Axonopus Affinis Research Articles

Critical notes on grasses (Poaceae) of Madeira, Portugal

As a result of fieldwork in the island of Madeira (Portugal) in the autumn of 2021 and the spring of 2022, nine non-native grasses are newly reported: Axonopus fissifolius, Chloris pycnothrix, Digitaria radicosa, D. violascens, Eragrostis multicaulis, Nassella hyalina, Paspalum notatum, P. urvillei and Sporobolus aff. fertilis. All are at least locally naturalized in the island of Madeira and, elsewhere in the world, they are often considered invasive species or weeds. In addition, the identity of species from the Hyparrhenia hirta and Setaria verticillata complexes is discussed. Finally, some miscellaneous notes on other noteworthy grasses are also presented.

Botanical composition gradients in silvopastoral systems on temperate native grasslands of Uruguay

AbstractSilvopastoral systems may provide important production and environmental benefits. The loss of cool-season (C3) grasses from temperate grazed native grasslands is associated with selective grazing and excessive solar radiation that limit their survival. Silvopastoral systems integrate trees with grasslands that provide shade to both cattle and herbaceous plants, potentially favoring C3 species. There is limited information about the effect of trees on the species and functional composition of native grasslands in the Campos biome in South America. The objective of this study was to detect gradients in the botanical composition of grasslands as affected by changes in the shade associated with distance to the trees and cardinal orientation in three situations defined by the combination of soil and tree species (Prosopis on Solonetz, Acacia on Brunisols, and Eucalyptus on Brunisols). Soil cover of the herbaceous species under trees was recorded in double transects located in the four cardinal directions. In all situations there were changes in pasture composition in the different shaded regions (total shade, partial shade, or full sun). Under the canopy, there was an increase of cool-season grasses such as Bromus catharticus Vahl, Lolium multiflorum Lam., Stipa hyalina (Nees) Barkworth, and S. setigera J.Presl. At greater distances from trees, cover of warm-season grasses, such as Axonopus affinis Chase and Paspalum notatum Flueggé increased. These gradients suggest that trees in silvopastoral systems can increase the abundance of cool-season species and potentially improve the forage nutritive value of the native pasture.

Eddy Covariance Measurements of Turbulent Heat Fluxes over a Grass-covered Surface in a Tropical Location

In this study, an Eddy Covariance (EC) system was deployed to measure the turbulent heat fluxes (sensible and latent heat fluxes) at a farmland located at Obafemi Awolowo University, Ile-Ife, Nigeria. The period of measurement was between 2016 and 2019. The surface of the measurement area was covered by grass (Axonopus fissifolius) and changes from leafy-green during the wet season to dry twigs during the dry season. The sensible heat flux, Hs obtained ranged between -0.8 and 181.9 Wm-2 while the latent heat flux, Hl varied between 0.9 and 218.0 Wm-2. The maximum daytime value of Hs peaked in January while the maximum daytime value of Hl peaked in October. The sensible heat flux was 59 % higher than the latent heat flux during the Harmattan months (January, February and December), while the latent heat flux was 63 % higher than the sensible heat flux during the wet months (April - November). The study concluded that 91 % of the energy available at the surface during the period of study, was used for evapotranspiration while only 9 % was used for sensible heating as shown by the distribution of the Bowen ratio.

Potential phytoremediation of Pampa biome native and invasive grass species cohabiting vineyards contaminated with Cu in Southern Brazil.

