Urochloa Ruziziensis Research Articles

Integrated Crop–Livestock Systems as a Strategy for the Sustainable Production of Corn and Soybean Grain in Tropical Sandy Soils

Integrated crop–livestock systems (ICLS) have sustainably intensified modern agricultural practices worldwide. This research assessed how production systems and crop types impact the chemical properties of an Oxisol in the Brazilian Cerrado, the grain yield of corn intercropped with palisade grass (Urochloa) in the off-season in an ICLS, and the grain yield (GY) of soybean in succession. Intercropped and monocropped systems were assessed in a three-year field experiment: corn + Urochloa ruziziensis–soybean; corn + U. brizantha cv. Piatã–soybean; corn + U. brizantha cv. Paiaguás–soybean (ICL–Paiaguás); corn–soybean under a no-tillage system (NTS); corn–soybean under a conventional tillage system (CTS); Piatã grass–continuous grazing (Perennial Piatã); and Paiaguás grass–continuous grazing (Perennial Paiaguás). The residual impact of phosphate fertilization was more pronounced in the ICLS treatments. In the soil layer from 0.0 to 0.2 m depth, ICLS–Paiaguás and Perennial Piatã had the most positive effects on soil chemical quality. In the last year, grain yield was highest in corn monoculture under the NTS and soybean in succession under the ICLS. ICL–Paiaguás improved soil chemical properties for soybean in succession. These results confirm that an intermittent pasture system for legume crops in sequence is an alternative that can maintain or improve soil chemical composition, and that CTS should be avoided in tropical sandy soils.

Long-Term Effect of Crop Succession Systems on Soil Chemical and Physical Attributes and Soybean Yield.

Most soybean producers in the Cerrado biome use the direct seeding system, making it essential to cultivate cash or cover crops in the off-season, to promote soil protection, as well as increase organic matter, which is directly related to improvements in the chemical and physical characteristics of these soils. In this sense, this work was conducted in Jataí, state of Goias, Brazil, to evaluate the physical-chemical attributes of the soil and the performance of soybeans cultivated in different crop succession systems cultivated for 6 years in the region of Jataí, GO. The experimental design was randomized blocks with four plots and four replications; the crops that followed soybeans were arranged as follows: T1-corn (Zea mays); T2-pearl millet (Pennisetum glaucum); T3-Urochloa ruziziensis; and T4-corn + Urochloa ruziziensis. Soybean yield components and grain yield were evaluated in two harvests (2020/2021 and 2021/2022). Deformed and undisturbed soil samples were collected in 2022 to assess soil fertility and for physical analysis. The data were subjected to analysis of variance (F test) and the means were compared using the Tukey test at 5% probability. The soybean-millet succession system stood out for the chemical and physical attributes of the soil: calcium, magnesium, base saturation, hydrogen + aluminum, and total porosity. The crop succession system did not affect yield for the two years analyzed, but the accumulated grain yields were higher in the crop succession soybean/corn intercropped. The results highlight the importance of using cover crops in improving the physical and chemical qualities of the soil in the long term. However, in the Cerrado, there is a predominance of the soybean/corn succession system motivated by financial issues to the detriment of the qualitative aspects of the soil, in which the introduction of Urochloa ruziziensis in intercropping with corn would improve the chemical attributes of the soil and have a long-term impact on the accumulated grain production.

Exploring the impact of cover crops in integrated pest management: pest and natural enemies population dynamics in no-tillage cotton production.

