Phosphorus in alkaline soils of the semiarid region, Brazil: inorganic fractions, capacity factor, and availability.

The study was designed to quantify the contents of Pi fractions and correlate them with the P capacity factor of soils in the Brazilian semiarid region. We also evaluated the effect of soil P doses contact time and P availability for maize plants in alkaline soils of the Brazilian semiarid region. Soil samples were collected between the Piranhas-Açu (RN) and Jaguaribe (CE) rivers valleys. The maximum phosphate sorption capacity was highly correlated with the values of remaining P, indicating that it can be used as a measure to estimate the P capacity factor of these soils. Maximum P sorption capacity correlated with Fe2O3 and Ca2+ contents and pH values. These results demonstrate that P sorption is explained by P adsorption on the surface of iron oxides and by its precipitation with Ca2+ in alkaline soils. The contact time increases promote plant P contents decreased substantially in the first 30 to 60 days after fertilization and decreased until 120 days of incubation but then tended to stabilize at the longest soil P contact times.

The clay content and P-remnant estimate the P capacity factor in alkaline soils.In alkaline soils, there is a predominance of P­Ca and P­Fe.The availability of P stabilizes after 120 days.The largest corn biomass occurs between the P doses of 256­288 mg dm⁻³.

Inoculation with Plant Growth-Promoting Bacteria to Reduce Phosphate Fertilization Requirement and Enhance Technological Quality and Yield of Sugarcane.

Phosphorus (P) is a critical nutrient for high sugarcane yields throughout its cultivation cycles, however, a higher amount of P becomes rapidly unavailable to plants due to its adsorption to soil colloids. Some plant growth-promoting bacteria (PGPBs) may be able to enhance P availability to plants and produce phytohormones that contribute to crop development, quality, and yield. Thus, this study aimed to evaluate leaf concentrations of nitrogen (N) and P, yield, and technological quality of sugarcane as a function of different levels of phosphate fertilization associated with inoculation of PGPBs. The experiment was carried out at Ilha Solteira, São Paulo-Brazil. The experimental design was randomized blocks with three replications, consisting of five phosphorus rates (0, 25, 50, 75, and 100% of the recommended P2O5 rate) and eight inoculations, involving three species of PGPBs (Azospirillum brasilense, Bacillus subtilis, and Pseudomonas fluorescens) which were applied combined or in a single application into the planting furrow of RB92579 sugarcane variety. The inoculation of B. subtilis and P. fluorescens provided a higher concentration of leaf P in sugarcane. The P2O5 rates combined with inoculation of bacteria alter technological variables and stalk yield of sugarcane. The excess and lack of phosphate fertilizer is harmful to sugarcane cultivation, regardless of the use of growth-promoting bacteria. We recommend the inoculation with A. brasilense + B. subtilis associated with 45 kg ha-1 of P2O5 aiming at greater stalk yield. This treatment also increases sugar yield, resulting in a savings of 75% of the recommended P2O5 rate, thus being a more efficient and sustainable alternative for reducing sugarcane crop production costs.

Path Analysis between Pest Occurrence and Nutritional Status of Soybean under Phosphate Fertilization.

BACKGROUND AND OBJECTIVE: The phytophagous insects select their host plants according to plant tissue nutritional quality. Thus, the objective of this study was to correlate the direct and indirect effects of phosphate fertilization on the nutritional status of the soybean crop and its relationship with the occurrence of insect pests. MATERIALS AND METHODS: The effect of phosphate fertilization on soybean was evaluated using two phosphate sources, Single Superphosphate (SSP) and Monoammonium Phosphate (MAP), applied at five rates of P2O5. A sampling of insects initiated from stage V5 and was done weekly. Leaves were collected for nutrient analysis stage R1, in stage R9 was harvest was carried out. SSP or MAP phosphate fertilization in soybean affected the incidence of Chrysodeixis includens, Helicoverpa armigera, Elasmopalpus lignosellus and Euschistus heros. RESULTS: The plants treated with MAP had the infestation reduced compared with plants treated with SSP. Higher contents of Cu and Fe in the leaf reduces the incidence of insect-pests, whereas the opposite occurred with Mn. The occurrence of E. lignosellus reduced soybean yield. CONCLUSION: Therefore, the source and rates of phosphorus in soybean fertilization change the concentration of macro and micronutrients in the leaves and affect the behavior and incidence of pest species.

