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To explore landscape spatial pattern changes and their driving factors over a 30 year period (1988 to 2018), we used visual interpretation and landscape pattern indexes to analyze remote sensing images of the upper Jinqiang River on a farming-pasture ecotone in the Tianzhu Tibetan Autonomous County. The results showed that: 1) Grassland was the largest landscape type with an area increase of 37.2 km2 over the 30 year period. In particular, the moderate-coverage grassland increased by 102.5 km2 during the last 10 years, and the shrubland decreased by 37.5 km2, being mainly converted to grassland. 2) From 1988 to 2018, the population increased by 13.9%, and the construction land area increased by 142.4%, whereas the cultivated land area decreased by 4.4 km2, and the degree of human disturbance increased by 20.2%. 3) The landscape shape index increased by 9.09, whereas the contagion and aggregation indexes decreased by 0.45% and 2.76%, respectively. The landscape tended to be complicated and fragmented. 4) Human activity appears to be the main factor driving the landscape pattern changes, followed by climate factors. National policy plays an important guiding role in environmental improvement. To realize ecosystem protection and sustainable development, reduction of excessive human activity impact on the farming-pasture ecotone in Eastern Qilian Mountains is essential.
Grasslands are important components of terrestrial ecosystems, and grazing is a key way in which grasslands are utilized and managed. In this study, 23 experimental results of grasslands in China were analyzed using meta-analysis. These results showed that the average effect size of grazing on evapotranspiration of grassland ecosystems was approximately −0.21 ± 0.04, and grazing activities significantly reduced the evapotranspiration of grasslands in China (P < 0.001). Furthermore, the order of decreasing average effect size of different grassland types was: meadow grassland, steppe, alpine grassland, and desert grassland. Except for desert grassland, grazing significantly reduced the evapotranspiration of the other grassland types. In addition, grazing intensity had a significant effect on the average effect size, and the order of influence on evapotranspiration was: heavy, light, then moderate. Thus, moderate grazing reduced evapotranspiration least, which was beneficial for the reduction of soil water loss. Both soil organic matter and total nitrogen had significant effects on the average effect value (P < 0.05), which could explain the effect value variation of 50.48% and 23.14%, respectively. In addition, future effective restoration of degraded grasslands and the improvement of soil organic matter and total nitrogen content will potentially reduce the average effect value of grazing on evapotranspiration, reduce the loss of soil water, and improve water use efficiency.
Studying the effects of supplementary sowing on grassland vegetation and soil provides a basis for restoration of degraded grasslands. In the Ningxia desert steppe, grassland protected from grazing and grassland after three years of restoration (by supplementary sowing of native species) were sampled for plant composition and community characteristics, diversity and stability. In addition, soil moisture and physicochemical properties of the 0 – 40 cm soil layer were determined. The relationship between vegetation changes and soil properties was analyzed. The results showed that: 1) The number of plant species in the restoration grassland increased; however, whereas the proportion of legumes and annual plants increased, the proportion of perennials and semi-shrubs decreased. 2) Supplementary sowing increased grass plant richness, coverage, height, and aboveground biomass, and the community stability improved significantly (P < 0.05); however, grassland species diversity, uniformity and dominance were unchanged. 3) The moisture content of the restoration grassland soil was higher than that of the enclosed grassland, as were the soil water holding capacity, capillary porosity, total porosity, and organic matter content. The available potassium content at 30 – 40 cm was higher in the restoration than in the enclosed grassland, but there was no significant difference in soil total nitrogen and alkaline hydrolysis nitrogen between the two grasslands (P > 0.05). 4) Soil organic carbon content and field water holding capacity were the most significant factors affecting the vegetation characteristics. It was concluded that supplementary sowing of degraded desert grasslands, according to local conditions, can improve grassland productivity, plant communities, soil nutrients, and the soil-water balance.
