Understanding the legacy effect of previous forage crop and tillage management on soil biology, after conversion to an arable crop rotation

Abstract

The soil ecosystem provides a habitat for numerous and diverse fauna which hold a pivotal role driving decomposition and nutrient cycling. However, changing land use or management can alter population dynamics, changing soil biology within the system. The implementation of different field management can improve soil fertility, whilst natural variations in plant species growth and root system may create changes to soil structure and properties. All plant species create a legacy effect within the soil to some extent; changing the environment either physically or through remaining plant residues. The impact of this legacy effect is difficult to perceive and only by monitoring will determine the change in soil faunal populations. An experiment investigated the hypothesis that previous forage cropping and establishment method would alter the diversity and abundance of soil fauna, during crop rotation. Four replicate plots of either perennial ryegrass (Lolium perenne), red clover (Trifolium pratense), white clover (Trifolium repens) or chicory (Cichorium intybus) (crop 1) were grown in a randomised block design (2009-2013), before becoming part of a crop rotation. These plots were split in spring 2013 and winter wheat (Triticum aestivum) established, either by ploughing or direct drilling; and harvested autumn 2013 (crop 2). Winter barley (Hordeum vulgare) was established using the same methodology in autumn 2013; and harvested autumn 2014 (crop 3). Soil fauna abundance after each crop rotation, including microfauna (nematodes), mesofauna (mites) and macrofauna (earthworms), showed legacy effects. Abundance of both earthworms and nematodes were affected by the original forage within crop 2; although after crop 3 the legacy effect began to diminish. Crop establishment method also affected abundance, although these were fauna dependent, with earthworm numbers being detrimentally affected by ploughing whilst nematode abundances increased with ploughing. Overall, the effect of perturbations and the consequences on biodiversity dynamics and function may have an important impact on crop sequence choices within agroecology.publishersversionPeer reviewe

The legacy of cover crops on the soil habitat and ecosystem services in a heavy clay, minimum tillage rotation

“…Live earthworms were sorted into adults and juveniles, and identified to species using the taxonomic key by Sherlock () and functional groups following Roarty, Hackett, and Schmidt (). Other macrofauna abundance and diversity were also quantified from the soil block taken for earthworm sampling as per Crotty et al () ( n = 6), with macrofauna found identified to order and counted per block. This included centipedes, millipedes, beetles (adults and larva), fly larva, spiders, woodlice, slugs, and snails.…”

Plant species identity drives soil microbial community structures that persist under a following crop

“…Legacy‐associated plant residues may lead to the persistence of microbial groups which are best suited to utilize those (Allison et al., 2013). Previous research has also illustrated the legacy effect that differing species of grassland plants have various trophic levels of soil biology, that is, fungi, nematodes, mites, and earthworms, in a rotational agronomic system (Crotty et al., 2016; Detheridge et al., 2016). What is currently not clear, however, is the extent and the persistence of the influence imparted by different sward types (i.e., monocultures of different species and their mixtures) on soil bacterial and fungal community structure, and whether both constituents of the microbiome respond in a similar manner.…”

Humusica 2, Article 15: Agro humus systems and forms

“…Crop fields, and to a lesser extent pastures and meadows, originate from natural or semi-natural environments which have been historically disturbed by mechanical (tillage), chemical (fertilizers, pesticides) and biological (vegetation change and seasonal collapse, grazing) practices (Green, 1989). However, these practices do not kill soil life, in particular the activity of ecosystem engineers (e.g., earthworms, enchytraeids), although in a constant state-of-change due to disturbances, is still visible (up to a certain threshold) in the form of aggregates and burrows, and continue to play a leading role in the maintenance of soil fertility through its control of soil microflora and other ecosystem services (Crotty et al, 2016;Fusaro, 2015;Van der Wal and De Boer, 2017;Wood et al, 2015;Lavelle et al, 2006). Litter is absent and cannot be used as a visual clue for characterizing the rate of recycling of organic matter, contrary to forests, heathlands and natural grasslands (Jenny et al, 1949).…”