Partition and macronutrients accumulation in pineapple under nitrogen doses and plant density

Studies related to the absorption and exportation capacity of macronutrients by irrigated pineapple are essential for the definition of adequate doses and fertilization management. The objective of this study was to evaluate the accumulation of biomass and macronutrients in the compartments (leaves, shoot, root, seedlings/slip, crown/top, and fruit) of ‘Vitória’ pineapple irrigated in the semiarid region after the use of nitrogen doses and population densities. The treatments, arranged in randomized blocks with three replicates, arranged in a 5x4 factorial scheme, consisted of five nitrogen doses (0, 5, 10, 15 and 20 g per plant) and four population densities (51,282, 76,923, 90,909, and 126,984 plants ha-1). The accumulation of biomass and macronutrients in the pineapple compartments was evaluated at the end of the growing cycle. The increase of N doses combined with the increase of the plant population promoted a linear increase in the accumulation of biomass and macronutrients by the pineapple plants. The leaves presented greater accumulation of macronutrients, followed by the seedlings, shoot, fruit, crown, and roots. The pineapple presented the following decreasing order of macronutrient absorption: K> N> Ca> P> Mg>S. At the dose of 20 g per plant of N and population of 126,984 plants ha-1 were exported from the area by fruits, 1,311 (12%), 150 (9%), 144 (11%), 52 (11%), 46 (12%) and 36 (12%) kg ha-1 of K, N, Ca, P, Mg, and S, respectively; and by the shoots, 2,426 (22%), 480 (29%), 147 (11%), 101 (21%), 67 (18%), and 45 (15%) kg ha-1 of K, N, Ca, P, Mg, and S, respectively.Studies related to the absorption and exportation capacity of macronutrients by irrigated pineapple are essential for the definition of adequate doses and fertilization management. The objective of this study was to evaluate the accumulation of biomass and macronutrients in the compartments (leaves, shoot, root, seedlings/slip, crown/top, and fruit) of ‘Vitória’ pineapple irrigated in the semiarid region after the use of nitrogen doses and population densities. The treatments, arranged in randomized blocks with three replicates, arranged in a 5x4 factorial scheme, consisted of five nitrogen doses (0, 5, 10, 15 and 20 g per plant) and four population densities (51,282, 76,923, 90,909, and 126,984 plants ha-1). The accumulation of biomass and macronutrients in the pineapple compartments was evaluated at the end of the growing cycle. The increase of N doses combined with the increase of the plant population promoted a linear increase in the accumulation of biomass and macronutrients by the pineapple plants. The leaves presented greater accumulation of macronutrients, followed by the seedlings, shoot, fruit, crown, and roots. The pineapple presented the following decreasing order of macronutrient absorption: K> N> Ca> P> Mg>S. At the dose of 20 g per plant of N and population of 126,984 plants ha-1 were exported from the area by fruits, 1,311 (12%), 150 (9%), 144 (11%), 52 (11%), 46 (12%) and 36 (12%) kg ha-1 of K, N, Ca, P, Mg, and S, respectively; and by the shoots, 2,426 (22%), 480 (29%), 147 (11%), 101 (21%), 67 (18%), and 45 (15%) kg ha-1 of K, N, Ca, P, Mg, and S, respectively

Estoques de carbono e nitrogênio em frações da matéria orgânica de solos cultivados com eucalipto nos sistemas convencional e fertirrigado

