Grassland Science最新文献

Grassland converted to cropland affected soil physical and chemical properties and soil microbes. However, these parameters were often studied separately and their combined responses to grassland reclaim remain unclear. To evaluate the impacts of grassland cultivation on soil microbial communities (based on phospholipid fatty acids, PLFAs) and the links between soil microbes and physicochemical properties, we performed a paired field experiment following the conversion from native grasslands to 30- to 60-year-old cropland in the agro-pastoral ecotone of northern China. The concentrations of soil organic carbon (SOC) and soil total nitrogen (STN) and the soil microbial biomass consistently decreased with grassland conversion to cropland. Grassland conversion also significantly decreased the relative abundance of bacterial and fungal PLFAs and the fungal to bacterial ratio (F:B) at 0–10 cm soil layer, but those parameters remained unchanged below 10 cm soil layers. Grassland conversion affected the microbial biomass mainly through soil C and N content rather than soil pH, moisture and aggregation. These findings revealed that cultivation-induced soil nutrient loss may enhance soil microbe depletion and affect microbial community assembly (shifts in fungi, arbuscular mycorrhizal fungi (AMF), actinomycete (Act), gram-positive (GP) and gram-negative (GN) bacteria). This implies that conversion of grassland to cropland should be avoided because of the risk of degradation of soil nutrient and microbes.

The objective of the study was to evaluate the effect of pre- and post-grazing targets on the forage accumulation and canopy characteristics of Marandu palisade grass (Brachiaria brizantha [Hochst. ex A. Rich.] Stapf. syn. Urochloa brizantha) to define grazing management strategies in Brazil's Cerrado biome. The experimental design comprised a randomized complete block with four replicates in a 2 × 2 factorial arrangement of treatments: two grazing frequencies (95% of light interception (LI95%) and maximum (LIMax) light interception of the forage canopy) and two grazing intensities (10 and 15 cm of post-grazing canopy height). Pastures were sampled to quantify forage mass and morphological components at pre- and post-grazing. The tillers population density and forage nutritive value were estimated at pre-grazing. Pastures managed with the LI95% target demonstrated greater basal (1,341 versus 1,193 tillers/m²) and aerial tillers (101 versus 53 tillers/m²) population densities, a greater leaf:stem ratio (3.8 versus 2.0), and a lower canopy height (33 versus 55 cm), forage mass (3,225 versus 4,320 kg/ha), stem proportion (30.6% versus 44.5%), and leaf (2.5% versus 2.8%) and stem (3.4% versus 3.8%) acid detergent lignin content than those managed with the LIMax target. In the Cerrado, Marandu palisade grass must be grazed when the canopy height reaches 33 cm. Furthermore, animals must be removed from the paddocks when the canopy height reaches 15 cm.

The content of photosynthetic pigments in herbage not only has a strong antioxidant function, but also can improve the health of animals and the quality of livestock products after being ingested by ruminants. Increasing the content of photosynthetic pigments can improve the feed value of herbage, which is of great significance in the process of animal feeding. The experiment aimed to investigate the effect of nitrogen (N) fertilizer levels on the contents of photosynthetic pigments and phytol in fresh Italian ryegrass (IR) herbages and their changes after drying under natural condition over two consecutive seasons. IR variety: Ace (for 2013–2014 season) and Inazuma (for 2015–2016 season) were planted in 3 blocks (4 × 6 m) from two separate fields (≥1 ha), three plots (2 × 2 m) were arranged in each block and three fertilization treatments, control: 0 kg N/ha, 60 N: 60 kg N/ha, and 120 N: 120 kg N/ha, were applied for each block. The results revealed that the crude protein, ether extract, photosynthetic pigments and phytol in IR (fresh herbage and hay) were increased with increasing N fertilizer levels. Photosynthetic pigments decreased obviously by hay preparation (chlorophylls: 40%–70%, phytol: 25%–47%, β-carotene: 72%–90%, lutein: 31%–69%). The decomposition of phytol and β-carotene was not affected by the growing year and N fertilizer levels. However, the decomposition of chlorophyll and lutein was affected by growing year, which was higher in 2014 than that in 2016. Also, the contents of total phytol and lutein of the fresh herbage and hay harvested in 2016 were higher (p < .05) than those harvested in 2014. In conclusion, higher N fertilizer levels could increase the photosynthetic pigments and phytol content in IR fresh herbage which contributes to improving the feed value. However, the content of photosynthetic pigments and phytol in IR hay decreased significantly. IR variety may also affect the nutrient content and their degree of decomposition during drying.

