Elemental sulfur recommendation for pH reduction in soils from Southern Brazil

ABSTRACT The elemental sulfur (S0) application may reduce soil pH, benefiting plants adapted to acid conditions and lessening problems of overliming. Nevertheless, there is no official recommendation for its application. The objective of the study was to quantify the S0 doses required to reduce the pH of soils from Southern Brazil. The experiment was carried out in the laboratory in a factorial scheme (5 × 5), with a completely randomized design and three replicates. The treatments consisted of five soils, and five doses of S0, corresponding to 0, 50, 100, 150, and 200% of the estimated dose need to reach pH 4.0. The applied doses of S0 resulted in reduction of pH and base saturation (V%) and increase of potential acidity (H + Al). These effects, however, were reduced due to the low rate of oxidation of the S0 applied (0.76-3.36%). The soil variables correlated with S0 oxidation were Mg2+ (0.86***), Al3+ (-0.82***), H + Al (-0.89***), V% (0.68***) and aluminum saturation (m%) (-0.87***). In the evaluated soils the oxidation of 50 kg ha-1 of S0 was required to reduce one unit of pH in H2O.

VARIABILIDADE ESPACIAL E CORRELAÇÃO DOS ATRIBUTOS DO SOLO COM PRODUTIVIDADE DO MILHO E DA SOJA

O emprego de técnicas de agricultura de precisão, associadas a análises geoestatísticas, possibilita mapear a variabilidade espacial existente em um campo de produção. O conhecimento da variabilidade é importante ferramenta na tomada de decisões quanto ao manejo da área, uma vez que possibilita que este seja realizado de forma localizada. O estudo foi realizado em um talhão da Fazenda Planalto, localizada no município de Maracaju – MS, com o objetivo de avaliar a variabilidade espacial e correlação entre os atributos químicos e granulométricos do solo e a produtividade do milho e da soja. Foi utilizada uma grade amostral contendo 187 pontos, utilizando-se 10 amostras simples de solo por ponto amostral. Não foi detectado dependência espacial para o cálcio, alumínio, acidez potencial, soma de bases, ferro e zinco. As melhores estimativas em locais não amostrados foram obtidos para a areia e argila. A produtividade da soja apresentou forte dependência espacial e se correlacionou positivamente de forma forte com o fósforo e moderada com o magnésio. Palavras-chave: Latossolo; dependência espacial; Glycine max; Zea mays. Spatial variability and correlation of chemicals and physical soil attributes with corn and soybean yield ABSTRACT: The use of precision farming techniques, associated with geostatistical analysis, makes it possible to map the spatial variability in a production field. The knowledge of variability is an important tool in decision making regarding the management of the area, since it allows it to be carried out in a localized manner. The study was carried out in a plot of Fazenda Planalto, located in the municipality of Maracaju - MS, with the objective of evaluating the spatial variability and correlation between the chemical and granulometric attributes of the soil and the corn and soybeans yield. A sampling grid containing 187 points was used, using 10 simple soil samples per sample point. No spatial dependence was detected for calcium, aluminum, potential acidity, sum of bases, iron and zinc. The best estimates in unsampled locations were obtained for sand and clay. The soybeans yield showed strong spatial dependence and was positively correlated strongly with phosphorus and moderately with magnesium. Keywords: Oxisol; spatial dependence; Glycine max; Zea mays.

Identification of the Potential of Acid Rock Drainage in the Tin Mine on Bangka Island

Bangka Belitung is one of the tin-producing areas in the world which is characterized by the large number of granite rocks in the area as the rock carrying cassiterite minerals. Granite rocks found on Bangka Island are rocks formed due to magma activity from acidic volcanic processes. The availability of acidic water is possible due to the presence of acid-carrying minerals from granite which causes acid rock drainage or acid rock water which generally occurs in mining areas, ex-mining and exploration in tin mines. Before making efforts to prevent environmental pollution, identification is needed regarding the potential acidity of the rock so that the pH and dissolved metal content that endangers survival can be prevented to a minimum.

Forest plantation productivity – soil interactions within Western Forest-Steppe of Ukraine: effects of pH and cations

Dark grey podzolized soils on the loess like loams, which are represented in the soil cover within fresh and humidity gradients in the Western Forest Steppe of Ukraine, are characterized by high forest vegetation potential, which ensure the formation of mostly pure and mixed larch and spruce stands with high level of the productivity. Despite the fact that both species are coniferous, their effect on the soil, in particular, on its acid-base indicators (actual and potential forms of acidity, sum of absorbed bases, degree of saturation of bases, content of mobile aluminium), which are important components of soil fertility, are specific. Due to the fact that there is a close interaction between forest plantations and soil properties, changing the participation of species in the stand, it is possible to adjust the actual soil fertility.The soils under both pure and mixed spruce and larch stands are characterized by a high level of potential acidity that reaches the high acidic values in the upper horizons. A similar reaction of soil solution under coniferous forests is caused by acid hydrolysis of aluminosilicates and accumulation of mobile Al in the rhizosphere zone. Simultaneously, the same acidic characteristics, including the presence of movable aluminium, are also found in soils under broadleaved plantations. In general, acid-exchange properties of soils (high potential acidity, unsaturation of bases and availability of movable aluminium) traditionally are considered as unfavourable for vegetation. However, our researches refute it and prove that within certain values, these indicators do not limit the productivity of pure and mixed spruce and larch stands.

