Luiz Arnaldo Fernandes’s research while affiliated with Federal University of Minas Gerais and other places

Alkaline soils can limit micronutrient uptake and increase ammonia loss in irrigated pastures. To address this, nitrogen and sulphur fertilization are commonly used to reduce soil pH. This study assessed the impact of five treatments on BRS Paiaguás grass: Urea (UR), ammonium sulphate (SA), ammonium nitrate (NA), urea with elemental sulphur (URS), and a control with no nitrogen (SN). Nitrogen treatments received 250 kg ha⁻¹ of N in four applications, and sulphur treatments received 60 kg ha⁻¹ of elemental S. Agronomic characteristics—including plant height, tiller count, dry matter yield, and leaf nutrient content—were measured over four growing periods and analyzed using Tukey’s test at a 5% significance level. Ammonium nitrate produced the highest dry matter yield (3,607.5 kg ha⁻¹), while urea led in tiller density (887 tillers/m²). Ammonium sulphate was the most effective at lowering soil pH, reducing it by 0.28 units. No changes in available phosphorus were observed, though potassium levels declined by 42% across the seasons. The study highlights the potential of choosing appropriate nitrogen sources and incorporating elemental sulphur to improve pasture productivity and regulate soil pH, ultimately enhancing fertility management in irrigated systems.

The present study evaluated the granular properties of organomineral fertilizers produced from charcoal fines (biochar) and natural phosphate with three distinct binders: cassava wastewater (CW), pyroligneous extract (PE), and bio-oil (BO). The objective was to ascertain the potential of these fertilizers to increase common bean production. To form the granules, a 3:1 ratio of biochar to natural phosphate was employed, along with five binder doses (50, 75, 100, 125, and 150 % of the biochar-phosphate mixture weight). The granules were evaluated based on their crushing strength, water absorption ratio (WAR), granule density, impact resistance index (IRI), salinity index (SI), and pH. The most optimal granules were selected for the experiment with the common bean, using a completely randomized design in a 3 × 4 + 4 factorial scheme with three replications. The treatments comprised three binders (CW, PE, and BO), four binder doses (75, 100, 125, and 150 %), and four controls: unfertilized soil (NS), natural phosphate (NP), biochar mixed with natural phosphate (B + NP), and biochar (B). Compared to the CW or PE granules, the BO granules exhibited superior crushing resistance, density, and IRI, accompanied by a reduced WAR. The PE granules exhibited a higher SI and a lower pH. The application of CW, PE, or BO granules resulted in a significant increase in shoot dry matter (SDM), with values of 98.31, 123.73, and 47.46 %, respectively, compared to the NS. Similarly, root dry matter (RDM) notably increased, with values of 331.03, 755.17 and 141.38 %, respectively. The physicochemical properties of organomineral fertilizers are influenced by the type of binder used, affecting common bean production. Further research is needed to ascertain the long-term effects of these slow-release fertilizers. Keywords biochar; bio-oil; cassava wastewater; pyroligneous extract; waste recovery

Growth-promoting bacteria increase the productivity and resistance of agricultural crops, contributing to production stability and reducing the use of chemical inputs. In this sense, legumes of the genus Cicer stand out as an excellent source of food for humans, but their overall productivity can be considered low (1.22 t ha⁻¹). The main reason for this low productivity can be attributed to insufficient investment in cultural practices, such as fertilization and use of bioinputs. In this context, this literature review describes the diversity, physiology, genetics, and biotechnological applications of symbiotic and non-symbiotic diazotrophic bacteria associated with plants of the genus Cicer, highlighting advances and future perspectives. The use of symbiotic bacteria, particularly from the genera Bacillus and Rhizobium in chickpea increases biological nitrogen fixation and reduces dependence on chemical fertilizers. Productivity can be increased when using some inoculant, especially if it was removed from the chickpea growing environment. Areas with high organic matter content are an important factor for biological fixation or plant growth promotion to occur. The integration of technological innovation and sustainable agricultural practices promises to transform the production of this legume, benefiting both farmers and the environment.