The alpine treeline ecotone is considered a warning line in response to global climate change. Changes in the ecological characteristics of vegetation types and species populations in the interlaced forest and grass belt are affected by climate change, soil nutrient status, and eco-chemical measurement characteristics. The status of the main soil nutrients in this sensitive ecological zone and its altitude gradient characteristics remain unclear. In early June 2019, soil samples were collected from 0 − 10 and 10 − 20 cm soil layers in two high mountain forest-grassland ecotones of the Minjiang River source area in different vegetation zones (meadow area: alpine meadow, tree species line: subalpine shrub zone, tree line: arbor shrub zone, and closed forest: dark coniferous forest) to determine soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), soil pH, and soil moisture content. Soil carbon, nitrogen, and phosphorus and the spatial distribution characteristics of water content and its influencing factors were analyzed. The results showed that vegetation type was the main factor affecting the physical and chemical properties of the soil in the forest–grassland ecotone in the Minjiang River area. The contents of total carbon (TC), TN, and SOC in the meadow area were significantly lower than those in the other vegetation zones (P < 0.05), and there was no significant difference in the contents of TC, TN, and SOC in the tree species line, tree line, and closed forest (P > 0.05). The TP content in the tree line was significantly lower than that in the other vegetation zones (P < 0.05). There was a significant correlation among TC, TN, SOC, and soil variable water content (P < 0.01). The correlation of soil physical and chemical properties was the weakest in the tree species line. The soil stoichiometric ratio was the largest in the tree line, and the spatial heterogeneity of soil C∶P and N∶P was strong in this vegetation type belt. The results showed that although there was no significant difference in the content of C, N, and P in the tree species line, tree line, and closed forest (P > 0.05), the interaction between the tree line and vegetation on soil physical and chemical properties was significant (P < 0.05).
To screen and isolate bacterial strains with high phosphate solubilizing efficiency from the rice rhizosphere and enrich the resources of these phosphate-solubilizing strains, Pikovskaya (PVK) medium and National Botanical Research Institute’s phosphate (NBRIP) medium were used. The ability of Pediococcus acidilactici 1.11 to dissolve phosphorus was tested. The obtained strains were observed under a scanning electron microscope and identified with 16S rRNA sequencing. The molybdenum-antimony colorimetric method was used to examine the effect of phosphorus dissolution. Two strains, Pseudomonas chlororaphis 1.49 and P. chlororaphis 1.209 were isolated. After culturing the isolated strains 1.49, 1.209, and 1.11 in NBRIP liquid medium for 168 h, the concentrations of the dissolved phosphorus were 109.3, 54.2 and 137.0 mg·L−1, respectively. Therefore, the identified strains were highly efficient phosphate solubilizers and could be used to develop bacterial fertilizer.
The anatomy and histochemistry of Artemisia selengensis from a wetland environment were studied using an optical microscope and epifluorescence microscope. The results showed that: 1) The adventitious roots in A. selengensis have a tetrarch vascular cylinder, endodermis, cortex, schizogenous aerenchyma, air spaces, lignified hypodermis, and a suberized exodermis and epidermis. The stems of A. selengensis include a pith cavity, cortex and epidermis. 2) Apoplastic barriers are found in roots and stems. The barriers in adventitious roots consist of the endodermis and exodermis with its Casparian bands and suberin lamellae (and some lignification), and a suberized epidermis. Stems have cuticles, endodermis and exodermis with its Casparian bands and suberin lamellae, and a suberized and lignified periderm. 3) The air space consists of aerenchyma in roots, and pith cavities and aerenchyma in stems. The stem of A. selengensis develops a conspicuous cortical expansi-schizogenous aerenchyma and aerial stem pith cavities. These combinations of traits enable A. selengensis to be well adapted to wetland environments.
