ABSTRACT This research aimed to evaluate the changes in the soil chemical attributes and their effects on the agronomic attributes of corn, after conversion from conventional tillage (PC) to no-tillage (SD), in a Inceptisol soil (Cambissolo Húmico alumínico léptico). In an experiment where PC and SD effects had been studied for 20 yr, main plots under PC were converted to SD and referred to as implemented SD (SDi) while plots under SD remained unaltered and were referred to as consolidated NT (SDc). The pH in water, exchangeable aluminum, potassium, calcium, and magnesium, extractable phosphorus, and total organic carbon (COT), were determined at the beginning of the experiment and after a 30-month period. The agronomic attributes of corn grown under SDi and SDc were also evaluated. At the end of the experiment, plots under SDi evidenced an increase in exchangeable aluminum and potassium and COT, and a decrease in pH and exchangeable calcium. Corn biomass accumulation in shoots and roots increased and higher grain yields were observed under SDc compared to SDi.

RESUMO Com a pesquisa objetivou-se avaliar as modificações nos atributos químicos do solo e o efeito disso no desempenho dos atributos agronômicos do milho, após converter o manejo conduzido como preparo convencional para a forma de semeadura direta, em um Cambissolo Húmico alumínico léptico. A pesquisa foi conduzida em um experimento onde o preparo convencional (PC) e a semeadura direta (SD) vinham sendo estudados há 20. Após a conversão de manejo, a SD foi mantida e denominada semeadura direta consolidada (SDc) e o PC foi convertido à SD a qual foi denominada semeadura direta implantada (SDi). Determinou-se pH em água, alumínio, potássio, cálcio e magnésio trocável, fósforo extraível e carbono orgânico total (COT), antes e ao final de 30 meses da conversão de manejo. Ao final da pesquisa avaliouse também os atributos agronômicos do milho cultivado na SDi e SDc. Ao final da pesquisa, a SDi propiciou aumento do alumínio e potássio trocável e do COT, e diminuição do pH e do Ca, em comparação ao início da pesquisa. Maior massa da parte aérea e raízes e produtividade de grãos de milho foi observada na SDc em comparação a SDi.

ABSTRACT Inadequate management of pasture soils in the Amazon has resulted in a predominance of degraded pastures. Considering the natural characteristics of this region can favor more appropriate strategies for sustainability, the objective of this study was to evaluate the differences in the chemical and physical attributes of pasture and forest soils in the Southern Amazon and to identify the most sensitive attributes of their fertility. Additionally, this study suggests appropriate management practices for sustainable pastures. Soil samples from the 0 to 0.20 m layer were analyzed to determine pH, exchangeable bases (calcium, magnesium, and potassium), exchangeable aluminum, potential acidity, phosphorus, organic carbon, bulk density, and texture. Pasture soils had a higher pH, calcium content, and bulk density than forest soils. However, the pasture soils had lower phosphorus and organic matter content. The soil organic carbon stocks were also lower in pasture soils, with levels 0.8 to 12 Mg ha-1 lower than in forest soils. The fertility attributes most sensitive to soil management in these pastures were phosphorus, pH, organic carbon, and bulk density. The lack of nutrients and soil and water conservation practices have contributed to the degradation of these pastures. Therefore, the recommended management for these pastures should aim to improve the organic matter content, reduce compaction, and replenish and cycle nutrients. sustainability Additionally 020 20 0.2 pH calcium, (calcium magnesium potassium, potassium , potassium) aluminum acidity texture content However 08 8 0. 1 ha1 ha ha- Therefore compaction 02 2

RESUMO O manejo inadequado de solos de pastagens na Amazônia resulta em predomínio de pastagens degradadas. Considerando as características naturais dessa região pode favorecer estratégias mais adequadas para sua sustentabilidade, o objetivo desse estudo foi avaliar as diferenças de atributos químicos e físicos de solos de pastagens e florestas no sul da Amazônia e identificar os atributos mais sensíveis de sua fertilidade. Além disso, sugerir práticas de manejo mais adequadas para essas pastagens em direção à sustentabilidade. Amostras de solo da camada de 0 a 0,20 m foram analisadas para determinação de pH, bases trocáveis (cálcio, magnésio e potássio), alumínio trocável, acidez potencial, fósforo, carbono orgânico, densidade aparente e textura. Os solos de pastagem tiveram maior pH, cálcio e densidade aparente do que os solos de floresta. No entanto, os solos de pastagem apresentaram menores teores de fósforo e matéria orgânica. Os estoques de carbono orgânico do solo também foram menores nas pastagens, com teores de 0,8 a 12 Mg ha-1 inferiores aos solos da floresta. Os atributos de fertilidade mais sensíveis ao manejo do solo nessas pastagens foram fósforo, pH, carbono orgânico e densidade aparente. A carência de nutrientes e de práticas de conservação do solo e da água têm contribuído para o estado de degradação dessas pastagens. Portanto, o manejo recomendado para essas pastagens deve visar a melhoria da matéria orgânica, redução da compactação, além da reposição e ciclagem de nutrientes. degradadas sustentabilidade disso 020 20 0,2 pH cálcio, (cálcio potássio, potássio , potássio) trocável potencial textura floresta entanto orgânica 08 8 0, 1 ha1 ha ha- Portanto compactação 02 2

