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Background and aims: The Brachiaria sp. (synonymous with Urochloa) is one of Brazil's main grass species used in livestock production and has become the focus of breeding genetic programs to enhance its resistance to drought, flooding, and pests, as well as improving its palatability to animals. However, there is a limited understanding of how genetic breeding can affect the soil microbiome and its potential functions. Thus, this study aimed to investigate the impact of four different Brachiaria varieties on the soil prokaryotic and fungal communities, with focus on the N-cycle. Methods: We combined molecular techniques, such as quantitative PCR and amplicon sequencing, to target prokaryotic and fungal communities and traditional soil and plant chemical analyses. The treatments were composed of the varieties of B. brizantha cv. Marandu (BM), B. ruziziensis (BR), Brachiaria spp. cv. Ipyporã (BI), B. brizantha cv. BRS Paiaguás (BP) and control without plants. Results: Our findings revealed that all varieties improved soil porosity, P content, organic carbon, and potential functions as Chemoheterotroph, Aerobic-Chemoheterotroph, and Pathotroph-Saprotroph groups. Soil acidity, nutrient availability, and porosity were the main drivers of the microbial communities. The study also identified the ability of each variety to recruit microbial nitrogen-fixers and ammonia-oxidizers. Conclusion: We highlighted that Brachiaria varieties can favor soil microbial communities related to the release of nutrients, resistance to pathogens, and environmental stress. Also, the BI variety showed a higher potential to improve soil quality by increasing soil porosity and potential AMFs. Besides that, all varieties showed some potential to benefit intercropping and crop rotation systems. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Micronutrient fertilization is usually neglected by producers, especially for peanut, a crop that is frequently grown in crop rotation systems due to its low perceived nutrient requirements. New peanut cultivars are able to achieve high yields when grown under suitable conditions. However, fertilization recommendation tables are dated and do not consider the need for micronutrients. To support improvements in these recommendations, this study quantified the micronutrient demand (B, Cu, Fe, Mn, and Zn) of three runner peanut cultivars (IAC Runner 886, IAC 505, and IAC OL3) during the biological cycle and the transport of these micronutrients to pods and kernels. The experiment was carried out in a randomized complete block with a split-plot design and nine replications. The whole plots consisted of the three peanut cultivars, and the subplots comprised nine plant samplings (at 14, 28, 42, 56, 70, 84, 105, 126, and 147 days after emergence (DAE)). These modern peanut cultivars exhibited high uptake and accumulation of Fe, but the proportion of Fe removed by pods and kernels was lowest among all analyzed micronutrients. The second-most-accumulated micronutrient was Mn. The maximum requirement for micronutrients of peanut occurred around 84 DAE, and IAC 505 had the highest micronutrient uptake and accumulation among the cultivars (especially at later stages), followed by IAC OL3 and IAC Runner 886. Our results provide new insights into micronutrient requirements for peanut and demonstrate the need for new fertilizer recommendation programs for peanut cultivation. [ABSTRACT FROM AUTHOR]

Common bean (Phaseolus vulgaris L.) has been grown under no‐till (NT), but nitrogen (N) management remains unclear when a previous cover crop is part of the farming system. In this study, we hypothesized that N applied to living cover crops, preceding the main grain crop of the rotation, can increase productivity and N‐use efficiency of the grain crop. Common bean was grown after palisade grass [Urochloa brizantha (Hochst. Ex A. Rich.) R.D. Webster] and ruzigrass [Urochloa ruziziensis (R. Germ. and C.M. Evrard) Crins] cover crops combined with N management [application to living cover crops 35 days before common bean seeding (DBS), 1 DBS, conventional, and control (zero‐N application)] in four experiment‐years. Dry matter (DM) and N content for palisade grass was consistently greater at termination relative to ruzigrass. Nitrogen application 35 DBS increased cover crop DM, N content, and the decomposition rate relative to the other N treatments. Greater common bean yield occurred following palisade grass than ruzigrass, and N application 35 DBS increased common bean yield compared to 1 DBS and conventional in one out of four experiment‐years. Only minor differences in the agronomic efficiency (AE) of applied N to cover crops were detected between 35 DBS and 1 DBS, and only for one experiment‐year, when palisade grass resulted in greater AE than ruzigrass. Applying N early to living crops such as palisade grass is an alternative N management strategy to the traditional approach for N fertilization in common bean. Core Ideas: Productivity and N content for palisade grass was greater than ruzigrass at termination.Palisade grass cover crop improved common bean yields relative to ruzigrass.Nitrogen applied to living cover crops is an alternative N management approach of applying N only to common bean. [ABSTRACT FROM AUTHOR]

