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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

Polyphenol oxidase (PPO) activity in red clover (Trifolium pratense) has been reported to reduce both proteolysis and lipolysis, resulting in greater N use efficiency and protection of PUFA across the rumen. Although high levels of PPO have been reported in grasses such as cocksfoot (orchard grass; Dactylis glomerata), no in vivo research has determined whether grass PPO elicits the same response as red clover PPO. To test the hypothesis that silage ensiled from grass with high levels of PPO protects N and PUFA across the rumen, 6 steers with ruminal and duodenal cannulas were offered cocksfoot silage (CO; high-PPO grass), perennial ryegrass silage (PR; Lolium perenne; low-PPO grass), or red clover silage (RC; high-PPO control) at 16 g DM/ kg BW daily with the experiment consisting of two 3 × 3 Latin squares with 21-d periods, consisting of 12 d of diet adaptation, 6 d of duodenal marker infusion, 2 d of duodenal sampling, and 1 d of ruminal sampling. All silages were well preserved, with DM of 34.4, 55.3, and 45.4% for CO, PR, and RC. Activity of PPO in silages was low due to deactivation but was greater in CO than either PR or RC (0.15 vs. 0.05 and 0.08 μkatal/g DM).Protein-bound phenol (mg/g DM) as a measure of the degree of oxidation and an indication of PPO protection was greatest for RC (15.9) but comparable for PR (10.1) and CO (12.2). Biohydrogenation of C18 PUFA was significantly lower on RC compared to the 2 grass silages with CO greater than PR. Despite lower levels of total fatty acid intake and subsequent duodenal flow, CO resulted in greater levels of phytanic acid and total branched and odd chain fatty acids in duodenal digesta than RC or PR. Ruminal ammonia concentration was greatest for RC, with no difference between the grasses. Duodenal flow of microbial N and efficiency of microbial protein synthesis were lowest for CO and comparable for RC and PR. The CO (high-grass PPO) did not result in elevated levels of C18 PUFA escaping the rumen or improve efficiency of total N transfer through the rumen compared to PR. The RC resulted in a greater flow of N and nonmicrobial N to the duodenum than the 2 grasses with PR greater than CO.