ABSTRACT Podzols are highly sandy soils, in which elements, such as potassium, needed by crops, are easily leached. Studies have indicated that biochar can contribute to increasing cation exchange capacity of the soil, which can improve the retention of bases. This study aimed to evaluate the effect of the poultry litter biochar combined or not with increasing doses of KCl, on leaching and soil base content, on the production of green manure biomass, and on the distribution of K in the soil-water-plant system. A 2 × 3 factorial experiment was conducted in randomized blocks with 6 repetitions: without and with biochar (1% v / v, produced from poultry litter) × without K, with 53.65 and 107.30 mg dm-3 of K (as KCl). The experiment was carried out in four steps: Step 1) Soil incubation with the treatments (for 20 days) followed by chemical analysis of the soil; Step 2) First leaching: the containers (made with PVC with 0.30 m high) received the newly incubated soil in the surface layer and soil without treatment in the subsurface layer. The containers received water until saturation plus 50 % of the total pore volume and the leached water was collected and analyzed; Step 3) Cultivation of green manure (Mucuna aterrima) in the containers of Step 2 and harvest within 40 days (evaluation of biomass and K content); Step 4) after the mucuna harvest, the containers were subjected to second leaching. The leaching solution and the soil from the surface and subsurface layers were collected for chemical analysis. Biochar increased the pH, cationic exchange capacity, P, K, Ca, and Mg levels in the newly incubated soil, in the surface and subsurface layer. The increasing doses of KCl proportionally increased biomass production and K accumulation in green manure, and the biochar increased this response and reduces the need for potassium fertilization by 50 %. With biochar, the accumulation of total K in the soil-plant-water system increases by 125 % and, in the soil-plant system, by 145 %. Biochar changes the K ratio in the soil-plant-water system. With biochar, proportionally, the highest accumulated percentage of K occurred mainly in the soil surface and subsurface layer, and did not result in higher percentages of K in the leached water. Biochar produced from poultry litter can be used as a good alternative to improve the chemical properties of Podzols and reduce nutrient losses.

Resumo O trabalho teve como objetivo avaliar o uso do lodo de esgoto tratado (LET) associado a substrato à base de casca de pinus (SC1) ou à base de fibra de coco (SC2), em diferentes proporções, como substrato para produção de mudas de vinhático. O experimento foi conduzido em casa de vegetação, localizada na unidade de apoio a pesquisa da Universidade Estadual do Norte Fluminense, de junho a novembro de 2016. Utilizaram-se 20, 40, 60, 80% de LET associados ao SC1 ou ao SC2, 100% de LET e o tratamento com SC1 com adubação convencional (controle). O lodo de esgoto foi higienizado com adição de cal a 15% do peso seco. Os resultados revelam que as menores proporções de LET no substrato resultaram em mudas com melhor crescimento em altura, diâmetro do coleto, área foliar, massa seca da parte aérea e do sistema radicular, comprimento e volume radicular. A nodulação foi negativamente influenciada nas mudas produzidas em proporções acima de 20% de LET. A agregação do torrão ao substrato não foi influenciada pela adição de LET, entretanto, houve aumento da curvatura do torrão nas mudas produzidas em maiores quantidades de LET. O conteúdo da parte aérea de N, P e K foi menor nas mudas produzidas em substrato com LET. Para produção de mudas de vinhático, sugere-se a proporção de 20% de lodo de esgoto associado ao SC1 ou SC2, não havendo prejuízos em relação às mudas produzidas em substrato comercial adubado, utilizado comercialmente.