O presente estudo teve o objetivo de avaliar os estoques de C e N nas frações lábeis e estáveis da MOS e da biomassa microbiana em resposta ao cultivo florestal com o uso de fertirrigação quando comparado ao cultivo convencional. Para tanto, duas áreas cultivadas com eucalipto num mesmo solo (Argissolo Amarelo), mas com manejos fertirrigado e convencional foram amostradas nas camadas de 0-10, 10-20, 20-40, 40-60 e 60-100cm de profundidade na linha e entrelinha de cultivo. A amostragem da entrelinha foi justificada pelo enleiramento e enterro de resíduos vegetais provenientes da colheita do cultivo anterior na entrelinha do cultivo atual. No final do ciclo de cultivo do eucalipto (sete anos), a deposição de serapilheira e os estoques de C e N na maioria das frações lábeis e estáveis da MOS foram maiores no sistema fertirrigado, com incremento de 50,34t ha -1 de C total (COT) e 5,62t ha -1 de N total (NT), na camada de 0- 100cm de profundidade, em comparação àqueles do sistema convencional. O solo da entrelinha de plantio, principalmente no sistema fertirrigado, apresentou maior estoque de C e N total e C nas frações das substâncias húmicas e na fração leve da MOS que no solo da linha de plantio, possivelmente em virtude da maior deposição e incorporação de resíduos vegetais do ciclo anterior na entrelinha do cultivo atual. A intensificação do manejo de florestas comerciais de eucalipto com o uso de fertirrigação possibilita aumentar a deposição de resíduos vegetais e sequestrar mais C e N, tanto em frações estáveis, quanto em frações mais lábeis da MOS, especialmente nas camadas de solo de até 40cm de profundidade.The objective of this study was to evaluate the C and N stocks in fractions of labile and more stable SOM fractions in response to intensification of forest cultivation through fertirrigation when compared to conventional stands. To that end, two areas planted with eucalyptus in the same (Ultisol), but with different managements (fertilized and irrigated and conventional system) were sampled in the 0-10, 10-20, 20-40, 40-60 and 60-100cm deep soil layers in line and interrow of the cultivation. The sampling interrow soil was justified by the ridged and burial of plant residues from previous crop cultivation in-between the substrate. At seven years old, eucalypt under fertirrigation increased the litterfall and the C and N stocks in the most labile and stable SOM fractions, leading to greater stocks of C and N in the 0-100 cm deep soil layer. The increments due to fertirrigation observed for total C was 50.34 and for the labile fraction was 5.62t ha -1 . The eucalypt interrow soil, especially in the fertirrigated treatment, presented larger stocks of total C and N and also larger C stocks in humic substances and light fraction of SOM possibly due to greater deposition and incorporation of vegetable residues from the previous cycle in the interrow current cultivation. The intensification of water and nutrients usage in short-rotation eucalypt stands is an alternative to increase the deposition of vegetable residues and C sequestration in more stable and labile SOM fractions, especially in the 0-40cm soil layer

BIOMARCADORES DERIVADOS DE PLANTA E DE MICRORGANISMOS EM SOLOS DE TABULEIROS COSTEIROS CULTIVADOS COM EUCALIPTO E AC\uc1CIA