ABSTRACT Large-scale mining operations, such as those associated with iron extraction, disturb soils and vegetation and create the need for effective rehabilitation practices. The Iron Quadrangle region of southeastern Brazil is one of the world’s biodiversity hotspots; however, iron mining activities threaten many natural and seminatural ecosystem types in which many rare/protected species occur. The Iron Quadrangle has four main ecosystem types: Atlantic Forest (AF), ferruginous rupestrian grassland with dense vegetation (FRG-D); ferruginous rupestrian grassland with sparse vegetation (FRG-S); and quartzite rupestrian grassland (QRG). To support rehabilitation and monitoring plans, we evaluated reference areas and identified soil and vegetative attributes that best differentiated between these four ecosystems. We measured thirty-four physical, chemical, and biological soil properties and two vegetation parameters and, using a multivariate analysis, detected: 1) correlations between properties and 2) differences between areas. We identified twelve properties that best differentiated the areas (in order from most to least relevant): nickel content; exchangeable aluminum; clay content; above-ground vegetation volume; aluminum saturation; particle density; bulk density; arsenic content; zinc content; lead content, fine sand plus silt content; and fine sand content. Soil physicochemical properties proved to be more sensitive to differences in ecosystem type, and in particular, parameters related to fertility and the presence of metals and semi-metals differentiated the AF from the FRG-D and FRG-S. Soil physical properties, including fine sand and silt content, were most important for differentiating QRG from the other ecosystems, possibly resulting from the exposure of quartzite material to erosive processes. This study demonstrates the importance of identifying appropriate reference areas for post-mining reclamation. Largescale Large scale operations extraction practices worlds world s hotspots however rareprotected rare protected occur AF, , (AF) FRGD FRG D (FRG-D) FRGS S (FRG-S) QRG. . (QRG) plans ecosystems thirtyfour thirty chemical analysis detected 1 2 relevant relevant) content aboveground above ground volume saturation density type particular semimetals semi FRGS. S. FRG-S processes postmining post reclamation (AF (FRG-D (FRG-S (QRG

ABSTRACT The objective of this study was to investigate the acidic soil physical and chemical alteration associated to vinasse application under laboratory conditions. The experiment was distributed in a factorial scheme (5 × 3), in a completely randomized design, with four replicates. The beneficial effects of five vinasse doses (without vinasse [0, only water], 50, 100, 150, and 200 m3/ha) in enhancing the physical and chemical properties of three acidic soils: Oxisol (SO), Ultisol (SU), and Argisol (SA) were studied after 30 days of incubation. Soil samples were collected in the 0-20 cm depth layer to determine physical and chemical properties such as pH (CaCl2), total acidity (AT), exchangeable acidity (Al3+), base cations (K+, Ca2+, and Mg2+), sums of bases (SB), cations exchange capacity (CIC), base saturation index (V%), and saturation of potassium (K), calcium (Ca), magnesium (Mg), and aluminum (Al). Results indicated that vinasse application enhanced the physical and chemical properties of the studied soils, since pH, base cations, SB, CIC, V%, and saturation of K, Ca, and Mg were increased, while AT, Al3+, and Al saturation were decreased. The most important effects in the improvement of physical and chemical properties of acidic soils were observed with a dose of 200 m3/ha of vinasse. The findings of this study suggest that vinasse could be a low-cost effective strategy as an alternative source for balancing soil acidity and would be an appropriate option for minimizing environmental pollution.

RESUMEN El objetivo de este estudio fue investigar las alteraciones físicas y químicas de los suelos ácidos asociadas a la aplicación de vinaza en condiciones de laboratorio. Los efectos beneficiosos de cinco dosis de vinaza (sin vinaza [0, solamente agua], 50, 100, 150 y 200 m3/ha), fueron estudiadas en el mejoramiento de las propiedades físicas y químicas de tres suelos ácidos: Oxisol (SO), Ultisol (SU) y Argisol (SA), después de 30 días de incubación. Las muestras de suelos fueron recolectadas en la capa de 0-20 cm de profundidad para la determinación de propiedades físicas y químicas como pH (CaCl2), acidez total (AT), acidez intercambiable (Al3+), cationes bases (K+, Ca2+ y Mg2+), suma de bases (SB), capacidad de intercambio catiónico (CIC), índice de saturación de las bases (V%), y saturación de potasio (K), calcio (Ca), magnesio (Mg) y aluminio (Al). Los resultados indicaron que la aplicación de vinaza mejoró las propiedades físicas y químicas de los suelos estudiados, porque se incrementaron tanto el pH como los cationes bases, la SB, la CIC, el V% y la saturación de K, Ca y Mg, y disminuyeron la AT, Al3+ y saturación de Al. Además, los efectos más importantes en el mejoramiento de las propiedades físicas y químicas de los suelos ácidos se observaron en la dosis de 200 m3/ha de vinaza. Los hallazgos de este estudio sugieren que la vinaza podría ser una estrategia efectiva de bajo costo como fuente alternativa para balancear la acidez del suelo y constituiría una opción apropiada para disminuir la contaminación ambiental.

