Biomass and decomposition of cover crop residues in monoculture and intercropping
The use of cover crops in autumn/winter, in the Planalto region of Rio Grande do Sul, contributes to the success of the no-tillage system. However, information about the biomass production and decomposition of such species in the region is still scarce, especially for cover crop species in consortium. The experiment was conducted in Não-Me-Toque, RS, on an Oxisol, evaluating nine treatments of four cover crops in monoculture [rye (Secale cereale L.), oat (Avena strigosa Schreb), pea (Pisum sativum subsp. arvense), and wild radish (Raphanus sativus L. var. oleiferus Metzg)] and five in intercropping [(rye + pea, radish + rye, oat + radish, rye + vetch (Vicia sativa L.) and oat + vetch)]. The decomposition dynamics of cover crop residues was evaluated in litter bags which were distributed on the soil surface and collected after seven, 14, 21, 28, 57, 117, and 164 days. Leguminous and cruciferous intercropped with Gramineae species resulted in greater biomass production compared to cultivation in monoculture. The nitrogen (N) accumulated in the pea and wild radish plants intercropped with rye and oat was similar to the N in the leguminous and cruciferous monocultures and exceeded the N values observed for the Gramineae species in monoculture by 220.4 %. By intercropping cover crops it was possible to reduce the decomposition rate of crop residues compared to the monoculture of leguminous and cruciferous species.