The stability of aggregates and organic carbon content after the application of gypsum, soil scarification and a succession of agricultural crops / A estabilidade dos agregados e do teor de carbono orgânico após a aplicação de gesso, escarificação do solo e uma sucessão de culturas agrícolas

Studies related to the monitoring of soil quality by physical attributes are important for the evaluation and maintenance of the sustainability of agricultural systems, besides indicating the appropriate management of the environment, aiming at its conservation and productivity. The objective of this study was to evaluate the stability of aggregates and organic carbon after the application of gypsum, soil scarification and a succession of crops. The treatments consisted of an absence and addition of gypsum, absence and presence of soil scarification, and three systems of crops in succession. The experimental design was made of randomized blocks, in a 2x2x4 factorial scheme, with eight replications. The aggregates were evaluated as stabled in water and soil organic carbon content. The treatment where gypsum was applied, as well as the soybean/maize/brachiaria/fallow (SMBF) succession system, presented better results in soil aggregation and higher levels of organic carbon.

Estudos relativos ao monitoramento da qualidade do solo pelos atributos físicos são importantes para a avaliação e manutenção da sustentabilidade dos sistemas agrícolas, além de sinalizar o manejo adequado do ambiente, visando à sua conservação e produtividade. Este trabalho teve por objetivo avaliar a estabilidade de agregados e teor de carbono orgânico, após a aplicação de gesso, escarificação do solo e sucessão de culturas. Os tratamentos consistiram na ausência e adição de gesso agrícola, ausência e presença de escarificação do solo, e três sistemas de sucessão de culturas. O delineamento experimental foi em blocos casualizados, em esquema fatorial 2x2x3 com oito repetições. Sendo avaliada a estabilidade dos agregados estáveis em água e teor de carbono orgânico do solo. O tratamento onde foi aplicado gesso agrícola e o sistema de sucessão SMBP apresentaram melhores resultados na agregação do solo e maiores teores de carbono orgânico.

Synthesis of enriched biochar as a vehicle for phosphorus in tropical soils

Phosphorus (P) is one of the nutrients that most limits agricultural productivity, especially in tropical soils. Enriched biochar has been proposed to increase the bioavailability of P and other nutrients in the soil. Thus, the objective of this study was to evaluate the availability of P in phosphate biochar (composed of biomass and soil) as a function of the triple superphosphate mixture before and after the pyrolysis process. We produced eight types of enriched biochar via pyrolysis by combining sandy or clayey soil with rice or coffee husk, and by adding triple superphosphate before or after pyrolysis. The heating of the phosphate fertilizer during the pyrolysis process resulted in a higher crystallinity of the phosphates, lower content of labile fractions of P and lower content of available P in phosphate biochars than when the superphosphate was added after pyrolysis. (AU)

Seasonal Variation of Plant Mineral Nutrition in Fruit Trees

Abstract This research evaluated the monthly variation of plant mineral nutrition in six species of fruit trees over a year. Leaf samples were taken from the fruit trees and nutritional status (N, P, K, Ca, Mg, Fe, Zn, Cu, Mn, and Mo) was determined in the leaves in a month basis from April until November for apple, persimmon and peach. Mandarin mineral nutrition was monitored for one year, and grape and fig from May to November. Using this data, the Diagnosis Recommendation Integrated System (DRIS) was also calculated to evaluate the nutrient balance in the plants. The concentration of N and P had seasonal differences, especially in apple and peach, which reached the peak during the summer. Apple, fig, and grape trees had large ranging on their mineral contents over the year, especially with the P and K levels reaching the minimum during the harvesting season. However, the seasonal changes in leaf micronutrient concentrations were not uniform and not affected by phenological stage. The DRIS data demonstrated that mandarin had the best nutrient balance compared to others and that K was the most limiting element among the fruit trees. In summary, the current data suggest the occurrence of a significant seasonality in mineral nutrition in these six fruit trees, especially in temperate ones.

Níveis críticos e faixas de suficiência nutricional em laranjeira-pêra na Amazônia Central obtidas pelo método DRIS / Critical levels and nutrient sufficiency ranges in orange of the Central Amazon determined by DRIS method