ABSTRACT Eucalyptus (Eucalyptus urograndis) production has significantly advanced over the past few years in Brazil, especially with regard to acreage and productivity. Machine learning has made significant advances in most varied fields of agrarian sciences. In this context, this study aimed to use physicochemical variables of the soil as well as climatic and dendrometric variables of eucalyptus to predict its height using the random forest algorithm. The study was conducted in the municipality of Três Lagoas, in Mato Grosso do Sul, Brazil. The original database consisted of 49 soil physicochemical variables collected at 0–0.20 m and 0.20–0.40 m, two dendrometric and four climatic variables, and one response variable related to the height of eucalyptus. A correlation matrix was applied to select variables. Furthermore, modeling was performed using the random forest algorithm, which performed well (r = 0.98, R2 = 0.96) in predicting the height of eucalyptus. Overall, the most important variables to predict the eucalyptus plant height included diameter at breast height (DBH), phosphorus content (P1), gravimetric moisture (GM1) at a soil depth between 0.00 m and 0.20 m, and exchangeable aluminum content (Al2) between 0.20 m to 0.40 m of soil.

Abstract: Oil activities have always been considered a source of contamination of soils and aquifers. Thus, given the possible use of petroleum coke as a filtering controller in a water-based fluid, its effect was evaluated on two typical soils of areas of oil operations in Monagas state, Venezuela, such as Morichal and Orocual. These, when physically characterized, turned out to be sandy soils and sandy loam, respectively. The soils were contaminated with said fluid in three different concentrations and 24 h later they were sown with beans (Vigna unguiculata) as a bioindicator, observing their germination, growth, number of leaves and color for 21 days. Subsequently, the properties of pH, electrical conductivity, cation exchange capacity and exchangeable aluminum to soils were determined and compared with the maximum values allowed in articles 49 and 50 of Decree 2635. Finally, based on a factorial statistical design, it was applied an ANOVA (α = 0.05) and Duncan's test to establish differences between soils, concentrations and properties. The study allowed concluding that the effect of the addition of the drilling fluid in its different concentrations to the soils, caused different behaviors in the properties: pH, electrical conductivity, exchangeable aluminum and cation exchange capacity according to the type of soil analyzed.

Resumen: Las actividades petroleras siempre se han considerado como fuente de contaminación de suelos y acuíferos. Así, ante el posible uso de coque de petróleo como controlador de filtrado en un fluido base agua, se evaluó su efecto sobre dos suelos típicos de áreas de operaciones petroleras en el estado Monagas, Venezuela; como son: Morichal y Orocual. Estos al ser caracterizados físicamente resultaron ser suelos arenosos y francos arenosos, respectivamente. Los suelos se contaminaron con dicho fluido en tres diferentes concentraciones y 24 h después se sembraron con frijol (Vigna unguiculata) como bioindicador, observándose durante 21 días su germinación, crecimiento, número de hojas y color. Posteriormente, se determinaron las propiedades de pH, conductividad eléctrica, capacidad de intercambio catiónico y aluminio intercambiable a los suelos y se compararon con los valores máximos permitidos en los artículos 49 y 50 del Decreto 2635. Finalmente, basados en un diseño estadístico factorial se aplicó un ANOVA (α=0.05) y test de Duncan para establecer diferencias entre los suelos, las concentraciones y las propiedades. El estudio permitió concluir que el efecto de la adición del fluido de perforación en sus diferentes concentraciones a los suelos, ocasionó comportamientos diferentes en las propiedades: pH, conductividad eléctrica, aluminio intercambiable y capacidad de intercambio catiónico según el tipo de suelo analizado.

