Felipe Vaz Andrade

Dry-Matter Production and Phosphorus Accumulation by Maize Plants in Response to the Addition of Organic Acids in Oxisols

Abstract Organic acids (OA) play an important role in phosphorus (P) availability in soils. They can be adsorbed with great energy by the soil mineral fraction, reducing P adsorption and increasing P availability to plants. The aim of this study was to evaluate the effect of different sources (acetic acid, AA; citric acid, CA; and humic acids, HA) and doses of OA on P uptake and dry‐matter production by corn plants grown in highly weathered soils. Samples (2 dm3) of a clayey Red Latosol, RL (Rhodic Haplustox), and a sandy loam Red Yellow Latosol, RYL (Typic Haplustox), were accommodated in plastic pots located in a greenhouse. Phosphorus (K2HPO4) and/orOA were applied at different timings: organic acid added before (OABP) or simultaneously (OASP) to the phosphate application. The OA doses ranged from 0.0 to 8.0 mmol L−1. The doses of humic acids ranged from 0.0 to 12 g dm−3 and were equivalent to an organic compost addition of 0 to 80 t ha−1. The addition of OA influenced dry‐matter production and P uptake by corn plants in both soils. The effectiveness of OA in increasing P uptake and dry‐matter production of corn plants followed the order humic acids>citric acid>acetic acid. In both soils, the greatest dry‐matter production and P uptake were obtained when OA were applied to the soil before P was added (OABP).

Organic acid adsorption and mineralization in oxisols with different textures

SUMMARY Organic acids play an important role in the nutritional conditions of plants. Their relevance is related to their formation dynamics, mineralization rate and adsorption by soil colloids. This study was carried out to evaluate the dynamics of mineralization and adsorption of organic acid (acetic acid - AA, citric acid - CA and humic acid - HA) applied to the soil. Samples of two Oxisols were used: Rhodic Haplustox (LV) and Typic Haplustox (LVA). The mineralization experiment was arranged in a 2 x 3 x 5 factorial design, based on the factors: two soils (LV and LVA) x three organic acid (OA) types (AA, CA and HA) x five OA rates (0, 1, 2, 4, and 8 mmol dm -3 ). Organic carbon mineralization in samples was measured by the C-CO2 efflux, produced by the microbial activity, in a 30-day (measurements after 4, 8, 12, 21, and 30 days) and in a 4-day experiment (measured after 24, 48, 72 and 96 h). Organic acid adsorption was tested in a 2 x 2 x 5 x 4 factorial design, with the factors and levels: two Oxisols; two organic acids (AA and CA); five OA rates (0, 1, 2, 4, and 8 mmol dm -3 ) and four adsorption periods (6, 24, 48, and 72 h). The C-CO2 production of soil treated with CA was highest. In the adsorption experiment, the affinity of CA to soil adsorption sites was greatest. The adsorption of organic acids to soils may be an important mechanism by which bioavailability and thus mineralization capacity by microbial activity are reduced.

Soil aggregation and organic carbon of Oxisols under coffee in agroforestry systems

Intensive land use can lead to a loss of soil physical quality with negative impacts on soil aggregates, resistance to root penetration, porosity, and bulk density. Organic and agroforestry management systems can represent sustainable, well-balanced alternatives in the agroecosystem for promoting a greater input of organic matter than the conventional system. Based on the hypothesis that an increased input of organic matter improves soil physical quality, this study aimed to evaluate the impact of coffee production systems on soil physical properties in two Red-Yellow Oxisols (Latossolos Vermelho-Amarelos) in the region of Caparao, Espirito Santo, Brazil. On Farm 1, we evaluated the following systems: primary forest (Pf1), organic coffee (Org1) and conventional coffee (Con1). On Farm 2, we evaluated: secondary forest (Sf2), organic coffee intercropped with inga (Org/In2), organic coffee intercropped with leucaena and inga (Org/In/Le2), organic coffee intercropped with cedar (Org/Ced2) and unshaded conventional coffee (Con2). Soil samples were collected under the tree canopy from the 0-10, 10-20 and 20-40 cm soil layers. Under organic and agroforestry coffee management, soil aggregation was higher than under conventional coffee. In the agroforestry system, the degree of soil flocculation was 24 % higher, soil moisture was 80 % higher, and soil resistance to penetration was lower than in soil under conventional coffee management. The macroaggregates in the organic systems, Org/In2, Org/In/Le2, and Org/Ced2 contained, on average, 29.1, 40.1 and 34.7 g kg-1 organic carbon, respectively. These levels are higher than those found in the unshaded conventional system (Con2), with 20.2 g kg-1.

