The parent material was the main factor that controlled the distribution of REEs in soils. The QRVs in soils followed the order (mg kg -1 ): Ce (18.8) > Nd (7.92) > La (6.32) > Pr (3.3) > Sm (1.97) > Gd (1.35) > Dy (0.85) > Er (0.55) > Yb (0.47) > Tb (0.37) > Lu (0.25). These values serve as a basis to assist the development of legislation, including REE thresholds for Brazilian soils.

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O objetivo deste estudo é a avaliação ambiental macroscópica das nascentes e suas áreas de preservação permanente e do leito localizados na bacia do riacho Corrente do Matões. O estudo foi conduzido na bacia do riacho Corrente dos Matões, onde foram realizadas viagens de campo a fim de avaliar a vegetação, impactos ambientais, aspectos geológicos, caracterização da área de preservação permanente associada à nascente, acesso direto de animais, presença de resíduos domésticos nas nascente e entorno, construções, captações de água, múltiplos usos, proximidade de atividades impactantes, além de  outros aspectos que foram anotados e registrados com uma máquina fotográfica e um GPS. Também foram realizadas coletas de amostras de água para avaliar a concentração de alguns elementos químicos. Diante da análise deste estudo registrou-se que o Riacho Corrente dos Matões possui cinco nascentes, sendo alimentado apenas por três. O estudo também revelou que de acordo com o uso do solo os impactos são diferentes na bacia do riacho Corrente dos Matões e que mesmo sendo um rio situado na zona rural, sofre pressões com o avanço da urbanização.