The nutritional status of orange trees depends of reference values that are appropriate to reflect their nutritional condition. The objective this work was to assess the nutrient reference values and evaluated the nutritional status of sweet orange trees in several orchard fields of Central Amazonia (municipalities of Iranduba, Manacapuru, Manaus, Presidente Figueiredo and Rio Preto da Eva). We used the Diagnosis and Recommendation Integrated System for multivariate relation (DRIS) method to establish the nutrient reference values. The nutritional status of 120 commercial orchards of orange grafted on rangpur lime was evaluated by the sufficiency ranges defined from the set of nutritionally balanced plants. For macronutrients, the nutritional sufficiency ranges were (g kg-1): 28-30 (for nitogen, N); 1.6-1.7 (phosphorus, P); 7-9 (potassium, K); 26-29 (calcium, Ca); 3.6-4.0 (magnesium, Mg); 1.7-2.0 (sulfur - S) and for micronutrients (mg kg-1): 47-56 (boron, B); 8-10 (copper, Cu); 84-93 (iron, Fe); 12-13 (manganese, Mn); 14-16 (zinc, Zn). For macronutrients, the critical levels were (g kg-1): 28 (for N); 1.6 (P); 7 (K); 26 (Ca); 3.6 (Mg); 1.7 (S) and for micronutrients (mg kg-1): 47 (B); 8 (Cu); 84 (Fe); 12 (Mn) and 14 for Zn. Nutritional standards obtained by the DRIS methods are in disagreement with the normal ranges proposed in the literature for most nutrients. In about 50% of orchards, the elements P, K, Ca, S, B, Cu e Fe were found below the critical levels. This suggests that orange producers in Central Amazonia should pay more attention to these elements when planning fertilization practices.

A avaliação do estado nutricional da laranjeira depende da definição de valores de referência que sejam adequados para refletir suas condições nutricionais. Neste trabalho, objetivou-se determinar os valores de referências e avaliar o estado nutricional de laranjeiras-pêra em diversas glebas na Amazônia Central (municípios de Iranduba, Manacapuru, Manaus, Presidente Figueiredo e Rio Preto da Eva). Utilizou-se o Sistema Integrado de Diagnose e Recomendação de relações multivariadas (DRIS) para estabelecer os valores de referência nutricional. O diagnóstico nutricional de 120 glebas comerciais de laranjeiras-pêra, enxertadas em limoeiro cravo foram avaliadas pelas faixas de suficiência definidas a partir do conjunto de plantas nutricionalmente equilibradas. Para os macronutrientes, as faixas de suficiência nutricional foram (g kg-1): 28-30 (para nitrogênio, N); 1,6-1,7 (fósforo, P); 7-9 (potássio, K); 26-29 (cálcio, Ca); 3,4-4 (magnésio, Mg); 1,7-2 (enxofre, S) e para os micronutrientes (mg kg-1): 47-56 (boro, B); 8-10 (cobre, Cu); 84-93 (ferro, Fe); 12-13 (manganês, Mn); 14-16 (zinco, Zn). Para os macronutrientes, os níveis críticos foram (g kg-1): 28 (para N); 1,6 (P); 7 (K); 26 (Ca); 3,6 (Mg); 1,7 (S) e para os micronutrientes (mg kg-1): 47 (B); 8 (Cu); 84 (Fe); 12 (Mn); 14 para Zn. Padrões nutricionais obtidos pelo DRIS discordam das faixas de suficiência propostas pela literatura para maioria dos nutrientes. Em quase 50% das glebas monitoradas, P, K, Ca, S, B, Cu e Fe estão abaixo dos níveis críticos propostos neste trabalho. Isto sugere que os produtores de laranja na Amazônia Central deveriam atentar-se para estes elementos no planejamento das fertilizações.

Potencial de resposta à adubação para N, P, K, Ca e Mg em cupuaçueiros avaliados por diferentes normas DRIS / Response potential to fertilization response for N, P, K, Ca and Mg in cupuaçueiros evaluated by different DRIS standards

O potencial de resposta à adubação é uma ferramenta utilizada para a interpretação dos valores dos índices DRIS, de forma que pode ser útil para verificar se diferentes grupos de normas resultam em diagnósticos distintos ou semelhantes entre si. Neste sentido, objetivou-se avaliar o comportamento do diagnóstico nutricional, submetidos a cinco grupos de normas DRIS. Para isto, amostras foliares de cupuaçueiros foram coletadas de pomares comerciais, cuja idade das plantas variou de 5 a 18 anos, sob monocultivo e sistemas agroflorestais (SAF's), obtendo-se para cada relação nutricional entre os nutrientes N, P, K, Ca, Mg, as normas DRIS bivariadas, as quais foram obtidas para o conjunto das populações monitoradas e para subpopulações específicas. As diferentes normas DRIS resultaram em diagnósticos semelhantes para N, P e Ca, enquanto que para K e Mg os diagnósticos produzidos distinguiram-se entre as normas resultando em desvios nutricionais.

The response of potential fertilization is a tool used to interpret the values of DRIS indices, so that it may be useful to see if different groups of rules might result in different or similar diagnosis among themselves. In this sense, it we aimed to evaluate the performance of the nutritional diagnosis, submitted to five groups of DRIS norms. For this, leaf samples were collected from commercial cupuaçueiro orchards, whose plant ages ranged from 5 to 18, with cropping or agroforestry (SAF). For each relationship among the nutrition nutrients N, P, K, Ca and Mg, we obtained bivariate DRIS standards for all populations and monitored for specific subpopulations. The different standards resulted in DRIS diagnoses similar for N, P and Ca and distinct for Mg and K the produced diagnoses stood out among the norms resulting in nutritional deviations.