Pedogênese e classificação de latossolos desenvolvidos de itabiritos no Quadrilátero Ferrífero, MG

Localizado na porcao centro-oeste do Estado de Minas Gerais, o Quadrilatero Ferrifero abrange uma area de aproximadamente 7.000 km2. Desde o seculo XVII, a regiao e conhecida como uma provincia aurifera e ferrifera, sendo por essa razao uma das regioes mais bem estudadas do Brasil no contexto geologico. A regiao e de topografia muito acidentada, onde predominam solos pouco evoluidos pedogeneticamente, com destaque para Cambissolos Haplicos, Neossolos Litolicos e Neossolos Regoliticos. Em menor proporcao e em rampas de coluvio (relevo suave ondulado), ocorrem Latossolos Vermelhos muito ricos em Fe, anteriormente denominados Latossolos Ferriferos. Neste trabalho, foram realizados estudos para caracterizar fisica, quimica e mineralogicamente amostras de nove perfis de Latossolos Vermelhos ferricos e perferricos, desenvolvidos de itabirito e rochas afins no Quadrilatero Ferrifero, com os objetivos de melhor entender sua genese e avaliar criterios taxonomicos que permitam sua diferenciacao no SiBCS, em niveis categoricos mais baixos. Os elevados valores de densidade de particulas sao peculiares nesses solos e, ao lado da estrutura forte, muito pequena e granular, sao fatores que contribuem para subestimar os teores de argila e superestimar os de silte, resultando em relacao silte/argila maior do que aquela proposta pelo SiBCS para os Latossolos. A variacao dos teores de SiO2, Fe2O3, Al2O3, TiO2, MnO, P2O5 e de alguns elementos-traco aponta para a diversidade na composicao quimica do itabirito ou, ainda, provavel mistura com rochas filiticas da regiao. Os valores das relacoes Fe2O3/TiO2 (nao molecular) e TiO2/Fe2O3 (molecular) revelaram-se diferentes daqueles sugeridos na literatura para separacao de Latossolos Vermelhos desenvolvidos de itabirito daqueles de rochas maficas. As fracoes areia, silte e argila apresentaram grande variacao na atracao magnetica, com as duas primeiras fracoes evidenciando maior magnetizacao, em razao da presenca de magnetita. Os valores de substituicao isomorfica de Fe por Al variaram 0,07 a 0,11 e 0,09 a 0,38 mol mol-1 nas estruturas da hematita e magnetita, respectivamente.

Influência da aplicação de dois resíduos industriais nas propriedades químicas de dois solos cultivados com café arábica

The large amount of industrial waste which currently causes serious environmental problems has demonstrated the need for the appropriate use of those materials which not only reduce environmental impact but have shown potential for agricultural use. The aim of this study was to evaluate the chemical effects of different amounts of slag and magnesium oxide on two soils planted with coffea arabica. The study was carried out using pots of 10 dm3 in a greenhouse at the Center for Agrarian Sciences of the Federal University of Espirito Santo. The experimental design was of randomized blocks with a factorial distribution of 2 x 3 x 6, and three replications, the factors being: two soils (dystrophic red-yellow clay loam and dystrophic red-yellow medium-texture loam), three additives (limestone as control and slag and magnesium oxide as waste), six amounts of corrective materials (0; 25; 50; 75; 100 and 125% of the required liming). After 180 days of culture, analysis of pH, H+ + Al3+, Al3+, Ca2+ e Mg2+ was carried out. The results showed that applications of increasing doses of magnesium oxide and slag, up to the limit of this study, further a decrease in soil acidity. Magnesium oxide has shown the greatest potential for soil-acidity correction and also as a source of magnesium for the soil.

Soil surface roughness under tillage practices and its consequences for water and sediment losses

The present study aims to determine the effects of soil management practices on soil surface roughness and the consequences of these phenomena on water and sediment losses. Laboratory experiment was conducted on a Chernozems clayey soil subjected to a sequence of two 30 min simulated rainfall of 50.8 mm h-1 and 114.3 mm h-1 and four soil management practices: contour tillage (CT), downhill tillage (DT), no-tillage simulated (NTs) and bare soil (BS). Soil surface roughness was evaluated using a laser distance meter. Results showed that the soil tillage in downhill or contour increased soil roughness by 2.90 and 2.76, respectively, reducing the water losses under low rain intensity by 12.8% and 6.4%. Soil surface roughness quickly changed after the onset of rain, and higher values of changes in soil roughness were observed for contour (22.73%) and downhill tillage (21.05%) managements. Soil coverage factor and the direction of tillage were the most important characteristics in contrast with soil surface roughness to reduce the sediment losses. No-tillage simulated (0.59 tha-1) and contour tillage (1.30 t ha-1) were the soil management practices with lower sediment losses compared to other managements studied. The principal theoretical implication of this study is that land use planning with agriculture, livestock must be designed to prevent the soil from being exposed, or if exposed, tillage in contour should be adopted. The input of litter on soil surface had an important role in reducing the sediment and water losses.