Abstract The aim of this work was to evaluate the treated sewage sludge (LET) associated with commercial substrate based on pinus bark (SC1) or based on coconut fiber (SC2), in different proportions, as substrate for the production of vinhático seedlings. The study was led in a greenhouse, located in the research support unit of the State University of North Fluminense. The treatments considered as substrates were 20, 40, 60, 80% of LET associated with SC1 or SC2, 100% of LET and the treatment with SC1 with conventional fertilization (control). The sewage sludge was sanitized with addition of lime to 15% of dry weight. The results showed that the lower LET proportions in the substrate resulted in seedlings with better growth in height, stem diameter, leaf area, dry mass of shoot and root system, root length and volume. The nodulation was negatively influenced in the seedlings produced in proportions above 20% LET. The aggregation of the clod was not influenced by the addition of LET, however, there was increase of the curvature of the clod in the seedlings produced in larger amounts of LET. The shoot content of N, P and K was lower in the seedlings with LET. For the production of vinatic seedlings, 20% of sewage sludge associated with SC1 or SC2, is suggested, with no losses in relation to the seedlings produced in commercial substrate that received fertilization, used commercially.

As raízes, geralmente, são os primeiros órgãos das plantas a apresentarem sintomas de deficiência de B. Plantas de grande porte são difíceis de serem manipuladas experimentalmente a fim de diagnosticar os efeitos das deficiências minerais em seus sistemas radiculares. Neste experimento, objetivou-se elucidar o efeito da deficiência de B na formação de raízes de diferentes diâmetros e na acumulação de nutrientes, bem como caracterizar sintomas visuais da deficiência de B em raízes de coqueiro-anão verde. Foram aplicados os seguintes tratamentos: solução nutritiva completa (+B) e solução nutritiva sem B (-B), distribuídos em delineamento inteiramente casualizado, com seis repetições. A unidade experimental constou de uma planta em um vaso plástico com 90 L de areia de praia purificada. Até o 60º dia após o transplante (4/3/2006), todas as plantas receberam solução nutritiva completa. No 61º dia depois do transplante, aplicaram-se os tratamentos citados. Decorridos 513 dias da indução da deficiência, coletaram-se as raízes (1/6/2007); após o processo de lavagem, as raízes foram então separadas em três diâmetros: finas (< 1 mm), médias (1 a 5 mm) e grossas (> 5 mm). Depois da separação, imergiram-se as raízes em água várias vezes para retirada da areia e, finalmente, elas foram lavadas em água desionizada. Após secagem em estufa, determinou-se a massa seca de cada tipo de raiz e, posteriormente, os teores de N, P, K, Ca, Mg, S, B, Cu, Fe, Mn e Zn. Os resultados indicaram que os maiores teores de N, P, Ca, Mg, S, B, Cu, Fe, Mn e Zn foram encontrados nas raízes finas do coqueiro em ambos os tratamentos, porém os de K foram maiores nas raízes grossas. A deficiência de B aumentou os teores de N, P e K em todas as raízes, os teores de Mg, S, Cu e Zn nas raízes finas, mas não afetou os teores de Ca, Fe e Mn. A deficiência de B reduziu a produção de raízes totais e finas em 29,7 e 48,3 %, respectivamente, e promoveu o engrossamento e escurecimento das raízes com ramificações curtas; as pontas das raízes necrosaram, causando superbrotamento radicular.

Roots are usually the first plant organs where boron deficiency symptoms appear. The experimental evaluation of the effects of mineral deficiencies on the root system of trees is rather difficult. This experiment aimed to evaluate the effect of boron deficiency on the formation of roots with different diameters and on nutrient accumulation and to characterize visual symptoms of B deficiency in roots of green dwarf coconut trees. The following treatments were applied: complete nutrient solution (+B) and nutrient solution without boron (-B) in a randomized design, with six replicates. The experimental unit consisted of one plant in a plastic pot containing 90 L of purified beach sand. Until the 60th day (3/04/2006), all plants were treated with a complete nutrient solution. On the 61st day after transplanting the above treatments were applied. The roots were collected 513 days (6/01/2007) after the induction of deficiency. After washing, the roots were separated in three diameters: fine (< 1 mm), medium (1 to 5 mm) and thick (> 5 mm). After the separation, the roots were immersed in water several times to remove the sand and finally washed in deionized water. After oven-drying, the dry matter of each root type was determined and thereafter the concentrations of N, P, K, Ca, Mg, S, B, Cu, Fe, Mn, and Zn were determined. Results indicated that the highest N, P, Ca, Mg, S, B, Cu, Fe, Mn, and Zn concentrations were found in the fine roots of the coconut tree in both treatments, but those of K were higher in the thick roots. The boron deficiency increased the N, P and K concentrations in all roots, the Mg, S, Cu and Zn concentrations in the fine roots, but Ca, Fe and Mn were not affected. The boron deficiency reduced the production of total and fine roots by 29.7 and 48.3 %, respectively; it induced root thickening and darkening and short ramifications; the root tips died off, causing root overgrowth.

