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.

The demand for mineral fertilizers has increased over the years. In the states of Amazonas and Roraima, acquiring conventional fertilizers used in agriculture is challenging due to the distance from large production centers. In these regions, alternative fertilizers are needed to maintain food security. However, research in agrominerals of silicate rock powders (SRP) is still incipient. The objective of this research was to characterize three important Units of Agrogeological Interest in the Manaus/Boa Vista axis in the Amazon region of Brazil: (i) EBAM Quarry: quartz monzonites from the Água Branca suite, partially potassified, (ii) Granada Mining Quarry: basalts from the Apoteri formation, and (iii) Samauma Quarry: riolites from the Iricoumé Group. Samplings were carried out followed by chemical analyses for determining macro and micronutrients, in addition to potentially toxic elements; petrographic analyses were performed for mineralogical characterization as well as granulometric analyses of the powders collected in the quarries. The results showed that the EBAM quarry rock powder meets the standards established by Brazilian legislation. It also has low levels of potentially toxic elements and only 15% quartz, indicating good safety in the use of this SRP, in addition to the large supply of the material already crushed, for which there is still no market. At the Granada Mineração quarry, SRP also has the necessary characteristics to classify as a soil remineralizer, including K₂O content above 1%. At Pedreira Samauma, although SRP does not qualify as an agromineral, it has more than 5% K₂O and 77% aphanitic matrix, which could result in a more accessible release of abundant K and Si to the soil–plant system. Using laser granulometry analysis, it was possible to make some considerations about the effects of the crushing process in such different lithotypes and, finally, to characterize and classify the prospects of greatest interest for “rochagem” in the Amazon.

Silicate agrominerals (SA) may be sustainable soil amendments that can minimize dependence on conventional fertilizers (CF). We evaluated the residual effects of SA application as a source of Si and as a soil remineralizer, using soils with contrasting chemical-physical features cultivated with soybean. The experiment was conducted under greenhouse conditions and treatments were arranged in a 5 × 2 + 2 factorial scheme: five rates of SA, two soils in addition to CF. The soil was incubated before cultivation, followed by the sequential sowing of corn and soybean. At the R4 phenological stage, when the pods were fully developed, soybean plants were harvested for anatomical leaf tissue analysis and P, Ca, Mg, and Si accumulation. After harvest, the soil was analyzed. Application of SA rates reduced potential acidity (H + Al) and exchangeable acidity (Al³⁺) and increased soil pH, sum of bases (SB), cation-exchange capacity (CEC), and base saturation (BS), in addition to promoting the nutrient’s availability and Si. Stomatal density was higher on the adaxial face of plants cultivated in the medium-textured soil. Silicate agrominerals can be used as a soil acidity corrector and remineralizer, improving the root environment and increasing the availability of nutrients and silicon.

FAVORABILIDADE À MECANIZAÇÃO AGRÍCOLA DE BACIAS HIDROGRÁFICAS POR MEIO DE SISTEMA DE INFORMAÇÕES GEOGRÁFICAS FÁBIO RODRIGO DE OLIVEIRA1, ROBERTO WAGNER LOURENÇO2, LUIS GUSTAVO FREDIANI LESSA³, CÉLIA REGINA LOPES ZIMBACK3 1 Doutorando em Ciências Ambientais, Universidade Estadual Paulista “Júlio Mesquita Filho”, Instituto de Ciência e Tecnologia de Sorocaba. Avenida Três de Março, 511, Alto da Boa Vista, CEP: 18087180, Sorocaba, São Paulo, Brasil. E-mail: fabio.rodrigo@unesp.br 2 Livre-Docente Doutor em Geociências e Meio Ambiente e Professor Associado - Universidade Estadual Paulista “Júlio Mesquita Filho”, Instituto de Ciência e Tecnologia de Sorocaba. Avenida Três de Março, 511, Alto da Boa Vista, CEP: 18087180, Sorocaba, São Paulo, Brasil. E-mail: roberto.lourenco@unesp.br 3 Professor Assistente Doutor da Faculdade de Ciências Agronômicas - FCA, da UNESP, Campus de Botucatu, lotado no Departamento de Ciência Florestal, Solos e Ambiente. Endereço: Av. Universitária, 3780, Altos do Paraíso, CEP: 18610-034, Botucatu, São Paulo, Brasil. E-mail: gustavo.lessa@unesp.br 4 Livre-Docente e Professora Aposentada Associada da Faculdade de Ciências Agronômicas - FCA, da UNESP, Campus de Botucatu, lotada no Departamento de Ciência Florestal, Solos e Ambiente. Endereço: Av. Universitária, 3780, Altos do Paraíso, CEP: 18610-034, Botucatu, São Paulo, Brasil. E-mail: czimback@gmail.com RESUMO: O desenvolvimento no meio rural demanda a adoção de técnicas de manejo e uso do solo que visam o desenvolvimento sustentável de práticas agrícolas para atender à crescente demanda por alimentos. Com isso, o objetivo do estudo foi classificar e mapear as terras favoráveis à utilização de máquinas e implementos agrícolas da Bacia Hidrográfica do Rio Pariquera-Açu, por meio de SIG. Foram utilizadas informações de textura, profundidade dos solos, uso da terra e declividade, classificados em graus de impedimento à mecanização agrícola (nulo, ligeiro, moderado e restrito). As Áreas de Preservação Permanente foram geradas, de acordo com o Código Florestal Brasileiro, e O definidas como áreas de restrição à mecanização agrícola, bem como uma unidade de conservação inserida na área de estudo (Parque Estadual de Proteção Integral da Campina do Encantado). A favorabilidade à mecanização foi avaliada com multicritério pelo método da combinação linear ponderada, sendo que 24,11% da área do estudo não possui impedimentos à mecanização e 17,5% possui impedimentos restrito ao manejo mecanizado. As técnicas de geoprocessamento foram eficientes na elaboração do mapa de favorabilidade à mecanização, sendo que a classe ligeira foi predominante quanto ao impedimento à mecanização em relação às demais classes: nula, moderada e restrita. Palavras-chaves: agricultura sustentável, geoprocessamento, mecanização agrícola. EVALUATION OF FAVORABILITY TO THE AGRICULTURAL MECHANIZATION OF WATERSHEDS BY GEOGRAPHICAL INFORMATION SYSTEM Development in the rural environment requires the adoption of techniques to achieve sustainable development. Therefore, the aim of the study was to classify and map the lands, favorable to the use of agricultural machines and implements of the Pariquera-Açu River Basin, through GIS. Information of soil texture, soil depth, land use and slope were used, classified in degrees of impediment to agricultural mechanization (null, mild, moderate and restricted). The Permanent Preservation Areas were generated, according to the Brazilian Forest Code, and defined as areas of restriction to agricultural mechanization, as well as a conservation unit inserted in the study area (State Park of Integral Protection of Campina do Encantado). Favorability to mechanization was assessed with multicriteria using the weighted linear combination method, with 24.11% of the study area having no mechanization impediments and 17.5% having impediments restricted to mechanized management. The geoprocessing techniques were efficient to elaborate the map of favorability to mechanization. Keywords: sustainable agriculture, geoprocessing, agricultural mechanization.

