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This study aimed to compare the conventional soybean ( Glycine max L.) cultivation method with integrated systems in an Latossolo Vermelho Acriférrico típico and how these systems affect soil cover biomass production, initial nutrient concentration in plant residues, soil respiration and microclimate, as well as soybean growth, physiology and productivity. A comparative analysis of microclimate and soil respiration, plant physiology, and growth was conducted between a conventional soybean monoculture (soybean grown without plant residues on the soil from the previous crop) and soybean grown in soil containing maize residues. Additionally, experiments were conducted to evaluate the effect of monocultures and previous integration between maize, three cultivars of Panicum maximum (Zuri, Tamani, and Quênia guinea grass) and Pigeon pea ( Cajanus cajan cv. BRS Mandarim) on soil health, physiological aspects, and soybean production. Our results indicated that all cultivars of Panicum maximum can be used in integrated systems. The triple consortium resulted in greater production of ground cover biomass and a higher concentration of nitrogen, phosphorus, potassium and sulphur, which contributed to lower soil temperature and greater humidity, without a concomitant increase in soil respiration. Consequently, soybeans grown in the resulting integrated systems cover biomass showed a higher net photosynthesis rate and increased leaf chlorophyll index, resulting in taller plants, with higher above-ground biomass production and 21.0% and a 36.8% increase in grain yield when compared to soybean cultivated on maize biomass and on soil without cover residue, respectively. The data presented in this study demonstrated that integrated systems, with the presence of grasses and legumes, improve soil climatic conditions and nutrient availability, enhancing soybean physiology and productivity characteristics, thus contributing to the sustainability of agricultural production, even in the short term. Further long-term research is strongly recommended.

The diversity of soils and climate in Brazil imposes the need to evaluate the adaptation of fodder species to soil and climate conditions to guide producers and technicians in choosing the best alternatives for their region. The objective of this study was to evaluate and identify fodder cultivars for pasture and soil cover with tolerance to drought and high production in the sandy soils of southern Bahia, Brazil. The performance of 29 commercial cultivars of perennial and annual tropical forage species was evaluated in six cuts in 2019 and 2020. The green and dry mass yield per cut and the daily dry matter accumulation rate were evaluated considering the periods of water surplus and deficit and the drought tolerance index for each cultivar was estimated. Grass and legume cultivars showed differences in establishment, yield in the water surplus, and in the re-establishment after the water deficit. Based on the values of the drought tolerance index and in the dry mass daily yields before and after the water deficit, the cultivars adapted and indicated for regional continuous grazing were Xaraés, Marandu, Massai, Tanzânia, Paiaguás, and Zuri, in that order. The grasses B. ruziziensis and B. decumbens were indicated for use as cover plants after the harvest due to their high capacity of establishment and short-term production. The annual and perennial legume plants were also indicated for cover, and the combination of cultivars and their potential for straw in direct planting or use in integrated systems still need to be validated.

Nitrous oxide (N2O) emissions resulting from nitrogen (N) fertilization have been documented. However, no data on the effects of other nutrients, such as phosphate (P) and potassium (K), on N2O emissions in integrated crop–livestock systems are available so far. In the 2015/2016 and 2016/2017 growing seasons, we measured N2O emissions from a long-term system, established in 1991 in the Cerrado biome (a tropical savanna ecoregion in Brazil), fertilized with two P and K levels. The studied no-tillage farming systems consisted of continuous crops fertilized with half of the recommended P and K rates (CC-F1), continuous crops at the recommended P and K rates (CC-F2), an integrated crop–livestock system with half of the recommended P and K rates (ICL-F1), and an integrated crop–livestock at the recommended P and K rates (ICL-F2). The cumulative N2O emissions (603 days) and soil chemical properties were analyzed as a 2 × 2 factorial design (long-term agricultural systems x fertilization). The cumulative N2O emissions from CC-F2 and ICL-F1 were 2.74 and 1.12 kg N ha−1, respectively. The yield-scaled N2O emissions from soybean were 55.5% lower from ICL-F1 than from CC-F2 in the 2015/2016 growing season. For off-season sorghum, the mean yield-scaled N2O emissions were 216 mg N2O m−2 kg−1 (in a range from 79.83 to 363.52 mg N2O m−2 kg−1, for ICL-F2 and CC-F1, respectively). The absence of pasture and the presence of soybean and sorghum promoted the highest cumulative N2O emissions, favored by the recommended rate in relation to half of the P and K. In the total evaluation period (603 days), the presence of grazed land in the years prior to this study and land fertilized with half the recommended P and K rates in an integrated crop–livestock system reduced the resulting cumulative N2O emissions by 59%. Thus, we conclude that crop–livestock systems can be beneficial in reducing P and K applications and also in mitigating N2O emissions in comparison with continuous cropping systems fertilized with the full recommended P and K rates. In view of the global fertilizer crisis, this aspect is extremely relevant for agriculture in Brazil and around the world.