Em experimento realizado no campo, nos anos agrícolas 1996/97 e 1997/98, em Latossolo Amarelo distrófico, cultivado com cana-de-açúcar, avaliou-se o efeito de aplicações sucessivas de composto de lixo urbano sobre a movimentação, em profundidade, dos metais Cd, Cr, Cu, Ni, Pb e zinco. No primeiro ano agrícola, além do tratamento testemunha, o composto de lixo foi aplicado nas doses de 20, 40 e 60 Mg ha-1 (base seca). No segundo ano, o composto foi reaplicado nas doses de 24, 48 e 72 Mg ha-1. Em relação aos metais Cd, Cr, Cu, Ni e Pb não se observou nenhuma evidência de movimentação ao longo do perfil do solo. O Zn apresentou mobilidade no solo, onde se verificou, ao final de 1997/98, incrementos significativos até a camada de 0,4-0,6 m de profundidade.

From 1996 to 1998, a field experiment was carried out to study the effects of successive application of a municipal solid waste compost on the movement of Cd, Cr, Cu, Ni, Pb, and Zn through the profile of a Yellow Latossol (Typic Hapludox) cropped with sugarcane. The compost was applied at rates of 20, 40 and 60 Mg ha-1 (dry base) in the first year, and of 24, 48 and 72 Mg ha-1 in the second year, respectively, plus a control treatment. The results demonstrated that there was no movement of Cd, Cr, Cu, Ni, and Pb through the profile of this acid soil. Nevertheless, Zn mobility was verified at the end of the second year, when content of Zn increased from 0.4 to 0.6 m layer.

Experimento de campo foi conduzido, nos anos agrícolas 1996/97 e 1997/98, para avaliar os efeitos de aplicações sucessivas de composto de lixo urbano sobre os teores de carbono orgânico, condutividade elétrica, pH e capacidade de troca de cátions (CTC) ao pH atual de um Latossolo Amarelo distrófico em que foi cultivada cana-de-açúcar. No primeiro ano agrícola, além dos tratamentos calagem + adubação mineral e testemunha, o composto de lixo foi aplicado nas doses de 20, 40 e 60 Mg ha-1 (base seca). No segundo ano, o composto foi reaplicado nas doses de 24, 48 e 72 Mg ha-1. Todas as propriedades químicas do solo estudadas aumentaram com as doses do composto, em ambos os anos agrícolas. Os incrementos observados nesses atributos, da primeira para a segunda aplicação, foram significativos, exceto a condutividade elétrica, que, embora tenha aumentado logo após a aplicação do resíduo, não atingiu níveis críticos e teve seus valores reduzidos com o tempo. Acúmulos nos teores de C orgânico do solo foram diretamente proporcionais às doses de aplicação. O aumento da CTC do solo foi conseqüência direta dos incrementos nos teores de C orgânico e nos valores de pH.

A field experiment was conducted, during the years of 1996/97 and 1997/98, to evaluate the effects of the successive application of solid urban waste compost on organic carbon, electrical conductivity, pH, and cation exchange capacity (CEC) at field pH in a Typic Hapludox cropped with sugarcane. In the first year, besides lime + mineral fertilizer and control treatments, the compost was applied at a rate of 0, 20, 40, and 60 Mg ha-1 (dry basis). In the second year, the compost was reapplied at a rate of 24, 48, and 72 Mg ha-1. All studied soil properties increased with rate of compost application in both years. Attributes increments from the first to the second application were significant, except for electrical conductivity, which increased soon after the residue application, but did not reach critical levels and decreased along the time. Accumulation of organic C in soil was direct proportional to compost application rate. The increase of soil CEC was a consequence of the increments on organic C content and pH value.