The objectives were (a) to evaluate whether grasses native to the Pampa biome, Axonopus affinis Chase, Paspalum notatum Flüggé and Paspalum plicatulum Michx, and the invasive grass Cynodon dactylon (L.). Pers have the potential to phytoremediate soil contaminated with Cu (0, 35 and 70mg Cu kg-1); (b) assess whether the growth of these species is compromised by the excess of Cu available in the soil; and (c) determine the impact of excess Cu on the physiological responses of the studied species. C. dactylon presented the best performance in soil contaminated with 35mg of Cu kg-1. In C. dactylon, the concentrations of chlorophyll b and carotenoids increased, as did the photosynthetic rate and plant growth. Phytotoxic effects of Cu in soil contaminated with 70mg of Cu kg-1 were more severe on A. affinis and led to plant death. The other species presented reduced photosynthetic and growth rates, as well as increased activity of antioxidant enzymes such as superoxide dismutase and guaiacol peroxidase. This very same Cu level has decreased photosynthetic pigment concentrations in P. notatum and P. plicatulum. On the other hand, it did not change chlorophyll a and b concentrations in C. dactylon and increased carotenoid concentrations in it. High values recorded for Cu bioaccumulation-in-grass-root factor, mainly in P. plicatulum, have indicated that the investigated plants are potential phytostabilizers. High C. dactylon biomass production-in comparison to other species-compensates for the relatively low metal concentration in its tissues by increasing metal extraction from the soil. This makes C. dactylon more efficient in the phytoremediation process than other species.

Experimental Study on Anti-Scour Property and Erosion Resistance of 3D Mat Materials for Slope Protection in Waterway Engineering

3D mats are environmentally friendly and ecological materials for protecting river and waterway banks. The anti-scour properties of the materials and the erosion resistance of the soil under them can be studied to provide decision support for the selection of slope protection materials and their applicable areas. In this paper, an indoor prototypical scouring experiment with a flume is carried out to study the anti-scour properties of three types of 3D mat materials (vegetation grass mats, Enkamat and reinforced Mike mat) and the erosion resistance of the underlying soil under typical combined conditions of flow rate and water stage. It is concluded that the 3D mats increase the resistance coefficient of the bed surface, and that with the same incoming flow, the average flow velocity is inversely related to the resistance coefficient. There are three scouring modes for 3D mats under the action of water flow: material failure caused by mechanical damage, performance failure caused by serious erosion of the soil mass and non-failure. Of the three mat materials, the reinforced Mike mats are more resistant to scouring than the other two unreinforced materials, and the erosion volume ratios of reinforced Mike mats, vegetation grass mats and Enkamat are 59.24%, 61.81% and 62.17%, respectively, under the same small flow rate and high water stage. The results show that the reinforced Mike mats have the best anti-scour property and soil conservation performance, followed by Enkamat and the vegetation grass mats. In addition, reinforced materials outperform non-reinforced ones in their anti-scour performance and their protection for the underlying soil on the bank slope.

How do native grasses from South America handle zinc excess in the soil? A physiological approach

The excess of zinc (Zn) in vineyard soils promotes grape yield restraints. Thus, it is urgent to set up sustainable strategies aiming at decrease phytotoxic potential of Zn for crops. The selection on biochemical and physiological bases of wild plants to intercrop with perennial ones might be the key step to identify and characterize unknown mechanisms of metal tolerance in these plant species. This study aimed to evaluate the physiological and biochemical responses of native grasses of South America exposed to high Zn concentrations in the soil. The soil was sampled in a non-anthropized area and it was incubated with the following Zn amounts: 0, 30, 60, 120, or 180 mg Zn kg−1 soil. The native grass species considered were: Axonopus affinis, Paspalum notatum, and Paspalum plicatulum. Dry mass accumulation, the nutritional composition of plants, photosynthetic parameters, antioxidant enzyme activities, and oxidative stress indicators have been evaluated. A. affinis specie increased photosynthetic rate, pigments concentrations, and biomass production as Zn increased in soil. While it did not enhance the reactive oxygen species, and did not show lipid peroxidation under Zn excess. On the other hand, species P. plicatulum and P. notatum were more sensitive to Zn excess in the soil, showing oxidative injuries, which reduced plant growth. Hence, results show that A. affinis possess the physiological and biochemical features for controlling the Zn availability in the soil supporting, thus, the idea of its effective use in agronomical strategies for containing the Zn toxicity problem.