Aiming to address the lack of suitable turfgrass species that can be used in stepping stone gaps in subtropical areas, four soil layers (2-, 4-, 8-, and 12-cm-thick) were set in outdoor floor tiles gaps, in which the native grass Euphorbia thymifolia was planted as the experimental material. Plant survival rate, component properties, biomass, and expansion ability were measured after summer. The effect of soil depth on the survival, growth, and reproduction strategies were analyzed. The results showed that: 1) Soil depth significantly affected the survival rate in summer (P < 0.05). Survival rate increased with the increase in soil depth; even in 2-cm-thick soil, with 16.90% soil water content and 76.80 ℃ surface temperature, the survival rate of E. thymifolia reached 85.67%. 2) The order of influence of soil depth on leaf characteristics was number > area > thickness > length > width, on stem characteristics was secondary branch number > stem length > plant height > primary branch number, on root characteristics was indefinite root number > main root diameter > lateral root number > main root length, and on flower characteristics was flower number per plant > inflorescence number per plant > flower number per inflorescence > seed number per flower > 1 000 seed weight. E. thymifolia exhibited extreme morphological plasticity, and could significantly adjust component properties according to soil depth (P < 0.05); therefore, E. thymifolia could complete its life cycle with plump seeds at all four soil depths. 3) Soil depth significantly affected biomass structure of E. thymifolia (P < 0.05). The biomass in 2-cm-thick soil was preferentially distributed to the root and adventitious root; however, in 4-cm-thick soil it was to the stem, whereas in soil depth of ≥ 8 cm it was to the flower and fruit. Therefore, the biomass could be reasonably distributed among components, which showed a growth strategy with reasonable biomass allocation. 4) Soil depth significantly affected branching and expansion ability of E. thymifolia (P < 0.05), with the order of influence being branching rate > expansion space > expansion area > extension density. For soil depths of 2–12 cm, the branching rate of stems 1 cm in length was 1.72～8.31 branch, the coverage area of each plant was 841～2 656 cm2, and the expansion density was 2.65～4.81 branch·cm−3. To summarize, E. thymifolia exhibited strong heat and drought resistance, and could adjust its growth strategy according to soil depth; therefore, it is suitable for promoting as a turfgrass for planting in stepping stone gaps.
Increased nitrogen deposition has a huge influence on terrestrial ecosystems. Desert ecosystems are more fragile than other ecosystems and are more sensitive to global change such as nitrogen deposition. In this study, three desert ephemeral species (Plantago minuta, Nepeta micrantha, and Eremopyrum distans) were used as the research subjects. Five nitrogen addition treatments were utilized to study the effects of aboveground and belowground biomass and root traits. The results showed that (1) 1.5, 3, 6, and 12 g·(m2·a)−1 concentrations of nitrogen had a significant effect on the root characteristics of the three ephemeral plants (P < 0.05). (2) Nitrogen addition of 1.5, 3, and 6 g·(m2·a)−1 concentrations significantly increased the aboveground and belowground biomass accumulation of the three desert ephemeral plants (P < 0.05); however, the 12 g·(m2·a)−1 treatment inhibited the biomass accumulation of P. minuta and N. micrantha, whereas it had no significant inhibitory effect on E. distans (P > 0.05). (3) The aboveground and belowground biomass characteristics of the three ephemeral species were correlated with plant root morphological characteristics. The root characteristics of various diameters were different from the aboveground and belowground biomass correlations, and there were also large distinctions between the different species. Therefore, the continuous increase of nitrogen deposition in desert areas might cause changes in the survival strategies and community structure of ephemeral species, and further affect the synusia structure of ephemeral plants.
To determine how the effects of environmental factors (e.g. climate changes and geographic location) on plant aboveground biomass and species richness, an experiment was conducted in the alpine grasslands including 13 study sites that were selected along the longitude, latitude, and elevation of the Qilian Mountains. Results showed that the spatial distribution pattern of the aboveground biomass and species richness of Qilian Mountain grassland show high to low from north to south and east to west. Aboveground biomass and species richness were significantly positively correlated with latitude and longitude (P < 0.05), while aboveground biomass was significantly positively correlated with mean annual precipitation and negatively correlated with mean annual temperature (P < 0.05). The mean annual precipitation determined the east-west distribution patterns of aboveground biomass in the grassland of Qilian Mountains. The north-south distribution patterns of aboveground biomass were affected by the coupling effects of air temperature and annual precipitation. The aboveground biomass and species richness could be well predicted by using longitude, latitude, altitude, mean annual precipitation and mean annual temperature. The results highlight the significance to the scientific management of Qilian Mountain National Park.
