Soil properties and not inputs control carbon : nitrogen : phosphorus ratios in cropped soils in the long term

摘要: Abstract. Stoichiometric approaches have been applied to understand the relationship between soil organic matter dynamics and biological nutrient transformations. However, very few studies explicitly considered effects of agricultural management practices on C : N : P ratio. The aim this study was assess how different input types rates would affect molar ratios bulk soil, microbial biomass in cropped soils long term. Thus, we analysed C, N, P inputs budgets as well properties three long-term experiments established types: Saria fertility trial (Burkina Faso), Wagga rotation/stubble management/soil preparation (Australia), DOK (bio-Dynamic, bio-Organic, “Konventionell”) cropping system (Switzerland). In each these trials, there a large range which had strong impact element concentrations soils. although were highly variable, they only weak ratios. At Saria, positive correlation found N : P ratio biomass, while no relation observed matter. Wagga, C : P significantly correlated total C : P, N : P, C : N ratios, but elemental composition biomass. trial, C budget soils, not related those We argue that responses are due differences among sites. is dominated by quartz some kaolinite, has coarse texture, fragile structure, low content. microorganisms feed (plant residues, manure). contrast, at contains illite haematite, richer clay nutrients, stable structure. protected from mineralization can therefore accumulate, allowing nutrients keep constant represents an intermediate situation, with high concentrations, rather where does accumulate. conclude important functioning term, it must be coupled precise assessment good understanding ability stabilize compounds.