Impact of crop management systems on soil nematode communities in South Brazil

Andressa Cristina Zamboni Machado,Francisco Skora Neto,Maurício Rumenos Guidetti Zagatto,Santino Aleandro Da Silva,Luiz Antonio Zanão Júnior

doi:10.1590/1678-992x-2020-0088

Andressa Cristina Zamboni Machado, Francisco Skora Neto + Show 3 more

Open Access

https://doi.org/10.1590/1678-992x-2020-0088

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Abstract

The analysis of nematode communities allows inferring consequences of management practices on the soil food web. We studied the taxonomic structure of nematode communities in preserved areas of the Atlantic forest (native forest = NF) in Ponta Grossa, Paraná State, Brazil, and in three different agroecosystems in neighboring areas to assess the effect of agricultural land use on nematode assemblages. Agroecosystems were located in a red latosol cropped during 30 years under conventional tillage (CT), no-tillage (NT), and minimal tillage (MT). We collected ten composite soil samples in each area in the summer. Nematodes were extracted by Baermann funnel and fixed with formalin. Subsequently, individuals were classified into taxonomic groups and counted on a Peters slide to determine densities of each taxon. Plant-parasitic and free-living nematodes were classified at the genus level. Data were analyzed with the parameters abundance, Bray & Curtis, Shannon-Weaver, and Simpson indexes. We recorded 35 genera and abundance of nematodes in MT and NT areas was more similar. Higher richness was observed in NF in relation to cropped areas, especially under NT and CT. The PCA and clustering analyses from both nematode communities and soil chemical characteristics showed that MT and CT were more similar and NT was clustered near NF. The replacement of native vegetation by cropping systems caused a reduction of nematode diversity, demonstrating the influence of agricultural practices on nematode communities.

Highlights

Nematodes are some of the most diverse soil animals and are capable to respond quickly to environmental changes; they have been used as indicators of soil health in different crop systems and native areas (Neher, 2001; van den Hoogen et al, 2020)
We studied the taxonomic structure of nematode communities in preserved areas of the Atlantic forest in Ponta Grossa, Paraná State, Brazil, and in three different agroecosystems in neighboring areas to assess the effect of agricultural land use on nematode assemblages
The Shannon-Weaver (H’) diversity index confirmed the indications based on number of genera relatively to the high diversity found in native forest (NF) and minimal tillage (MT) samples (Table 3)

Summary

Introduction

Nematodes are some of the most diverse soil animals (van den Hoogen et al, 2020) and are capable to respond quickly to environmental changes; they have been used as indicators of soil health in different crop systems and native areas (Neher, 2001; van den Hoogen et al, 2020). Bacterial-feeding nematodes can ingest a great number of bacterial cells per day and are attracted by high CO2 concentrations in their soil. Their preying capacity releases NH4+ readily available to plants and other animals in the soil solution (Lavelle, 1997). Abundance and diversity of nematodes in fields under different agricultural systems are used to infer disturbances to the soil fauna (van den Hoogen et al, 2019), as well as enrichment and disturbance of soil communities (Bongers, 1990; Ferris et al, 2001; Berkelmans et al, 2003). Most studies focus on the effects of tillage and cropping patterns on plant-parasitic nematodes and, to a lesser extent, on the free-living nematode communities (Sánches-Moreno et al, 2006)

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