Rock powder and organic fertilization in soil cultivated with black bean

The use of rock powder as a source of nutrients to plants can be an alternative or complement to mineral soluble and organic sources. Thus, the aim of this study was to evaluate the potential of different rock powder doses, associated or not with livestock manure, as a source of nutrients for bean and its effect on soil chemical attributes. The treatments consisted of the application of 0, 3, 6, 9 and 12 Mg ha-1 of rock powder, associated or not with livestock manure (17 Mg ha-1), applied on the soil surface, without incorporation. The experiment was carried out in completely randomized blocks, with three replicates, and in a factorial arrangement (5x2). The grain yield of bean, height plants and number of plants m-2 were not influenced by the treatments. On the other hand, the application of 3 Mg ha-1 of rock powder associated with livestock manure resulted in a higher number of grains per pod, and the increase in the rock powder doses affected the number of pods per plant. In the soil, only the manure application, regardless of the rock powder, resulted in effects: reduced potential acidity and potential cation exchange capacity, and increased phosphorus content and base saturation. Thus, rock powder, associated or not with livestock manure, is not effective in improving bean yield and soil chemical attributes after approximately three months of application, and the use of livestock manure, regardless of the rock powder doses, improves some chemical attributes in the soil.

‘Gigante’ cactus pear cultivated at different population densities in a mechanizable arrangement

ABSTRACT Cactus pear is a crop adapted to the climatic conditions of the Brazilian semiarid region, so it has contributed to the socioeconomic development of this region. The objective of this study was to evaluate the response of ‘Gigante’ cactus pear cultivated at different population densities in a mechanizable arrangement. The experimental design was in randomized blocks, with six population densities: 22,857; 34,286; 51,428; 62,857; 80,000 and 95,000 plants ha-1 and four repetitions. The following variables were evaluated: plant height, number of cladodes, cladode length, cladode width and cladode area index, green and dry matter yields, extraction/export of nutrients and soil chemical characteristics. Increase in population density in a mechanizable arrangement decreases the number of cladodes and increases the cladode area index. The maximum green and dry matter yield of cactus pear cultivated in arrangement that allows mechanization is expected with populations of 69,111.79 and 64,445.91 plants ha-1, respectively. Maximum values of extraction/export of nutrients in cactus pear tissue are expected at intermediate population densities (62,721.52-74,741.93 plants ha-1). Soil potential acidity has maximum value with 64,525.51 plants ha-1.

Chemical attributes of soil in agroforestry systems is conditioned by the management system adopted

The aim of this study was to evaluate the influence of vegetation management on soil chemical attributes during the implementation of an agroforestry system in Pará, Brazil. Three treatments were evaluated - T1 Control (secondary vegetation - SF), T2 - Fire management system (FMS) and T3 - Management system without vegetation burning (MSWB). Soil samples were collected at 30 cm deep to analyze chemical attributes. The data were analyzed using Analysis of Variance - ANOVA, and the t-test. Treatment T2 caused the most changes in soil chemical attributes on the first analysis showing increased pH, increased levels of N, P, K, Ca, Sum of bases, CEC and percentage of base saturation, and decreased potential acidity of Al in the short term. However, in the second evaluations 48 months later, there was an inversion, in which a reduction of pH, the contents of N, P, K, Ca, Sum of bases and percentage of base saturation, as well as increased potential acidity and of the contents of Al of the soil were observed. For treatments T1 and T3, there were no substantial soil attributes changes during the first and second evaluations. Thus, soil chemical attributes were altered according to the type of management of secondary vegetation and evaluation period during the implementation of Agroforestry Systems.

Bacterial strains decrease solubility of potassium in the soil

Current study verifies whether inoculation with strains of diazotrophic bacteria, with proven ability to solubilize potassium (K) in vitro, contributes towards the release of K in the soil after fertilization with phonolite rock powder. The experiment was conducted in containers with 0.3 dm-3 of soil containing low potassium content. Fifteen treatments were used, namely, 12 inoculated with the bacterial strains, a control treatment (without phonolite and without inoculation), one containing phonolite without inoculation and one containing KCl, soluble fertilizer, without inoculation. In treatments with phonolite and KCl, the doses of these materials were applied to provide the soil with 195 mg dm-3 of K. A completely randomized design with four replications was used. The soil was incubated during 90 days at room temperature and humidity at about 70% retention capacity. After this period, the content of K+ (Mehlich and resin), pH value and potential acidity (H+Al) were evaluated. Phonolite, associated with inoculation with most bacterial strains, increased the availability of potassium in the soil, pH rate and reduced potential acidity. Among the strains tested, UNIFENAS 100-01, UNIFENAS 100-16, UNIFENAS 100-27, UNIFENAS 100-39 and UNIFENAS 100-93 were the most efficient for the solubilization of K+ of the phonolite. In spite of the observed results, K content released by the bacterial strains in the soil decreased when compared to in vitro conditions, thus justifying the need for studies on bio-solubilization of soil to select the most efficient strains in the process.