Dallisgrass (Paspalum dilatatum Poir.), a warm-season forage, is a perennial grass with high nutritional value, good palatability and high-stress resistance in subtropical regions worldwide. However, very limited information is available on the cultivation of dallisgrass, especially in southwest China. Soils in different areas with pasture cultivation histories were collected and mixed evenly as substrate soil. Pot experiments after fertilization with nitrogen (N), phosphorus (P) and potassium (K) are used to analyze the dallisgrass growth characteristics, dry matter biomass (DM), photosynthetic characteristics, nutrient accumulation, agronomic efficiency (AE), partial factor productivity (PFP) and recovery efficiency (RE). A three-factor (N, P, K) and five-level (N: 0, 48.66, 120, 191.34 and 240 kg/ha; P: 0, 68.93, 170, 271.07 and 340 kg/ha; K: 0, 30.41, 75, 119.59 and 150 kg/ha) quadratic regression orthogonal rotation combination design was used with three experimental plots per management strategy for multiple comparisons within each harvest. Compared with no fertilization, the optimal treatment (OPT, N 48.66 kg/ha, P 68.93 kg/ha, K 119.59 kg/ha) increased yield by 46.3%, but the effect of NPK alone was not significant. This is because OPT improves the morphology and photosynthetic characteristics of dallisgrass, cause the dry matter during the growth period is significantly (p < .05) increased, and the average nutrient use efficiency (7.45%) under the OPT management measures was much higher than the under N, P and K fertilization alone (approximately 2.61 times). More meaningfully, we found that the demand for P and K fertilizer in dallisgrass in a typical subtropical mountainous region of China is higher than that for N. Overall, these findings have important implications for the cultivation of dallisgrass.

Perennial grasses display several positive attributes as suitable energy crops for use as a solid fuel for direct combustion, such as high annual production of dry matter per unit area, perennity and high harvest flexibility. This study aimed to characterize the chemical composition and calorific value of 18 elephant grass (EG) varieties (Pennisetum purpureum Schum.) and 10 other potential bioenergy feedstocks intended for direct combustion. Samples were obtained from 6-month-old EG and sorghum and 3-year-old eucalyptus, Mimosa caesalpiniaefolia, and bamboo plants. Sugarcane bagasse and straw, rice husk, corn stover, coconut husk, and fiber samples were also evaluated. The elemental composition, lower heating value (LHV), and cellulose (CEL), hemicellulose (HCEL), lignin (LIG) and ash contents (% dry matter) were analyzed. The results indicated that the EG genotypes showed significant differences when compared with other evaluated biomasses, but showed no differences among themselves. The EG varieties showed a mean LHV (16.7 MJ/kg) superior to that of rice husk, sugarcane bagasse, and sorghum and similar to that of sugarcane straw, coconut fiber, and corn stover. The EG varieties showed a mean ash content (4.74%) inferior to that of rice husk, sugarcane bagasse, coconut fiber, and sorghum; a mean CEL content (36.0%) similar to that of sugarcane straw, coconut fiber, corn stover, sorghum, and Mimosa caesalpinifolia; HCEL; a mean HCEL content (30.3%) superior to that of rice husk, bamboo, eucalyptus, M. caesalpinifolia, coconut husk, and fiber; and a mean LIG content (8.80%) superior to that of corn stover and similar to that of sorghum, sugarcane bagasse, and straw biomass. The significant capacity of EG to accumulate dry matter was associated with the biomass quality attributes (LHV and CEL, HCEL, LIG, and ash contents), thereby making it an excellent alternative to lignocellulosic feedstock for direct combustion.

