The use of cover crops is an important strategy for soil management in the Brazilian Cerrado to improve no-tillage (NT) systems. For this, it is necessary know the potential of cover crop species for biomass production, nutrient cycling, and persistence of residues on the soil surface in soils and climatic conditions of this biome. Thus, the experiment was developed to evaluate the agronomic potential of cover crops cultivated on an Oxisol (Latossolo Amarelo) in the Cerrado of Piauí, Brazil. The experiment was conducted from January 2015 to July 2016. The experimental design was in randomized blocks with 11 treatments and four replicates. The treatments consisted of single and intercropped cover species. The evaluations were: dry mass production, nutritional composition of the plants, nutrient accumulation by dry mass produced and decomposition rate of the dry mass produced for each treatment. The higher dry matter production was obtained with Crotalaria juncea, Cajanus cajan (cv. IAC-Fava larga), Pennisetum glaucum and Brachiaria ruziziensis. The lower dry matter production was obtained with Mucuna aterrima, and mix of Crotalaria spectabilis + Pennisetum glaucum. The higher nutrients accumulation in the plants occurred for Cajanus cajan (cv. IAC-Fava larga), Crotalaria juncea and Crotalaria spectabilis. The cover plants studied presented good potential for soil conservation, due to the permanence of residues on the surface, except for Mucuna aterrima and Crotalaria spectabilis.

This study aimed to estimate the nutrient absorption rate in soybean plants cultivated in succession to cover crops and under soil management systems. We performed two experiments with soybean grown on the remaining straw of Crotalaria spectabilis and Pennisetum glaucum (millet), under no-tillage (NT) and minimum tillage (MT), over the cropping years 2016/2017 and 2017/2018, in the Cerrado of Piauí state. The experimental design was a randomized blocks, arranged in split-plots. Plots corresponded to soil management systems and subplots to days after emergence (DAE) of soybean, with 3 replications. Nutrients contents were evaluated at 31, 38, 45, 52, 59, 66, 73, 80, 87, 94, 101, 108 and 115 DAE. Higher soybean dry matter (DM) production occurred in MT compared to no tillage. Crotalaria spectabilis enhanced accumulation of DM and N until stage R2. Accumulation of nutrients and DM in soybean cultivated on the straw of millet and C. spectabilis were similar across soil management systems. The phase of highest accumulation of nutrients and DM in soybean occurs between stages R5 and R7. All the nutrients, except Ca and Mn, are allocated to the grains during physiological maturity, in proportions higher than 50% of the total amount accumulated in soybean plants.

The conservation tillage systems is based on the surface protection by crop residue and reduced soil disturbance. These two principles can favor the soil quality and promote sustainable agricultural systems. The study was developed with the objective of measure soil microbial biomass, soil basal respiration, enzymatic activity and soybean yield in conservation systems cultivated with cover crops species in the Northeastern Cerrado. The experiment was carried out in 2016/2017 and 2017/2018 cropping seasons, performed in a randomized blocks design. The treatments were soil tillage systems allocated in the main plots: no-tillage (NT) and minimum tillage (MT) and the cover crops were allocated in the subplots: Pennisetum glaucum (millet), Urochloa ruziziensis (brachiaria), Crotalaria spectabilis (C. spectabilis), Crotalaria ochroleuca (C. ochroleuca), Pennisetum glaucum + Crotalaria spectabilis (millet + C. spectabilis) and spontaneous plants with three replicates. The evaluated variables were dry mass (DM) production and nutrient accumulation in cover crops; soil biological properties, namely microbial biomass carbon and nitrogen (MBC and MBN, respectively), respiration, metabolic quotient (qCO2), dehydrogenase enzymatic activity (DH), fluorescein diacetate (FDA); and soybean yield. The higher production of dry mass and nutrient cycling occurs with the intercropping millet + C. spectabilis and single millet. The highest soybean yield occurs in succession to C. ochroleuca and intercropping of the millet + C. spectabilis. Cover crops in conservation systems improve soil microbial quality and increase soybean yield.