The present study evaluated the granular properties of organomineral fertilizers produced from charcoal fines (biochar) and natural phosphate with three distinct binders: cassava wastewater (CW), pyroligneous extract (PE), and bio-oil (BO). The objective was to ascertain the potential of these fertilizers to increase common bean production. To form the granules, a 3:1 ratio of biochar to natural phosphate was employed, along with five binder doses (50, 75, 100, 125, and 150 % of the biochar-phosphate mixture weight). The granules were evaluated based on their crushing strength, water absorption ratio (WAR), granule density, impact resistance index (IRI), salinity index (SI), and pH. The most optimal granules were selected for the experiment with the common bean, using a completely randomized design in a 3 × 4 + 4 factorial scheme with three replications. The treatments comprised three binders (CW, PE, and BO), four binder doses (75, 100, 125, and 150 %), and four controls: unfertilized soil (NS), natural phosphate (NP), biochar mixed with natural phosphate (B + NP), and biochar (B). Compared to the CW or PE granules, the BO granules exhibited superior crushing resistance, density, and IRI, accompanied by a reduced WAR. The PE granules exhibited a higher SI and a lower pH. The application of CW, PE, or BO granules resulted in a significant increase in shoot dry matter (SDM), with values of 98.31, 123.73, and 47.46 %, respectively, compared to the NS. Similarly, root dry matter (RDM) notably increased, with values of 331.03, 755.17 and 141.38 %, respectively. The physicochemical properties of organomineral fertilizers are influenced by the type of binder used, affecting common bean production. Further research is needed to ascertain the long-term effects of these slow-release fertilizers.

O emprego do lodo de esgoto (LE) doméstico como fertilizante orgânico é uma opção para melhoria das propriedades físicas do solo. No entanto, a aplicação desse resíduo pode proporcionar efeitos positivos, insignificantes ou negativos nestes atributos, sendo necessária a investigação em diferentes condições experimentais. Assim, visou-se com esse trabalho avaliar o efeito do LE associado a fertilizantes minerais nos atributos físicos do Cambissolo Hálpico. O experimento foi conduzido em casa de vegetação utilizando-se seis tratamentos que envolveram a adubação a base de lodo de esgoto associado com cloreto de potássio e/ou calcário dolomítico e tratamento apenas com fertilizante mineral (NPK+C). Os atributos estudados foram: pH em água, matéria orgânica (MO) do solo, argila dispersa em água (ADA), argila dispersa (AD), grau de floculação (GF) e grau de dispersão (GD) de argilas, diâmetro médio ponderado (DMP) e diâmetro médio geométrico (DMG). O pH do solo foi menor nos tratamentos a base de lodo de esgoto, mesmo com a calagem. Enquanto o teor de MO foi menor no tratamento com NPK+C. O tratamento com adubação mineral apresentou os maiores valores de argila dispersa em água (ADA) e grau de dispersão de argilas (GD), consequentemente menor valor de grau de floculação (GF) em relação aos tratamentos adubados com lodo de esgoto e testemunha, que não diferiram entre si. Não houve diferença para estabilidade dos agregados via úmida e seca entre os tratamentos.

A utilização da biomassa lignocelulósica proveniente de resíduos domésticos tem se tornado uma escolha favorável na produção de bioenergia. No estado de Minas Gerais, a cadeia produtiva do pequi (Caryocar brasiliense Camb.) desempenha importante papel econômico e social. No entanto, a comercialização em grande escala desse produto pode gerar resíduos que, se não forem adequadamente gerenciados, representam um desafio ambiental significativo. Neste trabalho, foi avaliado o potencial energético da biomassa da casca de pequi para confecção de briquetes em diferentes proporções de umidade. Foram avaliadas propriedades físicas, mecânicas e térmicas da biomassa in natura em estudo. A caracterização imediata da biomassa revelou um alto teor de material volátil (74,41%), de carbono fixo (22,69%) e cinzas (2,90%), além de um poder calorífico de 14,23 MJ kg-1, mostrando a eficácia do material para produção de energia. A análise química evidenciou 69,38% de extrativos, 10,27% de lignina e 20,35 % de holocelulose. A análise termogravimétrica da casca se mostrou similar com a termo decomposição de biomassas lignocelulósicas. A confecção dos briquetes foi realizada em uma prensa hidráulica em diferentes proporções de umidade (5%, 7,5% e 10%). Os testes de resistência à compressão mostraram que briquetes com menor umidade possuem maior resistência. Os resultados deste estudo sugerem que a densificação da casca de pequi não apenas reduz significativamente o volume dos resíduos, como também resulta em uma diminuição de aproximadamente 90,42% do peso total, facilitando seu manejo e armazenamento, mas também oferece uma solução sustentável para a produção de bioenergia.

There are few long-term field studies on the effects of biochar on soil microbial abundance and diversity. This study aimed to evaluate doses of biochar in combination with mineral fertilizer on the activity and diversity of microorganisms in the soil of a sugarcane field. The experiment was carried out in a randomized block design, factorial 5 × 2, with four replications: five doses of eucalyptus (Eucalyptus grandis Hill ex Maiden × Eucalyptus urophylla S.T. Blake) wood biochar (0, 10, 20, 30, and 40 Mg ha⁻¹), with and without the application of nitrogen, phosphorus, and potassium (NPK) mineral fertilizer. Soil samples were collected from the sugarcane planting line and fertilized with biochar for two consecutive years. Regardless of the NPK fertilizer, over the two years of evaluation, the height growth of sugarcane plants and total organic carbon (TOC) increased linearly with biochar doses. For microbial biomass carbon (Cmic), soil basal respiration (SBR), metabolic quotient (qCO2), microbial quotient (qMIC), and Shannon diversity index (H), the highest values were obtained where fertility correction (WFC) treatments were applied, regardless of the year of evaluation, in biochar doses between 20 and 30 Mg ha⁻¹. On the other hand, the highest CO2 efflux values were obtained with zero doses of biochar, regardless of the NPK fertilizer applied, over the two years of evaluation. Therefore, the incorporation of biochar and NPK fertilizer into the soil contributes to increasing the soil's biological activity indicators and, consequently, the growth of sugarcane plants. It is essential to highlight the need for continuous assessments as the characteristics of biochar change over time. Keywords: microbial biomass carbon; soil basal respiration; total organic carbon; metabolic quotient; microbial quotient

