No abstract

Using organic amendments, including livestock slurry, in intensively managed agricultural grasslands may potential lead to multiple benefits, including plant nutrient supply to soils and long-term accumulation of soil organic matter. There is increasing interest in the extent to which biological slurry additives (mixtures of selected living or latent microorganisms added to slurry) are able to enhance soil fertility through mobilisation of key elements in the slurry and in the soil. However, little is known about the impacts of slurries amended with biological additives on carbon (C) partitioning within three pools: respired CO2, microbial biomass C (Cmic) and C retained in the soil. We report data from incubation experiments in which soils received livestock slurry treated with a commercial biological additive, alongside 14C-labelled carbohydrates of different lability (14C-glucose, 14C-glucose 6-phosphate (G6P), and 14C-cellulose). The aim of this experiment was to understand how slurry that has received a biological additive ultimately affects the partitioning of C within these pools, alongside how slurry additives influence soil microbial biomass and the priming effect (PE) in soil. The addition of slurry alongside carbohydrates to soil resulted in lower 14C biomass uptake and greater residual 14C activities in soil, as well as to lower cumulative respiration and PE, compared to the corresponding carbohydrate-only treatments. Competition in the soil between the indigenous microbial community and the microbial community associated with slurry is proposed to account for the apparent suppression of biomass uptake of added C-substrate and of cumulative respiration. Our findings also seem to indicate that the addition of a biological additive to slurry resulted in higher cumulative CO2 efflux from soil compared to the unamended slurry, both for glucose and G6P treatments. This suggests that biological slurry additives may have the potential to reduce the suppressive effect of slurry microorganisms on native soil microorganisms.

Following the Master in Integrated Environmental Management, held at the European School for Advanced Studies of IUSS (University Institute of Advanced Studies), University of Pavia, Pavia, Italy, I worked as a trainee at the consulting company Eco Auditing Ltd. Genoa, Italy. Eco Auditing is an Italian leading environmental consultancy to public and private institutions and it is specialised in environmental certifications, with expert consultants to assist in the design and implementation of environmental management systems applied to public bodies. Specifically, I was interested in the environmental certification of the municipality of Maratea, in the province of Potenza, in compliance with UNI EN ISO 14001.

Organic phosphorus (Po) compounds in soil often comprise a large component of soil total P (up to 84% for pasture), and represent a potentially significant source of P for agricultural production. Information on the quantities and forms of soil Po remains relatively limited, but we do know that inositol phosphates and their numerous metal-ion derivatives often constitute the dominant form of soil total Po. In addition, other phosphate esters, such as sugar phosphates, phospholipids and nucleic acids have often been identified in smaller quantities within soils. Various soil microorganisms, such as mycorrhizal fungi and phosphate-solubilising microorganisms (PSMs), can access inositol phosphates and other Po compounds. These microorganisms play an important role in the mineralisation of soil Po and the release of inorganic phosphorus compounds to soil solution or for direct plant uptake. Our research aims to explore the extent to which the coupled microbial and enzyme system with agricultural soils might be manipulated in order to increase the value derived from soil Po compounds as part of agricultural production. Specifically, we describe research focussed on inoculation experiments in which selected fungal and bacterial strains, alongside extracellular phosphatase enzymes, are trialled for their efficacy with respect to the mineralisation and solubilisation of Po compounds within soils. For example, arbuscular mycorrhizas (AMs) belonging to the phylum Glomeromycota could be introduced to soil ecosystems in order to benefit from the symbiotic endobacteria living inside the fungus whose genes are involved in mineral P acquisition. Such AMs could be mixed with strains of some of the most beneficial PSMs for Po mineralisation, e.g. Azospirillum spp., Bacillus spp., Penicillium spp. and Rhizobium spp. In addition, bacterial strains such as Bacillus amyloliquefaciens FZB24, FZB42 and FZB45, could be inoculated in soils due to their ability to secrete extracellular phosphatase enzymes. Our research focuses on the extent to which inoculations could increase the availability of phosphorus within soils for agricultural production, focussing largely on livestock farms and associated grass quality and yields. In particular, we will examine whether inoculation of livestock slurries and manures provides a vector for indirect manipulation of soil microbial and enzyme systems within livestock farms. The ultimate aim of this approach is to reduce the reliance of agricultural production on finite inorganic phosphorus fertiliser reserves.

The data presented here are related to the research article entitled ‘Effects ofsubstrate quality on carbon partitioning and microbial community composition in soil from an agricultural grassland’ [1]. Data illustrate cumulative CO2 efflux, microbial biomass C (Cmic), priming effect expressed as priming index (PI) and total phospholipid fatty acid (PLFA) profiles. The data were measured during four soil laboratory incubations using a silty clay loam soil under permanent grassland from May until August 2015. The soil was treated with carbohydrates of different complexity (glucose, glucose-6-phosphate (G6P) or cellulose) alone or in conjunction with livestock slurry amended or non-amended with a biological additive. Our data may be of great significance for further studies on microbial respiration and biosynthesis, and microbial community structure following slurry application to soil, alongside the potential beneficial effects of the addition of slurry amended with biological additives.