Efficacy of organic amendments to control Meloidogyne spp. in crops: a systematic review and meta-analysis

Purpose The aim of this meta-analysis and review study was to identify the original research works done on use of organic amendments against root-knot nematodes and to quantitatively analyse the effect of different organic amendment types, such as animal manure, composts, plant derivatives and plant residues, on root-knot nematodes in crops. Materials and methods The original studies conducted on RKN control using organic amendments were identified using database and literature searches. The articles were screened and data were extracted. The publication bias of the studies was calculated. The soil amendments used in experiments were identified into four main organic amendment categories: plant residues, composts, animal manure and plant derivatives (powders, pellets or extracts produced from plant or plant parts). A meta-analysis was performed calculating the response ratios (effect size) of different organic amendments against RKN favouring plant performances. Results and discussion All the amendment types, i.e. plant residues, composts, animal manures and plant derivatives, were found to be effective against RKN. Plant-based derivatives were the most effective against all RKN damage attributes followed by application of compost and animal manure. Poultry manure was the only effective animal manure to control RKN consistently based on the results. Plant residues were found to be the least effective against RKN; amongst these groups of organic amendments, the family Poaceae produced the most effective residues to control RKN. Conclusions Organic amendment application generally reduced the RKN population and damage by 63 compared to untreated conditions.