Owing to its contribution to the maintenance of carbon stocks, soil nitrogen and nutrient cycling for subsequent crops, the integrated systems become increasingly important for agricultural conservation. Thus, the objective of this study was to evaluate the biomass production of and total nutrient in Brachiaria spp. and Panicum maximum forage grasses used as mulch and soybean yields in an integrated crop–livestock system and second-crop maize succession system. The treatments consisted of the following cropping systems: Xaraes palisadegrass intercropped with soybean, Congo grass intercropped with soybean, Mombaça guinea grass intercropped with soybean, Tamani guinea grass intercropped with soybean and a soybean/maize succession system. The forage grasses were established during the soybean R6–R7 stage. Compared with Congo grass, Xaraes palisadegrass, Mombaça guinea grass and Tamani guinea grass produced more biomass and equivalent amounts of fertilizer returned to the soil and resulted in greater nutrient cycling, indicating the benefits of these grasses for use as mulch in integrated production systems. Maize had a greater C/N ratio, but the forage grasses also exhibited high potential by protecting the soil until the end of the soybean development cycle. The use of an integrated crop–livestock system combined with a forage cropping system provided greater soil nutrient cycling than the maize cropping system did, which resulted in increased soybean yields, thus contributing to the sustainability of agricultural systems.

In Brazil’s central savanna region, government policy is to encourage the conversion of conventional plough tillage (PT) agriculture to no-till (NT) and raise the productivity of under-utilized pastures, including their conversion to integrated crop-livestock (ICL) systems, with the objective of increasing soil organic carbon (SOC) at the expense of atmospheric carbon dioxide. An experiment was established in 1991 by liming and fertilizing at two levels an area of native vegetation (NV). The treatments, replicated in randomized plots, included pastures, continuous cropping and ICL systems under PT or NT. The aim of this study was to quantify the SOC accumulation to 100 cm depth under these treatments over time. The high C:N ratios suggested that there was a high proportion of charcoal present in the soil. Increasing fertilizer inputs had no overall significant effect on SOC stocks. Stocks of SOC changed little under pastures. Analyses of 13 C abundance showed that higher fertilizer inputs increased the decomposition rate of C derived from NV under pure grass pastures. Continuous cropping under NT preserved SOC and under PT there were significant losses. The highest SOC stocks were found under ILP treatments, but not all ILP treatments accumulated SOC even under NT. These results indicate that government initiatives to substitute PT with NT and to intensify beef cattle production will have only modest short-term gains in SOC accumulation.

Among integrated crop–livestock systems, forage succession is an advantageous strategy for the use of pasture to feed cattle in periods of low rainfall, as well as for the generation of biomass for the no-till system for the next crop. Different species have different abilities to accumulate nutrients in their biomass, which are then released into the soil through the decomposition of crop residues. This study aimed to evaluate soybean yield in an integrated crop–livestock system in comparison to soybean–maize succession system through the production, decomposition and nutrient accumulation in the biomass. The experiment had a randomized block design with four replicates. The treatments were three cropping systems: integrated crop–livestock with Paiaguas palisadegrass (Brachiaria brizantha cv. BRS Paiaguas), integrated crop–livestock with Tamani guinea grass (Panicum maximum cv. BRS Tamani) and maize grown in succession to soybean. The results showed that the use of the integrated crop–livestock system in the form of forage succession provided greater soil cover and nutrient cycling as a result of the better utilization of the animal's excreta, than the cropping of maize in succession and resulted in higher soybean productivity, thus contributing to agricultural sustainability. Paiaguas palisadegrass and Tamani guinea grass showed a C:N ratio greater than 30:1, indicating slow decomposition of plant residues. The forages accumulated amounts of nutrients in their biomass that met the soybean demand, resulting in higher grain yield.