Biochar can promote crop production and soil quality. However, its characteristics depend on the waste used in its production and its effects may vary according to the species being cultivated and the management adopted. The aim of this study was to evaluate the application of biochar from animal waste on soil quality and the agronomic characteristics of the cowpea. An experiment was set up to test three types of biochar (bovine-BB, swine-SB and poultry-BP), with added fertiliser (BBF, SBF and BPF) and two control treatments, including the addition of calcium magnesium oxide (CT) and calcium magnesium oxide with fertiliser (CTF), giving a total of eight treatments with four replications. There was a respective increase of up to 102.94%, 1048%, 1560% and 360.22% in stem diameter, number of pods, number of grains per pod and stem dry matter from adding the biochar. The poultry biochar increased each of the above parameters even with no added fertiliser. There was no difference in basal soil respiration or β-glucosidase enzyme activity, whereas organic carbon (TOC), total nitrogen (TN), microbial carbon and soil labile carbon were greater with biochar. BBF gave the highest TOC content (24.40 g kg⁻¹), while BP and BPF increased TN by around 61%. The application of biochar + fertiliser contributed to an average reduction of 56% in the soil metabolic quotient. Poultry biochar favoured both the agronomic characteristics of the cowpea and soil quality, while bovine biochar showed more marked results with the addition of fertiliser. Key words Carbon; Plant growth; Soil conditioner; Nitrogen; Vigna unguiculata.

The use of biochar in agriculture remains controversial due to the amounts applied and the small size of the particles which can cause respiratory problems when inhaled. With the aim of evaluating the effects of cattle manure biochar (CMB) on the chemical attributes of the soil and on plant growth and nutrition, a greenhouse experiment was conducted, with Urochloa brizantha ‘BRS Paiaguás’ grown in pots over five crop cycles, in weathered soil (Oxisol). CMB pellets, both enriched and not enriched with potassium phosphate (PK), were produced using cassava starch as the binder, in a ratio of 2:2:1 (biochar: PK fertiliser: binder) and 4:1 (biochar: binder), respectively. The CMB was produced at a pyrolysis temperature of 450 °C. The experimental design was completely randomised in a 2 x 2 x 2 + 1 factorial scheme, with five replications. The treatments were non-pelletised and pelletised CMB, with and without liming, and with and without PK, and an additional treatment with no fertiliser. The CMB improved the chemical properties of the soil, correcting acidity, increasing nutrient availability and improving the production of Urochloa brizantha ‘BRS Paiaguás’. The use of CMB enriched with phosphorus and potassium behaved as a slow-release organomineral fertiliser in Urochloa brizantha ‘BRS Paiaguás’. Key words Organomineral; Slow-release fertiliser; Use of waste; Pyrolysis

The inoculation of rhizobacteria such as Bacillus sp. together with balanced fertilization favor nutrient uptake and growth of cultivated legumes. In this sense, the objective was to evaluate the inoculation with a mix of Bacillus spp. and the application of doses of N on the growth and accumulation of nutrients in chickpea. The study was carried out in a randomized block design with four repetitions in a 2 x 6 factorial arrangement. The first factor consisted in the presence or absence of the Bacillus spp. mix (concentration of 1 x 107 CFU per mL) of root isolates and the second factor consisted in six doses of N: 0, 25, 50, 75, 100, and 125 kg ha-1, applied thirty days after plant emergence. At 75 days after emergence, the plants had the following decreasing order of nutrient accumulation in the aerial part (in kg ha-1): N (109.71) > K (68.94) > Ca (25.28) > Mg (10.17) > P (4.98) > Na (2.23). Inoculation with the Bacillus spp. mix increased rhizobia nodulation in the roots, K, Ca, and Na uptake, and chickpea growth as assessed by leaf, stem, root, and total dry mass. The application of different doses of N increased total and aerial dry mass, reduced Na accumulation and increased N uptake, and the application of 37 kg ha-1 of N is recommended to obtain greater aerial biomass in chickpea crops, combined with the inoculation of seeds with a mix of Bacillus spp.