Cinética de absorção de potássio em espécies de gramíneas forrageiras nativas do bioma Pampa

ABSTRACT: This study quantified K uptake kinetic parameters in grass species Paspalum notatum, Paspalum urvillei and Axonopus affinis to associate them with growth. Ten milliliters (10 ml) of nutrient solution were collected in two-liter pots - with five repetitions in 24 hours - in order to determine K concentrations in the samples. Shoot and root dry matter, root length, volume, diameter and surface area, as well as kinetic parameters associated with nutrient uptake (Vmax, Km, Cmin and I) were determined. Species P. notatum was the one presenting the highest root, shoot and total dry matter production, as well as the highest root volume. P. urvillei recorded the highest K content, which may be associated with thinner roots and greater root surface area. A. affinis recorded the highest Vmax value, which led to greater K uptake efficiency.

Growth and physiological potential of various turf grass species under graded shade levels

An study was carried out to evaluate the effects of graded shade levels on the growth and quality of turf grass species Cynodon dactylon (Bermuda grass), Zoysia matrella (Manilla grass), Stenotaphrum secundatum (St. Augustine grass), Paspalum notatum (Bahia grass), Paspalum vaginatum (Seashore Paspalum), Dactyloctenium aegyptium (Crowfoot grass), Axonopus affinis (Mat grass/Carpet grass) and Eremochloa ophiuroides (Centipede grass). These species grown under shade nets with different shading intensity of 25%, 50%, and 75% along with control (without shade net) were investigated at Division of Floriculture and Landscaping, IARI, New Delhi during 2017-19. Among the all species, Crowfoot grass and Zoysia found good under reduced irradiance conditionas compared to open conditions, while, St. Augustine, Bahia and Seashore Paspalum performed well from 25-50% reduced irradiance level but these were best under open conditions. Performance of Bermuda grass, Carpet grass and Centipede were not satisfactory under reduced irradiance level.

Tolerance and phytoremediation potential of grass species native to South American grasslands to copper-contaminated soils

Grass species native to South American can have mechanisms to tolerate copper (Cu) excess, which improves their use to phytoremediate Cu-contaminated soils . The aims of the present study are to assess the tolerance of grass species native to South American grasslands to copper-contaminated soils, as well as their adaptive responses under high Cu-stressed condition and to identify native grass species presenting the highest potential to be used for phytoremediation purposes. Soil samples were air-dried and their acidity, phosphorus and potassium levels were corrected, and the samples were incubated. Three Cu levels were used in the experiment: natural (Dose 0), with added of 40 mg kg−1 of Cu and with added of 80 mg kg−1 of Cu. Three Axonopus affinis, Paspalum notatum and Paspalum plicatulum seedlings were transferred to 5-L pots filled with soil in August and grown for 121 days. Soil solution was collected during cultivation with the aid of Rhizon lysimeters. Main concentrations of cations and anions, dissolved organic carbon and pH in the soil solution were analyzed and the ionic speciation was carried out. Cu toxicity impaired the growth of grass species native to South America, since Cu excess led to both changes in root morphology and nutritional unbalance. Among all assessed native species, Paspalum plicatulum was the one presenting the greatest potential to phytostabilize in Cu-contaminated soils, since it mainly accumulates Cu absorbed in the roots; therefore, its intercropping with grapevines is can be beneficial in Cu-contaminated soils.

Leaf and root attributes as growth and phosphorus uptake determinants in two grass species from South America’s natural grasslands

AbstractPhosphorus uptake by grass species from natural South American grasslands can change depending on root and leaf attributes capable of determining higher, or lower, relative growth rate. The aim of the current study is to investigate whether leaf and root attributes capable of determining leaf and root area production in native C4 grass species Axonopus affinis and Andropogon lateralis are related to higher relative growth rate (RGR), P uptake capacity (maximum P influx; Imax) and concentration. Species grown in 2-litre pots with added nutrition solution were subjected to two treatments, namely 5 μM P l−1 and 30 μM P l−1. Solution aliquots (10 ml) were collected for 30 hours at the end of the study to determine P concentrations. RGR was 3.6 and 2.8 times higher in A. affinis than in A. lateralis in treatments with 5 μM P and 30 μM P. Axonopus affinis recorded the highest P concentration in leaf tissue. This outcome was associated with Imax 85% higher in A. affinis. High RGR was associated with larger leaf and root surface area per dry mass unit, as well as with high P influx capacity and with higher affinity transporters. These species often prevail in areas accounting for greater natural fertility and are more responsive to phosphate fertilization.