Resumo A realização de queimas prescritas, com diferentes objetivos de gestão e manejo, vem sendo aplicada mais frequentemente em áreas protegidas. Com o intuito de compreender o efeito do fogo, o presente trabalho teve como objetivo avaliar a abundância e a diversidade dos microrganismos fúngicos em resposta ao uso do fogo e incêndios florestais. As amostras de solo anterior e após a queimada foram coletadas, sendo os fungos isolados pelo método de plaqueamento, posteriormente quantificados por meio da contagem das unidades formadoras de colônia (UFC g-1) e identificados ao nível de gênero. A média de UFC g-1 não apresentou diferença significativa entre os regimes de fogo avaliados, no entanto houve diferença significativa (p<0,05) para diversidade, tendo os dois anos de incêndios ocasionado menor diversidade de gênero. Os gêneros Aspergillus e Penicillium estiveram presentes em todas as áreas amostradas, com maiores valores de UFC g-1, enquanto os gêneros Mucor e Rhizopus apresentaram os menores valores. A média de unidade formadora de colônia (UFC g-1) e diversidade antes e após a queima prescrita diferiram estatisticamente (p<0,05), sendo que a média de UFC g-1 teve redução e a diversidade apresentou aumento após a passagem do fogo em todas as áreas avaliadas. A maior redução da média de UFC g-1 ocorreu para o mês de julho. Os valores de coeficientes de correlação de Pearson obtidos demonstraram correlação negativa significativa entre a média de UFC g-1, a diversidade e a temperatura (r=0,70; r=-0,98 e p<0,05). A variável diversidade apresentou correlação negativa com a temperatura, precipitação e umidade relativa do ar (r=-0,56; r=-0,86; r=-0,86 e p<0,05), indicando que houve influência direta destas variáveis na abundância e diversidade dos fungos do solo. Os parâmetros do solo (alumínio, acidez trocável, capacidade de troca de cátions, cálcio, magnésio, cálcio e magnésio, fósforo, pH, saturação por base e de alumínio) possuem relação direta com os fungos do solo.

Abstract Prescribed burning, with different objectives of management and handling, has been applied more frequently in protected areas. In order to understand the effect of fire, this work aimed to assess the abundance and diversity of fungal microorganisms in response to the use of fire and forest fires. Soil samples before and after burning were collected, with fungi isolated by the plating method, then quantified by counting the collony-forming units (CFU g-1) and identified at the gender level. The average CFU g-1 did not present a significant difference between the evaluated fire regimes, however, there was a significant difference (p<0.05) for diversity, and the two years of fires caused less gender diversity. The genders Aspergillus and Penicillium were present in all sampled areas, with higher CFU g-1 values, whereas genders Mucor and Rhizopus exhibited the lowest values. The average colony-forming unit (CFU g-1) and diversity before and after prescribed burning differed statistically (p < 0.05), while the average CFU g-1 had a reduction and diversity showed an increase after the passage of fire in all areas evaluated. The greatest reduction in the average CFU g-1 occurred for the month of July. Pearson’s correlation coefficient values obtained demonstrated a significant negative correlation between average CFU g-1, diversity and temperature (r = 0.70; r = -0.98 and p < 0.05). The diversity variable presented negative correlation with temperature, precipitation and relative humidity (r = -0.56; r = -0.86 and p < 0.05), thus indicating that there was a direct influence of these variables on the abundance and diversity of soil fungi. The soil parameters (aluminum, exchangeable acidity, cation EXCHANGE capacity, calcium and magnesium, phosphorus, pH, base and aluminum saturation) have a direct relation with the soil fungi.

ABSTRACT: A set of attributes endows the soils with distinctive characteristics and astute understanding is required in order to formulate suitable strategies for soil management. The aim of this study was to physically, chemically and mineralogically characterize samples of the main soil classes in Minas Gerais, Brazil, determine the point of zero salt effect (PZSE) and the point of zero charge (PZC), and ascertain the correlation between these factors and soil attributes. The soils evaluated presented different textural classes ranging from loamy sand (Entisol) to very clayey (some Oxisols and Ultisols). The soils differed substantially in terms of fertility, presenting a range from dystrophic (low fertility, base saturation < 50 %) to eutrophic character (fertility, base saturation ≥ 50 %), even within the same soil class, such as the Oxisols, which suggests the concurrence of the parent material. Highly weathered soils are predominant in Minas Gerais and these soils are composed predominantly of kaolinite, gibbsite, goethite and hematite. Traces of hydroxy-Al interlayered vermiculite and illite were also found in the Oxisols, Ultisols and Inceptisols. A correlation between the PZSE and the PZC in the A horizon was observed. A high degree of correlation was observed between the PZC and the exchangeable aluminum and the ratio of iron obtained by ammonium oxalate and dithionite-citrate (Feo/Fed) in both the A and B horizons of soil classes. The results obtained reinforce the importance of knowledge of soil attributes to the adoption of practices such as the management of phosphate fertilization in clayey soils and liming in soils rich in aluminum.