Avaliação de cultivares de alface adubadas com silicato de cálcio em casa-de-vegetação / Evaluation of lettuce cultivars fertilized with calcium silicate in greenhouse

O experimento foi conduzido no Departamento de Ciência do Solo da Universidade Federal de Lavras - UFLA, no período de junho a agosto de 2002. Objetivou-se avaliar a produtividade, o estado nutricional e a qualidade (classe de tamanho) de cultivares de alface cultivadas com doses de silicato de cálcio em vasos sob casa-de-vegetação. O delineamento experimental foi em blocos casualizados, com quatro repetições, com 1 planta/vaso, em esquema fatorial 3 x 4 + 3, sendo três cultivares de alface (Raider, Regina e Vera) e quatro doses de silicato de cálcio (0, 410, 1,000 e 2,000 mg dm-3); os tratamentos adicionais foram compostos pela aplicação de 820 mg dm-3 de carbonato de cálcio, para as três cultivares. O estado nutricional das plantas de alface foi avaliado pelo Sistema Integrado de Diagnose e Recomendação (DRIS). A aplicação da fonte silicato de cálcio não aumentou o crescimento das plantas e não aumentou o teor dos nutrientes nas plantas de alface, mas melhorou a nutrição das plantas para Si e aumentou a porcentagem de plantas sadias. A aplicação também aumentou a concentração de Mn, devido ao alto conteúdo de Mn no fertilizante aplicado (Silifértil®). As três variedades de alface comportaram-se como plantas não acumuladoras de Si.

The experiment was carried out at the Department of Soil Sciences of the Universidade Federal de Lavras - UFLA, from June to August 2002, with the objective to evaluate the productivity, the nutritional state and the quality (size class) of lettuce cultivars grown with calcium silicate in greenhouse. The experimental design was disposed in blocks with four replicates, in factorial arrangement with additional treatments: 3 x 4 +3, composed by three lettuce cultivars: Raider (group crisphead lettuce); Regina (group butterhead lettuce) and Vera (group looseleaf lettuce) and four calcium silicate rates (0, 410, 1.000 and 2.000 mg dm-3), additional treatments were composed of the application of calcium carbonate of 1.000 mg dm-3 for the three cultivars. The nutritional status of lettuce was evaluated by Diagnosis and Integrated Recommendation System. The application of calcium silicate fertilizer did not increase the growth of the plants and did not improve the concentration of nutrients in lettuce plants; but improved the lettuce nutritional status for Si and increased the percentage of leaves healthy. The application also increase Mn concentration, due to high content of Mn in the silifértil® fertilizer. The three varieties of lettuce behaved as non-accumulation plants of Si.

Relações nutricionais log-transformadas para avaliação nutricional de cupuaçueiros comerciais / Log-transformed nutrient ratio for evaluation nutritional of cultivated cupuaçu trees

A transformação logarítmica das relações bivariadas no cálculo das normas e dos índices do sistema integrado de diagnose e recomendação de nutrientes (DRIS) tem sido sugerida como uma forma de melhorar a acurácia do sistema, principalmente por diminuir a inconsistência na distribuição de freqüência entre as formas de expressão direta e inversa de uma mesma relação. Neste sentido, o objetivo deste trabalho foi avaliar o uso de relações log-transformadas entre diferentes populações de referência. Amostras foliares de cupuaçu foram coletadas de 153 pomares comerciais, cuja idade das plantas variou de 5 a 18 anos, cultivados em monocultivo ou sistemas agroflorestais, obtendo-se para cada relação nutricional entre os nutrientes N, P, K, Ca, Mg, Fe, Cu, Zn, e Mn as normas DRIS bivariadas log-transformadas e não transformadas, obtidas para o conjunto da população e para condições específicas. Os resultados mostraram que as relações log-transformadas contribuem para uma maior consistência dos resultados entre as formas direta e inversa entre diferentes normas DRIS.

The logarithmic transformation of the bivariate relationships in the calculation of integrated system of diagnosis and recommendation indices (DRIS) has been suggested as a way to improve the accuracy of the system, mainly by reducing the inconsistency between the frequency distribution of the forms expression of direct and inverse of the same relationship. Accordingly, the objective of this study was to evaluate the use of log-transformed relationship between different populations of reference. Cupuaçu leaf samples were collected at 153 commercial orchards; trees were part of either monoculture or agroforestry systems and ranged from 5 to 18 years old. For each individual, the nutritional relationship was calculated for the nutrients: N, P, K, Ca, Mg, Fe, Cu, Zn and Mn. Log-transformed and no- transformed nutrient ratio were obtained for the entire population and specific conditions.The results showed that the log-transformed relationship contributes to greater consistency of results between the direct and inverse forms between DRIS norms.