Changes in the management systems for the cultivation of different forest stands and the use of species rotation can lead to alterations in the quality of soil organic matter (SOM) and plant residue deposition. This study evaluated the stage of decomposition and the contribution of plant and microbial origin for SOM through biomarkers, such as lignin-derived phenols, carbohydrates and amino sugars in continuous short rotation eucalypt ( Eucalyptus urophylla x Eucalyptus grandis hybrid) (seven years) compared to a rotation system including acacia ( Acacia mangium Willd.) after short-rotation eucalypt; and long-rotation eucalypt (24 years). A native vegetation (Atlantic Forest) was used as a reference for the original site condition representative for the northern coast of Esp\uedrito Santo state. To do so, we estimated the content of total organic C (TOC), total N (TN) and the contents of lignin-derived phenols (VSC), the carbohydrates and the amino sugars derived from soil microorganisms, and acids/aldehyde ratio of groups vanilil ((Ac/Al)vanilil) and syringyl ((Ac/Al)syringyl) of the lignin, hexoses/pentoses (H/P) ratio of carbohydrates, besides glucosamine/muramic acid (Gluc/Ac. Mur) and glucosamine/galactosamine (Gluc/Gal) ratios for soil and litter samples. The results indicated that litter of the continuous short-rotation eucalypt has greater dry mass, lignin (VSC) and carbohydrates contents, C/N and VSC/N ratios; a similar proportion of coarse litter to fine litter and C content, but a lower N content in comparison to the species rotation system that includes the leguminous acacia. In the soil, acacia cultivation increases C, N and carbohydrates content, widened the acid/aldehyde ratio of vanilil groups of lignin and the glucosamine/muramic acid ratio of amino sugars derived from microbial activity. The longer rotation of eucalypt (24 years) increased C content and decreased the VSC/N ratio in SOM compared to the continuous short-rotation eucalypt, but still having C and N content lower than in soil of acacia and native forest. The smallest Ac/Al ratio of lignin-derived phenols in soils cultivated with eucalypt (in long and short-rotation) indicates that the SOM is in less advanced stage of decomposition (humification) than in the soil cultivated with acacia, and that under native forest. In soils under acacia, followed by that of short-rotation eucalypt, the higher glucosamine/muramic acid ratio suggested a greater contribution of fungi in SOM cycling, whereas in the native forest and long-rotation eucalypt there is greater abundance of bacteria-derived compounds. Overall, the results indicate that there was a recovery in the quality of the soils cultivated with eucalypt for a longer rotation and also with acacia in relation to the continuous short-rotation eucalypt.Altera\ue7\uf5es no sistema de manejo pelo cultivo de diferentes povoamentos florestais e a utiliza\ue7\ue3o de rota\ue7\ue3o de culturas podem levar a altera\ue7\uf5es na qualidade da mat\ue9ria org\ue2nica do solo (MOS) e deposi\ue7\ue3o de res\uedduos vegetais. O presente estudo avaliou o est\ue1dio de decomposi\ue7\ue3o e a contribui\ue7\ue3o de compostos de origem vegetal e microbiana para a MOS por meio de biomarcadores, tais como: fen\uf3is derivados de lignina, carboidratos e aminoa\ue7\ufacares em monocultivos do Eucalyptus urograndis (clone do Eucalyptus urophylla S. T. Blake x Eucalyptus grandis W. Hill ex Spreng) de ciclo curto (sete anos), sistemas de cultivo de rota\ue7\ue3o de ac\ue1cia ( Acacia mangium Willd.) ap\uf3s monocultivo de eucalipto, monocultivo de eucalipto de ciclo longo (24 anos) e mata nativa (Mata Atl\ue2ntica) como condi\ue7\ue3o original de solo do litoral Norte do Esp\uedrito do Santo. Para tanto, foram estimados nas amostras de solo e serapilheira os teores de C org\ue2nico total (COT), N total (NT), teores de fen\uf3is derivados de lignina (VSC), carboidratos e aminoa\ue7\ufacares derivados da atividade microbiana no solo e, as rela\ue7\uf5es \ue1cidos e alde\ueddos dos grupamentos vanilil ((Ac/Al)Vanilil) e siringil ((Ac/Al)Siringil) da lignina, rela\ue7\ue3o hexoses/pentoses (H/P) dos carboidratos e, rela\ue7\uf5es glucosamina/\ue1cido mur\ue2mico (Gluc/Mur.) e glucosamina/galactosamina (Gluc/Gal) dos aminoa\ue7\ufacares. Os resultados indicaram que na serapilheira do monocultivo de eucalipto de ciclo curto houve maior deposi\ue7\ue3o da mat\ue9ria seca, teor de lignina (VSC) e carboidratos, rela\ue7\ue3o C/N e VSC/N; Semelhante propor\ue7\ue3o de res\uedduos grossos, res\uedduos finos e teor de C e, menor teor de N, comparado \ue0quela sob rota\ue7\ue3o de ac\ue1cia. No solo, o cultivo de ac\ue1cia aumentou os teores de C, N e carboidratos, aumentou a rela\ue7\ue3o \ue1cido/alde\ueddo do grupamento vanilil da lignina e a rela\ue7\ue3o glucosamina/\ue1cido mur\ue2mico dos aminoa\ue7\ufacares derivados da atividade microbiana. O aumento do tempo de cultivo do eucalipto (24 anos) incrementou o teor de C e reduziu a rela\ue7\ue3o VSC/N na MOS em compara\ue7\ue3o ao monocultivo de eucalipto de ciclo curto, e apresentou teor de C e N inferiores \ue0queles observados no solo de ac\ue1cia e mata nativa. A menor rela\ue7\ue3o \ue1cidos/ alde\ueddos (Ac/Al) dos fen\uf3is derivados de lignina no solo cultivado com eucalipto (de curto e longo ciclo) indica que a MOS encontra-se em est\ue1dio menos avan\ue7ado de decomposi\ue7\ue3o do que no solo cultivado com ac\ue1cia, e naquele de mata nativa. Nos solos de ac\ue1cia, seguido por aquele de eucalipto, a maior rela\ue7\ue3o glucosamina/\ue1cido mur\ue2mico sugere maior participa\ue7\ue3o de fungos na comunidade microbiana, enquanto nas \ue1reas de mata nativa e eucalipto de ciclo longo h\ue1 mais abund\ue2ncia de compostos derivados de bact\ue9rias. Neste sentido, observou-se a recupera\ue7\ue3o na qualidade do solo cultivado com eucalipto de ciclo longo e rotacionado com ac\ue1cia em rela\ue7\ue3o ao monocultivo de eucalipto de ciclo curto

Chickpea production in response to fertilization with zinc and doses of phosphorus

