Grassland Science最新文献

Tithonia diversifolia (Hemsl.) A. Gray has significant potential as a forage source in silvopastoral systems, particularly in tropical conditions. However, its intensity and frequency management differ from those commonly applied to grasses. This study aims to evaluate T. diversifolia under two harvest intensities (30 and 40 cm stubble height) and four harvest frequencies (21, 28, 35 and 42 days), aligning with Brazil's traditional tropical grass management practices. Biomass production and nutritive value of forage, as well as in vitro rumen fermentation parameters, were assessed. We observed that the tested harvest intensities have a limited impact on the biomass production and nutritional value of T. diversifolia. Despite the linear increase in biomass production, lower harvest frequencies (i.e., longer regrowth period) significantly affect nutritional value, impacting the products of ruminal fermentation, as indicated by the in vitro assay. The methane production per gram of degraded organic matter (OM) and the OM allocated for microbial biomass production are affected by the harvest frequencies. Additionally, we observed that rainfall and canopy height have a stronger correlation with biomass production than harvest frequencies controlled by days. We conclude that T. diversifolia is minimally affected by harvest intensities and, for Brazilian edaphoclimatic conditions, it can be harvested with higher frequencies than those suggested for other regions.

Understanding the complex relationship between environmental factors and ecosystem services contributes to effective restoration of degraded grasslands and sustainable management of grassland ecosystems. This study establishes 760 grassland sampling plots (1.5 × 1.5 m) with the aim of exploring the effects of environmental factors on functions and services of grassland ecosystems in Inner Mongolia, China. The results of Monte Carlo permutation test indicate that annual precipitation (eigenvalue = 0.431), mean annual temperature (eigenvalue = 0.035) and slope (eigenvalue = 0.098) have greater influences on grassland ecosystem services compared to other environmental factors (e.g., soil properties, grazing and elevation). Annual precipitation promotes plant traits and diversity and then positively influences net primary productivity (NPP) (r² = 0.62 p < 0.05). In addition, it promotes community resilience (ET) and then positively influences NPP-WS, NPP-WY, NPP-SE (r² = 0.53 p < 0.05). Mean annual temperature exerts a negative influence on water yield (WY), windbreak sand fixation (WS) and soil erosion (SE) (r² = 0.41 p < 0.05). Slope has negative influences on plant traits and ecosystem stability, ultimately affecting on NPP-WS and WY-WS (r² = 0.43 p < 0.05). Disturbance exerts a dual effect, positively enhancing community variability but negatively influencing resilience, while actively modulating the trade-off intensity of WY-SE (r² = 0.42 p < 0.05). This study reveals the effects of climate, topography and grazing disturbance on grassland ecosystem services, providing data and theoretical support for the protection and management of temperate grassland ecosystems.

Dactylis glomerata is a perennial cool-season forage widely grown in China, which is ideal for livestock. Previous studies have found that the proportion of heterofermentative lactic acid bacteria (LAB) in fresh and naturally fermented D. glomerata was remarkably low. In this study, we established six groups, namely, a natural fermentation group (CK, control without LAB additives) and five additive groups (T1B1, T1B3, T1B5, T1B9 and B groups, where T represented a compound LAB mixture composed of Lactobacillus plantarum, Pediococcus pentosaceus and P. acidilactici in equal proportions. B represented of L. buchneri. The T1B1, T1B3, T1B5, T1B9 and B groups were created by combining the T and B LAB at ratios of 1:1, 1:3, 1:5, 1:9 and 0:10, respectively) to examine the impact of incorporating varying proportions of homofermentative and heterofermentative LAB on the fermentation quality and aerobic stability of D. glomerata. The results indicated that the fermentation quality and nutrient retention of D. glomerata silage in the T1B9 group were superior to other groups either after ensiling for 60 days or aerobic exposure for 8 days. The aerobic stability was enhanced while the fermentation attained its optimal state. The results suggest that the targeted addition of additives lacking LAB bacterial species based on the microbial community attached to the forage itself can effectively improve forage silage quality.

Livestock manure is usually used as an organic fertilizer, yet its direct application to soil can cause several environmental problems, including greenhouse gas (GHG) emissions, N₂O emissions and nutrient runoff into ecosystems. Transforming animal manure (AM) into biochar may mitigate these problems. This study evaluated the effects of combining AM biochar and agricultural waste (AW) biochar made from rice husk on soil and forage properties under potted conditions (85 × 32 × 24.2 cm³ pot). Five biochar treatments (100AW, 75AW25AM, 50AW50AM, 25AW75AM and 100AM, as volumetric ratio) were applied in four replicates. Chemical fertilizers—ammonium sulfate, potassium sulfate and superphosphate—were used as the nitrogen, potassium and phosphorus sources at rates 1.0, 0.5 and 0.5 kg/are, respectively. Soil samples were collected at 10 cm depth for physicochemical analyses, such as bulk density, total pores space, soil pH, water content, cation exchange capacity (CEC), available phosphorus (P), total carbon (TC), total nitrogen (TN) and soil microbial abundance. These analyses were conducted in the greenhouse at 60-, 130-, and 190 days post-biochar application. Due to the suboptimal growth under greenhouse conditions, the grass was reseeded upon transferring the pots outdoors, resulting in successful growth. Carbon dioxide (CO₂) emissions were measured every 10 days for 190 days in the greenhouse and additional 40 days outdoors. Results indicated that 50AW50AM biochar or more AM biochar applications reduced soil bulk density, increased total pore space, improved the water retention and increased the soil TC and TN contents compared to AW biochar alone. High AM biochar application did not affect soil microbial abundance, cumulative CO₂ emissions or grass yield. Though grass yield effects were limited, biochar nutrient enrichment may be valuable for enhancing soil and plant productivity.