Phosphate: Coupling the functions of fertilization and passivation in phytoremediation of manganese-contaminated soil by Polygonum pubescens blume.

Phosphate (P) fertilization is a commonly used agronomic practice. However, research on bioremediation is very limited. This study's principal objective was to evaluate the role of P in the growth and heavy metals (HMs) accumulation of Polygonum pubescens Blume cultured in Mn-contaminated soil. To this end, the effects of sodium dihydrogen phosphate (SDP) and single superphosphate (SSP) on the growth, Mn bioremediation efficiency, organ HMs, and physiological parameters related to antioxidant stress of P. pubescens were examined. The results showed that both SDP and SSP increased soil pH and available P but decreased available HMs. Phosphate significantly (P < 0.05) promoted P. pubescens height and biomass. Average height increased by 36.1% and 32.6% with SDP and SSP, respectively, with corresponding biomass increases of 71.8% and 135%. Phosphate significantly (P < 0.05) reduced Mn concentrations, especially in leaves, where the values decreased by >50.0% for DSP and SSP. Total Mn significantly (P < 0.05) decreased with DSP amendment but significantly (P < 0.05) increased by 38.5% with SSP (200 mg kg-1) through an increase in biomass. Phosphate significantly (P < 0.05) decreased all organ HM concentrations and translocation, indicating that less HM stress occurred with P amendment. The changes in reactive oxygen species, antioxidants and non-antioxidant materials further supported these results. Pearson correlation analysis revealed negative relationships between soil available P and HMs, indicating a novel role of P in HM passivation. The uncommonly high Ca concentrations in leaves suggested that Ca plays a vital role in promoting growth and alleviating HM stress in P. pubescens, which warrants further study.

Yield increase of corn inoculated with a commercial arbuscular mycorrhizal inoculant in Brazil / Rendimento de grãos da cultura do milho com inoculante micorrízico arbuscular comercial no Brasil

ABSTRACT: Arbuscular mycorrhizal fungi (AMF) play an important role in plant growth. However, there are no reports of legally commercialized AMF-based inoculants for agricultural crops in Brazil. The objective of this research was to evaluate the agronomic efficiency of a Rhizophagus intraradices inoculant in combination with phosphate fertilization in grain yield of corn under different edaphoclimatic conditions in Brazil. Experiments were conducted in five Brazilian states (Goiás, Mato Grosso, Minas Gerais, Rio Grande do Sul and Santa Catarina) in a 2 x 3 factorial scheme, with two inoculation treatments (inoculated and non-inoculated seeds) and three doses of phosphate fertilization (0, 50 and 100% of the recommended P). At the end of the crop cycle (stages R4-R5), inoculation provided increases in biomass (average of 48%) regardless of the applied dose of P, higher P absorption, and 54% average increase in grain yield. In conclusion, the mycorrhizal inoculant increases biomass yield, P uptake and corn grain yield under different edaphoclimatic conditions in Brazil, especially in soils that originally had low or medium levels of available P.

RESUMO: Os fungos micorrízicos arbusculares (FMA) desempenham um papel importante no crescimento das plantas, no entanto, não há relatos de inoculantes legais baseados em AMF para culturas agrícolas no Brasil. O objetivo deste trabalho foi avaliar a eficiência agronômica de um inoculante a base de Rhizophagus intraradices em combinação com a adubação fosfatada no rendimento de grãos de milho sob diferentes condições edafoclimáticas no Brasil. Os experimentos foram conduzidos em cinco estados brasileiros (Goiás, Mato Grosso, Minas Gerais, Rio Grande do Sul e Santa Catarina) em esquema fatorial 2 x 3, com dois tratamentos de inoculação (sementes inoculadas e não inoculadas) e três doses de adubação fosfatada (0, 50 e 100% do P recomendado). No final do ciclo da cultura (estágios R4-R5), a inoculação proporcionou aumentos na biomassa (média de 48%), independentemente da dose aplicada de P, maior absorção de P e aumento médio de 54% no rendimento de grãos. Conclui-se que o inoculante micorrízico arbuscular aumenta a produção de biomassa, a absorção de P e a produtividade de grãos de milho em diferentes condições edafoclimáticas no Brasil, especialmente em solos que originalmente apresentavam níveis baixos ou médios de P.