Chickpea cultivation in Brazil has not yet been consolidated, and studies aiming at the adequate nutritional management for this crop are necessary. This work aimed to evaluate the production of chickpea plants (cultivar BRS Aleppo) subjected to fertilization with zinc and P doses. The experimental was completely randomized, with four replications, in a 3 x 5 factorial scheme, corresponding to three fertilization treatments with Zn (without Zn addition; 50% of Zn applied at sowing, via soil + 50% applied at flowering, via leaves; and 100% applied at sowing, via soil) and five doses of phosphorus (0, 60, 120, 180, and 240 kg ha-1 of P2O5). The 100-grain mass (M100), pod mass (MV), number of pods (NV), number of grains (NG), total grain mass (MGT), yield (PROD), dry matter of the shoot part (MSPA) and plant residues (MSRV), and agronomic efficiency (EA) were characterized. There was an isolated effect of the P doses on the M100, MGT, PROD, MSPA, and MSRV characteristics. The application of 240 kg ha-1 resulted in an increase in the production components and a maximum yield of 3,018 kg ha-1, indicating the need to adopt higher doses of P2O5 to increase chickpea production in tropical soils. However, the highest agronomic efficiency was obtained after the application of 60 kg ha-1 of P2O5, along with Zn at sowing.Chickpea cultivation in Brazil has not yet been consolidated, and studies aiming at the adequate nutritional management for this crop are necessary. This work aimed to evaluate the production of chickpea plants (cultivar BRS Aleppo) subjected to fertilization with zinc and P doses. The experimental was completely randomized, with four replications, in a 3 x 5 factorial scheme, corresponding to three fertilization treatments with Zn (without Zn addition; 50% of Zn applied at sowing, via soil + 50% applied at flowering, via leaves; and 100% applied at sowing, via soil) and five doses of phosphorus (0, 60, 120, 180, and 240 kg ha-1 of P2O5). The 100-grain mass (M100), pod mass (MV), number of pods (NV), number of grains (NG), total grain mass (MGT), yield (PROD), dry matter of the shoot part (MSPA) and plant residues (MSRV), and agronomic efficiency (EA) were characterized. There was an isolated effect of the P doses on the M100, MGT, PROD, MSPA, and MSRV characteristics. The application of 240 kg ha-1 resulted in an increase in the production components and a maximum yield of 3,018 kg ha-1, indicating the need to adopt higher doses of P2O5 to increase chickpea production in tropical soils. However, the highest agronomic efficiency was obtained after the application of 60 kg ha-1 of P2O5, along with Zn at sowing

Are biomass partitioning and nutrient accumulation in industrial tomato influenced by NPK fertilization?

This study aimed to evaluate the uptake, accumulation, and partitioning of nitrogen (N), phosphorus (P), and potassium (K) in the tomato crop fertilized with doses of NPK. The main plots consisted of three doses of N: 90, 135, and 180 kg ha-1, P: 270, 405, and 540 kg ha-1, and K: 225, 337, and 450 kg ha-1 (equivalent to 50, 75, and 100 % of the fertilization recommendation for industrial tomato), while the subplots consisted of the evaluation periods: 20, 40, 60, 80, and 100 days after transplanting (DAT). The dry matter and the accumulation of N, P, and K were characterized in the different plant components (leaves, stems, fruits, and total). The order of nutrient uptake for the hybrid BRS Sena was defined as K> N> P. The dose corresponding to 50 % NPK resulted in the maximum accumulation of total dry matter of 400 g per plant at 64 DAT and the total accumulation of 10, 1.14, and 14.51 g per plant of N, P, and K, respectively. The intermediate dose of NPK resulted in the maximum accumulation of total dry matter of 468 g and accumulations of 14, 1.6, and 19 g per plant of N, P, and K. At 100 % of the NPK recommendation, there was 514 g per plant of total dry matter, with maximum accumulations of 15, 1.6, and 18 g per plant of N, P, and K. The maximum accumulation rate of N, P, and K occurs at 60, 64, and 70 DAT for the fertilization recommendations corresponding to 50, 75, and 100 % NPK, respectively.Objetivou-se avaliar a absorção, acúmulo e partição de nitrogênio (N), fósforo (P) e potássio (K) pelo tomate rasteiro irrigado com doses de NPK. O delineamento experimental foi blocos ao acaso, com quatro repetições. As parcelas principais foram constituídas de três doses de N: 90, 135 e 180 kg ha-1, P: 270, 405 e 540 kg ha-1 e K: 225, 337 e 450 kg ha-1 (equivalentes a 50, 75 e 100% da recomendação de adubação para o tomateiro industrial) e nas subparcelas foram amostradas plantas nas épocas: 20, 40, 60, 80 e 100 dias após o transplantio (DAT). Caracterizou-se a matéria seca e acúmulo de N, P e K, nos componentes da planta (folha, haste, frutos e total). A ordem de absorção de nutrientes para o BRS Sena foi K>N>P. Na dose 50% de NPK houve máximo acúmulo de 400 g por planta de matéria seca total aos 64 DAT, e acúmulo total de 10; 1,14 e 14,51 g por planta de N, P e K, respectivamente. Na dose intermediária da recomendação de adubação NPK com produção 468 g por planta de matéria seca total houve acúmulos de 14; 1,6 e 19 g por planta de N, P e K. Em 100% da recomendação de adubação NPK, houve 514 g por planta de matéria seca total com máximos acúmulos de 15; 1,6 e 18 g por planta de N, P e K. A taxa de máximo acúmulo de N, P e K ocorre aos 60, 64 e 70 DAT para as recomendações de adubação 50, 75 e 100% NPK, respectivamente. A exportação dos macronutrientes seguiu a ordem decrescente K>N>P, para todas as recomendações de adubação NPK

