Grassland Science最新文献

The sustainable supply of whole crop maize (WCM, Zea mays L.), as the domestic high-quality forage source, is causing great concern among the related parties in the Republic of Korea. Many new cultivars were introduced or developed in recent decades. This study was conducted to construct the WCM weather-crop yield prediction model considering cultivar maturity as well as to evaluate the effects of local climatic factors on yield. Data on the nationwide adaptability tests of WCM cultivars and the meteorological data were collected and merged into a dataset (n = 386, 22 years) after data cleansing. Three climatic variables, including the accumulation values of growing degree days, precipitation, and sunshine hours from seeding to harvesting, were generated. Then, the dataset was split into two sub datasets considering cultivar maturity. Subsequently, the models, including the three climatic variables and the cultivated location, were constructed for both sub datasets. The finesses and accuracy of the models were confirmed by residual diagnostics and 3-fold cross-validation. The accumulated temperature, sunshine time, and precipitation were found to significantly affect the WCM yield variance, while the precipitation factor caused stresses to the yield, which indicates water management is important for WCM cultivation.

Ticktrefoil (Desmodium) species from the USDA, ARS, Plant Genetic Resources Conservation Unit (PGRCU) germplasm collection in Griffin, GA, were evaluated for their potential livestock nutraceutical (nutritional + pharmaceutical) value in a field small plot study at the Fort Valley State University (FVSU) Agricultural Research Station, Fort Valley, GA. Horse marmalade (Desmodium discolor Vogel), greenleaf ticktrefoil (Desmodium intortum [Mill.] Urb.), panicledleaf ticktrefoil (Desmodium paniculatum [L.] DC.), Hawaii ticktrefoil (Desmodium sandwicense E. May) and twisted ticktrefoil (Desmodium tortuosum [Sw.] DC.) were established in a greenhouse and transplanted to field plots, with plant material from each species harvested, freeze-dried, ground and analyzed for nutrient content and bioactivity. Crude protein (CP) levels in D. discolor and D. tortuosum averaged 233 g/kg, whereas CP in D. intortum, D. paniculatum and D. sandwicense ranged from 99 to 157 g/kg. The Desmodium species had in vitro true digestibility values of 755 to 878 g/kg. There were no detectable condensed tannins in D. discolor and D. tortuosum, whereas D. intortum, D. paniculatum and D. sandwicense averaged 88, 89 and 73 g/kg total condensed tannin, respectively. There were species differences in flavonoid content (p < .01), with the highest delphinidin and cyanidin concentrations in D. sandwicense and D. paniculatum, respectively. There were no detectable levels of delphinidin or cyanidin for D. discolor or D. tortuosum. Quercitin and kaempferol concentrations were highest in D. intortum and D. paniculatum, respectively, whereas D. discolor and D. tortuosum had the lowest values. The highest protein precipitable phenolics and total phenolic concentrations were for D. paniculatum. Desmodium species have potential as nutraceutical forage for livestock and warrant further investigation.

In Japan, additional potassium fertilization is used as a countermeasure for radiocesium-contaminated grasslands in the Tohoku and North Kanto regions. A 2-year pot experiment was conducted to assess the efficacy of using tall fescue (Festuca arundinacea Schreb.), a low-cesium-absorption grass species, to replace orchardgrass (Dactylis glomerata L.), the most common forage grass species in these regions, to reduce potassium fertilization and improve the forage mineral balance. The treatments were a combination of two grass species (tall fescue and orchardgrass) and two potassium application rates (0 [K0] and three times the conventional amount [K3]) with four replications. The grass species and potassium application rate had significant (p < .001) effects on plant cesium-137 concentrations. The results of the generalized linear mixed-model analysis indicated that when tall fescue replaced orchardgrass, cesium-137 in the forage grass was reduced to 34% and that the K3 treatment reduced cesium-137 to 46% relative to the K0 treatment. The difference in cesium-137 concentration between the two grass species increased as the soil exchangeable K₂O content decreased. The equations for estimating the cesium-137 concentration (y [g/kg]) from the exchangeable K₂O content (x [g/kg]) were obtained as y = 63.7e^–2.095x for tall fescue and y = 185.5e^–3.327x for orchardgrass. These equations indicate that tall fescue cultivation can reduce the risk of elevated radioactive Cs in the grass by reducing potassium fertilizer to approximately half that of orchardgrass. There were no differences in the response of plant potassium concentrations or the potassium/(calcium + magnesium) equivalent ratio to soil exchangeable K₂O content among the grass species. However, the mineral balance of forage can be improved by reducing potassium fertilizer applications for cesium-137 remediation. Tall fescue has good potential to remediate contaminated grasslands as it reduces additional potassium fertilization and improves the mineral balance of forage.