Phosphorus requirement and partitioning in oat cultivars / Demanda e partição de fósforo em cultivares de aveia-branca

ABSTRACT: Maintenance fertilization changes with nutrient requirements and partitioning, but these are not well known for oat cultivars. The aim of this study was to evaluate whether phosphorus (P) requirements and partitioning vary among cultivars of oat (Avena sativa L.). The UPFA 'Ouro', UPFPS 'Farroupilha', IPR 'Afrodite', URS 'FAPA Slava', 'Barbarasul', 'FAEM 007', URS 'Taura', and 'URS 21' were cultivated in a Latosol with high P content in a greenhouse in 2015. Plants were sampled at physiological maturity and divided into roots, stem, leaves, and grain tissues. Phosphorus content and the dry matter weight of these parts were evaluated and the uptake amount and partitioning of P were estimated. The values of these variables differed across cultivars, except the P content in the grain ('average', 4.0g P kg-1). 'Afrodite' and 'FAPA Slava' have lower requirements and partitioning of P in the grain, but these did not vary among the other cultivars. Requirements and partitioning of P in stem and leaves increased in the following order: 'Ouro' and 'Farroupilha'<'Taura' and 'FAPA Slava'<'URS 21'<'Afrodite', 'Barbarasul' and 'FAEM 007'. Requirement and partitioning of P in roots, stem, leaves, and grain differs across cultivars, which indicates that this factor, besides how the oat is used (such as for grain, pasture, silage, cover crop), can be used to improve maintenance fertilization.

RESUMO: A adubação de reposição varia com a demanda e a partição de nutrientes, mas isso é pouco conhecido em relação as cultivares de aveia. O estudo objetivou avaliar se a demanda e a partição de fósforo (P) diferem entre cultivares de aveia-branca. As cultivares 'UPFA 'Ouro', 'UPFPS Farroupilha', 'IPR Afrodite', 'URS 21', 'URS FAPA Slava', 'Barbarasul', 'FAEM 007', 'URS Taura' e 'URS 21' foram cultivadas em um Latossolo com teor alto de P, em estufa agrícola, no ano de 2015. Na maturação fisiológica, as plantas foram fracionadas em raízes, colmo, folhas e grão e o teor de P e a massa seca desses órgãos foram avaliados, estimando-se a quantidade e a partição desse nutriente. O valor dessas variáveis diferiu entre cultivares, exceto o teor de P do grão (média 4,0g P kg-1). Nessa parte da planta, a demanda e a partição desse nutriente foi menor na 'Afrodite' e na 'FAPA Slava', não diferindo entre as demais cultivares. Na parte vegetativa (colmo + folhas), o valor dessas variáveis aumentou na seguinte ordem: 'Ouro' e 'Farroupilha'<'Taura' e 'FAPA Slava'<'URS 21'<'Afrodite', 'Barbarasul' e 'FAEM 007'. A demanda e a partição de P em raízes, colmo, folhas e grão variam com a cultivar, indicando que esse fator, além da finalidade de uso da aveia-branca (grão, pastejo, silagem, cobertura do solo, etc) podem ser utilizados para melhorar a adubação de reposição.