ABUNDÂNCIA NATURAL DE 15N E FORMAS DE NITROGÊNIO EM ARGISSOLO CULTIVADO COM EUCALIPTO E ACÁCIA

http://dx.doi.org/10.5902/1980509821121The nutrients nitrogen and one of the most demanded by plant species, and its presence in soil under organic or mineral forms available to plants is linked to quality and quatity of plant residues added to the soil. The study aimed to evaluate the influence of cultivation of eucalyptus and acacia in the composition of organic and inorganic N forms and the natural abundance of 15N in an Ultisol. For this, we collected soil and litter samples in continuous short-rotation eucalypt (Eucalyptus urophylla x Eucalyptus grandis hybrid) (seven years) compared to a rotation system including acacia (Acacia mangium Willd.) after short-rotation eucalypt; and long-rotation eucalypt (24 years). A native vegetation (Atlantic Forest) was used as a reference for the original site condition representative for the northern coast of  Espírito Santo state. To do so, we evaluated the content of total organic C, total N, N-NH4+, N-NO3-, C/N ratio, fractionation of organic N and 15N natural abundance in soil and litter. Among the forms of organic-N hydrolyzed, the N-amino was the fraction with the highest contribution of organic N (39%), followed by the fraction of N-unidentified (27%), the fraction of N-amide (18%) and N-hexosamine (15%). The acacia plantation presented smaller natural abundance of 15N and higher levels of total N and soil organic C, and increased organic forms of N-hydrolyzed, when compared to the eucalyptus short-rotation soil. This indicates the increase of labile N-organic forms in the soil for the plants and reduction of humification of soil organic matter (SOM) of acacia. Thus, the crops rotation with acacia after eucalyptus contributed to the increase of organic forms in the soil, important for the nutrition of plants, because they are potential sources of nutrients to the plants in a short-time period.The nutrients nitrogen and one of the most demanded by plant species, and its presence in soil under organic or mineral forms available to plants is linked to quality and quatity of plant residues added to the soil. The study aimed to evaluate the influence of cultivation of eucalyptus and acacia in the composition of organic and inorganic N forms and the natural abundance of 15N in an Ultisol. For this, we collected soil and litter samples in continuous short-rotation eucalypt (Eucalyptus urophylla x Eucalyptus grandis hybrid) (seven years) compared to a rotation system including acacia (Acacia mangium Willd.) after short-rotation eucalypt; and long-rotation eucalypt (24 years). A native vegetation (Atlantic Forest) was used as a reference for the original site condition representative for the northern coast of  Espírito Santo state. To do so, we evaluated the content of total organic C, total N, N-NH4+, N-NO3-, C/N ratio, fractionation of organic N and 15N natural abundance in soil and litter. Among the forms of organic-N hydrolyzed, the N-amino was the fraction with the highest contribution of organic N (39%), followed by the fraction of N-unidentified (27%), the fraction of N-amide (18%) and N-hexosamine (15%). The acacia plantation presented smaller natural abundance of 15N and higher levels of total N and soil organic C, and increased organic forms of N-hydrolyzed, when compared to the eucalyptus short-rotation soil. This indicates the increase of labile N-organic forms in the soil for the plants and reduction of humification of soil organic matter (SOM) of acacia. Thus, the crops rotation with acacia after eucalyptus contributed to the increase of organic forms in the soil, important for the nutrition of plants, because they are potential sources of nutrients to the plants in a short-time period.http://dx.doi.org/10.5902/1980509821121O nitrogênio e um dos nutrientes mais demandados pelas espécies vegetais, sua presença no solo, sob formas orgânicas ou minerais disponíveis para as plantas, está vinculada à qualidade e quantidade dos resíduos vegetais aportados ao solo. O estudo teve o objetivo de avaliar a influência do cultivo do eucalipto e da acácia na composição das formas orgânicas e inorgânicas de N e, na abundância natural de 15N em um Argissolo Amarelo. Para isso, foram coletadas amostras de solo e serapilheira em monocultivos do Eucalyptus urograndis (clone do Eucalyptus urophylla S. T. Blake x Eucalyptus grandis W. Hill ex Spreng) de ciclo curto (sete anos), sistemas de cultivo de rotação de acácia (Acacia mangium Willd.) após monocultivo de eucalipto, monocultivo de eucalipto de ciclo longo (24 anos) e mata nativa (Mata Atlântica) como condição original de solo do litoral Norte do Espírito do Santo. Foram avaliados os teores de C orgânico total, N total, N-NH4+, N-NO3-, relação C/N, fracionamento do N orgânico e abundância natural de 15N no solo e serapilheira. Das formas de N-orgânico hidrolisado, o N- amino foi a fração que apresentou maior contribuição (39%), seguida pela fração de N- não identificado (27%), da fração N-amida (18%) e N-hexosamina (15%). O povoamento de acácia promoveu menor abundância natural de 15N e maiores teores de N total e C orgânico no solo e aumentou as formas orgânicas de N-hidrolisado, quando comparado àqueles de eucalipto de ciclo curto. Isto indica o aumento de formas lábeis de N orgânico no solo para as plantas e redução da humificação da matéria orgânica do solo (MOS) de acácia. Neste sentido, a rotação de cultivos florestais com acácia após eucalipto de ciclo curto contribuiu para o aumento de formas orgânicas no solo, importantes para a nutrição de plantas, por serem potenciais fontes de nutrientes às plantas em curto período de tempo