RESUMEN Los suelos tropicales son característicamente ácidos y pobres en nutrientes, lo cual limita su productividad agrícola. Estos suelos usualmente son tratados con cal, pero su baja solubilidad limita su efectividad para mejorar la fertilidad. El uso de yeso agrícola ha ganado mucha atención debido a su mayor solubilidad y movilidad en el suelo, disponibilidad local y bajo precio. Por tanto, se realizó un estudio para determinar tales efectos en diez suelos acidos Colombianos con baja fertilidad y diferentes características físicas y químicas. Muestras de estos suelos (0-20 cm) se secaron al aire, tamizaron (<2 mm) y transfirieron a vasos plásticos. Dosis crecientes de yeso se aplicaron por cuadruplicado: 0,0; 0,25; 0,5; 1,0; 2,0; 4,0; 8,0 y 16,0 g kg-1. Los suelos se humedecieron para mantenerlos a 50% de su máxima capacidad de retención de agua durante dos semanas. Se midió pH, Al+3, Ca+2, Mg+2, K+, S-SO4 -2 y P-H2PO4 -2 usando métodos estandarizados. Los resultados muestran que al adicionar yeso agrícola se incrementó significativamente (P<0,05) los niveles de Ca+2-K+ intercambiable, saturación de Ca+2 , S-SO4 -2 y Al+3 intercambiable, particularmente con dosis mayores de 4,0 g kg-1. En contraste, con el incremento de la dosis de yeso agrícola disminuyeron significativamente la saturación de Al+3 , y el pH; los niveles de Mg+2 no fueron significativamente afectados. El uso de las pruebas de incubación de yeso agrícola es promisorio para detectar mejoras en el suelo a través del incremento en los niveles de Ca2+ y S-SO4 2- y la disminución de la saturación de Al3+.

ABSTRACT Tropical soils are characterized by acidity and poor plant nutrient availability, limiting their agricultural productivity. These soils are commonly amended with lime, but its low solubility impairs its effectiveness to enhance soil fertility. The use of gypsum has gained attention among farmers due to its higher solubility and mobility in the soil, local accessibility, and low price. Therefore, this study was conducted to determine the effects of Agricultural Gypsum (AG) addition on ten Colombian acid soils that had poor fertility and contrasting their physical and chemical characteristics. Surface (0-20 cm) soil samples were air-dried, sieved (<2 mm), and transferred into plastic vases, 40 g (dry base) per vase. Increasing rates of gypsum were added by duplicate: 0.0, 0.25, 0.5, 1.0, 2.0, 4.0, 8.0, and 16.0 g kg-1. Then, the soils were incubated for two weeks and watered to maintain 50% of their maximum water holding capacity. Soil pH, Al+3, Ca+2, Mg+2, K+, S-SO4 -2, and P-H2PO4 -2 were measured using standard methods. The results showed that AG addition significantly (P<0.05) increased soil exchangeable Ca+2-K+, Ca+2 saturation, S-SO4 -2 concentration, and exchangeable Al+3, particularly with doses above 4.0 g kg-1. In contrast, soil Al+3 saturation, P-H2PO4 -2 and pH significantly decreased as the AG doses increased, while soil exchangeable Mg+2 levels were not significantly affected. The use of gypsum incubation tests could be promissory for its effects on soil amelioration associated mainly to increase soil exchangeable Ca2+ and S-SO4 2- and to decrease Al3+ saturation.

Abstract Peru produces coffees of different qualities because it has very diverse ecosystems, the production of specialty coffees is an opportunity for economic and social improvement for small producers considering that the price of coffee is related to the sensory quality of the drink in ever larger market niches. In this study, the effect of the physical-chemical characteristics of the soil and the altitude of the farms on the sensory quality of coffee was evaluated in 56 high-altitude coffee farms in agroforestry systems of the upper jungle of Cusco, the physical and chemical characterization was carried out of the soils of farms located between 1312 and 1910 meters above sea level in the Tunquimayo - Quellouno - Cusco area and the sensory quality of the coffee was evaluated using SCAA methodology. It was found that the acidity and the aluminum concentration of the soils increases with altitude, the levels of available phosphorus, calcium and exchangeable potassium are low, while the changeable magnesium is high. In the coffee sensory quality test, 50% of the farms obtained scores of 80 - 84, the same ones that qualify as Very Good specialty coffee; the altitude contributed positively to the increase in attributes such as personal appreciation, sweetness, balance, aroma and flavor; concluding that the altitude and soil characteristics such as phosphorus (P) and cation exchange capacity (CEC) influence the sensory quality of coffee.

Resumen El Perú produce cafés de diversas calidades porque posee ecosistemas muy diversos, la producción de cafés especiales es una oportunidad de mejora económica y social para los pequeños productores considerando que el precio del café está relacionado con la calidad sensorial de la bebida en nichos de mercado cada vez mayores. En este estudio se evaluó el efecto de las características fisicoquímicas del suelo y la altitud de las fincas sobre la calidad sensorial del café en 56 fincas de café de altura en sistemas agroforestales de la selva alta del Cusco, se realizó la caracterización física y química de los suelos de fincas ubicadas entre 1312 a 1910 msnm de la zona de Tunquimayo - Quellouno - Cusco y se evaluó la calidad sensorial del café utilizando metodología de la SCAA. Se encontró que la acidez y la concentración de aluminio de los suelos aumenta con la altitud, los niveles de fósforo disponible, calcio y potasio cambiables son bajos; mientras que el magnesio cambiable es alto. En la prueba de calidad sensorial del café, el 50% de las fincas obtuvo puntajes de 80 - 84, los mismos que califican como café especial del tipo Muy Bueno; la altitud contribuyó positivamente a que los atributos como la apreciación personal, la dulzura, el balance, el aroma y el sabor del café se incrementen; concluyéndose que la altitud y las características del suelo como fósforo (P) y capacidad de intercambio catiónico (CIC) influyen en la calidad sensorial del café.