Antropossolos em sítios arqueológicos de ambiente cárstico no norte de Minas Gerais

The occupation and territorial dispersion of the first settlers in South America, especially in Brazil, are still little known and require continuous interdisciplinary studies involving anthropology, archeology, and soil science. Under natural limestone shelters, pre-Columbian populations lived for thousands of years, introducing and removing materials of different nature and from different origins, resulting in the development of very peculiar anthropogenic soils, which have been little investigated so far. To deepen the knowledge on this type of soil, we evaluated the physical, chemical and mineralogical properties of the soil of two limestone shelters, Lapa do Boquete and do Malhador, located in the National Park Cavernas do Peruacu, in northern Minas Gerais, which is considered one of the most important archaeological regions of the country. The samples were subjected to the physical, chemical and mineralogical analyses, total attack, total organic carbon, and fractionation of inorganic P forms. The chemical properties of these soils are consistent with the calcareous nature of the local rock, with high pH values (> 7.7). The cation exchange complex consists almost entirely of exchangeable bases, especially Ca and Mg, reaching V valuesof 100 %. High P contents (131-749 mg dm-3) were also extracted (Mehlich-1). The predominant soil fraction was sand, with a loamy texture in all layers. The presence of oxides with magnetic attraction in all fractions is noteworthy, especially in the sand fraction, mainly associated with the carbonized layers. The soil matrix is made predominantly by 1:1 silicate minerals (kaolinite) associated with 2:1 minerals, mainly illite. According to the results, soil genesis is polycyclic, marked by pronounced climate changes, and associated with distinct periods of human occupation, resulting in the formation of pedogenetic layers that seem unrelated with each other.

Propriedades físicas do solo em função de manejos em lavouras de cafeeiro conilon

Physical soil properties as a function of management in crops of conilon coffee Agricultural soils are subject to change in their properties, according to the type of use and management systems adopted. The objective of this study was to evaluate, in different sampling sites, the physical properties of soils cultivated with conilon coffee under different managements in the South of Espirito Santo State, Brazil. Samples were collected from the layers 0,00-0,20 m and 0,20-0,40 m in the upper part of the coffee plant canopy, in relation to the direction of the slope. Coffee crops, representative of the South of the Espirito Santo State, with the same soil class (dystrophic Red Yellow Latosol (Oxisol) hilly relief), were used for the study ,including the following managements: M1 – drip irrigation, liming every two years, fertilization, cleared and use of the straw of conilon; M2 - manuring, cleared and weedings; M3 - weedings and mowing. For each management, the following sampling sites were evaluated: UT upper third, MT - medium third; LT - lower third, along the slope. The physical soil properties evaluated were: bulk density, total porosity, macroporosity, microporosity and soil resistance penetration. For the experimental conditions, the soil resistance penetration, the macroporosity and microporosity important physical indicators of the quality of the soil were shown, influenced by the management, sampling site and evaluation depth.

Soil, water, and nutrient losses from management alternatives for degraded pasture in Brazilian Atlantic Rainforest biome

The objective of this study was to evaluate sediment, water and nutrient losses from different pasture managements in the Atlantic Rainforest biome. A field study was carried out in Alegre Espiríto Santo, Brazil, on a Xanthic Ferralsol cultivated with braquiaria (Brachiaria brizantha). The six pasture managements studied were: control (CON), chisel (CHI), fertilizer (FER), burned (BUR), plowing and harrowing (PH), and integrated crop-livestock (iCL). Runoff and sediment samples were collected and analyzed for calcium (Ca), magnesium (Mg), potassium (K), phosphorus (P) and organic carbon contents. Soil physical attributes and above and below biomass were also evaluated. The results indicated that higher water loss was observed for iCL (129.90mm) and CON (123.25mm) managements, and the sediment losses were higher for CON (10.24tha-1) and BUR (5.20tha-1) managements when compared to the other managements. Majority of the nutrients losses occurred in dissolved fraction (99% of Ca, 99% of Mg, 96% of K, and 65% of P), whereas a significant fraction of organic carbon (80%) loss occurred in a particulate form. Except for P, other nutrients (Ca, Mg and K) and organic carbon losses were higher in coarse sediment compared to fine sediment. The greater losses of sediment, organic carbon, and nutrients were observed for CON followed by BUR management (p<0.05). Our findings indicated that the traditional pasture management adopted in the Atlantic Rainforest needs to be rethought and burned management should be avoided. Based on the water, soil, and nutrient losses from various practices, to reduce pasture degradation, farmers should adopt edaphic practices by applying lime and fertilize to improve pasture growth and soil cover, and reducing soil erosion in the hilly Brazilian Atlantic Rainforest biome.

Organic Acids and Diffusive Flux of Organic and Inorganic Phosphorus in Sandy-Loam and Clayey Latosols

This study evaluated the effects of organic acids on the diffusive flux of phosphorus (DFP) along time. Treatments were a factorial 2 × 2 × 2 × 2 × 5 design: two soils (clayey Red Latosol and a sandy-loam Red-Yellow Latosol), two organic acids (citric acid, CA, and humic acid, HA), and two phosphorus (P) sources [monopotassium phosphate (KH2PO4) and inositol hexaphosphate (IHP)] either with or without heating (100 °C) of the soil. The soil plus treatments, in all combinations, were placed in contact with an anion exchange resin and the P in the resin was measured after 2, 4, 6, 10, and 15 days. The DFP was greater when the soils were treated with CA than when treated with HA. Citric acid was more effective in increasing the DFP from KH2PO4, whereas HA was the organic ligand that promoted a larger DFP when the source was IHP.