CARBON AND NITROGEN STOCKS IN THE ALFISOL SUBMITTED TO THE Eucalyptus urograndis MONOCULTURE AND Acacia mangium ROTATION

A busca de sistemas sustent\ue1veis de manejo do solo tem levado pesquisadores a desenvolverem novas t\ue9cnicas de cultivo. Dentre elas, destacam-se no Brasil estudos realizados com esp\ue9cies florestais capazes de fixar N2 atmosf\ue9rico e aumentar o estoque de C e N em fra\ue7\uf5es l\ue1beis e est\ue1veis da mat\ue9ria org\ue2nica do solo (MOS). O presente estudo teve por objetivo avaliar as altera\ue7\uf5es nos estoques de C e N em fra\ue7\uf5es das subst\ue2ncias h\ufamicas, da fra\ue7\ue3o leve da MOS e da mat\ue9ria microbiana em solos cultivados com Eucalyptus urograndis em rota\ue7\ue3o curta, eucalipto em rota\ue7\ue3o longa e povoamentos de Acacia mangium que sucederam plantios de eucalipto em rota\ue7\ue3o curta, tendo como refer\ueancia o solo de floresta nativa (Mata Atl\ue2ntica) adjacente. Foram quantificados os estoques de C org\ue2nico total e N total (COT e NT), nas fra\ue7\uf5es das subst\ue2ncias h\ufamicas (fra\ue7\ue3o \ue1cido f\ufalvico-AF, fra\ue7\ue3o \ue1cido h\ufamico-AH e fra\ue7\ue3o humina-H), C e N da fra\ue7\ue3o leve da MOS (C-MOL e N-MOL) e estoque de C e N da mat\ue9ria microbiana (C-BM e N-BM). Os resultados indicaram que o cultivo do eucalipto em rota\ue7\ue3o curta apresentou menores estoques de COT e NT, nas fra\ue7\uf5es das subst\ue2ncias h\ufamicas e, de N na mat\ue9ria microbiana em compara\ue7\ue3o ao solo sob rota\ue7\ue3o com Acacia mangium. O cultivo de Acacia mangium e o aumento do tempo da rota\ue7\ue3o do eucalipto incrementaram os estoques de C e N da maioria das fra\ue7\uf5es l\ue1beis (C-MOL, N-MOL e C-BM) e est\ue1veis (C e N nas subst\ue2ncias h\ufamicas), indicando tend\ueancia de recupera\ue7\ue3o dos seus estoques para valores pr\uf3ximos daqueles originais (mata nativa), sendo superiores aos estoques obtidos na \ue1rea de eucalipto em rota\ue7\ue3o curta.The pursuit of sustainable systems of soil management has led researchers to develop new techniques of cultivation. Among them, studies with forest species able to fix atmospheric N2 and increase C and N stocks in labile and stable soil organic matter (SOM) stand out in Brazil. The study aimed to evaluate changes in stocks of C and N in fractions of humic substances, light fraction of SOM and microbial biomass in soils of short-rotation Eucalyptus \u201curograndis\u201d, long rotation plantations and stands of Acacia mangium which succeeded short rotation eucalyptus monoculture, in comparison to the soil of native forest (Atlantic Forest). It was obtained the total organic carbon (TOC) and total nitrogen (TN) stocks, C and N stocks in the fractions of humic substances (fulvic acid fraction-AF, humic acid fraction-HA and humin fraction-H), C and N in light fraction of SOM (C-LOM and N-LOM) and C and N microbial biomass (CMB and N-MB). The results indicated that the short rotation eucalyptus cultivation reduced total organic carbon stocks, total nitrogen, C and N in the humic substances, and N storage in the microbial biomass compared to Acacia mangium soil. The cultivation of Acacia mangium and the increase of the eucalyptus rotation time increased stocks of C and N of the labile (C-LOM, N-LOM and C-MB) and stable fractions (C and N in humic substances) indicating a significant recovery of their stocks to levels approaching those original (native), and higher than stocks obtained in the soil of short rotation eucalypt

