Abstract

ARUANI, María C; AZPILICUETA, Claudia V; REEB, Pablo  and  ARIAS, María A. Ensamble de nematodos en una cronosecuencia en suelo salino y fertilizado, en un huerto frutícola. Cienc. suelo [online]. 2017, vol.35, n.1, pp.47-55. ISSN 1850-2067.

Soil nematode assemblage was studied in a chronosequense (S1, S2 y S3) that included 2008-2009, 2009-2010 and 2010-2011 growing seasons of a pear commercial orchard with different nitrogen fertilizer management: 776, 375 and 80 kg N ha^-1, respectively, in a silt loam saline soil (5.2 dS m^-1). Nitrogen application in S1 and S2 was split in seven times and in S3 in three times. Soil characteristics, nematode abundance, ecological indices, and fruit yield were evaluated. Organic matter (4.2%), nitrate (29.5 mg kg^-1) content and soil pH (7.64) did not change in the chronosequence. Smectite clays, that are one of dominant minerals in the soil, exhibit high buffering capacity and high resistance to change in pH when the nitrogen fertilizer is applied to the soil. Plant-feeding nematodes were the most abundant trophic group (48%) and the families belonging to the herbivores of c-p 2 guild were dominant. Aporcelaimellus represented a 16% of total abundance of nematodes. In S1, the increase in enrichment index (78.6%) was attributed to the high abundance of bacterivores of c-p=1 guild (Ba₁) and fungivores of c-p=2 guild (Fu₂), where the rate of nitrogen applied was greater, respect to S2 and S3. The numbers of Panagrolaimidae and Rhabditidae increased in S1. Soil nitrate content was not correlated with Ba₁ and Fu₂ abundance. Neither omnivores and carnivores density nor indices of structure (81.4%), channel (14.2%) and basal (11.1%) were altered by nitrogen application in the growing seasons. The low value of channel index indicated a bacterial decomposition pathway of soil organic matter. The pear fruit yield was similar in the chronosequense.

Keywords : Electric conductivity; Nematodes functional group; Pear tree; Nitrogen fertilization; Upper Valley of Rio Negro.

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