Resumo

DE SA PEREIRA, Eduardo; GALANTINI, Juan  e  QUIROGA, Alberto. Calidad de cultivos de cobertura en sistemas de siembra directa del sudoeste bonaerense. Cienc. suelo [online]. 2017, vol.35, n.2, pp.337-350. ISSN 1850-2067.

No-tillage system with fall/winter cover crop (CC) ensures that large amounts of different types of organic residue are supplied to the soil. The biochemical composition of each residue, especially its C:N ratio and lignin, plays an important role in nitrogen (N) and carbon (C) soil dynamics, as well as the availability of nutrients for the next crop. The objective of this study was to evaluate the quality parameters of CC based on the quantity and quality of the residue contributed. The experiments were carried out on Argiudioles typical of the Coronel Suárez (Pcia. de Bs. As.) Species used as cover crops were: Oats (Avena sativa L.), Hairy vetch (Vicia sativa L. Thell.), Clover persia ‘‘grazing’’ (Trifolium resupinatum L var. ‘‘Lightning’’), Clover persia ‘‘coverage’’ (Trifolium resupinatum L. var. ‘‘Laser’’). The determinations were: a) Production of forage (Mg MS ha^-1), b) N, c) neutral detergent fiber (NDF) and acid (FDA), nonstructural carbohydrates (CNES), carbon (C%) and Lignin. The aerial biomass of Hairy vetch presented the highest concentrations of N in the dry matter (MS) produced. When the oats were fertilized they were able to increase the contributions of N to the soil present in the aerial biomass of the residue to 50%. The aerial biomass of Hairy vetch presented the highest yields and concentrations of lignin. The different CC presented C:N and LIG:N ratios that were based on the amount of MS produced by the aerial biomass of the crop and its phenological state at the time of drying. The temperature and the moment of evaluation modified quantity and quality of the residues. The parameters evaluated were sensitive to these changes.

Palavras-chave : Coverage crops; Cellulose; Hemicellulose; Lignin.

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