Spatial distribution of phosphorus in the soil and soybean yield as function of fertilization methods / Distribuição espacial de fósforo no solo e produtividade da soja em funçãodos modos de adubação

The method of phosphate fertilization is a factor that may affect soil phosphorus availability, directly affecting soybean (Glycine max) yield. Thus, the objective this study evaluated combinations of phosphate fertilization methods on lateral and depth distribution of phosphorus (P) in the soil, as well as soybean yield. Experimental design was randomized blocks, 5x4x8 factorial with split plots, evaluated within each fertilization method: 100% broadcast, 75% broadcast and 25% in the sowing furrow, 50% broadcast and 50% in the row, 25% broadcast and 75% in the sowing furrow, 100% in the sowing furrow and control (No P fertilization), with four replications. The P content was evaluated at the depths 0-5, 5-10, 10-15 and 15-20 cm and in eight lateral distributions every 5 cm (starting between two rows, through the sowing furrow and finishing in the middle of the next row). The method of broadcasting 100% of phosphate fertilization did not present differences in the evaluations of lateral distribution for phosphorus content, however, the methods of phosphate fertilization 75 and 100% in the sowing furrow performed better at the depths 0-5 and 5-10 cm, exactly on central lateral distributions. Increased plant height and soybean yield were observed as the amount of phosphorus increased in sowing furrow instead of broadcast application.

O modo de adubação fosfatada é um fator que pode influenciar a disponibilização de fósforo no solo, afetando diretamente a produtividade das plantas de soja (Glycine max). O objetivo deste estudo foi avaliar combinações dos modos de adubação fosfatada na distribuição lateral e na profundidade de fósforo (P) no solo, assim como a produtividade da soja. O delineamento experimental foi em blocos casualizados, fatorial 5x4x8 com parcelas subdividas, avaliadas dentro de cada modo de adubação: 100% a lanço, 75% a lanço e 25% na linha, 50% a lanço e 50% na linha, 25% a lanço e 75% na linha, 100% na linha e testemunha (sem fertilização P), com quatro repetições. Os teores de P foram avaliados nas profundidades de 0-5, 5-10, 10-15 e 15-20 cm e em oito distribuições laterais em espaçamento de 5 por 5 cm no solo (iniciando na entre linha, passando pela linha de plantio e indo até o meio da próxima entre linha). O modo de adubação fosfatada 100% a lanço não apresentou diferença nas avaliações de distribuição lateral para os teores de P, todavia, os modos de adubação fosfatada 75 e 100% em linha de plantio apresentaram superioridade nas profundidades 0-5 e 5-10 cm, justamente em distribuições laterais centrais. Houve um aumento na altura e produtividade das plantas de soja conforme aumentava-se a quantidade de P na linha de plantio em detrimento a aplicação de P a lanço.

Quality of 'Fuji Suprema' apples influenced by long-term annual addition of phosphorus to the soil / Qualidade de frutos de maçã 'Fuji Suprema' influenciada pela adição anual de longo prazo de fósforo ao solo

ABSTRACT: Fertilization of apple orchards with phosphorus (P) has received less attention than with nitrogen and potassium. In Brazil, the information about apple response to soil P addition is meager. The objective of this study was to evaluate the long-term effect of annual soil P addition on quality and mineral composition of apple fruits. The experiment started in 2010, in a commercial orchard located in the São Joaquim, Southern of Brazil. The orchard consisted of ´Fuji Suprema', planted in high-density on a Haplumbrept soil. Treatments consisted of 0, 40, 80, 120 and 160kg ha-1 P2O5 applied annually starting in 2010 broadcast over the soil surface along the tree row. Evaluations were performed from 2012/2013 through 2014/2015 growing seasons. We harvested three samples from each experimental unit. One sample was cold stored in a controlled atmosphere chamber for six months; the others were immediately evaluated for firmness, total soluble solids, titratable acidity (TA), skin color, and the concentrations of N, P, K, Ca and Mg in the fruit flesh. Application of P to the soil affected only flesh firmness at harvest and TA after six months of storage in the 2012/2013 season, as well as firmness after six months of storage in the 2013/2014 season. In the 2014/2015 season, the addition of P reduced fruit color but only at harvest. Addition of P to the soil affected the levels of P in the fruit in the 2012/2013 season, as well as N and the N/Ca ratio of fruit in the 2014/2015 season. Overall, attributes related to fruit quality of cultivar Fuji Suprema were slightly affected by long-term annual addition of P to the soil.