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In no-tillage rotation systems, the recovery of nitrogen (N) fertilizer in the soil–plant system is affected by soil fertility and biological changes caused by the surface application of lime (L) and phosphogypsum (PG). Here we assessed the effect of surface-applied L and/or PG on the fate of 15N-labeled fertilizer, soil chemical properties, microbial gene copy number (16 S rRNA of prokaryotes and genes of N cycle) and grain yield of maize (Zea mays L. intercropped with ruzigrass) in rotation with soybean [ Glycine max (L.) Merrill] during two growing seasons. We found that applying L improved soil fertility, particularly when combined with PG (LPG treatment), resulting in higher grain yield. Moreover, compared with the control, the recovery of 15N-labeled ammonium sulfate [(15NH 4) 2 SO 4 ] increased in maize and ruzigrass dry matter but decreased in soybean grown on the residue of the first growing season in two treatments (L and LPG). The losses of 15N-labeled fertilizer were highest in the control and PG treatments. A large amount of 15N-labeled fertilizer was found in the deep layers of PG-amended soil, indicating leaching of fertilizer-derived 15N. Conversely, the analysis of soil microbial N cycle genes revealed that the abundances of denitrifiers were highest in the control (no correctives applied), suggesting that the N fertilizer remaining in the soil increased denitrification rates. Surface application of a combination of L and PG is clearly a feasible strategy for increasing soil fertility, 15N recovery from fertilizer, and grain yield while reducing environmental pollution associated with nitrification and denitrification. • Lime+phosphogypsum boost soil nutrient availability and 15N recovery by crops. • Low 15N recovery implied a higher concentration of the fertilizer in deep soil layers. • N cycle genes abundance increased in fertile soils. • Higher abundance of N cycle genes is related to the greater 15N recovery by crops. [ABSTRACT FROM AUTHOR]

This study assessed soil Phosphorus (P) fractions and lability according to crops in rotation and crop residue P inputs under long-term no-till (NT) in weathered tropical soils. Two experiments were established in split-plot designs with fall-winter as the main plot and spring as the subplots. In one experiment, sunflower and triticale were grown in Typic Rhodudalf (TR) soil in fall-winter; in the other experiment, monocropped and intercropped ruzigrass and grain sorghum were grown in Rhodic Hapludox (RH) soil in fall-winter. In both experiments, sunn hemp, forage sorghum, and pearl millet were grown in the spring; an additional fallow treatment was established in spring in TR. Soybean was grown every year in the summer in both experiments. After 12 (TR) and 9 (RH) years, the crop residue quality (e.g. N content and lignin-N ratio) and P inputs of the various crops were assessed. In addition, soil P fractions were determined according to the Hedley procedure. High-quality residue enhanced P recycling by soybean under crop rotation with sunn hemp in both experiments, sunflower in TR, and ruzigrass in RH. Sunn hemp increased soil labile P by 13% compared with pearl millet in TR and by 40% compared with forage sorghum and pearl millet in RH. Forage sorghum in spring enhanced P mod-labile in TR, effect also observed for monocropped grain sorghum and ruzigrass in fall-winter in RH compared to both intercropped. In general, crop rotation under NT improved soil P lability, particularly the biological P pool, suggesting positive impacts from crop residue quality. The results of this study can be used to guide P fertilization strategies for NT cropping systems in tropical soils. • Crop rotation improves phosphorus recycling under no-till in tropical soils. • Cover and cash crops increase soil P lability under no-till. • Sunn hemp and sorghum enhanced soil P lability in both soils. • The organic P pool is influenced mainly by the crop residue type in crop rotation. [ABSTRACT FROM AUTHOR]