In resource-limited agroclimatic environments such as the semiarid and arid regions of the world, mineral undernourishment has been a major limitation to grazing livestock productivity. A soil amendment that has the potential to increase plant mineral uptake and reduce nutrient losses in grassland systems is biochar. The objective of this study was to evaluate the effects of biochar and nitrogen application rates on forage tissue mineral concentrations, soil constituents and leachate quality in a semiarid environment. Treatments were the factorial combination (3 × 3) of three biochar application rates (0, 8.9 and 17.8 Mg/ha) and three N application rates (0, 80 and 120 kg N/ha) arranged in a randomized complete block design experiment with four replications. Treatment means were considered different p ≤ .05. Forage tissue phosphorus concentration was altered by biochar rate × year interaction and a main effect of N rate. Tissue phosphorus concentration was greater at 17.8 Mg biochar/ ha rate than the 0 and 8.9 Mg/ha rates in 2019. For the N rate effect, forage tissue phosphorus concentration was greatest at 0 kg N/ha rate and lowest at 120 kg N/ha rate. The concentration of potassium in the forage was influenced by a biochar rate × N rate interaction. At 120 kg N/ha rate, tissue potassium concentration was greater at 8.9 and 17.8 Mg biochar/ ha rates than the 0 Mg biochar/ha rate. After three years of evaluation, this study demonstrated that biochar used independently or through its interaction with nitrogen fertilizer or year, had a positive influence on the forage minerals phosphorus, potassium, sodium and manganese and the tendency to also positively influenced the forage sulfur and boron concentrations.

Grazing exclusion is a commonly used method to protect and recover herbaceous plants in grasslands, and woody expansion is a common phenomenon in grasslands. However, the effects of grazing exclusion on shrub reproduction remain poorly understood. We investigated the effects of long-term grazing exclusion (0, 8, 30 and 34 years) on reproductive effort of Caragana microphylla in the semi-arid Inner Mongolia Steppe. Our results showed that the 8-year grazing exclusion significantly increased the number of flowers, juvenile pods, mature pods and seed (seed number increased 33.5%) of C. microphylla, however, the 30- to 34-year grazing exclusion significantly decreased seed production (seed number decreased 77.9% and 88.1%) of C. microphylla. The 8-year grazing exclusion had no significant effect on the single flower weight, while the 30- to 34-year grazing exclusion significantly decreased (31.7% and 38.7%) the single flower weight. The grazing exclusion had no significant effect on the seed number per pod. The 8-year grazing exclusion significantly increased sexual allocation (31.6%), and it had no significant effect on sexual allocation efficiency; however, the 30- to 34-year grazing exclusion significantly decreased the sexual allocation (50.4% and 70.4%) and sexual allocation efficiency (55.5% and 60.1%). The 8-year grazing exclusion significantly increased seed weight and seed vigor (seed weight increased 18.7%, seed vigor index increased 28.7%), whereas the 30- to 34-year grazing exclusion decreased these indexes (seed weight decreased 14.2% and 21.0%, seed vigor index decreased 9.1% and 14.7%). These results indicated that the 8-year grazing exclusion increased reproductive effort of C. microphylla, while the 30- to 34-year grazing exclusion sharply decreased the reproductive effort of this shrub species. Our study suggests long-term grazing exclusion limited the expansion of shrubs in grassland by decreasing sexual reproduction and thus inhibiting population growth of shrubs.

