Background: The dynamics of phosphorus (P) in the environment is important for regulating nutrient cycles in natural and managed ecosystems and an integral part in assessing biological resilience against environmental change. Organic P (Po) compounds play key roles in biological and ecosystems function in the terrestrial environment being critical to cell function, growth and reproduction. Scope: We asked a group of experts to consider the global issues associated with Po in the terrestrial environment, methodological strengths and weaknesses, benefits to be gained from understanding the Po cycle, and to set priorities for Po research. Conclusions: We identified seven key opportunities for Po research including: the need for integrated, quality controlled and functionally based methodologies; assessment of stoichiometry with other elements in organic matter; understanding the dynamics of Po in natural and managed systems; the role of microorganisms in controlling Po cycles; the implications of nanoparticles in the environment and the need for better modelling and communication of the research. Each priority is discussed and a statement of intent for the Po research community is made that highlights there are key contributions to be made toward understanding biogeochemical cycles, dynamics and function of natural ecosystems and the management of agricultural systems

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Silicon (Si) application has improved yield and stress tolerance in sugarcane crops. In this respect, C:N:P stoichiometry makes it possible to identify flows and interaction between elements in plants and their relationship with growth. However, few studies have investigated the influence of Si on physiological variables and C:N:P stoichiometry in sugarcane. As such, this study aimed to assess the effect of increasing Si concentrations on the growth and stoichiometric composition of sugarcane plants in the early growth stage. The experiment was conducted in pots, using four Si concentrations (0, 0.8, 1.6 and 3.2 mM). Biomass production, the concentration and accumulation of C, N, P and Si as well as the relationship between them were assessed. Silicon application increased biomass production, the rate of photosynthesis, instantaneous carboxylation efficiency and C, N, P and Si accumulation, in addition to altering stoichiometric ratios (C:N, C:P, N:P and C:Si) in different parts of the plants. The decline in C concentration associated with greater N and P absorption indicates that Si favoured physiological processes, which is reflected in biomass production. Our results demonstrate that Si supply improved carbon use efficiency, directly influencing sugarcane yield as well as C and nutrient cycling.

A ureia é o principal fertilizante nitrogenado utilizado na adubação de cobertura no milho; no entanto, apresenta elevada suscetibilidade às perdas de N por volatilização de amônia. Uma alternativa é o tratamento da ureia com inibidor de urease ou revestimento com camadas de polímeros, classificados como fertilizantes nitrogenados de eficiência aumentada. Neste contexto, o presente trabalho objetivou avaliar o efeito da aplicação de doses de nitrogênio na forma de fertilizantes nitrogenados de eficiência aumentada e ureia em cobertura na cultura do milho. Utilizou-se o delineamento em blocos casualizados em esquema fatorial 3 x 4 + 1. As fontes utilizadas foram: ureia comum; ureia tratada com inibidor de urease e ureia revestida com polímeros testados nas doses de 32,5, 65, 130 e 260 kg ha-1 de N. A massa de cem grãos e a massa seca de parte aérea de plantas aumentaram de forma linear com as doses de N. O teor de nitrogênio na folha e a produtividade de milho foram superiores quando se utilizou ureia tratada com inibidor de urease ou revestida com polímeros, principalmente nas doses de 130 e 260 kg ha-1 de N. Neste sentido, a utilização de fertilizantes nitrogenados de eficiência aumentada não apenas aumentou mas também melhorou o suprimento de N para o milho aumentando ainda a produtividade de grãos.

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