THE 15N NATURAL ABUNDANCE AND NITROGEN FORMS IN ULTISOL CULTIVATED WITH EUCALYPTUS AND ACACIA

O nitrog\ueanio e um dos nutrientes mais demandados pelas esp\ue9cies vegetais, sua presen\ue7a no solo, sob formas org\ue2nicas ou minerais dispon\uedveis para as plantas, est\ue1 vinculada \ue0 qualidade e quantidade dos res\uedduos vegetais aportados ao solo. O estudo teve o objetivo de avaliar a influ\ueancia do cultivo do eucalipto e da ac\ue1cia na composi\ue7\ue3o das formas org\ue2nicas e inorg\ue2nicas de N e, na abund\ue2ncia natural de 15N em um Argissolo Amarelo. Para isso, foram coletadas amostras de solo e serapilheira em monocultivos do Eucalyptus urograndis (clone do Eucalyptus urophylla S. T. Blake x Eucalyptus grandis W. Hill ex Spreng) de ciclo curto (sete anos), sistemas de cultivo de rota\ue7\ue3o com ac\ue1cia ( Acacia mangium Willd.) ap\uf3s monocultivo de eucalipto, monocultivo de eucalipto de ciclo longo (24 anos) e mata nativa (Mata Atl\ue2ntica) como condi\ue7\ue3o original de solo do litoral Norte do Esp\uedrito do Santo. Foram avaliados os teores de C org\ue2nico total, N total, N-NH4+, N-NO3-, rela\ue7\ue3o C/N, fracionamento do N org\ue2nico e abund\ue2ncia natural de 15N no solo e serapilheira. Das formas de N-org\ue2nico hidrolisado, o N-amino foi a fra\ue7\ue3o que apresentou maior contribui\ue7\ue3o (39%), seguida pela fra\ue7\ue3o de N-n\ue3o identificado (27%), da fra\ue7\ue3o N-amida (18%) e N-hexosamina (15%). O povoamento de ac\ue1cia promoveu menor abund\ue2ncia natural de 15N e maiores teores de N total e C org\ue2nico no solo e aumentou as formas org\ue2nicas de N-hidrolisado, quando comparado \ue0queles de eucalipto de ciclo curto. Isso indica o aumento de formas l\ue1beis de N org\ue2nico no solo para as plantas e redu\ue7\ue3o da humifica\ue7\ue3o da mat\ue9ria org\ue2nica do solo (MOS) de ac\ue1cia. Nesse sentido, a rota\ue7\ue3o de cultivos florestais com ac\ue1cia ap\uf3s eucalipto de ciclo curto contribuiu para o aumento de formas org\ue2nicas no solo, importantes para a nutri\ue7\ue3o de plantas, por serem potenciais fontes de nutrientes \ue0s plantas em curto per\uedodo de tempo.The nutrients nitrogen and one of the most demanded by plant species, and its presence in soil under organic or mineral forms available to plants is linked to quality and quatity of plant residues added to the soil. The study aimed to evaluate the influence of cultivation of eucalyptus and acacia in the composition of organic and inorganic N forms and the natural abundance of 15N in an Ultisol. For this, we collected soil and litter samples in continuous short-rotation eucalypt ( Eucalyptus urophylla x Eucalyptus grandis hybrid) (seven years) compared to a rotation system including acacia ( Acacia mangium Willd.) after short-rotation eucalypt; and long-rotation eucalypt (24 years). A native vegetation (Atlantic Forest) was used as a reference for the original site condition representative for the northern coast of Esp\uedrito Santo state. To do so, we evaluated the content of total organic C, total N, N-NH4+, N-NO3-, C/N ratio, fractionation of organic N and 15N natural abundance in soil and litter. Among the forms of organic-N hydrolyzed, the N-amino was the fraction with the highest contribution of organic N (39%), followed by the fraction of N-unidentified (27%), the fraction of N-amide (18%) and N-hexosamine (15%). The acacia plantation presented smaller natural abundance of 15N and higher levels of total N and soil organic C, and increased organic forms of N-hydrolyzed, when compared to the eucalyptus short-rotation soil. This indicates the increase of labile N-organic forms in the soil for the plants and reduction of humification of soil organic matter (SOM) of acacia. Thus, the crops rotation with acacia after eucalyptus contributed to the increase of organic forms in the soil, important for the nutrition of plants, because they are potential sources of nutrients to the plants in a short-time period

Carbon and nitrogen stocks in organic matter fractions in alfisol under eucalypt and pasture