ABSTRACT In the last 15 years, it has been considering that in Cuba the process of soils degradation by acidification occurs with some intensity. It is about that 40 % of the whole Cuban territory the soils are affected by this process, with an increase or 2.9 % annually. Besides, that with erosion processes occur the acidification of soils. The objective of this paper is to demonstrate that this problem is no really. The increase of soil acidity by soil erosion take place only in Allitics Group of soils, which have a B horizon with a high content of exchangeable aluminum and pH value equal or less than 4,5, but these soils are few extensive in Cuba occupying 555 400 ha that is only 5 % of the territory. The main objective of this paper is to demonstrate that soils of Brown Siallitic Group (that are the most extensive in Cuba, occupying 2 355 800 ha, that is 21 % of the country), when are affected by erosion process increase the pH value because these soils with the depth the pH value is higher. These results show that the acidification process in Cuban soils isn´t so intensive, as is present in some papers.

RESUMEN En los últimos 15 años se viene planteando en Cuba que el proceso de degradación de los suelos por acidificación ocurre con cierta intensidad. Se plantea que el 40 % del territorio está afectado por este proceso y se pronostica que hay un incremento del mismo de 2,9 % anualmente. Además, que con la erosión se acidifican los suelos. En este trabajo se demuestra que la acidificación por erosión solamente ocurre en Cuba en los suelos del Agrupamiento Alítico, ya que el horizonte B tiene un contenido alto en aluminio cambiable y pH igual o menor de 4,5. Pero estos suelos son poco extensivos en Cuba donde ocupan solamente 5 % del territorio nacional. El principal objetivo lo constituye el demostrar que en los suelos del Agrupamiento Pardos Sialíticos (que son los más extensivos de Cuba, 21 % del territorio), aumenta el pH en profundidad, por lo que cuando se erosionan no se acidifican, sino que aumenta el pH. Estos resultados demuestran que el proceso de acidificación tan intenso para los suelos de Cuba, como se plantea en algunos trabajos, no ocurre realmente.

Resumen Introducción. El manejo orgánico del cacao representa el 60 % de la producción en el Perú y se utilizan grandes cantidades de compost preparado con diferentes insumos, en busca de mejorar la calidad del suelo y los rendimientos del cacao. Objetivo. Se evaluó el efecto de la aplicación de compost de plumas de pollo sobre los principales indicadores químicos del suelo en una plantación de cacao CCN-51, en el poblado de Nuevo Progreso, provincia Padre Abad en la región Ucayali-Perú. Materiales y métodos. Se utilizo un diseño de bloques completo al azar, con cuatro tratamiento y cuatro repeticiones en donde: CP1 fue testigo absoluto, CP2 compost de plumas a razón de 2 000 kg. ha-1, CP3 compost de plumas a razón de 4 000 kg. ha-1 y CP4 compost de plumas a razón de 6 000 kg. ha-1. Se evaluaron los principales indicadores químicos de calidad del suelo: potencial de hidrogeno (pH), materia orgánica (MO), nitrógeno total (N), fosforo disponible (P), potasio (K+), calcio (Ca2+), magnesio (Mg2+), aluminio (Al3+), cadmio disponible (Cd2+), acides cambiable (AC) y capacidad de intercambio de cationes (CIC). Resultados. Los resultados mostraron disminución del aluminio intercambiable y acides cambiable e incrementos de la materia orgánica, nitrógeno, fosforo, y potasio, según la proporción de compost aplicado, estos indicadores presentaron diferencias significativas (p<0.05); el pH, calcio y cadmio disponible no presentó diferencias significativas (p<0.05). Conclusión . El compost de plumas (CP) mejoró significativamente los niveles de MO, N, P y K+, indicadores que definen la calidad del suelo y reducen los niveles de aluminio, este ultimo de suma importancia en suelos ácidos.