Aesthetic and sensory quality of Emerald grass (Zoysia japonica) as a function of substrate cultivation and mineral fertilization

Abstract Ornamental lawns, such as Emerald grass (Zoysia japonica), require adequate fertilization management for their development, as well as the substrate used as a base in cultivation is of great importance to improve the aesthetic quality of the species. These two factors together, can provide a better acceptance of the turfgrass, through sensory analysis. Thus, the objective of this study was to evaluate the aesthetic and sensory quality of the Emerald grass, as a function of cultivation on substrates and mineral fertilization. The work was carried out from September to December 2012, in a 5x3 factorial scheme [5 substrates x (2 fertilizers + control)], with 3 repetitions. Emerald grass mats were implanted in 8.5 L containers, filled with 5 substrates: S1 = soil, S2 = soil + sand (2:1), S3 = soil + organic compost (1:1), S4 = soil + compost organic + sand (2:1:1) and S5 = compost + sand (3:1). And the fertilizers used were based on a NPK formulation (10-10-10) applying 60 g m-2, and 125 g m-2 of a commercial product. Were evaluated: lawn height, relative chlorophyll index, dark green color index, and sensory analysis for appearance and color attributes and acceptability index. It was observed that the substrates based on organic compost presented the best results for the evaluated parameters, and the fertilizations carried out with the commercial product and the formulated NPK, presented similar results in the grass development evaluations, while the sensorial analysis is an important tool for accepting the aesthetics of a lawn.

Growth strategies as determinants of CO2 sequestration and response to nitrogen fertilisation in C4 grasses in South American natural grasslands

Grass species grown in South American natural grasslands present different growth strategies related to variations in specific leaf area (SLA), leaf dry matter content (LDMC) and possible nitrogen (N) allocation. Nitrogen fertilisation can have effects on physiological processes such as CO2 assimilation; however, these responses can change depending on the growth strategy adopted by each species. The aim of the present study is to determine the effects of N fertilisation on SLA, LDMC and CO2 assimilation in eight C4 grass species: Axonopus affinis, Paspalum pumilum, P. notatum, P. urvillei, P. plicatulum, Andropogon lateralis, Saccharum angustifolium and Aristida laevis. These species were cultivated in pots filled with soil subjected to two conditions of N availability: nil (control) and 200 mg N kg–1 soil. The SLA of Axonopus affinis was 5.4 times higher than that of Aristida laevis. Axonopus affinis and P. pumilum recorded the lowest LDMC, their leaves showed 53% lower LDMC than observed for Aristida laevis, on average. Resource-capture species showed variation in leaf area with N addition to values 20% higher than the control, whereas species characterised by a resource-conservation growth strategy recorded variation in leaf area with N addition to values only 8% higher than the control. With N addition, the CO2 assimilation of resource-capture species represented variation (increase) nine times that of resource-conservation species compared with their respective controls. Resource-capture species have greater CO2 capture potential than resource-conservation species, mainly a result of N addition.

