Quality reference values (QRV) for potentially toxic elements (PTE) in soils are established as a tool for prevention and monitoring of soil pollution. These values should be periodically revised in order to ensure soil safety for agricultural purposes. Brazil is market leader for several commodities; therefore, the safety of Brazilian soils is of worldwide strategic importance. The objective of this study was to determine the natural background concentrations and the QRV for As, Ba, Cd, Cr, Ni, Pb, Se, and Zn by investigating 30 representative pedotypes in the São Paulo State, one of the most important agro-industry economy at worldwide level. Multivariate statistical analysis was applied to determine the sources of PTE and their variability. The mean natural background concentrations of PTE in the soils were generally lower to those reported in literature. QRV, calculated for each element as the 75th and 90th percentiles, were lower (75th for As, Cd, Pb, and Zn), similar (75th for Ba, Cr, and Se) or above (90th for Ba, Cr, and Se and 75-90th for Ni) those previously proposed by the Brazilian environmental protection agencies. The results indicate that 75th percentile may be too restrictive. The PTE in the investigated soils appear to have comes mainly from two primary natural sources: a prevalent one of geogenic and a secondary of pedogenic origin. These results confirm the predominant natural source of selected PTE in the investigated soils, thus sustaining the possibility of using the data set to develop QRV for the State of São Paulo.

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Some silicate rocks are a rich source of potassium (K), with the possibility for use in agriculture. The present study aimed to evaluate the agronomic efficiency index (AEI) of nepheline syenite (NS) and phonolite (PN) rocks in comparison with potassium chloride (KCl) as a K source in maize production. An experiment was conducted in a greenhouse in Ilha Solteira, São Paulo, Brazil. A maize hybrid was grown in 8 L pots filled with 6 kg of soil with a low K concentration and contrasting physical attributes (medium and sandy texture). A completely randomized design in a 3 × 6 factorial scheme was used, consisting of three K sources (NS, PN, and KCl) and six rates (0, 50, 100, 150, 200, and 400 mg kg−1) with four replications. All plants were harvested 45 days after emergence to evaluate biomass production, macronutrient (N, P, K, Ca, Mg, and S) concentration and uptake, stem diameter, and leaf chlorophyll index. After crop harvest, soil was collected for further chemical evaluation, which included organic matter (OM), pH, cation exchange capacity (CEC), H+Al, Al, sum of bases (SB), base saturation (BS), P, K, Ca, Mg, and S. In addition, AEI of NS and PN were also verified in relation to KCl. The application of NS and PN had a similar effect on soil chemical attributes (MO, pH, SB, CEC, and BS) as well as on the concentrations of K, Ca, Mg, and S, in both soils. The increase in NS and PN rates provided linear growth of shoot dry matter. Leaf macronutrient concentrations were similar for NS and PN compared to KCl. All three K sources (NS, PN, and KCl) increased K accumulation in maize plants. Maize treated with KCl had the largest AEI, followed by PN and NS. However, the results indicated similar AEI with both rocks as a K source for maize, especially with application of the highest K rates. This research demonstrated the efficiency of NS and PN as alternative K sources for maize.

As imagens de satélite de alta resolução espacial se tornaram muito importantes na análise, interpretação e quantificação das transformações ambientais ocorridas ao longo do tempo, permitindo o monitoramento da dinâmica do uso e ocupação do solo, e o monitoramento de áreas protegidas por lei, promovendo instrumentos para um desenvolvimento sustentável, que concilia a produção agrícola e a proteção dos recursos naturais. O presente trabalho é uma análise espacial dos fatores de perturbação e seus potenciais impactos ambientais nos recursos hídricos identificados na Área de Proteção Ambiental (APA) Corumbataí-Botucatu-Tejupá – Perímetro Botucatu-SP em sua porção localizada dentro do município de São Manuel, Estado de São Paulo, por meio de imagens digitais do Google Earth Pro dos anos de 2010 e 2016. Identificou-se  oito áreas com fatores de perturbação (A, B, C, D, E, F, G, H) onde foram detectados focos de desmatamento e avanço de pastagem e monoculturas sobre áreas de preservação ambiental, tais como nascentes e locais de potencial recarga de aquífero. Essas ocupações irregulares geram impactos na produção de água, tais como impermeabilização do solo, escoamento superficial e erosão com transporte de sedimentos. Esse procedimento é aplicável à municípios de pequeno e médio porte para detecção e monitoramento de inconformidades ambientais.