O cultivo de florestas plantadas de eucalipto em \ue1reas de pastagem tem propiciado altera\ue7\uf5es no estoque de C e N no solo, em especial pelas diferentes caracter\uedsticas de cada planta e manejo dos res\uedduos vegetais; o eucalipto pode localizar maior estoque de C e N origin\ue1rio de res\uedduos da parte a\ue9rea na camada superficial do solo, e aumentar a rela\ue7\ue3o C/N dos res\uedduos vegetais em decomposi\ue7\ue3o. Tais diferen\ue7as podem causar redu\ue7\ue3o no estoque de C e N nas fra\ue7\uf5es qu\uedmicas, f\uedsicas e biol\uf3gicas do solo, tanto nas fra\ue7\uf5es mais l\ue1beis, quanto nas mais recalcitrantes. Este trabalho teve como objetivo avaliar os estoques de C org\ue2nico total (COT) e N total (NT), estoque de C e N nas subst\ue2ncias h\ufamicas (\ue1cidos f\ufalvicos, h\ufamicos e h\ufaminas), fra\ue7\ue3o leve (C-MOL e N-MOL) e biomassa microbiana (C-BM e N-BM) em amostras de solos coletadas nas camadas de 0-0,10, 0,10-0,20, 0,20-0,40, 0,40-0,60 e 0,60-1,00 m de profundidade, na linha (EL) e entrelinha (EEL) do solo sob cultivo de eucalipto na quarta rota\ue7\ue3o com seis anos de idade, e em \ue1rea de pastagem cultivada com brachiaria (P). O estoque de carbono org\ue2nico total e de carbono na fra\ue7\ue3o leve do solo nas primeiras camadas do solo (at\ue9 0,60 m) foi superior na entrelinha do eucalipto em compara\ue7\ue3o \ue0quele cultivado com pastagem e na linha de cultivo do eucalipto, possivelmente favorecido pela incorpora\ue7\ue3o de res\uedduos da colheita do ciclo anterior de eucalipto na atual entrelinha. Por meio da determina\ue7\ue3o da abund\ue2ncia natural de 13 na camada de 0-0,20m de solo verificou-se que 29 e 37% do carbono presente na mat\ue9ria org\ue2nica do solo (MOS) ap\uf3s 28 anos de cultivo derivaram do eucalipto (planta C3), respectivamente, na linha e entrelinha, o que correspondeu \ue0 taxa de ciclagem m\ue9dia da MOS nesse solo de 1,04% (linha) e 1,32% (entrelinha) ao ano. No solo da entrelinha, observou-se que o C-C3 proveniente do eucalipto incrementou o estoque de C org\ue2nico do solo, mesmo com a substitui\ue7\ue3o do C-C4 proveniente da pastagem, ap\uf3s 28 anos de cultivo do eucalipto. Para o nitrog\ueanio nas subst\ue2ncias h\ufamicas, verificou-se estoques semelhantes entre o solo da entrelinha do eucalipto e o de pastagem, e superior ao do solo da linha do eucalipto, at\ue9 1 m de profundidade. O solo de eucalipto (EL e EEL) teve estoques de C e N na biomassa microbiana semelhante \ue0quele cultivado com pastagem.The cultivation of eucalypt in areas of pasture has resulted in changes of C and N storage in soil, mainly due to the different characteristics of each plant and their biomass management; the largest stock of C and N can be found under eucalypt, originating from the biomass at the soil surface layer and increasing the C/N in decomposition of plant residues. These differences may cause a decrease in the storage of C and N fractions in the chemical, physical and biological soil, both in the more labile, an the more recalcitrant fractions. This study aimed to evaluate the stocks of total organic carbon (TOC) and total N (TN), the stock of C and N in humic substances (fulvic acids, humic and humin), the light fraction (C-MOL and N-MOL) and the microbial biomass (C-BM and N-BM) in samples of collected from the layers 0-0.10, 0.10-0.20, 0.20-0.40, 0.40-0.60 and 0.60-1.00 m in depth, line (EL) and interline (EEL) from the soil under eucalypt in the fourth rotation with six years of age, and from an area of cultivated pasture with Brachiaria (P). The total organic carbon stock and carbon in the light fraction in the first layers of soil (0.60 m) was higher in the interline of eucalypt compared with that from the cultivated pasture and the line of eucalypt, probably favored by harvest residue from the previous cycle of eucalypt buried in the current interline. By determining the natural abundance of 13 in the 0-0.20m soil, it was found that 29% and 37% of carbon present in the soil organic matter (SOM) after 28 years of cultivation in the line and interline, respectively, was derived from eucalypt (C3 plants), which corresponded to an average rate of cycling of SOM in this soil of 1.04% (line) and 1.32% (interline) per year. In the soil interline it was observed that the C-C3 from the eucalypt increased the stock of soil organic C, even with the replacement of C-C4 from the pasture, after 28 years of eucalypt cultivation. For nitrogen in humic substances, a similar stock was obtained for the soil of the interline of eucalypt and that of the pasture, which was higher than that of the soil line of eucalypt, up to 1 m deep. The soil of eucalypt (EL and EEL) showed a stock of C and N in microbial biomass similar to that of cultivated pasture