CARBON AND NITROGEN IN SOILS AND HUMIC FRACTIONS OF DIFFERENT PEDOFORMS IN THE ATLANTIC FOREST BIOME

Relief is a soil formation factor that can modify the distribution of soil organic matter (SOM) fractions in a landscape. The objective of this study was to evaluate the effect of the relief on SOM fractions, considering their distribution in different topographic positions, segments, in two pedoforms (concave and convex) in areas covered with forest in the Atlantic Forest biome. The two pedoforms were selected in adjacent areas and divided into segments considering the topographic variation. The carbon and nitrogen origins were evaluated in the extract up to 100 cm of depth. Soil samples from the 0-5, 5-10, and 10-20 cm layers were collected for chemical characterization and fractioning (granulometric and chemical) of the SOM. The soil density in the 0-5 and 5-10 cm layers was determined to calculated the carbon stocks. The isotopic composition showed predominance of 13C. The highest organic carbon and particulate carbon contents were found in the convex pedoform. The distribution of humic fractions showed that the larger part of the humidified carbon was in the humin fraction. The humin and fulvic acid fractions were higher in the convex pedoform. The carbon stocks were, in general, higher in the convex pedoform, decreasing as the soil depth increased; and nitrogen stocks presented no differences. The higher carbon and nitrogen contents were found in the convex pedoform and in the lower region of the concave pedoform

INFLUENCE OF SOIL COVER ON ORGANIC MATTER AND EDAPHIC VARIABLES IN ITATIAIA-RJ NATIONAL PARK

Forest ecosystems in the Middle Valley region of Paraíba do Sul have undergone profound changes throughout history. Currently, degraded pastures and secondary forest fragments predominate in different successional stages, responsible for numerous environmental services, among them the sequestration and stabilization of CO2. In order to understand successional processes, their influence on soil variables and soil organic matter (SOM), different land uses and geomorphological diversity must be considered, since environmental variability can influence this dynamic. The objectives of the study were to evaluate physical and chemical variables and the organic matter of soils located in the southern slope of the Itatiaia National Park (RJ); as well as to characterize possible patterns under coverings of Dense Ombrophilous Forest and pastures and indicate which cover would accumulate the highest levels of carbon (C) and in its most stable forms. The pasture areas had the highest C averages, but more stable fractions of SOM were found in the different stages of forest succession. An increase in SOM stability was also observed due to the progression of successional stages

No-tillage in organic production system: production parameters and biomass decomposition

Soils of sandy texture in the first layers are of great occurrence throughout Brazil. Because of its fragility, it is essential to use crop practices, such as the adoption of a no-tillage system, to promote benefits to these soils. The objective of this study was to evaluate biomass production, nutrient accumulation, decomposition rates, half-life time and dynamics of the N, P and K release of cover crops residues in organic vegetables cropping on no-tillage system in Seropédica-RJ. The experiment was conducted using a randomized block design with multiple replicates and six fractions: crotalaria (Crotalaria juncea), forage peanuts (Arachis pintoi), brachiaria (Brachiaria brizantha), millet (Pennisetum americanum), a cocktail of seeds, and an area of spontaneous vegetation. Dry matter decomposition and nutrient release were evaluated at 15, 30, 60, 90 and 120 days by the litter-bags method. Crotalaria presented higher dry mass production (15.48 Mg ha-1). The legumes had the highest N contents, being the largest values in the crotalaria. For K, the crotalaria also presented the highest values. In relation to decomposition and nutrient release the millet presented the highest half-life time (98 days), while the peanut presented the lowest (23 days).Solos de textura superficial arenosa são de grande ocorrência em todo o Brasil. Em função dessa fragilidade, torna-se indispensável o emprego de práticas culturais, como a adoção do sistema de plantio direto a fim de promover uma série de benefícios a estes solos. Neste estudo objetivou-se avaliar a produção de fitomassa, o acúmulo de nutrientes, as taxas de decomposição, tempo de meia vida e dinâmica da liberação de N, P e K de resíduos de plantas de cobertura para cultivo de hortaliças orgânicas sobre plantio direto em Seropédica-RJ. O experimento foi conduzido utilizando o delineamento em blocos ao acaso com quatro repetições e seis tratamentos: crotalária (Crotalaria juncea), amendoim forrageiro (Arachis pintoi), braquiária (Brachiaria brizantha), milheto (Pennisetum americanum), um coquetel das sementes e uma área de vegetação espontânea. A decomposição de massa seca e a liberação de nutrientes foram avaliados aos 15, 30, 60, 90 e 120 dias através de sacolas de decomposição (litter bags). A crotalária apresentou maior produção de massa seca (15,48 Mg ha-1). As leguminosas apresentaram os maiores teores de N, sendo o maior acúmulo observado na crotalária. Já para K a crotalária também apresentou os maiores valores. Em relação à decomposição de massa seca e a liberação de nutrientes o milheto foi à planta de cobertura que apresentou o maior T1/2 vida (98 dias), enquanto o amendoim apresentou o menor (23 dias).   &nbsp