The present study aimed to determine the effect of combining sulfur (S) with nitrogen (N) in pastures of Marandu palisade grass (Urochloa brizantha [A. Rich.] R.D. Webster) at an early stage of degradation. The experiment was conducted in São Luís de Montes Belos (located in the Brazilian Cerrado region), starting in October 2019 and ending in September 2021. The design used was a randomized block design arranged in a factorial scheme, where the plots were made up of S doses and the subplots of N doses, with four replications. Five S doses (0, 65, 130, 195 and 260 kg/ha) and three N doses (0, 100 and 200 kg/ha) were assessed. Doses of S and N promote increases in the green ground cover rate and the green color index. The combined application of 200 kg/ha of N and 150 kg/ha of S results in an average forage productivity of 15.59 Mg/ha, representing a 21.93% increase in biomass production in previously degraded Marandu palisade grass pastures. This demonstrates that the interaction between S and N positively influences the recovery of degraded pastures in tropical climate regions, as evidenced by the improvement in ground cover rate and forage production.

Grazing causes major disturbances to grassland ecosystems and may alter soil enzyme activity. However, the mechanism by which grazing intensity, livestock type, grazing duration and environmental (e.g., climate and soil) factors affect the response of soil enzymes to grazing is currently unknown. This meta-analysis investigated the response of soil enzymes to grazing and the underlying intrinsic mechanisms based on 443 observations collected from 38 studies. Overall, grazing had a negative effect on soil enzyme activity, especially the activities of β-glucosidase, sucrase, urease and alkaline phosphatase. Activity in response to grazing varied depending on the grazing intensity, grazing animals and grazing duration. Negative effects increased with increasing grazing intensity, as both moderate and heavy grazing significantly reduced activity by 10.08% and 20.06%, respectively. All levels of grazing intensity significantly reduced carbon-cycle-related sucrase but there were no significant effects on N-acetyl-β-D glucosaminidase or leucine aminopeptidase, two enzymes involved in the nitrogen cycle. Among grazing animals, sheep, cattle and mixed grazing all significantly reduced activity, with the exception of the positive effects of cattle grazing on the activities of β-glucosidase and protease, both of which participate in the carbon cycle, and N-acetyl-β-D glucosaminidase, involved in the nitrogen cycle. However, while short-term (<5 years) and medium-term (5–10 years) grazing significantly reduced activity, the negative effects were ameliorated as the number of grazing years increased, such that long-term grazing (>10 years) had no significant effects. The interactions between climate, soil and other factors and grazing in terms of the impact on soil enzyme activity varied. Because soil enzymes mediate nutrient cycling, maintaining soil health requires that decision-makers appropriately reduce grazing intensity while increasing grazing duration.

Pastures in animal production are widely used, but production is conditioned to several factors. The nutritional composition of forage can be altered by soil conditions, season, plant maturity and morphology, so it is important to monitor its quality through chemical analysis. To optimize this type of analysis and speed up decision-making by farmers and technicians, the use of near-infrared spectroscopy (NIRS) is a tool that has been successfully applied. This research aimed to develop predictive models for chemical components of Megathyrsus maximus cv. Tanzania using NIR spectroscopy. Laboratory determinations of ash, crude protein (CP), in vitro dry matter digestibility (IVDMD), neutral detergent fiber (NDF) and acid detergent fiber (ADF) of 345 forage samples were used as reference data and correlated with their NIRS spectra. To calibrate the models, principal component analysis and partial least squares regression were applied. The results indicated that the prediction models of the studied parameters presented a coefficient of determination (R²) equal to or greater than 0.90; residual predictive deviation rate (RPD) greater than 3.0; error interval ratio (RER) greater than 12; close mean square error values between calibration and validation; and optimal number of latent variables (LV) between seven and eight for model calibration. For CP and IVDMD prediction, the regions with the highest simultaneous contribution were 1,414, 1996 and 2,384 nm; while for NDF and ADF, 1714, 1784, 1786, 2,160, 2,320 and 2,450 nm. The success in the development of predictive models by NIR spectroscopy to evaluate dry matter digestibility and other main chemical attributes of M. maximus cv. Tanzania shows that the quality of the models developed in this study enables them to be used alternatively in routine laboratory analysis in a quick, reliable and accurate way.