This study was conducted to evaluate the physical characteristics of the biomass crop Erianthus arundinaceus as a bedding material for broiler and to compare it with existing bedding materials. Three physical characteristics were evaluated: the water absorbability, the water-holding capacity, and the cushioning property. E. arundinaceus, shredded to five different particle sizes, was compared with sawdust, which is a typical bedding material used worldwide, and three alternatives: recycled paper, rice husks, and bagasse. E. arundinaceus absorbed water 5.0 to 10.2 times its weight, and water absorbability increased with decreasing particle size. E. arundinaceus held water around twice its weight regardless of the particle size. The cushioning property of E. arundinaceus tended to improve with increasing particle size. For each physical property, the total average value of the E. arundinaceus samples was compared with the values of other bedding materials. The water absorbability of E. arundinaceus was significantly higher than that of sawdust, recycled paper, and rice husks (p < .01). The water-holding capacity of E. arundinaceus was significantly higher than those of sawdust, recycled paper, rice husks (p < .01), and bagasse (p < .05). The cushioning property of E. arundinaceus was significantly higher than those of sawdust and recycled paper (p < .01). When E. arundinaceus had an average particle size of less than 2.33 mm, it exceeded sawdust in all physical characteristics, suggesting that E. arundinaceus could replace sawdust as a favored bedding material. Our observations of surface structures revealed that the stem pith of E. arundinaceus has a spongy structure, which may contribute to its high water absorbability and water-holding capacity. Moreover, the outermost layer of the E. arundinaceus stem appears to function like a leaf spring, contributing to the high cushioning property.

Among the cereal crops, whole-crop wheat (Triticum aestivum L.) has become a common silage material in many countries of the world. However, there was little information about its planting methods. In order to obtain a optimum planting and utilization methods, this research investigated the effects of wheat-legume cultures on the fermentation quality and protein degradation of silage. In the present research, wheat, alfalfa (Medicago sativa L.), common vetch (Vicia sativa L.), milk vetch (Astragalus sinicus L.) and smooth vetch (Vicia villosa L.) were planted by monoculture and mixture of wheat with other one, and they were ensiled. There were no significant differences in pH value, lactic acid, acetic acid and butyric acid contents among all silages with wheat, either monoculture or mixture with legume (p > .05). The wheat-legume silages had higher lactic acid and lower butyric acid contents than their corresponding legume silages (p < .05). The non-protein nitrogen and peptide-N contents of wheat silage were significantly lower than those of wheat-legume silages (p < .05). Aminopeptidase and acid proteinase activities of monoculture legume and wheat-legume silages were significantly higher than those of wheat silage (p < .05). Overall, the chemical composition of forage has a greater influence on the fermentation quality and protease activity of silage compared to epiphytic microbes. The wheat-legume cultures could effectively improve the fermentation quality of silage compared to monoculture legumes and wheat.

Elytrigia elongata, a rhizomatous and sparse-type perennial herb of the Triticeae tribe, with stronger drought and salt tolerance, is an important wild genetic resource for wheat variety improvement. However, no precise information about seed germination and biochemical responses of this species to drought, salinity and mixed saline–alkaline stresses is available. Hence, this experiment was conducted to investigate the effects of three abiotic stresses on seed germination and physiological characteristics of two E. elongata accessions. The results showed that drought and mixed saline–alkaline stresses impair seed germination and bud seedling growth of E. elongata. However, seed germination and bud seedling growth were promoted by 50 mmol/L, but inhibited by 100–200 mmol/L salinity treatments. The malondialdehyde (MDA) content was increased and the activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) in the bud seedlings were significantly increased (p <.05) with increasing osmotic stress from 0 to −0.4 MPa, and salinity and mixed saline–alkaline from 0 to 150 mmol/L, but reduced at −0.75 MPa osmotic stress and 200 mmol/L salinity and mixed saline–alkaline stresses. Under the same salinity and mixed saline–alkaline treatment, the activities of SOD and CAT of EE030 were higher than those of EE024 except in 200 mmol/L salinity treatment; however, the MDA content of EE030 was lower than that of EE024, except in 150 mmol/L salinity treatment. In conclusion, the results of this study demonstrated that E. elongata seeds are more tolerant to salinity stress than to drought and mixed saline–alkaline stresses, and EE030 seed are more tolerant to three abiotic stresses than are the seeds of EE024.