Conservation agriculture plays an important role in the sustainability of production systems, notably for globally significant crops such as cotton. This study explores the integration of the no-tillage system (NTS) with integrated pest management (IPM) by incorporating cover crops. The aim is to assess the impact of these living or dead covers on the management of insect populations, the indices diversity of phytophagous insects and natural enemies, and to investigate the population fluctuation of these arthropods, considering a variety of crops in the NTS before and after cotton planting. The trial, conducted over two consecutive cropping seasons in Mato Grosso do Sul State, Brazil, employed a randomised block design with four repetitions. The treatments included cover crops with the highest potential for use in the region, such as millet (Pennisetum glaucum glaucum L.), corn (Zea mays L.), brachiaria (Urochloa ruziziensis), black velvet bean (Stizolobium aterrimum), forage sorghum (Sorghum bicolor L.), and white oats (Avena sativa L.) and a mix of white oats with brachiaria. The results indicated that the black velvet bean stands out as the most effective cover crop, providing the best performance in terms of non-preference to the attack of the evaluated pest insects. Conversely, brachiaria proves to be more susceptible to infestations of Dalbulus maidis (DeLong and Wolcott) (Hemiptera: Cicadellidae), and Diabrotica speciosa (Germar, 1824) (Coleoptera: Chrysomelidae). The study underscores the relevance of the judicious choice of cover crops in IPM and in promoting agricultural biodiversity, creating a strategic tool to enhance the sustainability and efficiency of the cotton production system in the context of the NTS.

Resistência de poáceas forrageiras ao Blissus pulchellus Montandon (Hemiptera: Blissidae)

ABSTRACT Chinch bugs [Blissus pulchellus Montandon (Hemiptera: Blissidae)] suck the phloem from susceptible forage grasses, injecting toxins that destroy plant vessels and compromise the flow of water and nutrients, leading to plant death. Thus, the aim of this study was to assess eight forage grasses for antixenosis resistance to B. pulchellus and compare the anatomical characteristics of leaf sheath tissue from resistant and susceptible species/cultivars. Experiments were conducted in a laboratory and greenhouse, using choice and no-choice tests with the following forage grasses: Urochloa ruziziensis, U. humidicola, U. brizantha ‘Piatã’, U. brizantha ‘Paiaguás’, U. brizantha ‘Marandu’, Panicum maximum ‘Mombaça’, P. maximum ‘Zuri’, and Andropogon gayanus. The oviposition results demonstrated that in the choice test there was a change in the stink bug’s behavior in relation to grasses four hours after infestation, with U. humidicola, P. maximum ‘Mombaça’ and ‘Zuri’, U. brizantha ‘Marandu’ and A. gayanus, proving to be less attractive to insects. It is concluded that U. humidicola, P. maximum ‘Mombaça’ and ‘Zuri’, U. brizantha ‘Marandu’, and A. gayanus are less attractive to B. pulchellus. A. gayanus and P. maximum ‘Mombaça’ and ‘Zuri’ showed non-preference resistance (antixenosis) to oviposition by B. pulchellus. The resistance of U. humidicola, P. maximum ‘Zuri’, and A. gayanus to B. pulchellus may be associated with greater compaction and lignification of the parenchyma and sclerenchyma cells of leaf sheaths.

Qualitative Production of Mixture Silage within a Sustainable Concept

Climate change and seasonality in forage production have caused alterations in animal feed. Thus, this study evaluated the composition of silages from soybean (Glycine max (L.) Merrill) mixed with tropical grasses. The experimental design was randomized blocks with four replications. Treatments were silage from soybeans, silage from soybeans with Aruana Guinea grass (Megathyrsus maximus cv. Aruana), and silage from soybeans with Congo grass (Urochloa ruziziensis cv. Comum). Silos were stored for 60 days in the laboratory at room temperature. The silage from soybeans with Aruana Guinea grass showed the highest contents of dry matter, crude fiber, neutral detergent fiber, insoluble nitrogen in neutral detergent fiber, and insoluble nitrogen in acid detergent fiber but the lowest levels of crude protein and ether extract. The highest content of mineral material and hemicellulose was observed in the silage from soybeans with Congo grass. The silages from soybeans and soybeans with Congo grass showed no significant differences for acid detergent fiber and lignin. In conclusion, the use of tropical grasses as a component to improve the quality of silage from soybeans is an alternative for forage conservation in ruminant production systems, especially at the dry season.