Abstract Introduction. Organic management of cocoa accounts for 60% of production in Peru and large amounts of compost prepared with different inputs are used, in order to improve the quality of the soil and cocoa yields. Objective. Evaluated the effect of the application of chicken feather compost on the main soil chemical indicators in a cocoa plantation CCN-51 un the Town of Nuevo Progreso, province of Padre Abad in the Ucayali-Peru region was evaluated. Materials and methods. A randomized complete block design was used, with four treatments and four repetitions where: FC1 was an absolute witness, FC2 feather compost at a rate of 2,000 kg. ha-FC3 feather compost at a rate of 4,000 kg. ha-1 and FC4 feather compost at a rate of 6 000 kg. ha-1. The main chemical indicators of soil quality were evaluated: hydrogen potential (pH), organic matter (OM), total nitrogen (N), available phosphorus (P), potassium (K+), calcium (Ca2+), magnesium (Mg2+) , aluminum (Al3+), available cadmium (Cd2+), changeable acids (AC) and cation exchange capacity (CEC). Results. The results showed a decrease in exchangeable aluminum and changeable acidity and increases in organic matter, nitrogen, phosphorus, and potassium, depending on the proportion of compost applied, these indicators presented significant differences (p <0.05); The pH, calcium and cadmium available did not show significant differences (p <0.05). Conclusion. Feather compost (FC) significantly improved the levels of OM, N, P and K+, indicators that define soil quality and reduce aluminum levels, the latter of utmost importance in acidic soils.

Resumo Introdução. O manejo orgânico do cacau representa 60% da produção no Peru e grandes quantidades de composto preparado com diferentes insumos são utilizados, a fim de melhorar a qualidade do solo e os rendimentos do cacau. Objetivo Foi avaliado o efeito da aplicação de composto de penas de galinha nos principais indicadores químicos do solo em uma plantação de cacau. CCN-51 na cidade de Nuevo Progreso, província de Padre Abad, na região de Ucayali-Peru. Materiais e métodos. O delineamento experimental utilizado foi o de blocos completos casualizados, com quatro tratamentos e quatro repetições, sendo: CP1 testemunha absoluta, CP2 composto de penas a uma taxa de 2 000 kg. ha-1, CP3 composto de penas a uma taxa de 4 000 kg. ha-1 e CP4 a uma taxa de 6 000 kg. ha-1. Os principais indicadores químicos de qualidade do solo foram avaliados: potencial hidrogênio (pH), matéria orgânica (MO), nitrogênio total (N), fósforo disponível (P), potássio (K+), cálcio (Ca2+), magnésio (Mg2+) , alumínio (Al3+), cádmio disponível (Cd2+), ácidos mutáveis (AC) e capacidade de troca catiônica (CEC). Resultados. Os resultados mostraram uma diminuição do alumínio trocável e dos ácidos trocáveis e aumento da matéria orgânica, nitrogênio, fósforo e potássio, dependendo da proporção de composto aplicado, esses indicadores apresentaram diferenças significativas (p <0,05); O pH, cálcio e cádmio disponíveis não mostraram diferenças significativas (p <0,05). Conclusão. O composto de penas (CP) melhorou significativamente os níveis de MO, N, P e K, indicadores que definem a qualidade do solo e reduzem os níveis de alumínio, este último de extrema importância em solos ácidos.

ABSTRACT Soils originating from the Caiuá sandstone formation have low soil organic matter (SOM), clay content, and cation exchange capacity (CEC). The predominance of one component over the other might decisively influence the CEC of these soils. Particle size distribution and selective dissolution procedures associated to a suit of methods to determine the exchangeable capacity properties might clarify the relative importance of each soil component. The objective of this work was to evaluate the contribution of the different components of the solid fraction and their intrinsic attributes to the CEC of sandy-loam soils and their relation to the total organic carbon (TOC), C:N ratio, and soil mineralogy. For this purpose, 34 soil samples were selected from the Caiuá sandstone formation with significant variation in the carbon content. Clay size fraction was characterized by X-ray diffraction, routine chemical analysis, and total specific surface area-SSA T using EGME, before and after the removal of SOM with sodium hypochlorite solution. Different values of CEC and effective cation exchange capacity (ECEC) were determined following standard procedures. The soils presented high sand content (82.9 ± 5.9 %) and the mineralogy of the clay fraction is dominated by kaolinite (>80 %) with the presence of illite, 2:1 clay minerals, and small amounts of iron and aluminum oxides. The CEC and ECEC values at pH 7.0 and ~5.6, respectively due to the SOM are 408.6 and 148.7 cmol c kg -1 of carbon, respectively. The SOM was responsible for 32 to 84 % (average 52 %) and 24 to 67 % (average of 46 %) of the CEC and ECEC of the soils, respectively. The CEC and ECEC of the inorganic fraction are 2.32 and 0.78 cmol c kg -1 of minerals, respectively. The CEC of the clay fraction increased with the TOC but decreased exponentially with the clay content. The total carbon content increased linearly with the C/N ratio. The SSA T showed a significant (p<0.05) and positive correlation with the TOC and with the CEC of the soils.

