P analysis in fertilizers using LIBS.

-Light soils occupy 8% of the Brazilian territory and are especially expressive in the new and last agricultural frontier in Brazil: the Matopiba region -in the states of Maranhão, Tocantins, Piauí, and Bahia -, where they represent 20% of the area. These soils fit into the textural classes of sand and loamy sand or sandy loam, down to 0.75-m soil depth or deeper, and they are mainly represented by Neossolos Quartzarênicos (Quartzipsamments) and, partly, by Latossolos (Oxisols) and Argissolos (Ultisols). The understanding of soil functioning depends on the establishment of distinguishing criteria for: organic matter dynamics; content and mineralogy of the clay fraction; coarse sand and total sand contents, in relation to those of fine sand; mean diameter of the sand fraction; and water retention capacity. These criteria can contribute for the zoning and for the conservation and fertility management of light soils, as well as for the estimation of their agricultural potential. Integrated production systems, such as crop-livestock and crop-livestock-forestry integration, besides no-tillage with crop rotation, mixed forestry planting with legumes, and the use of green manure and cover crops are relevant for the proper management of these soils. The objective of this review was to characterize light soils and to highlight the main challenges regarding their agricultural potential and their conservation and fertility managements, in face of the expansion and consolidation of the new Brazilian agricultural frontier.

-The objective of this work was to evaluate agronomic and P recovery efficiencies of a granulated organomineral phosphate fertilizer (OMF) produced from poultry litter, compared with those of monoammonium phosphate (MAP), in soils with different textures. The experiment followed a 2x2x4+2 factorial arrangement, with two Oxisols (sandy loam and clay loam textures), two sources of P (OMF and MAP), four levels of P (50, 100, 200, and 400 mg kg -1 ), besides two control treatments without P application. The treatments were evaluated in 10-kg pots filled with soil, during four successive cultivations of corn without replacing the P absorbed by the plants, in order to evaluate the actual and residual effects of the fertilizers. Available P contents in the soil were higher with the MAP fertilizer in the sandy loam soil, with no significant differences between fertilizers in the clay loam soil. OMF had a greater immediate effect and promoted a higher dry matter yield in the first cultivation; however, the residual effects of the fertilizers did not differ in the other cultivations. P accumulation by plants was not affected by the fertilizer used. OMF had higher agronomic efficiency, but P recovery efficiency did not differ significantly between fertilizers. OMF performance indicates good potential use of poultry litter as fertilizer, in organomineral formulations.Index terms: Zea mays, biomass accumulation, phosphate fertilization, P recovery efficiency, tropical soils.Eficiência agronômica e de recuperação de P de fertilizante fosfatado organomineral granulado produzido com cama de frango em solo arenoso e argilosoResumo -O objetivo deste trabalho foi avaliar as eficiências agronômica e de recuperação de P de fertilizante fosfatado organomineral (FOM) granulado, produzido com cama de frango, comparadas às do monoamônio fosfato (MAP), em solos com diferentes texturas. O experimento seguiu um arranjo fatorial 2x2x4+2, com dois Latossolos (texturas areia franca e franco argilosa), duas fontes de P (FOM e MAP), quatro doses de P (50, 100, 200 e 400 mg kg -1 ), além de dois controles sem aplicação de P. Os tratamentos foram avaliados em vasos com 10 kg de solo, durante quatro cultivos sucessivos de milho sem reposição do P absorvido pelas plantas, para permitir as avaliações de efeito imediato e residual dos fertilizantes. Os teores de P assimilável no solo foram maiores com o MAP, no solo areia franca, sem diferenças significativas entre fertilizantes no solo franco argiloso. O FOM teve maior efeito imediato e promoveu maior produção de matéria seca no primeiro cultivo; no entanto, o efeito residual dos fertilizantes não diferiu nos demais cultivos. O acúmulo de P pelas plantas não foi influenciado pelo fertilizante utilizado. O FOM apresentou maior eficiência agronômica, mas a eficiência de recuperação de P não diferiu significativamente entre os fertilizantes. O desempenho do FOM indica bom potencial de uso da cama de frango como fertilizante, em formulações organominerais.Termos para indexação: Zea mays, acúmul...

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Under natural conditions the germination of oil palm seeds may take years, and it is usually uneven and has a very low rate. To increase the germination rate it is necessary to break the dormancy, through heat-treatment (HT). In the germination of oil palm seeds produced by Embrapa Western Amazon the HT used is at 40 °C during 80 days. The objective of this study was to evaluate the periods of 40, 50, 60 and 80 days of HT at 40 °C on seeds germination of six oil palm cultivars BRS C2001, BRS C2328, BRS C2501, BRS C2528, BRS C3701 and BRS C7201. The statistical design was randomized block, 6 x 4 factorial, with four replications of 500 seeds each. The minimum HT period for maximum germination ranged from 45 days for BRS C2328 (70%) to 80 days for BRS C2528 (84%). For BRS C7201 was not observed significant effect of the HT period for seed germination, estimated as 82%. The maximum germination of oil palm seeds varies with the duration of heat treatment. With the exception of cultivar BRS C2528, heat treatment may be less than 80 days.