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New agricultural practices and land-use intensification in the Cerrado biome have affected the soil carbon stocks. A major part of the native vegetation of the Brazilian Cerrado, a tropical savanna-like ecoregion, has been replaced by crops, which has caused changes in the soil carbon (C) stocks. To ensure the sustainability of this intensified agricultural production, actions have been taken to increase soil C stocks and mitigate greenhouse gas emissions. In the last two decades, new agricultural practices have been adopted in the Cerrado region, and their impact on C stocks needs to be better understood. This subject has been addressed in a systematic review of the existing data in the literature, consisting of 63 articles from the Scopus database. Our review showed that the replacement of Cerrado vegetation by crop species decreased the original soil C stocks (depth 0–30 cm) by 73%, with a peak loss of 61.14 Mg ha−1. However, when analyzing the 0–100 cm layer, 52.4% of the C stock data were higher under cultivated areas than in native Cerrado soils, with a peak gain of 93.6 Mg ha−1. The agricultural practices implemented in the Brazilian Cerrado make low-carbon agriculture in this biome possible.

Forest soils are N 2 O sources and commonly act as CH 4 sinks. This study evaluated the dynamics of the CH 4 and N 2 O fluxes of soils under Eucalyptus plantations and native Cerrado vegetation, as well as possible interactions between environmental factors and fluxes. The study was carried out in the Distrito Federal, Brazil, during 26 months, in three areas: in two stands of the hybrid Eucalyptus urophylla × Eucalyptus grandis, planted in 2011 (E1), and in 2009 (E2) and native Cerrado vegetation (CE). Measurements to determine the fluxes in a closed static chamber were carried out from Oct 2013 to Nov 2015. Soil and climate factors were monitored. During the study period, the mean CH 4 fluxes were-22.48,-8.38 and-1.31 μg CH 4 m-2 h-1 and the mean N 2 O fluxes 5.45, 4.85 and 3.85 μg N 2 O m-2 h-1 from E1, E2 and CE, respectively. Seasonality affected plantations in the studied sites. Cumulative CH 4 influxes were calculated (year-1:-1.86 to-0.63 kg ha-1 yr-1 ; year-2:-1.85 to-1.34 kg ha-1 yr-1). Cumulative N 2 O fluxes in the three sites were ≤ 0.85 kg ha-1 yr-1. The change in land use from Cerrado to Eucalyptus plantations did not significantly changed regarding greenhouse gases (GHG), compared to the native vegetation. Flux rates of both gases (N 2 O and CH 4) were low. Temporal variations in GHG fluxes and different ages of the stands did not cause significant differences in cumulative annual fluxes.

The objective of this work was to evaluate soil carbon fractions under cover crops cultivated after corn (Zea mays), with or without nitrogen topdressing fertilization, in a long-term experiment in the Brazilian Cerrado. The experiment was carried out in a randomized complete block design, in split-plots with three replicates. The plots were represented by the cover crops, and the subplots, by the presence or absence of N topdressing for corn. The following cover crop species were planted after the harvest of the 30F53VYHR corn hybrid: 'BRS Mandarin' pigeonpea (Cajanus cajan), sunn hemp (Crotalaria juncea), oilseed radish (Raphanus sativus), and black mucuna (Mucuna aterrima). After the cutting of the cover crops, soil samples were collected at 0.0‒0.10 and 0.10‒0.20 m soil depths. After corn harvest, samples of its residues were taken. The cover crops alter the soil chemical and physical fractions, especially fulvic acid and soil particulate organic carbon. Nitrogen topdressing for corn decreases fulvic acid, but increases the humic acid/fulvic acid ratio and particulate organic carbon in the deeper soil layer.

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The objective of this work was to evaluate the influence of sorghum and cover plant cropping systems before soybean cultivation on the occurrence of weeds during soybean growing in the Brazilian Cerrado. The experiment was carried out in a randomized complete block design, with four replicates. The treatments comprised six cropping systems before soybean: sorghum (Sorghum bicolor), palisade grass (Urochloa brizantha), and Congo grass (Urochloa ruziziensis) as cover plants, alone or intercropped, in addition to fallowing. Weeds were evaluated as to: density, dry matter mass, diversity, importance value, and similarity. The greatest similarity of weeds ocurred in single crops of sorghum, palisade grass, and Congo grass, in comparison with their intercroppings. Congo grass before soybean promoted a greater reduction in weed diversity overtime, when compared with palisade grass. The absence of cover crops before soybean cultivation increased weed infestation during the soybean cycle. The cropping systems with sorghum intercropped with cover crops before the soybean cultivation affect the diversity and the importance value of weed species.

Sorghum (Sorghum bicolor (L.) Moench) may be harmlessly intercropped with Urochloa species during the off-season in the Brazilian Cerrado. At the end of the sorghum cycle, forages can be used for straw production for soybean (Glycine max L.) as the summer crop. This study aimed to evaluate sorghum cultivated during the off-season, intercropped with palisade grass (Urochloa brizantha cv. 'Marandu' (Hochst. ex A. Rich). R. D. Webster) and Congo grass (Urochloa ruziziensis (R. Germ. and Evrard) Crins) in two row spacings (0.5 and 0.7 m) for their effect on plant growth, dry mass production, sorghum yield and soybean grain yield.The experiment was a randomized block design: a 3 × 2 factorial scheme, with three levels of intercropping (palisade grass, Congo grass or sole cropping) and two levels of row spacing (0.5 or 0.7 m) with four replicates. Several physiological growth indexes were estimated from 10 to 60 days after emergence (DAE), including dry matter production and sorghum agronomic performance. Sorghum accumulated 0.22 g of dry matter d -1 at 10 to 60 DAE, and was not affected by intercropping. The dry mass gain of forages (0.04 g d -1 on average) was not affected by sorghum either. Higher sorghum grain yield (2,922 kg ha -1 ) was observed under the 0.5-m row spacing when compared to the 0.7-m spacing. The results indicate that palisade or Congo grass may be used as companion crops for sorghum with no grain yield loss, be it to improve soybean grain yield, soil cover or integrated crop systems, aiming at sustainable intensification.

The present study aimed to assess the effect of fourteen years of implementation of a successional and biodiverse agroforestry system (AFS) in a degraded agricultural field located in the Cerrado region of Central Brazil on the carbon and nitrogen dynamics. To track short term soil N dynamics we sampled instantaneous soil N rates in four seasonal periods (wet-dry, dry, dry-wet, wet) and to track long term C and N dynamics we measured C and N stable isotopes in the plant-litter-soil system. As additional data we determined the aboveground biomass; resorption rates of foliar and, soil C and N stocks.  The measured aboveground biomass was 19.2 Mg C ha-1. The mean resorption rate of foliar N was 49.3%. C:N ratio was 20.4 ± 1.4 and 14.2 ± 0.32 in the litter layer and the topsoil, respectively. Soil N-NH4+ was predominant over N-NO3-. After 40 days, the cumulative N-N2O emission was 0.33 kg ha-1. The mean C and N stocks were 3.8 Mg N ha-1 and 43.6 Mg C ha-1, respectively. The averaged soil δ15N was 6.8‰. Soil δ13C was -20.3‰. After 14 years of implementation, approximately 40% of the total C in the topsoil (0-20 cm depth) was derived from the AFS biomass input, predominantly from the C3 photosynthetic pathway. The studied biodiverse AFS that replaced a degraded agricultural field in the Cerrado region showed to be responsive both in terms of soil and plant C and N pools and fluxes.