Resumo

ODERIZ, Juan Agustín et al. Raíces de cultivos de cobertura: Cantidad, distribución e influencia sobre el N mineral. Cienc. suelo [online]. 2017, vol.35, n.2, pp.249-258. ISSN 1850-2067.

The objectives of the work were: i) Evaluate the amount and distribution of rye and vetch roots as cover crops (CC); ii) Quantify the contribution of N-roots in the profile and their impact on N-nitrate availability in the soil. The study was carried out in two soils: Petrocalcic Paleustoll and Typic Ustipsamment in long duration trials with rotations including CC and sorghum or maize for silage. Treatments were a control without CC (T), rye (C), rye fertilized with 60N (C+N), vetch (V), and vetchrye consociation (VC) arranged in a completely randomized block design with four replicates. At the end of CC growing season in 2015 root quantity, quality and distribution up to 1 m depth stratified every 0,20 m (BRT), aerial biomass (BA) and N-nitrates in soil were determined. In the Ustipsamment vetch root biomass at 1 m depth (3165 kg ha^-1) was lower than rye alone or with N (4459 kg ha^-1). In this soil, the grass showed higher root biomass accumulation in the first 20 cm (88%) than the legume (62%). In contrast, in the Paleustoll no differences were found between V and C or C+N, which produced on average 4195 kg ha^-1 of roots at 1 m depth, value that was lower than the corresponding to VC (5014 kg ha^-1). In this soil, BRT in the uppermost soil layer was similar between species (57%). In general, BRT/BA ratio in V was higher than C (0.98 and 0.49). N-root contribution varied between 50 and 75 kg ha^-1. A linear and positive relationship was found between N-root and mineral N starting from 15-30 days from the end of CC at 0-20 cm depth and from 45-65 days for the 20-100 cm stratum depending on soil type.

Palavras-chave : Vetch; Rye; Paleustoll; Ustipsamment.

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