RUBBER TREE RESPONSE TO N, P and K DOSES IN FERTILIZATION AT PLANTING

The objective of this study was to evaluate the growth, root and shoot dry mass accumulation and nutritional status of rubber tree in the initial stage of cultivation, under different combinations of nitrogen (N), phosphorus (P) and potassium (K). Combinations of the following doses were tested: 0, 20, 40 and 80 kg ha-1 of N; 0, 75, 150 and 300 kg ha-1 of P2O5; and 0, 25, 50 and 100 kg of K2O. Under the soil and climate conditions analyzed, the combinations of NPK fertilization applied at planting only caused significant growth responses of rubber tree plants as a function of the absence of N and its presence at the dose of 80 kg ha-1. Through leaf analysis it was possible to verify that N fertilization and P fertilization are adequately meeting the needs of rubber tree plants, while the K doses tested did not reach the adequate levels of sufficiency

PERFORMANCE OF SPECIES Mabea fistulifera AND Eucalyptus urograndis WITH USE OF CELLULOSE RESIDUE IN DEGRADED AREAS

The planting of forest species contributes to the recovery of degraded areas, and the use of industrial waste can favor this process. However, there is still little information on this aspect in Cerrado. The objective of this work was to evaluate the performance of seedlings of the native species Mabea fistulifera Mart. and of the exotic hybrid Eucalyptus urograndis, under fertilization with residue of the industrial production of cellulose, in monospecific plantations in degraded area. Fertilization treatments, applied in the planting line, were three doses of the residue (10, 15 and 20 Mg ha -1); conventional mineral fertilizer (NPK); absence of fertilization (control). The experimental design was a randomized block design, with a portion of subdivided parts: species in the portions (15 m x 60 m, n = 4 / species) and treatments in the subportions (15 m x 12 m, n = 1 / treatment / portion) total of 18 plants in each subplot. Survival rate and growth attributes (height, crown diameter, stem diameter at ground level) were evaluated for two consecutive years. The largest increases in seedling survival and growth of both species were provided by mineral fertilization, followed by the 10 Mg ha -1 dose of the residue, which should be the recommended

Distribuição dos agregados e carbono orgânico influenciados por manejos agroecológicos.

O objetivo deste estudo foi verificar a influência do manejo agroecológico na distribuição dos agregados estáveis em água e no teor de carbono orgânico dos agregados em diferentes coberturas vegetais. Foram selecionadas cinco áreas, a saber: sistema agroflorestal; cultivo de figo (Ficus carica L.); consórcio maracujá (Passiflora edulis S.)–Desmodium sp.; cultivo de feijão (Phaseolus vulgaris L.), em manejo convencional, e cultivo de milho (Zea mays L.), em plantio direto. Em cada área, foram coletadas amostras de terra indeformadas, nas profundidades de 0 - 5 e 5 - 10 cm, e avaliada a estabilidade dos agregados e o teor de carbono orgânico nos agregados (COAGR). A maior massa de agregados encontra-se na classe de 2,00 mm, em ambas as profundidades, com exceção do cultivo de feijão. Nas duas profundidades, a classe de 2,00 mm apresentou os maiores valores de COAGR para a área do consórcio macaracujá - Desmodium sp

Comparative herbaceous phytosociology in agroforestry and Calophyllum brasiliense monoculture on a river terrace.

Invasive forage grasses, especially the Urochloa genus, impact reforestation worldwide. The aim of this study was to evaluate management influence on phytosociology of the herbaceous layer, defined as the layer of herbs, sub-shrubs, shrubs and vines, in two agroforestry systems (AFS) (Simple and Biodiverse) in succession to a reforestation of guanandi (Calophyllum brasiliense), compared to monoculture of this specie taken as control. The experiment was conducted in Pindamonhanga (SP), Brazil, from 2011 to 2014, in a randomized block design with eight replications and 144.0 m² plots. In Simple SAF area, food crops were grown alongside C. brasiliense rows: sweet cassava (Manihot esculenta) in rotation with arrowroot (Maranta arundinacea), pigeon pea (Cajanus cajan), banana shrub (Musa sp.), and juçara palm (Euterpe edulis). In Biodiverse AFS, fourteen native tree species were also planted alongside the food crops. Altogether 41 non-stratified species, 38 genera and 24 botanical families were identified; the most abundant families were: Asteraceae, Poaceae e Cyperaceae. The similarity between the areas diverged after three years of management, with the predominance of Commelina benghalensis and M. arundinacea in the AFS areas and Urochloa decumbens in the monocultive, mainly, due to the shadow gradient established for the three systems

