231 Highlights • The soil microbiome refers to the diverse collection of microorganisms present in soil, many of which can mediate essential soil functions such as nutrient cycling and plant pest and disease suppression. • There is growing international interest in the potential to manipulate the soil microbiome to deliver improved agricultural and environmental outcomes. • Molecular techniques are rapidly increasing understanding of the soil microbiome structure and function but manipulating soil microbiomes for pasture resilience still presents signifcant science challenges. Keywords: ecosystem services, microorganisms, nutrient cycling, rhizosphere Background It is estimated that a gram of agricultural soil can contain between thousands and tens-of-thousands of different species of microorganisms, so just a handful of soil can contain more diversity of life than all the plants and animals present in a rainforest (de Vrieze 2015; Wakelin 2018). Microorganisms (i.e., bacteria, archaea, viruses, fungi, and other microeukaryotes) present in soil have come to be known collectively as the soil microbiome. The soil microbiome can be defned in many ways (Berg et al. 2020) but here we adopt the defnition as the entire habitat of the soil microorganisms, which includes the microbiota themselves, their collective genetic information, and the biotic and abiotic factors within their habitat. Soil microorganisms have been described as “the eye of the needle” through which carbon (C) and nutrient transformations are mediated (Jenkinson 1977; Wakelin 2018), highlighting their essential role in cycling of organic matter and soil fertility. More recently they have also been described as “the littlest farmhands” (de Vrieze 2015), acknowledging their vital role in agriculture. The importance of soil microorganisms has been recognized for more than a century (Fierer 2017) but the lack of methods necessary to visualise and study soil microorganisms has meant that soil has historically been regarded as a proverbial “black box”. However, recent ISSN 0118-8581 (Print) ISSN 2463-4751 (Online) https://doi.org/10.33584/rps.17.2021.3475 Insights into the soil microbiome and prospects for its manipulation for improved pasture resilience Shengjing SHI 1 , Sean D.G. MARSHALL 1 , Nicole SCHON 1 , Bryony B.E. DIGMAN 1 , Nigel L. BELL 2 , Maureen O’CALLAGHAN 1,* 1 AgResearch Ltd., Lincoln Science Centre, 1365 Springs Road, Lincoln 7674 2 AgResearch Ltd., Ruakura Research Centre, 10 Bisley Road, Hamilton 3214 *Corresponding author: maureen.ocallaghan@agresearch.co.nz global initiatives are placing value on soil microbiology for delivery of key ecosystem services that underpin robust functioning of soil and water systems required for plant growth (e.g., Keesstra et al. 2016), and this is driving new international research efforts. There is also growing interest in the potential of soil microbiology to deliver benefcial outcomes for New Zealand’s productive sectors (Wakelin 2018). Some of this new interest is driven by farmers who want to maximise soil function and may have questions about the scientifc validity of the burgeoning range of microbial products and soil additives on offer today, many of which come with substantial (often unvalidated) product claims. There is also increasing interest in improving “soil health” on-farm, however being able to identify and manipulate the soil microbiome for desired outcomes remains diffcult. Fortunately, with the advent of new molecular approaches, increased understanding of the soil microbiome in managed ecosystems is emerging (Chen et al. 2019). New Zealand’s pastoral sector is built upon its productive soils. Pasture production and resilience are impacted by many factors including climate, management practices and soils, including soil microbiology. Important to ensuring pasture growth throughout the year is understanding how plants respond to stress events. Here we defne resilient pastures as those that incur less reduction in production and recover faster after a stress event (e.g., drought/ fooding, pest/disease pressure) (Walker et al. 2004). As our pastures refect the soils in which they grow, it is axiomatic that soil microbiology will impact pasture resilience, and possibly that the resilience of soil microbial communities themselves plays an important role of supporting pasture resilience. It is important to acknowledge that in comparison with other disciplines contributing to pasture resilience (e.g., soil biogeochemistry, plant breeding), soil microbiome research is still in its infancy, especially in New Zealand. We have only relatively recently begun to consider the role of the soil microbiome in pastoral agriculture, so defnitive commentary on its impact on pasture resilience per se will therefore be limited and to some extent speculative at this stage.