Legacy soil phosphorus bioavailability in tropical and temperate soils: Implications for sustainable crop production

Improving phosphorus (P) use efficiency is key to improving the productivity and sustainability of cropping systems and slowing the exploitation rate of mineral P resources required for fertilizer production. At present, large amounts of added P in fertilizers and manure each year are retained in the soil and are not used by the crop. This ‘legacy P’ progressively accumulates in soil and represents an untapped P resource in tropical soils while in temperate soils it contributes to eutrophication. In the context of legacy P, the aim of this study was to quantify changes in soil P pools of contrasting bioavailability (determined using conventional chemical extraction procedures) during 12 successive brachiaria (Urochloa ruziziensis) cropping cycles in which no additional P was added. The study was undertaken in the greenhouse with 10 tropical (Brazil) and 6 temperate (UK) agricultural topsoils. Above-ground dry matter yield (DM) and P offtake was measured at each harvest alongside operationally-defined measures of the labile, moderately-labile and non-labile P pools at the start and end of the experiment. Over twelve repeated cultivation cycles, brachiaria demonstrated an ability to efficiently mine legacy P from all measurable soil pools across both sets of soils. This included the depletion of up to 87 % of non-labile soil P in some soils from the UK and up to 66 % from soils in Brazil after one year. While the amounts of initial labile P showed the closest positive relationship with plant P export, contrary to expectation the non-labile P pool also clearly contributed to plant nutrition across all the soils. As a cover crop, brachiaria clearly possesses traits which enable both the solubilization and efficient capture of soil P that can be harnessed to actively recycle historically non recalcitrant soil P fractions. Incorporating brachiaria into crop rotations or intercropping systems therefore shows promise as a strategy to enhance the longer-term sustainability of soil P management.

Performance of Cowpea as a function of residues of organomineral fertilizers applied in corn crop

Organomineral fertilizers can be an excellent alternative through exploitation of the residues left by application in previous crops. Therefore, the objective of this study was to evaluate the agronomic characteristics of cowpea fertilized with residual organomineral fertilizers from the first corn crop in southern Maranhense. The experimental design was randomized blocks, arranged in a split-plot design, with three replications. Two cowpea cultivars (BRS Tucumaque and BRS Nova era) were sown in the plots. The residues of three phosphate fertilizers were sown in the subplot (two of which were organomineral fertilizers and one phosphate fertilizer (single superphosphate). At cowpea harvest, five plants were collected per plot for the following variables: number of nodes on the main stem at maturity, number of legumes per plant, number of grains per legume and weight of one thousand grains, and yield in kg ha-1. The cowpea cultivars are influenced by the cropping system (with and without U. ruziensis and organomineral sources). However, in soils with high phosphorus contents, the absence of U. ruziensis and fertilization or the use of organomineral or super simple fertilization promoted higher grain yields. The cultivar BRS Tucumaque had the highest grain yield. Organomineral and mineral fertilizer residues showed effective alternatives for increasing phosphorus availability in areas with Urochloa ruziziensis.

Nitrous Oxide Emissions and Ammonia Volatilization from Pasture after Cattle Dung and Urine Applications in the Dry and Rainy Seasons of the Brazilian Cerrado

An important source of greenhouse gases in Brazil is the nitrous oxide (N2O) emission from pasture, and microorganisms play an important role in nitrogen transformations in the soil. This study aimed to evaluate N2O emission and NH3 volatilization from bovine excreta in pasture in an integrated crop–livestock system (ICL) in the Brazilian Cerrado. Three treatments (urine, dung and control) were performed in two pastures (Area 1—three-year pasture of Urochloa ruziziensis and Area 2—one-year pasture of Urochloa brizantha cv. Piatã), with two application times of the excreta (dry and rainy season), during two successive years of application. Compared to the control, the excreta deposition on ICL increased soil N2O and NH3 fluxes. In the dry season, N2O fluxes were associated with higher ammonium (NH4+) availability. In the rainy season, these fluxes were related to NO3− availability and water-filled pore space (WFPS). In both areas, NH3 volatilization was higher after urine than dung application, especially in the dry season. The highest N2O emission factors were obtained for urine (0.32%), the rainy season (0.36%), and older pasture (Area 1: 0.24%). All these values were below the mean IPCC default values (0.77%). These results indicate that N2O emissions in pasture should be evaluated in regional conditions.