EFFECT OF MYCORRHIZAL INOCULATION AND SUBSTRATE COMPOSITION ON SEEDLING GROWTH OF TWO ATLANTIC FOREST TREE SPECIES

The search for more efficient biotechnological tools for forest regeneration has increased over the past decades. Mycorrhizal inoculation is a valuable strategy to promote seedling growth, but its efficiency depends on the substrate used. This study aimed to investigate the effects of arbuscular mycorrhizal fungal inoculation and different types of substrates on the growth of Pseudobombax grandiflorum and Apuleia leiocarpa seedlings. Experiments were carried out under greenhouse conditions in a completely randomized 6 × 2 factorial design (six substrates and two inoculation levels) with six replications of 12 treatments. Both species showed similar growth patterns. Plants grown in inoculated substrates composed of 70% Cambisol and 30% bovine manure or 80% Cambisol and 20% Biomix showed improved nutritional status. These substrates had good physical and chemical characteristics (pH and P and N levels), which favored plant development and mycorrhizal symbiosis. P. grandiflorum seedlings showed enhanced growth in inoculated substrate composed of 80% Cambisol and 20% Biomix and in inoculated Cambisol fertilized with P. For A. leiocarpa, the best results were observed for seedlings grown in inoculated substratescomposed of 80% Cambisol and 20% Biomix, 70% Cambisol and 30% bovine manure, or Cambisol fertilized with P

CHEMICAL ATTRIBUTES AND ORGANIC MATTER IN FOREST COMPLEX SEASONALLY FLOODED IN RESTINGA OF MARAMBAIA, RIO DE JANEIRO STATE

Esse trabalho teve como objetivo avaliar as propriedades qu\uedmicas e caracterizar a mat\ue9ria org\ue2nica de solos sob duas forma\ue7\uf5es florestais periodicamente inundadas, na ilha da Marambaia, RJ. Essas forma\ue7\uf5es apresentam diferen\ue7as quanto ao grau de satura\ue7\ue3o h\ueddrica do solo, causada pela influ\ueancia do len\ue7ol fre\ue1tico, sendo que na forma\ue7\ue3o 1 (F1) o len\ue7ol apresenta-se mais pr\uf3ximo \ue0 superf\uedcie em compara\ue7\ue3o \ue0 forma\ue7\ue3o 2 (F2). Amostras foram coletadas nas camadas 0,00-0,05, 0,05-0,10 e 0,10-0,20 m. As propriedades ed\ue1ficas avaliadas foram: pH, H++Al+3; Ca+2, Mg+2, Na+, K+, P, N, carbono org\ue2nico total (COT) e satura\ue7\ue3o por bases (V%); carbono da fra\ue7\ue3o humina (C-HUM), carbono da fra\ue7\ue3o \ue1cido h\ufamico (C-FAH) e carbono da fra\ue7\ue3o \ue1cido f\ufalvico (C-FAF). Valores estatisticamente superiores de pH foram observados para F1. Em F2 verificaram-se maiores valores de Mg+2, P, N e V%. Foi verificada correla\ue7\ue3o entre os teores de Mg+2, N, \ue1cido h\ufamico e \ue1cido f\ufalvico em F1 com o len\ue7ol fre\ue1tico, e do len\ue7ol em F2 com os elementos Na+ e K+. A fra\ue7\ue3o C-HUM foi a mais representativa do carbono org\ue2nico total, seguida por C-FAH e C-FAF. Os teores de COT foram maiores na forma\ue7\ue3o F1. A rela\ue7\ue3o C/N foi menor em F2, com valores variando entre 9 e 12, e em F1 foram verificados maiores valores dessa rela\ue7\ue3o, variando de 9 a 15. Dentre as vias de forma\ue7\ue3o dos solos de constitui\ue7\ue3o org\ue2nicas, em ambas as \ue1reas a principal via de acumula\ue7\ue3o da mat\ue9ria org\ue2nica \ue9 a de heran\ue7a.This study aimed to evaluate and characterize the chemical properties of soil organic matter under two periodically flooded forest formations on the island of Marambaia, Rio de Janeiro. These formations differ on the degree of soil water saturation, caused by the influence of water table, and in the (F1) formation presents the water table nearer the surface compared to the (F2) formation. Samples were collected in layers from 0.00 to 0.05, 0.05-0.10 and 0.10-0.20 m. The soil properties evaluated were: pH, H+ + Al+3, Ca+2, Mg+2,Na+, K+, P, N, total organic carbon (TOC) and base saturation (V%), humin carbon fraction (C-HUM), carbon of humic acid fraction (HAF-C) and fulvic acid fraction carbon (FAF-C). Statistically higher pH values were observed for F1. In F2 there are higher values of Mg+2, P, N and V% value. Correlation was found between the concentrations of Mg+2, N, humic acid and fulvic acid with water table in F1, and water table in F2 with Na+ and K+. Fraction C-HUM was more representative of the total organic carbon, followed by C-HAF and C-FAF. The TOC levels were higher in F1. The C / N ratio was lower in F2, with values ranging between 9 and 12, and F1 were found higher values of this relationship, ranging from 9 to 15. Among the pathways of formation of organic soils in both areas it appears that the major route for organic matter accumulation is the inheritance route