Nutrients and carbon cycling processes in integrated production systems are essential for agroecological sustainability in the Cerrado of Northeast Brazil. However, quantitative and process-level understanding remains limited. This study aimed to characterize off-season plant residue decomposition under different production arrangements through the assessment of dry biomass, bromatological composition, and litter decomposition kinetics. The experiment was conducted in the off-season of the 2022/2023 agricultural year at Barbosa farm (Brejo, Maranhão, Brazil), in a Yellow Argisol (Ultisol), with Aw prevailing climate. We evaluated residues of soybean, Urochloa brizantha cv. Marandu, maize, maize + Marandu, Megathyrsus maximus cv. BRS Tamani, Eucalyptus, Eucalyptus + Tamani, and native forest, representing crop–livestock integration (CLI), livestock–forestry integration (LFI), no-tillage soybean (Soybean-NT), and native forest (control). For each treatment, 0.20 × 0.20 m, 2 mm mesh nylon litterbags (nº = 4 replicates) were filled with 20 g of oven-dried plant residues cut into ~10 cm pieces. Litterbags were placed on the soil surface and sampled at 0, 30, 60, and 118 days to estimate the decomposition rate (k), C and N mineralization, and macronutrient dynamics. Residues differed in initial composition, with Eucalyptus and Eucalyptus + Tamani showing higher C contents (41–43%), while Marandu and Soybean-NT had greater concentrations of N (37.8–39.2 g kg⁻¹), P (2.37–2.42 g kg⁻¹), and Mg (2.38–2.83 g kg⁻¹). The Eucalyptus + Tamani mixture exhibited the highest decomposition rate (k = 0.0041), which was about 40% greater than Soybean-NT (k = 0.0026), and faster C release, whereas N in maize residues remained immobilized for up to 118 days. CLI and Soybean-NT enhanced nutrient cycling efficiency, with K+ increasing 17.3-fold (1.1 to 18.9 g kg⁻¹) and N 1.2-fold (1.8 to 2.3%) compared to native forest. Overall, residue quality, especially C/N ratio and lignin, regulated decomposition and integrated systems, particularly LFI, which conferred greater resilience and nutrient cycling efficiency in the Cerrado.

Cover crops play a crucial role in promoting soil protection, enhancing organic matter content, facilitating nutrient cycling, and improving overall soil quality. The objective of this study was to evaluate the biomass production, nutrient accumulation, and decomposition rate of cover crops intercropped with Theobroma cacao trees in a full-sun system. The research was conducted in Ilhéus, Bahia state, Brazil. The experimental design employed randomized blocks with three treatments, four decomposition times, and four replications. The treatments consisted of three cover crops: 1) pigeon pea (Cajanus cajan); 2) brachiaria (Urochloa decumbens); and 3) spontaneous vegetation. Decomposition rates were evaluated using litter bags at specific intervals: 0, 47, 94, 116, and 136 days after field deposition. Dry biomass production and nutrient accumulation by the cover crops were also measured. Spontaneous vegetation and brachiaria treatments exhibited the highest potassium accumulation, while no significant differences were observed among the treatments for the other evaluated nutrients. Moreover, spontaneous vegetation and brachiaria demonstrated higher decomposition rates, with 16.7% and 26.7% of the deposited material remaining at the end of the 136-day study period, respectively. In contrast, the decomposition rate of pigeon pea proved to be slower, with a remaining dry mass of 38.3%, indicating longer persistence in the soil, and consequently a greater half-life time. The cover crops investigated in this study are regarded as promising options for intercropping with cocoa, as they exhibit an average dry mass production of 10 Mg ha-1. This value falls within the desired range for conservationist systems. When selecting species for intercropping, it is crucial to consider the decomposition rates these plants. This consideration ensures that the soil surface remains covered for an extended duration, leading to enhanced conservation and improvement of the soil’s physical, chemical, and biological properties. Soil conservation can be effectively achieved by choosing cover crop species with slower decomposition rates, thereby contributing to the overall health and quality of the soil. Highlights: This study evaluated biomass production, nutrient accumulation, and decomposition rate of cover crops intercropped with Theobroma cocoa trees in a full-sun system. The cover crops investigated exhibit an average dry mass production of 10 Mg ha-1. Spontaneous vegetation and brachiaria treatments exhibited the highest potassium accumulation. Pigeon pea proved to be slower decomposition rate and largest remaining dry masso on the soil. In contrast, Spontaneous vegetation and brachiaria demonstrated higher decomposition rates, consequently less remaining dry mass.