RESUMO: A adubação com fósforo (P) em pomares de maçã tem recebido menos atenção que adubações com nitrogênio e potássio. No Brasil, as informações sobre a resposta da macieira a adição de P ao solo é escassa. O objetivo deste estudo foi avaliar o efeito a longo prazo da adição anual de P ao solo na qualidade e composição mineral de maçãs. O experimento iniciou em 2010, num pomar comercial localizado no município de São Joaquim, Sul do Brasil, com a cultivar 'Fuji Suprema', instalado em alta densidade (aproximadamente 2.000 plantas ha-1) em um solo Haplumbrept. Os tratamentos consistiram de 0, 40, 80, 120 e 160kg ha-1 P2O5 aplicados anualmente a partir de 2010, na superfície do solo ao longo da fileira das árvores. As avaliações foram realizadas nas estações de crescimento de 2012/2013 até 2014/2015. Três amostras de 10 frutos de cada unidade experimental foram colhidas. Uma amostra foi armazenada em uma câmara fria de atmosfera controlada por seis meses; os outros foram imediatamente avaliados quanto à firmeza, sólidos solúveis totais, acidez titulável (AT), cor da epiderme e as concentrações de N, P, K, Ca e Mg na polpa dos frutos. A aplicação de P ao solo afetou apenas a firmeza de polpa na colheita e AT após seis meses de armazenamento na safra 2012/2013, bem como a firmeza após seis meses de armazenamento na safra 2013/2014. Na safra 2014/2015, a adição de P reduziu a cor dos frutos, mas apenas na colheita. A adição de P ao solo afetou os níveis de P nos frutos da safra 2012/2013, bem como N e a relação N / Ca de frutas na safra 2014/2015. Em geral, os atributos relacionados à qualidade dos frutos da cultivar Fuji Suprema foram ligeiramente afetados pela adição anual prolongada de P ao solo.

Phosphate fertilizer affected rhizospheric soils: speciation of cadmium and phytoremediation by Chlorophytum comosum.

Experiments were conducted to investigate the effect of phosphate fertilization on chemical speciation of cadmium (Cd) in the rhizospheric soil of Chlorophytum comosum, a potential cadmium hyperaccumulator. The results revealed that when 200 mg kg-1 phosphate was applied into the soil, the Cd contents in the exchangeable fraction (EXC), carbonate-binding fraction (CA), and Fe-Mn oxides-binding fraction (Fe-Mn) were the highest, and the Cd content in the residual fraction (RES) was the lowest. Phosphate fertilization could enhance Cd conversion from RES into CA and weak RES, thereby improving the bioavailability of Cd and enhancing Cd enrichment and adsorption by C. comosum. The total Cd content in the soil was reduced by 10.15 mg kg-1 in the planted group, which was significantly different from the control group (p < 0.01). The highest bioaccumulation coefficient (BC) values in root and aboveground parts appeared when the phosphate rates were 276 and 217 mg kg-1, whereas the highest translocation factor (TF) occurred with a phosphate rate of 188 mg kg-1. Phosphate fertilization facilitated phytoremediation of Cd-polluted soil by C. comosum.

Resposta da cana-de-açúcar a doses de fósforo fornecidas por fertilizante organomineral / Response of sugarcane to doses of phosphorus provided by organomineral fertilizer

Em solos tropicais, o fósforo é o nutriente mais limitante da produção agrícola, sendo adicionado em grande quantidade para atender as exigências das culturas. Para avaliar a resposta da cana-de-açúcar a doses de P2O5 fornecidas por fertilizante organomineral, conduziu-se um experimento em vasos plásticos (200 L), cultivando-se mudas de cana-de-açúcar em Latossolo Vermelho distrófico, textura muito argilosa. O delineamento experimental utilizado foi o de blocos casualizados, com seis tratamentos e quatro repetições. Os tratamentos constaram de quatro doses de P2O5 (40, 80, 120 e 160 kg ha-1) fornecidas com fertilizante organomineral, um tratamento controle que não recebeu aplicação de P2O5 e um tratamento que recebeu 160 kg ha-1 de P2O5 via fertilizante mineral. Os fertilizantes foram incorporados em 100 kg de solo da porção superior de cada vaso e, em seguida, foram transplantadas três mudas da variedade IAC 95-5000. Aos 231 dias após o transplantio, realizou-se a colheita de todas as plantas do vaso, sendo avaliadas as seguintes características: produção de colmos, rendimento de açúcar e variáveis tecnológicas. Os resultados obtidos indicam que a produção de colmos e o rendimento de açúcar da cana-planta aumentaram com as doses de P2O5 fornecidas pelos fertilizantes. As duas fontes fosfatadas foram semelhantes em influenciar os parâmetros tecnológicos da cana-planta. A aplicação do fertilizante organomineral na dose de 130 kg ha-1 de P2O5 pode substituir a adubação mineral fosfatada (160 kg ha-1 P2O5) e proporcionar economia de 18,8% no uso de fertilizantes.

