Work

Microbial Responses and Maize Performance in Soil Treated with Leaf and Seed Extracts of Neem

Year: 2026

Type: article

Abstract: Neem (Azadirachta indica A. Juss) extracts are widely used in agriculture as organic pesticides, but their effects on soil microbiota are uncertain. This study evaluated the impact of aqueous extracts of neem leaves and seeds on soil microbial activity, maize (Zea mays L.) development, and arbuscular mycorrhizal fungus (AMF) dynamics. The experiment used a 2 × 3 + 1 factorial design, with two extract sources (leaf and seed), three concentrations (5%, 10%, and 20%), and a control. The soil treated with 20% seed extract showed the highest microbial respiration (16,512 mg C-CO2·kg−1·day−1) and total organic carbon (15.10 g·kg−1) but the lowest microbial biomass (1330 mg·kg−1) and microbial quotient (0.10%), indicating a stressed microbial environment. Paradoxically, maize plants under this same treatment exhibited a superior height, stem diameter, and biomass. Furthermore, the AMF spore density significantly increased in the seed extract treatments, suggesting a stress-induced reproductive response. These findings reveal that, although neem seed extract can negatively affect soil microbiota, it promotes maize growth, likely due to its organic and bioactive compounds. Thus, neem extract demonstrates potential as an organic input, but its application must be carefully managed due to potential ecological trade-offs.

Source: Grasses

DOI: 10.3390/grasses5020017

Authors: Dayanne Camelo, Leila Maria de Sousa Tavares, Emanuel Dias Freitas, Paulo Furtado Mendes Filho

Institutions: Universidade Federal Rural de Pernambuco, Instituto Federal de Educação, Ciência e Tecnologia do Ceará, Universidade Federal do Ceará

Language: English

Topic: Agriculture, Plant Science, Crop Management

Subfield: Plant Science

Field: Agricultural and Biological Sciences

Domain: Life Sciences

SDGs: Zero hunger, Life on land

Open Access status: gold

Estimated APC paid: $1,207