In recent years, agricultural production systems have intensified, making it necessary to improve the food supplied to animals, where sorghum silage is one of the most commonly used roughages. The sorghum genotypes present significant differences in dry matter losses, fermentative profiles and nutritional values, allowing the identification of materials with high potential for producing high-quality silages that meet the dietary demands of ruminants and are recommended for use. Therefore, this work aimed to evaluate silages from 15 sorghum genotypes for different purposes to identify materials that could be recommended for silage production in the Amazon biome. The experiment was carried out in Sinop/MT to evaluate the fermentative characteristics and chemical composition of the sorghum silages. Fifteen sorghum genotypes, 15F30005, 15F30006, CMSXS 5027, 5030, 5043, 5045, 201934B008, CMSXS 7501, BRS 658, BRS 659, Volumax, BRS 511, BRS Ponta Negra, BRS 716 and AGRI-002E, were ensiled in experimental silos with six replications per treatment. For the content of NH₃-N, BRS 658 and BRS 659 had the lowest average, 29.9 g NH₃-N/kg total N. The highest average dry matter content was from BRS 658, BRS 659, AGRI-002E and BRS 716, at 295.0 g/kg. The highest average crude protein content of 78.1 g/kg dry matter (DM) was obtained from BRS658 and BRS 659. For lignin, BRS 659, Volumax, Ponta Negra, 15F30006, CMSXS 5027 and CMSXS 5030 had the lowest average value, 49.5 g/kg DM. All the genotypes evaluated presented characteristics suitable for ensiling. The materials with the highest nutritional value were the commercial varieties BRS 658, BRS 659 and Ponta Negra. The experimental varieties 15F30005, CMSXS 5027 and CMSXS 5030 demonstrated similar nutritional values to the commercial varieties, making them promising candidates for future release, commercialization and use in animal feed silage.

Human activities have caused biodiversity loss and climate change, altering critical ecosystem functions. Numerous empirical studies have focused on the relationship between plant diversity and primary productivity or its stability. However, ecosystem functions such as pollination and nutrient cycling would be regulated by biological interactions among multiple trophic levels. Here, we examined the relationship between plant diversity, pollination attributes, and seed productivity in a biodiversity experiment conducted in Inner Mongolia in 2018 and 2019, differing in intra-annual precipitation patterns. We found that pollinator visitation frequency did not affect seed productivity in both years. In 2018, we observed that flowering plant richness and flower vulnerability had positive effects on seed productivity. In 2019, however, only network evenness had a negative effect on seed productivity. The consistent effect of pollination network structure but not visitation frequency on seed productivity across two growing seasons suggests that complementary plant-pollinator interactions rather than mass effects of pollinator visitation regulate plant reproduction in the studied system. Since the relative contributions of flowering plant richness and plant-pollinator interactions on seed productivity would vary due to intra-annual precipitation patterns, as presented here, observations across multiple years should be required to fully reveal the ecosystem consequences of plant-pollinator interactions.

Drought is a major factor affecting annual forage production and quality. The present study aimed to characterize drought stress–responsive changes in carbohydrate composition and forage quality–related parameters as being linked to the responses of physiological parameters during the regrowth of Kentucky bluegrass (Poa pratensis L.). Drought treatment gradually decreased leaf water potential (Ψ_w) to a minimum value of −2.94 MPa at day 46. Drought-responsive increases in H₂O₂ concentration and lipid peroxidation were significant from day 22 (Ψ_w = −1.38 MPa), accompanied by the decreased chlorophyll content. Drought stress repressed Rubisco large subunit and several thylakoid membrane protein complexes (PSI, PSII dimer, PSII monomer and cytochrome b6/f). Drought also increased glucose, fructose and sucrose concentrations from day 22. A distinct increase in monosaccharides and disaccharides coincided with a reduction of fructan, especially from day 36 onward, when the enzymatic activity of fructan exohydrolases (1-FEH and 6-FEH) became greatly enhanced. Significant changes in forage nutritional parameters also occurred from day 36 (Ψ_w = −2.74 MPa), as shown by increases in neutral detergent fiber, acid detergent fiber (ADF) and ADF-lignin with enhanced activity of polyphenol oxidase, as well as a decrease in crude protein content. These drought-responsive changes in nutritional parameters were strongly correlated with a decrease in in vitro dry matter digestibility (IVDMD). A correlation analysis revealed that drought-induced accumulation of H₂O₂ along with decreasing Ψ_w was closely associated with increases in fiber compounds and ADF-lignin leading to a decrease in IVDMD. Our results indicate that drought-responsive reductions in forage quality mainly occurred under severe drought stress (day 36 to day 46, Ψ_w ≤ −2.74), when H₂O₂ accumulation and lipid peroxidation were high, were characterized by an accompanied increase in ADF.