In tropical soils, phosphorus is the most limiting nutrient of agricultural production, added in large quantities to satisfy crop requirements. A pot experiment (200 L) was carried out, cultivating sugarcane seedlings in a Dystrustox, to evaluate the response of sugarcane to doses of phosphorus provided by organomineral fertilizer. The design of the experiment was of randomized blocks in four replications with six treatments. Treatments consisted in four doses of P2O5 ((40,80,120 e 160 kg ha-1) provided by organomineral fertilizer, an additional treatment, with no fertilizer, and 160 kg ha-1 of P2O5 provided by mineral fertilizer. The fertilizers were incorporated in 100 kg soil of the upper layer in each container and, subsequently, three sugar-cane seedlings variety IAC 95-5000 were transplanted. The plants were harvested 231 days after seedling transplanting to the pots, evaluating the following characteristics: stalk production, sugar yield and technological parameters. The results indicate that the stalk yield and sugar yield of plant cane increased with doses of P2O5 provided by the fertilizers. The two sources of phosphorus were similar in influencing the technological parameters of the plant cane. Organomineral fertilizer, applied in dose of 130 kg ha-1 de P2O5 can substitute phosphorus mineral fertilization (160 kg ha-1 P2O5), presenting up 18,8% economy in fertilizers use.

Efeito de doses de fósforo no desenvolvimento da cultura do crambe / Effect of phosphorus doses in the development of crambe culture

O crambe é uma brássica de inverno, com alto teor de óleo que serve como fonte de matéria prima para a produção de biodiesel. Vem chamando a atenção dos produtores por ter ciclo curto, que varia de 90 a 100 dias. O experimento teve como objetivo avaliar o efeito de doses de fósforo - P2O5 (0, 15, 30, 60 e 90 kg ha-1) na adubação de base da cultura. O experimento foi realizado no município de Umuarama­ PR, em Latossolo Vermelho distrófico típico, empregando-se o delineamento experimental em blocos casualizados, com quatro repetições. A adubação fosfatada contribuiu para o aumento da produtividade e da massa seca. Para massa de 100 grãos e teor de óleo, não houve diferença significativa entre os tratamentos.

Crambe abyssinica is a winter crucifer, with high oil content being used as a source of raw material for biodiesel production. It's getting the attention of farmers because of its short cycle, which ranges from 90 to 100 days. The experiment objectified to evaluate the effect of phosphorus doses- P2O5 (0, 15, 30, 60 and 90 kg ha-1) in basic fertilization of the crop. The experiment was conducted in Umuarama County, Parana State, in Latossoil Red dystrophic typical, by using a randomized complete blocks design with four replications. Phosphate fertilization contributed to increase yield and dry mass. For the characteristics mass of 100 grains and oil content, there was no significant difference between treatments.

Nitrogênio e fósforo no desenvolvimento inicial da guavira [Campomanesia adamantium (Cambess. ) O. Berg] cultivada em vasos / Effect of nitrogen and phosphorus supply on initial development of guavira [Campomanesia adamantium (Cambess. ) O. Berg] cultivated in pots

