Inputs of carbon to soil may be used to stimulate microbial growth and immobilize excess nitrogen from sources such as livestock urine. However, the growth responses of microbial taxa to carbon inputs under conditions of excess soil nitrogen remain poorly understood. Using DNA metabarcoding and a field-based soil lysimeter experiment, we characterised the temporal responses (up to 112 days) of bacterial and fungal communities to a simulated bovine urine event plus inputs of labile carbon (sucrose) at two concentrations. Fungal communities were impacted more strongly than bacterial communities by carbon inputs following the simulated urine event, with more variable responses among taxa. Chytridiomycota and Glomeromycota richness were most negatively affected, and Tremellomycetes richness most positively affected, by carbon inputs. A minority of fungal ASVs had greatly increased proportional abundances in response to carbon, while fungal trophic composition became highly dominated by saprotrophs by the experiment end. Bacterial taxa showed consistent trends of declining (to about 14 days) and recovering (to 112 days) richness in response to urine and carbon inputs, but carbon-related evenness and proportional abundance trends varied between taxa. Proportional abundances of Actinobacteria, Bacteroidetes, Betaproteobacteria, and Gammaproteobacteria increased in response to carbon, whereas proportional abundances of Acidobacteria, candidate division WPS-1, Planctomycetes, Deltaproteobacteria, and Verrucomicrobia decreased. These results show that labile carbon inputs to limit nitrate leaching support the recovery of bacterial communities to bovine urine events but may have long-term impacts on fungal community composition and function, with potential consequences for soil food webs, carbon sequestration, and agricultural productivity.

The biodiversity and structure of deep agricultural soil communities are poorly understood, especially for eukaryotes. Using DNA metabarcoding and co-occurrence networks, we tested whether prokaryote, fungal, protist, and nematode biodiversity declines with increasing depth (0–0.1, 0.3–0.5, and 1.1–1.7m) in pastoral soil; whether deep soil organisms are subsets of those at the surface; and whether multi-kingdom networks become more interconnected with increasing depth. Depth-related richness declines were observed for almost all detected fungal classes, protist phyla, and nematode orders, but only 13 of 25 prokaryote phyla, of which nine had increasing richness with depth. Deep soil communities were not simply subsets of surface communities, with 3.8%–12.2% of eukaryotes and 13.2% of prokaryotes detected only in the deepest samples. Eukaryotes mainly occurred in the upper soil layers whereas prokaryotes were more evenly distributed across depths. Plant-feeding nematodes were most abundant in top soil, whereas bacteria feeders were more abundant in deep soil. Co-occurrence network structure differences suggested that deep soil communities are concentrated around scarce niches of resource availability, in contrast to more spatially homogenous and abundant resources at the surface. Together, these results demonstrate effects of depth on the composition, distribution, and structure of prokaryote and eukaryote soil communities.

The two most significant signatures of the Anthropocene—agriculture and urbanisation—have yet to be studied synoptically. The term periurban is used to describe territory where the urbanising trend of the planet extends into multiscapes. A periurban praxis is required that spatially reconciles urbanisation and agriculture, simultaneously permitting urban growth and the enhancement of critical ecosystem services provided by agricultural hinterlands. This paper presents a synthesis of four fields of ecological research that converge on periurban multiscapes—ecological urbanism, landscape ecology, ecosystem services science and agroecology. By applying an ecosystem services approach, a diagram is developed that connects these fields as a holistic praxis for spatially optimising periurban multiscapes for ecosystem services performance. Two spatial qualities of agroecology—‘ES Density’ and ‘ES Plasticity’—potentiate recent areas of research in each of the other three fields—ecology for the city from ecological urbanism, landscape metrics from landscape ecology (particularly the potential application of fractals and surface metrics) and ecosystem services supply and demand mapping and ‘ES Space’ theory from ecosystems services science. While the multifunctional value of agroecological systems is becoming widely accepted, this paper focuses on agroecology’s specific spatial value and its unique capacity to supply ecosystem services specifically tailored to the critical ecosystemic demands of periurban multiscapes.

There is increasing evidence that the accessibility of soil organic matter (SOM) to microbial decomposers is more important than chemical recalcitrance for regulating SOM stability. We show that the rapid reduction in SOM decomposition following the addition of sorptive mineral phases to soils in laboratory conditions leads to decreased accessibility of SOM to microbial decomposers due to the formation of organo‐mineral complexes. We manipulated SOM accessibility in a short‐term microcosm experiment by adding different proportions of a sorptive mineral material derived from an aluminium‐rich allophanic soil to a constant mass of soil to determine the effects on SOM decomposition after 1, 4 and 8 days. The decrease in SOM decomposition with increasing proportion of added sorptive mineral phase occurred within 1 day and did not change further at 4 and 8 days. In a second experiment, we added three proportions of the sorptive mineral phases (0%, 15% and 50%) to three soils with different carbon (C) concentrations and measured rates of SOM decomposition, changes in water extractable C, the formation of organo‐mineral complexes inferred from pyrophosphate‐extractable aluminium, and the natural abundance ¹³ C isotopic composition of CO ₂ derived from SOM decomposition. We confirmed that the proportional decreases in SOM decomposition with increasing organo‐mineral complexes and decreasing microbial access to SOM was the same for the three soils, suggesting that the effects are independent of soil C concentration and pH. We also showed that the short‐term reductions in SOM accessibility led to microbial decomposition of more ¹³ C enriched substrates, suggesting preferential stabilisation of plant‐derived ( ¹³ C depleted) substrates. Our study demonstrated that SOM accessibility and decomposition could be reduced rapidly and proportionally to the amount of added sorptive mineral phases resulting from increased organo‐mineral interactions irrespective of the initial soil organic carbon concentration. Highlights: Addition of sorptive mineral phases reduced short‐term soil organic matter (SOM) decomposition by the same proportion for three soils. Relatively ¹³ C depleted SOM was preferentially adsorbed onto the mineral phases. The reduction in SOM decomposition was attributed to reduced microbial access due to increased organo‐mineral interactions. The effects occurred rapidly and proportionally to the amount of added sorptive mineral phases.

It is critical that we move our understanding of the ecosystem services (ESs) produced by landscapes from the present abundance of analysis to a fundamental basis of design. This involves enhancing the ability to understand and model the interconnected, coevolving system of humans and the rest of nature, thus contributing to the design of sustainable landscapes. In this paper, we hypothesise that the spatial configuration of landscape components (the size and arrangement of tree clumps, paddocks, crops, water features, etc.) impacts the production of regulating ESs, which in turn have a leveraging effect on provisioning and cultural ESs. Drawing on the precepts of Ecological Field Theory, we present the development and implications of a conceptual Geographic Information System (GIS)-based model, ESMAX, that utilises the idiosyncratic distance-decay characteristics of regulating ESs. These ‘ES fields’ are visualised as radiating into the landscape from their source components, addressing a gap in biophysical reality that has been identified as a shortcoming of existing ES modelling based on landcover proxies. Hypothetical landscape arrangements of simplified landscape components are tested with ESMAX across three regulating ESs: cooling effect, nitrogen retention, and habitat provision. The model calculates the overall ES performance of each landscape arrangement by tabulating the ES fields produced and, critically, the nonlinear response where fields overlap. The results indicate a primary sensitivity to the size of components and a secondary sensitivity to the arrangement of components. Consequently, ESMAX can be used to design landscape configurations that (1) maximise the production of specific regulating ESs and (2) improve the utilisation of natural ES-producing resources.