Common carpetgrass (Axonopus fissifolius) control with POST herbicides

AbstractReductions in MSMA use for weed control in turfgrass systems may have led to increased common carpetgrass infestations. The objective of our research was to identify alternative POST herbicides for control of common carpetgrass using field and controlled-environment experiments. Field applications of MSMA (2.2 kg ai ha−1) and thiencarbazone + iodosulfuron + dicamba (TID) (0.171 kg ai ha−1) resulted in the greatest common carpetgrass control 8 wk after initial treatment (WAIT): 94% and 91%, respectively. Thiencarbazone + foramsulfuron + halosulfuron (TFH) (0.127 kg ai ha−1) applied in the field resulted in 77% control 8 WAIT, whereas all other treatments were ≤19% effective at 8 WAIT. All treatments resulted in greater common carpetgrass control when applied in the greenhouse. Applications of MSMA, TFH, and TID resulted in the highest common carpetgrass control in the greenhouse 8 WAIT: 94%, 94%, and 91%, respectively. Control with nicosulfuron (0.035 kg ai ha−1) and trifloxysulfuron (0.028 kg ai ha−1) (81% and 75%, respectively) was greater in the greenhouse than observed in the field 8 WAIT. Sequential applications of foramsulfuron (0.058 kg ai ha−1) resulted in only ≤11% common carpetgrass control 8 WAIT, regardless of application site. All herbicide treatments in the greenhouse resulted in reduced aboveground common carpetgrass biomass 8 WAIT compared to the nontreated control (12.9 g). Aboveground biomasses of common carpetgrass in response to MSMA, TID, TFH, nicosulfuron, and trifloxysulfuron were 1.6 to 2.1 g, regardless of treatment. Reduced efficacy of foramsulfuron was reflected in greater biomass (4.7 g) in response to treatments. Thiencarbazone + iodosulfuron + dicamba may be an alternative to MSMA for common carpetgrass control; however, long-term assessment may be warranted to evaluate treatment effectiveness. Further investigation into application timing may be necessary to enhance the efficacy of TFH for the control of common carpetgrass.

Resilience in the functional responses of Axonopus affinis Chase (Poaceae) to diurnal light variation in an overgrazed grassland

Overgrazed grasslands of Southern Brazil are responsible in part for the degradation, low productivity and loss of biodiversity of the grassland ecosystems submitted to such management. Axonopus affinis Chase, the carpet grass, is a dominant creeping grass species in overgrazed grasslands. The species readily spreads, is highly tolerant of frequent defoliation and to trampling. In any natural environment, different light intensity regimes vary considerably along the day. Such phenomenon requires a high level of plasticity, resistance, and resilience from plants. Within this context, the aim of this study was to describe the mechanisms of photochemical activity in Axonopus affinis (Poaceae) in response to natural variations in daylight. Here we report hysteresis related functional behavior in overgrazed grasslands. This study was conducted in grassland vegetation within an experimental overgrazed area from the Embrapa Pecuária Sul, Bagé/Rio Grande do Sul, Brazil (austral spring 2014). By means of preferential sampling, homogeneous areas with a 90% dominance of Axonopus affinis Chase were selected. In the present study 60 sample units were analyzed (young leaves, non-damaged and fully expanded). Photochemical variables and OJIP curves were sampled in two distinct conditions along one day, under light intensities labeled as: 1 – high photosynthetic photon flux density (HI), when under full sunlight; and 2 - low photosynthetic photon flux density (LI), when under cloudy days. It was possible to quantify and identify the alternative stable states of A. affinis in response to light resource availability, expanding the interpretation of the multivariate analysis (triangular trajectory) and therefore, contributing to univariate metrics (bimodal trajectory). In this study, HI produced hysteretic behavior while LI of dynamic photoinhibition in A. affinis. The ΔF/Fm′ variable was the most important mechanism to explain the plasticity of A. affinis in HI and LI (R2 > 0.98 in function of the PCoA coordinates). However, the non-photochemical quenching activity was responsible for the stability in the OJIP curve. Therefore, A. affinis presented photochemical mechanisms that contribute to the occupation and dominance of overgrazed grasslands with different light regimes.

The potentials of biological geotextiles in erosion and sediment control during gold mine reclamation in Ghana