O objetivo deste trabalho foi avaliar o desenvolvimento inicial da guavira (Campomanesia adamantium) cultivada sob diferentes doses de fósforo e nitrogênio. O experimento foi realizado em casa de vegetação, da Universidade Federal da Grande Dourados, em Dourados-MS. Foram estudadas cinco doses de fósforo (20, 120, 200, 280 e 380 kg ha-1), na forma de superfosfato simples e cinco doses de nitrogênio (6, 36, 60, 84 e 114 kg ha-1), na forma de sulfato de amônio. Os tratamentos foram definidos utilizando-se a matriz experimental Plan Puebla III, dando origem a nove combinações, respectivamente, de doses de fósforo e de nitrogênio (kg ha-1): 280 e 84; 280 e 36; 120 e 6; 120 e 36; 120 e 84; 200 e 60; 380 e 84, 20 e 36 e 280 e 114. O delineamento experimental utilizado foi blocos casualizados, com quatro repetições. A unidade experimental foi composta por cinco vasos, com uma planta por vaso. A colheita das plantas foi feita aos 270 dias após o transplante (DAT). Sob as maiores doses de P e N utilizadas observaram-se as maiores alturas de plantas (38,12 cm), aos 261 DAT; o maior número de folhas por planta (54), aos 186 DAT; a maior massa seca de folhas (5,68 g planta-1), a maior área foliar (610 cm² planta-1), a maior massa seca de raiz (6,2 g planta-1) e o maior número de ramos (3 planta-1) aos 270 DAT. O teor de clorofila foi em média de 36 ICF. Recomenda-se o uso de 380 kg ha-1 de fósforo e de 114 kg ha-1 de nitrogênio para o melhor desenvolvimento inicial da guavira.

The aim of this trial was to evaluate the initial development of Campomanesia adamantium grown under different phosphorus and nitrogen rates. The experiment was conducted in a greenhouse at the Universidade Federal da Grande Dourados, Dourados-MS. It was studied five phosphorus rates (20, 120, 200, 280 and 380 kg ha-1) in the form of superphosphate and five nitrogen rates (6, 36, 60, 84 and 114 kg ha-1) in the form of ammonium sulfate. Treatments were defined using the Plan Puebla experimental matrix, resulting in nine combinations, respectively, of phosphorus and nitrogen (kg ha-1): 280 and 84, 280 and 36, 120 and 6, 120 and 36, 120 and 84, 200 and 60, 380 and 84, 20 and 36 and 280 and 114. The experimental design was randomized block with four replications. Experimental unit consisted of five vessels, with one plant per pot. The trial harvest was carried out 270 days after transplanting (DAT). Highest rates of N and P resulted on the greatest plant height (38.12 cm) reached after 261 DAT, maximum number of leaves per plant (54) at 186 DAT, highest dry weight of leaves (13.99 and 5.68 g plant-1) and root (15.9 and 6.2 g plant-1), greatest leaf area (610 cm² plant-1) and number of branches (3 planta-1), all at 270 DAT. The average of Chlorophyll levels was 36 ICF. Thus, it's recommend the supply of high doses of phosphorus (380 kg ha-1) and nitrogen (114 kg ha-1) for guavira cultivation.

Produção de matéria seca e eficiência nutricional para P, Ca e Mg em leguminosas herbáceas / Dry matter production and nutritional efficiency for P, Ca and Mg in herbaceous legumes

As leguminosas para adubação verde têm sido introduzidas nos sistemas agrícolas para a recuperação de solos desgastados pelo uso intensivo. O objetivo desse trabalho foi avaliar a resposta de leguminosas herbáceas à aplicação de calcário e fósforo sobre a produção de biomassa e eficiência nutricional para o P, Ca e Mg. O experimento foi desenvolvido em casa-de-vegetação do Departamento de Ciência do Solo da Universidade Federal Rural da Amazônia, utilizando-se um Latossolo Amarelo distrófico coletado na profundidade de 0 - 20 cm, em Belém, PA. O delineamento experimental usado foi o de blocos ao acaso, com arranjo de tratamentos em um fatorial 3³, onde foram comparadas três espécies de leguminosas: mucuna preta (Stizolobium atterrimum), mucuna cochinchinensis (Stilozobium cochinchinensis) e feijão-de-porco (Canavalia ensiformes); três níveis de calagem: de calcário dolomítico (0, 4 e 8 t.ha-1) e de fósforo (0, 25 e 45 mg.dm-3), com quatro repetições cada um. Mucuna cochinchinensis e o feijão de porco produziram maiores quantidades de biomassa vegetal do que a mucuna preta, sendo que a primeira espécie acumulou maior quantidade de P e a segunda maior quantidade de Ca. Mucuna cochinchinensis apresentou maior eficiência de utilização de P, Ca e Mg na ausência da calagem. Nos solos intemperizados com baixa concentração de P, Ca e Mg, o feijão-de-porco e a mucuna cochinchinensis poderão ter melhor desempenho do que a mucuna preta, visto que apresentaram maior eficiência de translocação e de utilização desses nutrientes, respectivamente.

