Investigating the impact of ecosystem change within agriculture on the soil food web.

The soil invertebrate food web drives nutrient cycling and decomposition. However, the food web can be affected by perturbations differently depending on plant type within an ecosystem. An experiment was set up to test the hypothesis that previous forage cropping and cultivation method would alter the soil ecosystem leading to changes in the food web, during crop rotation. Plots were grown containing monocultures of chicory (Cichorium intybus), red or white clover (Trifolium pratense, T. repens) and perennial ryegrass (Lolium perenne). Four replicate plots of the forages were established (12 x 7.5m) in 2009; these were split (10 x 3.75m) in spring 2013 and wheat established either after ploughing, or seeds directly drilled; with wheat harvested autumn 2013. It was hypothesised that direct drill would disturb the food web less than ploughing, whilst the plots which were previously legumes would retain a different soil faunal
population, even though the crop was the same across all plots. The effect on soil faunal populations of these previous different forage crops and sowing method were assessed after wheat harvest; the soil fauna sampled included microfauna, mesofauna, and macrofauna. Overall our results have shown that for a number of soil faunal groups across the three scales of sampling, the previous forage still had a significant effect over the current soil food web, even though the ecosystem has now been standardised between the different plots. There was also a significant affect over all soil faunal populations when assessing the difference in cultivation method – plough versus direct drill. Our findings have begun to show the linkage between soil biodiversity and the effect of agriculture on the whole ecosystem and shows the potential for managing a healthy soil food web and maintaining it, within agricultural production.