Soil erosion is a significant environmental impact of surface mining affecting the initial establishment of vegetation, especially on steep slopes, during reclamation. Consequently, we investigated the potentials of biological geotextiles constructed from two local plants, Pennisetum purpureum and Broussonetia papyrifera, in reducing erosion and sedimentation during reclamation at Newmont Ghana Gold Limited. Six experimental plots were constructed on a 33% slope waste rock, covered with a 70-cm layer of stockpiled subsoil. Concrete gutters, lined with silt fence, were installed at the lower end of each plot to collect eroded sediment. The two kinds of biological geotextiles, “York” mat and elephant grass mat, were used with bare ground as control in a randomized block design with two replicates each. Data on sediment yield was collected after each substantial rainfall. The performance of each geotextile in reducing soil loss was expressed as a percentage from the mean total sediment yield. With total precipitation of 306 mm in the period April 18, to July 4, 2016, both elephant grass mat and York mat significantly (p < 0.05) reduced soil loss by 56.6% and 97.3%, respectively, compared to the control, indicating both mats were effective in erosion and sediment control. The relatively high performance of York mat was mainly attributed to its more fibers that provided less surface cover (70%) as well as flexibility of the fibers which enabled the mat to absorb more water during rainfall thus increasing its weight. This increase in weight promoted better drapability, with better erosion and sediment control. Gully formations at the site were primarily due to high concentrated runoff flows from the top of reclaiming benches, with time delays between completion of earthworks, geotextile placement, and seeding of plants as predisposing factors. The York mat (YM) and the elephant grass mat (EM) individually acted as cover and protected the highly erodible graded mine slope against the erosive forces of tropical rain and runoff until vegetation establishment. Even so, planning and coordinating the reclamation program such that all earthworks are completed at the end of the dry season to enable geotextile installation and plant seeding at the onset of rains, together with installation of temporary slope drains in preventing gully formations from concentrated runoff flows, are considered to contribute significantly to the general reclamation success at Newmont Ghana Gold Limited (NGGL) and similar mine sites.

Substrates and fertilization in the development of São Carlos grass

Sao Carlos grass ( Axonopus affinis ) is recommended for use in industrial areas, residential gardens and country houses, and has tolerance to semi-shaded areas. The experiment was carried out at UNESP, Campus de Ilha Solteira - SP, in the period from 06/28 to 12/14/2014, in a greenhouse (Pad & Fan, mean temp 25°C and average luminosity 2500 lux). The grass was implanted in black plastic containers (8.46 liters), and the experimental design was a 3x4 factorial composed of three substrates: soil, soil + organic matter (1: 1) and soil + organic matter + sand (2:1:1), and three chemical fertilizers: Forth Jardim ® , Maxgreen S2 ® and NPK (10-10-10), and without fertilization. The organic matter showed a beneficial effect on the development of the turfgrass, as well as the use of Forth Jardim®.

Remote sensing of the ocean surface refractive index via short-wave infrared polarimetry

The linear polarization of sunlight reflected by ocean surfaces in the short-wave infrared (SWIR), at geometries where specular reflection dominates the signal, is a direct function of the refractive index of the surface microlayer (SML). This simple physical concept is at the base of a novel technique presented in this study. We invert observations obtained by the airborne Research Scanning Polarimeter (RSP) in the sunglint region, where each pixel's radiance is dominated by the signal originating from the wave slopes oriented precisely to cause specular reflection. The SWIR wavelength ensures minimization of aerosol interference when radiance travels through the atmosphere; strong absorption by the water body then limits the penetration depth to the first micrometer or so, effectively probing the SML. The resulting Degree of Linear Polarization (DoLP) is then governed by the refractive index via the Fresnel law for the specific pixel geometry, independently of the windspeed. The selected dataset concerns several field deployments from both low- and high-altitude aircraft, including total reflectance measurements with the sole purpose of accounting for the residual aerosol effect. Stable retrievals from transects above pure seawater yielded values of refractive index that match the values published in the literature within an accuracy of 5 × 10−4. Flying over the oil spill caused by the explosion of the Deepwater Horizon platform, detected variations were found compatible with the presence of an oil slick. The robustness of the results, guaranteed by the high RSP polarimetric accuracy (≤ 0.2%), opens the possibility for remote-sensing detection of other entities that similarly affect the refractive index including whitecaps, microplastics, biological gels, seaweed and grass mats.