Azospirillum brasilense Inoculation in a Maize–Urochloa–Rice Cropping System Promotes Soil Chemical and Biological Changes and Increases Productivity

Large quantities of cover crop residues in the soil, combined, or not, with the inoculation of seeds with diazotrophic bacteria, can increase organic matter (OM) and protect soil microorganisms, such as arbuscular mycorrhizal fungi (AMF) and dark septate endophytic (DSE) fungi. Thus, the use of these sustainable biotechnologies can benefit microbial interactions, soil fertility and rice production in the Brazilian Cerrado region. In this study, we evaluated the effects of maize and Urochloa ruziziensis, intercropped or individually, as cover crops and an inoculation of Azospirillum brasilense on the chemical (fertility) and biological (C–microbial biomass and C–CO2 released) attributes of soil and the effects of root colonization by AMF and DSE on the yield of rice grown in succession in highlands. The experiment was conducted under field conditions, in a typical dystrophic Red Oxisol. The experimental design consisted of randomized blocks arranged in strips, incorporating a combination of eight residual cover crops: ((1) maize, (2) maize–I (I = inoculation of seeds with A. brasilense), (3) Urochloa (U. ruziziensis), (4) Urochloa–I, (5) maize + Urochloa–I, (6) maize + Urochloa–I, (7) maize–I + Urochloa and (8) maize–I + Urochloa–I). This was accompanied by two treatments of rice as a successor crop (inoculated or not with A. brasilense), with four replicates, totaling 64 experimental units. A cover crop and rice seed inoculation prompted increases in OM and AMF relative to DSE, while the inoculation of rice, regardless of the cover crop treatment, increased the soil’s P content. The combination of maize + Urochloa–I and inoculated rice as the next crop generated increases in its sum of bases (SBs) and cation exchange capacity (CEC). There was a 19% increase in rice grain yields when the seed was inoculated.

Symbiotic relationships and biological effects of inoculation with plant growth-promoting bacteria in forage species

Brazil has the largest commercial cattle herd and it is the largest commercial exporter in the world, an important characteristic of Brazilian cattle raising is having most of its herd raised to pasture. Due to the high cost of chemical fertilizers, the interest for bacterial inoculants has grown. The objective of this work was to identify forage specimens with better association with different bacterial strains in order to promote plant growth. Experiments, with a completely randomized design, where three forage species were evaluated: white oat (Avena sativa L.), brachiaria ruziziensis (Urochloa ruziziensis) and Millet (Pennisetum glaucum), inoculated with four bacterial strains: Azospirillum brasilense, Herbaspirilum seropedicae, Ensifer adherens and Leclercia adecarboxylata. Seed asepsis was performed with acidified hypochlorite and afterward the seeds were transferred to agar / water medium and incubated for 48 h at 32 ° C in the dark. The pre-germinated seeds were placed in test tubes containing 25 mL of MS medium and inoculated with 106 CFU.mL-1 of each of the strains, except for E. adherens which was inoculated with 104 CFU.mL-1. After 21 days of in vitro culture, the following factors were evaluated: length, fresh and dry weight of shoot and root biomass, gross protein and total nitrogen quantification, root morphology by staining with 1% methylene blue, stoma morphology and microbial counting (epiphytic and endophytic). Data were submitted to ANOVA and compared by the Tukey test (p >5%). The different forage species presented different behavior in relation to the association with the bacterial strains. Oats and Brachiaria were considered as more responsive to the bacterial association than Millet because they presented a larger increment in the size of central / lateral roots and root area. Although Oat presented significant results for BP and TN, Brachiaria had a larger epi and endophytic population, indicating that it was preferential for bacteria.

Clearfield upland rice intercropped with Urochloa ruziziensis for grain, increased revenue and environmental preservation

