Search

Biofumigation, the burying of Brassicaceaous plant tissues to suppress soil pests, is an increasingly practiced technique. However, the efficiency of biofumigation varies considerably and motivated our meta-analysis on the topic. We meta-analyzed data from 46 publications where 934 experiments used 363 unique controls, in order to determine effectiveness of this practice compared with untreated controls, and to identify which aspects of treatment regimens were most important for ensuring success. Biofumigation generally reduced pest abundance, reduced incidence of disease, and increased crop yield by 30% over values seen in untreated controls. Neither the plant part incorporated, nor the method used to incorporate it, were important predictors of success. Contrary to our expectations, we found no evidence that solarization was beneficial, and only treatment regimens without solarization were generally effective. While treatment regimens varied, the most effective treatment combination that we identified was the incorporation of young Eruca and Raphanus plants, with high glucosinolate concentrations, applied at high doses with short exposure times to suppress the nematode Globodera in Solanaceous plants. Each component of this regimen would likely increase the effectiveness of biofumigation efforts aimed at other soil pests.

Soil aggregation is a crucial aspect of ecosystem functioning in terrestrial ecosystems. Arbuscular mycorrhizal fungi (AMF) play a key role in soil aggregate formation and stabilization. Here we quantitatively analyzed the importance of experimental settings as well as biotic and abiotic factors for the effectiveness of AMF to stabilize soil macroaggregates. We gathered 35 studies on AMF and soil aggregation and tested 13 predictor variables for their relevance with a boosted regression tree analysis and performed a meta-analysis, fitting individual random effects models for each variable. The overall mean effect of inoculation with AMF on soil aggregation was positive and predictor variable means were all in the range of beneficial effects. Pot studies and studies with sterilized sandy soil, near neutral soil pH, a pot size smaller than 2.5 kg and a duration between 2.2 and 5 months were more likely to result in stronger effects of AMF on soil aggregation than experiments in the field, with non-sterilized or fine textured soil or an acidic pH. This is the first study to quantitatively show that the effect of AMF inoculation on soil aggregation is positive and context dependent. Our findings can help to improve the use of this important ecosystem process, e.g. for inoculum application in restoration sites.