GEOPROCESSAMENTO APLICADO À IDENTIFICAÇÃO DE ÁREAS APTAS PARA IMPLANTAÇÃO DE PIVÔS CENTRAIS NO MUNICÍPIO DE ITATINGA/SP JOSÉ RENAN DA SILVA E SILVA1; RENATO AUGUSTO PAMPLONA PEREIRA2; DIEGO AUGUSTO DE CAMPOS MORAES 3 E LUIS GUSTAVO FREDIANI LESSA4 1Departamento de ciência florestal, solos e ambiente – FCA/UNESP. Brasil. jose.renan@unesp.br ORCID (https://orcid.org/0009-0004-7321-8550) 2Departamento de ciência florestal, solos e ambiente – FCA/UNESP. Brasil. rap.pereira@unesp.br ORCID (https://orcid.org/0000-0003-3944-2431) 3Departamento de ciência florestal, solos e ambiente – FCA/UNESP. Brasil. diego.c.moraes@unesp.br ORCID (https://orcid.org/0000-0001-9371-6179) 4Departamento de ciência florestal, solos e ambiente – FCA/UNESP. Brasil. gustavo.lessa@unesp.br ORCID (https://orcid.org/0000-0002-1940-844X) 1 RESUMO A acurácia na utilização dos recursos naturais desempenha um papel crucial na preservação da integridade do solo, da água, das plantas e, também, da atmosfera no contexto agrícola. Por isso, é imperativo adotar estratégias de planejamento que visem à eficiência máxima desses recursos. Com uma projeção significativa, espera-se que até 2040 a extensão de terras irrigadas por meio do pivô central alcance aproximadamente 4,2 milhões de hectares. As geotecnologias desempenham um papel de grande importância no cenário agrícola ao possibilitar o monitoramento da dinâmica temporal e espacial das propriedades rurais em todas as etapas da cadeia de produção. Então, objetivou-se avaliar as áreas que são aptas para receber sistemas de irrigação por pivô central no município de Itatinga/SP. Cerca de 52,5% do território do município de Itatinga/SP, que são agricultáveis, possui alta aptidão para a implantação de irrigação por pivô central. Se somarmos as áreas ótimas e boas, obtemos uma porcentagem de 93,8%. O método utilizado revelou eficácia na tomada de decisões e pelo custo acessível, uma vez que os dados foram adquiridos de forma gratuita por meio de plataformas digitais. Palavras-chave: SIG, Uso do solo, Mapeamento Temático, Manejo de águas, AHP. SILVA, J. R. S; PAMPLONA, R.A.P; MORAES, D. A. C; LESSA, L.G.F GEOPROCESSING APPLIED TO THE IDENTIFICATION OF AREAS SUITABLE FOR IMPLEMENTATION OF CENTER PIVOTS IN THE MUNICIPALITY OF ITATINGA/SP 2 ABSTRACT The accuracy of the use of natural resources plays a crucial role in preserving the integrity of soil, water, plants and the atmosphere in the agricultural context. Therefore, it is imperative to adopt planning strategies that aim to maximize the efficiency of these resources. With a significant projection, it is expected that by 2040, the extent of land irrigated through the central pivot will reach approximately 4.2 million hectares. Geotechnologies play a very important role in agricultural scenarios by enabling monitoring of the temporal and spatial dynamics of rural properties at all stages of the production chain. Therefore, the objective was to evaluate the areas that are suitable for receiving central pivot irrigation systems in the municipality of Itatinga/SP. Approximately 52.5% of the territory of the municipality of Itatinga/SP, which is arable, is highly suitable for implementing central pivot irrigation. If we add the optimal and good areas, we obtain a percentage of 93.8%. The method used proved to be effective in decision-making and affordable, since the data were acquired free of charge through digital platforms. Keywords: GIS, Use of the soil, Thematic Mapping, Water management, AHP.