AbstractIntercropping perennial forage grasses into cereal crops is an alternative to recover degraded pastures. However, the intercrop of forage grasses, such as Urochloa ruziziensis (R. Germ. and C. M. Evard) Crins (Congo grass), can lead to losses in cereal yield. Therefore, it is necessary to develop management strategies that allow forage grass establishment without major losses in cereal yield in intercropping. The objective was to study the agronomic and economic impacts of intercropping U. ruziziensis into a Clearfield upland rice (Oryza sativa L.) cultivar in the state of Goiás, Brazil, in two growing seasons. Treatments included forage grass seeds sowing method (broadcast or incorporation to the soil) and sowing times (at rice sowing, 20 days after emergence [DAE], and 45 DAE of rice). Also, imazapyr + imazapic herbicide was applied to restrict the competitive effect on rice yield. Monocropping control plots were also evaluated. Grain yield was measured on rice. Forage grass dry matter yield was measured at 30, 60, and 90 days after harvesting (DAH) of rice. Crude protein content was analyzed at 90 DAH. Profitability was calculated for each cropping system relative to rice monocropping. Intercropping of rice and U. ruziziensis sowed at 45 DAE provided the highest grain yield relative to other assessed intercropping treatments as well as rice monocropping. Concurrent sowing of rice and incorporated U. ruziziensis seeding provided the greatest economic return. This reformed cropping system improved land and pasture output, which can reduce the pressure to convert more land to agricultural use.

Sowing depth and seed specific weights on emergence of the weed Urochloa ruziziensis on field conditions

Sowing depth and seed specific weights on emergence of the weed Urochloa ruziziensis on field conditions

Effects of Harvesting Method on Seed Yield and Seed Quality in Urochloa ruziziensis (cv. ‘OKI-1’ and cv. ‘Br-203’)

Two field trials were conducted in Northern Thailand from 2018 to 2020 to determine the best manual harvesting method for maximizing seed yield and seed quality of two Urochloa ruziziensis cultivars, cv. OKI-1 and cv. Br-203. Four manual seed harvesting methods were implicated in a randomized complete block design with four replicates. The four methods were as follows: knocking seeds from seedheads into a nylon net receptacle and collecting them once every day (T1); knocking seeds from seedheads into a nylon net receptacle and collecting them once every three days (T2); allowing ripe seeds to fall into a nylon net sheet that was stretched as a receptacle beneath the seedheads and collecting seeds once every five days (T3); and covering the tied seedheads with a nylon net bag and collecting seeds once every five days (T4). The highest pure seed yield was obtained from T3 in cv. Br-203 (333.11 kg/ha), as well as the highest trend in cv. OKI-1 (534.67 kg/ha). T3 produced 22–46% and 11–27% more pure germinated seed yields than the other methods in cv. Br-203 and cv. OKI-1, respectively. As a result, T3 was recommended for higher seed yield, convenient seed harvest, and reduced manual seed harvest time.

Grazing effect on different forage species in yield of soybean-pasture succession

Integrated crop-livestock systems play a crucial hole on sustainable intensification due simultaneous increase the land use efficiency and minimize nutrient leaching due an intensification of nutrient cycling. However, these benefits depend on a good planning and management of the production system. The main objective of this study was to investigate biomass composition, soybean yield and beef cattle performance using three distinct forage cultivars within two cropping systems: Integrated Crop-Livestock System (ICLS) and the Pure Crop System (CS). The three forage cultivars used were: Urochloa ruziziensis, Urochloa brizantha cv. Xaraés, and Megathyrsus maximus cv. BRS Quênia. The experimental area was split into 24 plots, with each plot assigned one of the cropping systems and a specific forage cultivar. The ICLS involved soybean cultivation during spring-summer followed by cattle grazing during the autumn-winter. Conversely, the CS functioned as a pure crop system, utilizing soybean cultivation alongside forage as a cover crop. Soybean yield did not differ between ICLS and CS, neither between forage cultivars (4110 ± 627.0 kg ha−1). Animal performance did not differ between forage cultivars, resulting in average daily gain equals to 0.538 ± 0.316 kg of BW day−1. Animal production per area also was not affected by forage cultivars, yielding 145.0 ± 56.8 kg of BW ha−1. For comparison between systems, beef cattle production was converted in soybean equivalent based on commodities values. ICLS proportionated an increment of 624 ± 135 kg ha−1 per year of soybean equivalent yield, representing 15% increase in land use efficiency compared to the CS system. Therefore, beef cattle grazing in off-season of cash crops can enhance the sustainable intensification of food production. The forage species choice seems not be a paramount question for this model of ICLS.