Clarifying the relationship between plant and soil characteristics under different establishment years of artificial grassland can improve the adaptive management ability of alpine grassland, which is of great significance to the sustainable development of alpine grassland ecosystems. This study used field quadrat surveys and indoor analyses to determine the plant community and soil nutrient characteristics of artificial grasslands with different establishment years and analyzed the characteristic differences and internal relations under different establishment years combined with correlation analysis and redundancy analysis. The results showed that the vegetation coverage decreased significantly (p < .05) after the establishment of 5 years, the biomass of artificial grassland decreased with the increase in establishment years and the species diversity index showed a “V-shaped” change. With the increase in establishment years, the total nutrients of the artificial grassland increased, and the available nutrients decreased. The results of correlation analysis and redundancy analysis showed that soil nutrients in the 0–30 cm soil layer were intrinsically correlated with biomass and soil pH, soil water content and soil bulk density were significantly correlated with plant community changes during the establishment of artificial grassland. This study will help to clarify the changes in plant and soil characteristics of artificial grassland with different establishment years and provide a scientific and theoretical basis for restoring degraded alpine grassland.

The negative impacts of sika deer (Cervus nippon) on Japanese serows (Capricornis crispus) are a subject of concern in the mountainous regions of Japan. To develop a methodology to collect information with regard to the abundance and habitat selection of sympatric large mammals using drones (unmanned aerial vehicles; UAVs) equipped with thermal infrared and red-green-blue (RGB) sensors, surveys were conducted at night and in the early morning in a high mountainous habitat. Despite the similar size and shape in thermal infrared images for sika deer and Japanese serows, species identification based on body color using RGB images was possible during the period from dawn to early morning. The UAV surveys also revealed the large abundance of deer (>40 deer/km²) and suggested different habitat selection between deer and serows in the alpine grassland. Our results were the first snapshots of sympathetic deer and serow distribution. UAV surveys using both thermal infrared and RGB sensors in early morning could be useful for research and monitoring of large mammals in open areas, such as grasslands, marshlands, high mountains, farmlands and drylands.

Mixed seeded plots of timothy (Phleum pratense L.) and galega (Galega orientalis Lam.) were established in multiple seeding times from 2014 to 2017 to determine the latest sowing limit in the Konsen region, northern Japan, where growing conditions are severe. Although low yields were observed in some cases when the soil freezing depth was deeper than average, the dry matter yield of the first crop of galega in the year after sowing was higher under conditions that ensured pre-overwintering plant length growth of 30 cm or more, as compared with growth of less than 30 cm. Galega rhizomes were observed under conditions of pre-overwintering plant length of 28 cm or more, but not under conditions of less than 28 cm in length. Therefore, achieving 30 cm plant length prior to overwintering is desirable when sowing galega in the Konsen region. Furthermore, the effective cumulative temperature (ECT) required for pre-overwintering galega to reach 30 cm in plant length was 1079°C, for which seeding dates were calculated to be July 10 and June 29 in terms of calendar days, with 80% and 90% probability. In the Konsen region, galega should be sown earlier than in other regions of Hokkaido to ensure the growth rate because of the effects of soil freezing on overwintering performance.

It is common in southern China that rice (Oryza sativa L.) fields are sown with a cover crop like Italian ryegrass (Lolium multiflorum L.) following autumn harvest. The objective of the present research was to compare the effects of different no-tillage methods on the yield, nutritive composition and silage fermentation quality of Italian ryegrass. Italian ryegrass was planted in winter fallow paddy fields on 9 days (NT9) and 5 days (NT5) prior to rice harvest and on 1 day after rice harvest for 2 years. Sowing prior to harvest was no-tillage, and sowing after rice harvest was either no-tillage (NT1) or conventional tillage (CK). The grass was harvested and ensiled two times each year. The growing year had no significant effects on the yield and most nutrition components, while it had significant effects on pH value, butyric acid and NH₃-N contents of silage. There were no differences in the yield, nutritional composition and silage fermentation quality among sowing methods. The neutral detergent fiber and acid detergent fiber of NT1 decreased slightly compared with NT9, NT5 and CK (p > .05). There was no difference in silage fermentation quality among the four treatments. The best sowing method for Italian ryegrass with second cut in winter fallow paddy was no-tillage sowing after rice harvest.