The legumes used for green manure have been introduced in agricultural systems for recovering degraded soils by intensive use. The objective of this work was to evaluate the response of herbaceous legumes to liming and P application on dry matter and its nutritional efficiency. The experiment was developed in greenhouse at the Soil Science Department of the Federal University Agricultural of Amazon (Brazil). Soil used was a dystrophic Yellow Latosol, sampled in the 0 - 20 cm depth. A randomized block experimental design was used with treatments arranged in a factorial 3³, comparing three legume species: velvet bean (Stizolobium atterrimum), "mucuna cochinchinensis" (Stilozobium cochinchinensis) and jack bean (Canavalia ensiformes); three doses of liming (0, 4 and 8 t ha-1 of limestone) and of triple superphosphate (0, 25 and 45 mg P dm-3 of soil), with four replications each one. Results showed that "mucuna cochinchinensis" and jack bean produced higher amounts of dry matter than velvet bean. The first species accumulated higher amount of P and the second species higher amount of Ca in the tissue. The "mucuna cochinchinensis" species showed higher use efficiency of Ca, Mg and P in the absence of liming. The jack bean and mucuna cochinchinensis can have better performance than velvet bean, in weathered soils with low concentration of P, Ca and Mg, since they presented higher translocation efficiency and use of these nutrients, respectively.

Avaliação de fontes e doses de fósforo no crescimento inicial do milho / Evaluation of sources and rates of P fertilizers on the initial growth of corn

O fósforo é componente vital para todos os seres vivos e é essencial para a produção agrícola. No Brasil, a maior parte dos solos agricultáveis tem baixos teores de fósforo disponível. Para atender as exigências das plantas e suprimento adequado de fósforo há a necessidade da aplicação de adubos fosfatados. Dentre as opções de fontes no mercado, os fosfatos totalmente acidulados são os usualmente comercializados. Com o aumento do uso dos fosfatos naturais reativos, a avaliação da eficiência da aplicação do fertilizante é importante no manejo da adubação fosfatada. O experimento foi realizado em casa de vegetação, utilizando um Nitossolo. O delineamento experimental empregado foi o inteiramente casualizado com os tratamentos arranjados em um fatorial 4 x 2 com quatro repetições. O objetivo do trabalho foi avaliar os efeitos de fontes e doses de fósforo no crescimento inicial do milho. A produção de matéria seca e os teores de P da parte aérea das plantas de milho aumentaram com o incremento das doses de fósforo, dependentemente da fonte de P considerada. Contudo, o Superfosfato Triplo foi mais eficiente que o fosfato de Arad, garantindo melhor nutrição e crescimento inicial das plantas de milho.

Phosphorus is an essential element for all living organisms and important also for agricultural production.The content of P in most agricultural soils in Brazil is low. In order to supply the plant needs and the soilfixation, application of P fertilizer is required. Among the various options of P fertilizers in the market, thetotally acidified phosphates are usually commercialized. The evaluation of the efficiency of the reactivenatural phosphates as P fertilizers is important due to the increase of the utilization of cheaper sourcesof natural P. The experiment was carried out in green house, using a Nitossolo. The experimental designused was complete randomized design, with the treatments in a 4x2 factorial arrangement, and fourreplications. The objective of the experiment was to evaluate the effects of sources and rates of P on thegrowth of corn. The production of dry matter and the content of P on the corn leave and stalks (aboveground corn parts) increased as rates of P increased, regardless the P sources tested. However, theTriple Super Phosphate was more efficient compared with Arad phosphate, providing better nutritionand initial growth of corn plants