Hepatic and renal lesions in sheep intoxicated with Urochloa hybrid Mulato II in Argentina.

A flock of 48 sheep in Argentina grazing on a pasture of hybrid Urochloa (formerly Brachiaria) Mulato II (Urochloa ruziziensis × Urochloa decumbens × Urochloa brizantha) developed facial dermatitis, severe jaundice, and weakness after brief physical activity. Blood biochemistry of 3 animals revealed azotemia, elevated aspartate aminotransferase activity, and increased direct, indirect, and total bilirubin concentrations. The urine was markedly turbid and contained large concentrations of bile pigments and protein. At autopsy of 2 animals, there was severe jaundice and subcutaneous submandibular edema. The livers were enlarged, intensely yellow, and had a marked acinar pattern. Gallbladders were distended, and the kidneys were diffusely dark in one animal and yellow-green in the other. Microscopically, there was lymphoplasmacytic and histiocytic cholangiohepatitis with abundant crystals in the lumen of bile ducts and in the cytoplasm of macrophages. The proximal and distal convoluted renal tubules had protein casts in their lumens, and crystals were observed in the lumen and epithelial cells. Lectin histochemistry showed strong affinity for Arachis hypogaea agglutinin in hepatic macrophages. In the one sheep that was tested for heavy metals, copper concentrations in the liver and kidney were within the RIs. Despite the immediate change of pasture, morbidity and mortality were 100% within 3 mo. The association between the consumption of this pasture, and the clinical, biochemical, pathology, and lectin histochemistry findings confirmed intoxication with Urochloa hybrid Mulato II. To our knowledge, intoxication by this hybrid of Urochloa has not been reported previously.

The Impact Ground Phonolite Rock's Potassium Solubilization in Tropical Soil Depends on the Cultivated Forage Species.

Cover crops can be used to accelerate the solubilization process of low-solubility fertilizers; thus, the aim of this study was to evaluate the potential of grasses in solubilizing potassium from phonolite rock powder. With a 2 × 5 factorial scheme, two doses of phonolite rock powder, equivalent to 0 and 8 t ha-1, were combined with four grass species (Urochloa ruziziensis, U. decumbens, U. humidicola, and Andropogon gayanus), besides a control treatment without any cover crop. The dry matter production of the aerial parts of the plants was evaluated at days 40 and 70 post-emergence, and then the concentration of potassium in the plants and the soil was evaluated (exchangeable, non-exchangeable, structural, and total potassium contents). In the soil, the phonolitic rock powder increased the exchangeable, non-exchangeable, structural, and total K contents, favoring the absorption of K and the production of the dry mass of the three Urochloa, but U. decumbens stood out because it promoted greater availability of K in the system compared to the cultivation of other plant species. This research proposes the inclusion of U. decumbens in production systems that receive phonolitic rock, constituting a sustainable strategy to improve its agronomic efficiency.

Signaling Molecules for Increasing Urochloa ruziziensis Tolerance to Abiotic Stresses

Signaling Molecules for Increasing Urochloa ruziziensis Tolerance to Abiotic Stresses

Sistema de consórcio de milho com gramíneas forrageiras e o uso de doses reduzidas do herbicida mesotrione

ABSTRACT Sowing forage grass species of the genera Urochloa and Panicum simultaneously with corn can hinder crop grain yield, requiring the application of low herbicide rates for suppressing their growth and preventing potential competition with corn plants. Therefore, the objective of this study was to evaluate the use of low rates of the herbicide mesotrione for inhibiting the growth of forage grass species (Urochloa ruziziensis and Panicum maximum, cultivars BRS Tamani and BRS Zuri) sown simultaneously with corn crop, as well as the recovery capacity of these grasses. Two experiments were installed, as first and second crop seasons, in a randomized experimental block design with four replications, using a 3×4 factorial arrangement and three control treatments with corn alone. Each of the three forage grasses was sown simultaneously with corn and subjected to post-emergence application of four mesotrione rates (0, 48, 96, and 144 g ha-1) with atrazine (1.25 kg ha-1). Weeds, forage grasses, and corn plants were evaluated. BRS Tamani was the most tolerant forage to mesotrione, while BRS Zuri was the most sensitive. The application of mesotrione + atrazine in the corn-forage grass intercropping system contributed to weed control. The tested forage grasses did not affect corn grain yield in the first or second crop season, even with no herbicide application.