Intercropping of young grapevines with native grasses for phytoremediation of Cu-contaminated soils

Intercropping may be a strategy for phytoremediation of vineyard soils with high copper (Cu) content. The study aimed to evaluate the contribution of South American native grasses in limiting Cu availability and toxicity in soils grown with grapevines. The soil used in the experiment was collected in natural grassland with no history of cultivation. The samples were air-dried; acidity, P and K levels were corrected and samples were then incubated. We used three Cu levels - natural content (Dose 0) and the addition of 40 and 80 mg Cu kg−1 of soil (Dose 40 and 80). At each Cu dose, grapevine was grown in three cropping treatments: monocropping, intercropping with Paspalum plicatulum and intercropping with Axonopus affinis. In intercropping, two grass seedlings were transplanted into each experimental unit 35 days prior to the transplanting of the grapevines. The soil solution was sampled and ionic speciation was carried out. At 70 days after planting, we sampled the grapevines to determine dry matter, morphological parameters and nutrient concentration in the roots and shoots. Intercropping young grapevines with Paspalum plicatulum and Axonopus affinis was efficient in promoting the growth of young grapevines at moderate and low levels of Cu contamination by reducing Cu bioavailability. This indicates that maintaining native grasses in young vineyards is an effective strategy for phytoremediating Cu-contaminated soils and obtaining a grape production system with reduced interventions in the native environment, in addition to contributing to soil protection and nutrient cycling.

Vegetation composition and forage mass in grassland with a double structure under two winter grazing regimes

ABSTRACT: Remnant areas of Pampas grassland have a distinct double structure. Efficiency of livestock farming on these grasslands depends on practices that are synchronized with natural variation. This study examined the changes in vegetation composition and forage mass during winter to understand the effects of grazing methods in a natural pasture with a double structure that was grazed by heifers. An experimental area in the municipality of Bagé, Rio Grande do Sul, was subjected to continuous or rotational grazing treatments, with two replicates each. Frequency of the structural composition and forage mass of the lower stratum and animal weight was measured at the beginning and end of the experimental period (June 7 to October 7, 2016, respectively). Data were analysed with PCA ordination, regression and variance analysis. Both structural composition and forage mass changed during the experimental period. Axonopus affinis and Paspalum notatum were characteristic of continuous grazing, while Mnesithea selloana and Axonopus argentinus characterized rotational grazing (the latter had the highest levels of forage mass). Although, grazing methods changed the composition of forage mass in winter, they did not affect average daily gain of the animals.

Biochar addition changed the nutrient content and runoff water quality from the top layer of a grass field during simulated snowmelt

Biochar has the potential to decrease the leaching of nutrients from agricultural systems to watercourses. We applied cattle slurry (0 or 40 t ha−1) and different amounts of spruce biochar (0, 10, 20 or 40 t ha−1) to the surface of a boreal grass field in autumn and analyzed the nutrient content in the soil and the regrowth of grass (Phleum pratense) in the autumn over three years. In addition, four grass mats from each treatment were lifted each autumn and stored for 2–3 months outdoors (between −36 °C and 12 °C) for simulated snowmelt experiments. In the following winter, 30 kg snow was added to the grass mats and slowly melted with infra-red heaters over a 7-day period. All surface runoff water was collected and the concentrations of nitrate nitrogen (NO3-N), ammonium nitrogen (NH4-N), total nitrogen (TN), dissolved phosphate phosphorus (PO4-P), total phosphorus (TP), dissolved total potassium (K), dissolved organic carbon (DOC) and pH were measured. Biochar temporarily improved growing conditions by increasing pH values and the content of plant available acid ammonium acetate extractable P (PAc) and K (KAc) in the soil, which also increased losses in surface runoff during the first snowmelt. In contrast, the biochar retained slurry- and mineral fertilizer-originated NO3-N on the soil during the three year experiment and prevented NO3-N losses in surface runoff during the first snowmelt after autumnal slurry addition. The biochar-induced increase in phosphorus (P) loss in surface runoff during the first snowmelt after slurry application was considerable (0.1–0.5 kg P ha−1) and the decrease in nitrogen (N) loss was moderate (0.2–0.6 kg N ha−1) compared to annual P and N losses in surface runoff in an adjacent field. The surface application of biochar can be recommended for the inhibition of nutrient losses to watercourses via surface runoff only if the capacity of used biochar to retain both N and P can be verified before application.