The objective of this study was to evaluate N 2 O fluxes from integrated crop-livestock (ICL) and integrated crop-livestock forest (ICLF) systems, continuous pasture and native Cerrado. The experiment was conducted at Embrapa Cerrados, Planaltina-DF, in a Red Oxisol, between February 2012 and April 2014, following the transition of crop to livestock, which began in March 2012, with the sowing of Brachiaria brizantha cv. Piatã, intercropped with sorghum. The experimental design was a randomized block with three replications. The treatments were: cultivated area intercropped with rows of Eucalyptus , spaced 2 × 2 m between plants and 22 m between rows (ICLF); and an area cultivated without tree species (ICL), and also two adjacent reference areas: native Cerrado and continuous pasture. N 2 O productions were characterized by fluxes below 20 μg N m −2 h −1 . The ICL system had the highest cumulative flux with 2.84 kg N ha −1 , while the ICLF system obtained cumulative fluxes of 2.05 kg N ha −1 . The native Cerrado showed a negative balance, with –0.05 kg N ha −1 . The dry season was mostly characterized by low N 2 O fluxes ranging between 10 μg N m −2  h −1 and negative values, whereas higher N 2 O fluxes were observed after precipitation events, especially those following a long drought period. The water filled pore space was the factor that best explained N 2 O fluxes, but higher fluxes were observed after the application of nitrogen fertilizer. There was a positive correlation between microbial biomass carbon and N 2 O fluxes in the ICL and ICLF systems.

Integrated crop-livestock systems have been recently adopted in several agricultural regions of Brazil. Studies involving the effect of adopting integrated systems on greenhouse gas mitigation are essential for choosing sustainable agricultural systems. In this study, the emissions of nitrous oxide in a crop-livestock system (4-year crop/pasture rotation) compared with two continuous crop (CC) areas under conventional and no-tillage management were investigated. The treatments consisted of continuous cropping under no-tillage (CC-NT), continuous cropping with annual heavy disc harrow (CC-CT), an integrated crop-livestock system under no-tillage (CLS-NT) and native Cerrado as a reference. Considering the cumulative N 2 O emissions in a year, the CC-CT emitted 2.55 kg N-N 2 O ha −1 , higher than the Cerrado, which emitted 0.55 kg N-N 2 O ha −1 . All the agricultural systems emitted more N 2 O than the Cerrado, however, the two conservation systems CC-NT and CLS-NT had lower emissions than the CC-CT, and were responsible for 1.90 and 1.52 kg N-N 2 O ha −1 , respectively. In the agroecosystems, the highest N 2 O fluxes were observed after fertilization and rainfall events. In the CC systems, N 2 O emissions were greater than in the integrated system during the sorghum/off-season period, but in the CC-CT emissions were greater than in CC-NT. During the soybean cycle no differences in emissions were observed between both CC systems, which surpassed that in CLS-NT that was occupied by Brachiaria pasture. The annual cumulative N 2 O emissions in CLS-NT were close to that observed in the Cerrado indicating this system to be an agricultural practice with potential to mitigate N 2 O emissions.

In the Brazilian savanna, there is a risk that soil fertility of pastures declines to a level below that of the native savanna because of low fertilizer application. To evaluate biophysical pasture sustainability we compared regularly fertilized productive pasture (PP), degraded pasture fertilized 13 yr previously (DP), and native savanna (Cerrado, CE) in an on‐farm experiment. We determined (i) biomass productivity of the pastures and (ii) nutrient concentrations in Anionic Acrustoxes from three plots under each of CE, DP, and PP. From the 0‐ to 2‐m soil layer, we sampled solid phase in January 1998 and soil solution during two rainy seasons (1997‐1998 and 1998‐1999). The mean aboveground biomass production (dry weight) was 2.1 Mg ha−1 yr−1 for DP and 4.1 Mg ha−1 yr−1 for PP. In the solid phase of the 0‐ to 0.15‐m layer, mean total N and S and exchangeable Ca and Mg concentrations increased in the order CE < DP < PP, while NaHCO3–extractable P was not significantly different among CE, DP, and PP. In the soil solution at 0.15‐m depth, pH and concentrations of Ca and Mg also increased in the order CE < DP < PP. At the 2‐m depth, only K, Mn, and NO3–N concentrations in soil solution were slightly higher under the pastures than under CE indicating an increased risk of leaching losses to below the rooting zone. Thus, topsoil fertility in both pastures is increased compared with CE, and little leaching occurs. Some fertility indicators in DP are still improved compared with CE 13 yr after a single fertilization.