Crown vetch (Coronilla varia L.) is a widely spread legume species that can be used as a forage crop for herbivores. The crown vetch herbage was ensiled with 0, 4, or 8% of crushed barley grain on a wet basis. The crude protein (CP) and neutral detergent fiber in organic matter (NDFom) contents of crown vetch herbage were higher than those of crown vetch silages (p < .05). The malondialdehyde (MDA) concentrations of herbage and silages with barley grain were lower than that of silage without barley grain (p < .05). The linoleic acid (C18:2) percentage of total fatty acids in forage decreased with the ensiling process (p < .05). The addition of crushed barley grain in the ensiling process of crown vetch herbage preserved the α-linolenic acid (C18:3) percentage of total fatty acids (p < .05). The crushed barley grain positively affected dry matter (DM) and ammonia-nitrogen levels, acidity value (pH and lactic, acetic and propionic acids) and in vitro ruminal fermentation values (cumulative gas production, metabolic energy [ME], net energy lactation [NEL] and organic matter digestion [OMd]) of crown vetch silage (p < .05). The concentration of volatile fatty acids (acetic, butyric, propionic, iso-valeric and iso-butyric acids) in the in vitro ruminal fermentation fluid was similar in herbage and silages of crown vetch (p > .05). Consequently, crushed barley grain (especially 4% rate) in the ensiling process of crown vetch increased hemicellulose, easily digestible carbohydrates, linoleic acid, α-linolenic acid in silage and in vitro ruminal digestion parameters, positively affected silage acidity and decreased lipid peroxidation.

This study monitored spatiotemporal variation in aboveground biomass of a paddock (1.1 ha) in a sown tropical grass pasture under cattle grazing over a 22-year period (1995–2016) by nondestructively estimating biomasses of 182 fixed locations (0.5 × 0.5 m each) in the paddock at about monthly intervals during the annual stocking season (May to October or November). The mean aboveground biomass of the paddock varied seasonally and interannually between 33 and 605 g DM/m² and was explained by a regression model including positive effects of mean air temperature, N fertilizer rate and total precipitation during the preceding 60 days (R² = 0.311, P < 0.001). The coefficient of variation of aboveground biomass, as an indicator of spatial (within-paddock) variability, varied seasonally and interannually between 0.16 and 0.94, and was described by a model incorporating a positive effect of cumulative stocking density during the preceding 40 days and negative effects of mean air temperature, total precipitation during the preceding 20 days and N fertilizer rate during the preceding 60 days (R² = 0.277, P < 0.001). The spatial distribution pattern of aboveground biomass in the paddock was persistent (P < 0.05) or not persistent over the study period, almost without being reversed. In detail, patterns in the mid stocking season tended to maintain mutual similarity in the entire range of the intervals between the measurements (364–7,694 days), whereas those at the beginning and near end of the stocking season lost mutual similarity as the interval increased. There was no indubitable evidence that the changes in botanical composition destabilized the spatial distribution pattern of aboveground biomass. The results indicate the need for assessing how the long-term stability of the within-paddock distribution pattern of aboveground biomass affects agronomic and ecological performance of the grazing system.

Semiarid grasslands contribute significantly to global soil carbon (C) storage. Carbon loss from these systems via microbial decomposition is controlled by abiotic and biotic factors such as soil moisture and temperature and C input. Plant litter in these systems can be present above the soil surface or mixed with surface soil by trampling, especially in intensively grazed areas. A quantitative understanding of abiotic factors' interactive effect is critical for predicting soil C dynamics in response to grassland management and environmental conditions changes. Therefore, we conducted a 3-month laboratory incubation experiment to quantify the impact of litter placement and soil moisture on soil carbon dioxide (CO₂) emissions under three controlled temperatures. The treatments including three litter placements (no litter, litter on top and litter mixed with surface soil) and three soil moisture levels (23%, 37% and 50% water-filled pore space [WFPS]) were incubated at three temperatures (10°C, 20°C and 30°C). Carbon dioxide fluxes were measured every 2 weeks. Soil CO₂ fluxes were higher for all moisture and litter treatments initially and declined overtime at 20°C and 30°C. Mixing litter with soil increased the cumulative CO₂ emissions by 24% and 19.5% at 20°C and 30°C, respectively, compared to no litter. Also, soil-litter mixing compared with litter on top showed a 14.3% and 21.6% increase in cumulative CO₂ emissions at temperatures of 20°C and 30°C, respectively. At all temperatures, 37% and 50% WFPS resulted in similar cumulative CO₂ emissions. The results from this study indicate that rising temperatures from 10°C to 30°C accelerate the effect of soil litter mixing on increasing CO₂ emissions compared to litter on top and no litter.