ABSTRACT In the region of Canindeyú, milk production is one of the main forms of saving for small producers. However, the use of agricultural inputs is not practiced in the production of pastures, generally due to the lack of information on their importance, mainly fertilization. The objective of this work was to characterize the physical and chemical attributes of soils under Marandu grass and determine their productivity using different fertilizations. The study was conducted in four areas located in the district of Jasy Cañy. In order to evaluate the chemical attributes, soil samples were collected before fertilization in the 0-10 cm and 10-20 cm layers, using the levels of Ca2+, Mg2+, K+, extractable P, base saturation, aluminum saturation, exchangeable acidity, Al3+, CTCpH7,0, pHCaCl2 and organic matter as chemical indicators of soil quality. For dry matter production and height of the pasture, a complete randomized block design was used and the treatments consisted of control (without fertilization), nitrogen fertilization (100 kg ha-1) and fertilization with N-P2O5-K2O (100-40-80 Kg ha-1). Based on the results the soils present a medium acidity, with no Al3+ toxicity, good base saturation, low MO and CTCpH 7.0, lack of Ca2+, K+ and extractable P and high Mg2+ content in relation to Ca2+. Fertilization with N and N-P2O5-K2O provided significant increases in dry matter yield and height of Marandu grass presenting high responsive capacity, and it is possible to conclude that fertilization is the fundamental factor for pasture productivity.

RESUMO No departamento de Canindeyú da região oriental do Paraguai a produção de leite constitui uma das principais formas de economia para os pequenos produtores agropecuários, porém, o uso de insumos agrícolas não é uma prática na produção de pastagens, geralmente em razão do alto custo envolvido nestas práticas, especialmente do uso de adubos. O objetivo deste trabalho foi caracterizar os atributos químicos de solos sob pastagem de capim-Marandu e determinar sua produtividade por efeito de diferentes adubações. O estudo foi realizado em quatro áreas localizadas no distrito de Jasy Cañy. Para as avaliações dos atributos químicos foram realizadas coletas de solo antes da adubação, nas camadas 0-10 e 10-20 cm, determinando-se os teores de Ca2+, Mg2+, K+, P disponível, saturação por bases, saturação por alumínio, acidez trocável, Al3+, CTCpH7,0, pH CaCl2 e matéria orgânica. Para a avaliação da produção de matéria seca e altura do dossel foi utilizado o delineamento de blocos completos ao acaso e os tratamentos consistiram na testemunha, adubação nitrogenada (100 kg ha-1) e adubação com NPK (100-40-80 kg ha-1). Com base nos resultados verificou-se que os solos são medianamente ácidos, com ausência de toxicidade por Al3+, boa saturação por bases, baixo teor de MO e de CTCpH 7,0, carência de Ca2+, K+ e de P disponível e elevado teor de Mg2+ em relação ao Ca2+. A adubação com N ou NPK proporcionou aumento significativo na produção de matéria seca e na altura do dossel, sendo possível concluir que a adubação é fundamental para a produtividade da pastagem.

A fava-d’anta é uma espécie nativa do cerrado que apresenta potencial econômico e medicinal, mas com pequeno número de informações sobre aspectos da nutrição mineral. Com o objetivo de avaliar a influência de níveis de saturação por bases sobre os atributos químicos do solo e o crescimento inicial e produção de flavonoides totais em mudas de fava-d’anta, conduziu-se um experimento em delineamento de blocos casualizados, com sete tratamentos: saturação por base natural do solo (3%), e os demais tratamentos com 10, 20, 30, 40, 50 e 60 % de saturação, com cinco repetições. A elevação da saturação de bases por meio da aplicação de doses de óxido de cálcio e magnésio refletiu na melhoria dos atributos químicos do solo por meio do aumento do pH, da CTC e das concentrações dos cátions trocáveis Ca+2 e Mg+2, e redução da acidez trocável, acidez potencial e saturação por alumínio. A altura, biomassa seca e o teor de flavonoides totais das plântulas de fava-d’anta não foram influenciados pela elevação da saturação por bases, entretanto houve decréscimo do diâmetro do coleto. Assim, as condições naturais do solo do Cerrado propiciam o melhor desenvolvimento da espécie, evidenciando a sua tolerância à acidez do solo.

Fava-d'anta is a native species from Cerrado that presents economic and medicinal potential, with a small number of information on aspects of mineral nutrition. In order to evaluate the influence of base saturation levels on chemical attributes of the soil, initial growth and total flavonoid production in fava-d'anta seedlings, an experiment was conducted in a randomized block design with seven treatments: saturation by natural base of the soil (3%), and treatments with 10, 20, 30, 40, 50 and 60% saturation, with five replications. The increase of the base saturation through the application of doses of calcium and magnesium oxides reflected the improvement of chemical attributes of the soil by increasing the pH, CEC and concentrations of exchangeable cations Ca+2 and Mg+2, as well as reduction of exchangeable acidity, potential acidity and saturation by aluminum. The height, dry biomass and the total flavonoid content of the fava-d'anta seedlings were not influenced by the increase of the base saturation, however, there was a decrease in the collar diameter. Thus, the natural conditions of the Cerrado soil provide the best development of the species, evidencing its tolerance to soil acidity.