Biomassa, teor de nitrogênio e relação c/n de culturas de cobertura de inverno estabelecidas em áreas manejadas no sistema plantio direto no Alto Uruguai gaúcho

Abstract

Cover crops grown in the winter off-season are of great importance to protect the soil and provide organic matter, as the decomposition of straw residues recycles important nutrients used by subsequent crops in a no-tillage system. The use of these plants in the southern region of Brazil can provide improvements in the physical, chemical and biological conditions of the soils, as well as in the productivity of crops of economic interest. This work aimed to evaluate the total productivity of shoot dry mass, the N and C contents present in the DM, the C/N ratio of the residues and the accumulation of kg of N/ha present in the DM, of different managements of cover crops. of soil in single and intercropped cultivation. The experiment was carried out during the 2021/22 crop year, on a property located in Barão de Cotegipe – RS, on Dystrophic Red Latosol, implemented in a randomized block design, with eight treatments and four replications: T1: Fallow; T2: Black oat (Avena strigosa Schreb); T3: Rye (Secale cereale); T4: Forage turnip (Raphanus sativus); T5: Vetch (Vicia sativa L.); T6: Black oat + Forage turnip + Vetch; T7: Rye + Forage turnip + Vetch; T8: Black oat + Rye + Forage turnip + Vetch. The results obtained in the experiment were submitted to analysis of variance, and using the Tukey test at 5% probability through the SISVAR software. Some treatments showed significant effects on the variables. The consortium on T8 had the highest DM/ha production (8771,8 kg); the vetch crop (T5) had the highest nitrogen content in DM, being 7,34%; In terms of carbon content in MS, there was not significance between treatments; Among the C/N ratios, rye (T3) had the highest ratio of 23,77; And regarding the accumulation of N in the MS, the T6 and T7, were the ones that most accumulated nitrogen in the MS, reaching 295,75 and 293,75 kg of N/ha respectively