Cover crop diversity for sustainable agriculture: Insights from the Cerrado biome

AbstractBrazil is one of the largest soybean producer of the world and the Cerrado biome has played a pivotal role in this expansion. Because of the economic and agronomic challenges associated with the maize production as a second summer crop in this region, cover crops are gaining popularity as a strategy to diversify the agricultural system while enhancing soil health. This study assessed the benefits of single species of cover crops and a mix of cover crop species in between harvest seasons to the soybean grain yield and nematode suppression. The study was carried out for 3 years in two locations within the Cerrado biome. We evaluated six cover crop treatments after soybean cultivation: (1) Mix of cover crops (Pennisetum glaucum, Crotalaria spectabilis and Urochloa ruziziensis), (2) P. glaucum (Pearl millet), (3) C. spectabilis, (4) U. ruziziensis (Congo grass) (5) Urochloa brizantha cv. Marandu (Marandu palisadegrass) and (6) U. brizantha BRS Paiaguás (Paiaguás palisadegrass). Pennisetum glaucum and U. brizantha cv. Marandu produced highest amounts of biomass on a 3‐year average. In one site, P. glaucum produced more biomass than other cover crops by 210%. Tropical grasses (U. ruziziensis, Marandu and Paiaguás), along with the cover crop mixture, exhibited intermediate biomass levels in the site with higher P. glaucum biomass production and did not differ from P. glaucum in the other site. Cover crops varied nutrient uptake depending on the species. Decomposition rates varied among cover crops as expected, with C. spectabilis decomposing rapidly and releasing substantial amounts nutrients, particularly nitrogen. In contrast, the cover crop mixture had a slower decomposition. The choice of cover crop significantly influenced soybean population and yield, with some variability across years and locations. The cover crop mixture consistently supported higher soybean populations and yields, highlighting its potential for enhancing soybean production, nutrient cycling and nematode suppression. It effectively reduced nematode abundance in soybean roots, highlighting its role in nematode management. Our findings emphasize the robustness and versatility of cover crop mixtures in mitigating weather variability across years and sites. They consistently performed well in terms of biomass production, nutrient uptake, soybean yields and nematode control. This study highlights the vital role of cover crops in the Cerrado ecosystem, enhancing soil health, crop productivity and environmental sustainability. The choice of cover crop species and mixtures offers a valuable tool for farmers seeking resilient and sustainable agricultural practices amid changing environmental conditions.

Secondary metabolites of Urochloa ruziziensis on growth, nodulation, and spectral responses of soybean

Ruzigrass (Urochloa ruziziensis) is a widely cultivated plant alongside soybeans, particularly in integrated crop and livestock systems, due to its fast growth and adaptability to different conditions. This study aimed to assess the impact of secondary metabolites found in ethanolic extract from ruzigrass on soybean growth, nodulation, spectral responses, and soil microbiological attributes. The ethanolic extract of ruzigrass presents total concentration of flavonoids (852.5 µg g−1), including naringenin and kaempferol. Increasing doses (100, 200, 300, and 400 kg ha−1) of the extract were then applied to the soil in a greenhouse to cultivate soybean plants. The spectral analysis indicated that higher doses of ruzigrass extract enhanced photochemical reflectance, chlorophyll absorption, and total chlorophyll indices. However, the normalized differential vegetative index decreased in response to the treatments. Generally, increasing doses of ruzigrass extract led to linear improvements in plant height, leaf area, shoot dry mass, pod count, nodule count, nitrogen content, and soil microbial activity. On the other hand, root dry massand relative chlorophyll content decreased with higher doses of the extract. In conclusion, the application of Urochloa ruziziensis extract, containing secondary metabolites caused a reduction in root development and an increase in spectral indices related to abiotic stresses in soybeans. There was an increase in the biological attributes of the soil with a significant, increasing linear adjustment in the doses of ruzigrass extract applied, as well as in the soybean production components.