A comprehensive evaluation of the phenotypic diversity of 130 oat germplasms was made using genetic diversity indexes. Principal components analysis and cluster analysis were used to investigate the genetic diversity of agronomic characteristics from different sources. The results showed high genetic diversity indices for 14 traits. The highest index value was for height (1.91), followed by root length (1.90). The largest coefficient of trait variation was the effective number of tillers (48.85%), followed by the number of tillers (45.66%). According to principal component analysis, the first four main components (layer factor, tiller factor, main ear length factor, leaf width factor) explained 77.65% of the variation. The cluster analysis showed that ten quantitative traits could be used to classify plants into four groups. Groups Ⅰ and Ⅱ were important parents for screening oats, group Ⅲ was not found to be prominent, and groups Ⅳ and Ⅴ had excellent comprehensive traits. Results showed that the quality of oat germplasms could be determined by comprehensive evaluation and two-dimensional sorting. The best germplasms identified here can be used as parents to screen high-yield forage oats or to select multi-target traits.
Mixed seeding is an important method for establishing grassland in cold alpine regions. In this study, a field experiment using Onobrychis viciifolia and Elymus nutans mixed in different ratios (100∶0, 70∶30, 50∶50, 30∶70, and 0∶100) was conducted from 2018−2019 in Tianzhu County to explore growth dynamics and inter-species competition. The results showed that the biomass of mixed communities reached a maximum at the end of the first growing season. The land equivalent ratio (LER) was relatively high and the aboveground biomass was larger (3 172.2 kg·ha−1) when the ratio of O. viciifolia to E. nutans was 70∶30. Competition between O. viciifolia and E. nutans was weak [the competitive ratio (CR) was close to 1] and the actual yield loss (AYL) of the community was close to, or less than 0. During the second year, the CR and aggressivity (A) of O. viciifolia was higher than that of E. nutans because the absolute and natural heights were low in June. As community growth continued, the absolute and natural heights changed consistently so that the growth space tended to be filled. The competitive strength of O. viciifolia (CR, A) was different from that of E. nutans during this stage. The range of LER was 1.33～1.68 and the AYL was 24.0%～57.0%. The biomass of the 30∶70 ratio was 9 178.8 kg·ha−1 and was the highest of all the treatments, being equivalent to 3.6 times that of O. viciifolia and 1.6 times that of E. nutans when grown alone. The mixed grassland with different ratios of O. viciifolia and E. nutans performed differently at different growth stages. The total biomass of the two growth seasons was highest when the planting ratio was 30∶70. The ratio of mixing for grassland seeding should be adopted based on demand.
In order to evaluate the nutritional value of early and late maturing oat (Avena sativa) varieties during different growth periods, the cornell net carbohydrate and protein system (CNCPS) was used to measure the protein and carbohydrate nutrients. and the content of these components during each A. sativa growth period was analyzed. The milk-filling stage showed the highest proportion of available protein in both varieties, and the proportion of structural carbohydrate was highest during the flowering stage. However, the degradable fiber content was highest during the milk-filling stage. Comparing the content of each component in each growth stage, it was found that the degradable protein content of late maturing oats was higher than that of early maturing oats, whereas the content of non-degradable protein was lower. The available carbohydrate content of late maturing oats was also higher than that of early maturing oats. It was concluded that the two varieties of oats have higher utilization values when harvested at the filling stage, and the quality of late maturing oats is better than early maturing oats for forage feeding and roughage preparation.
In August 2019, a disease survey was conducted on the 2nd-age cultivated alfalfa (Medicago sativa) in Minzhu Township, Daowai District, Heilongjiang Province. Symptoms appeared oval or irregular, small black spotson the surface of the alfalfa stalks. This disease can seriously damage phoem tissue. This study identified the pathogen and the biological characteristics of the pathogen. According to both morphological characteristics, analysis of multiple loci, and pathogenicity test, the pathogen was identified as Colletotrichum americae-borealis. Studies on the biological characteristics of pathogen showed that the optimal medium, nitrogen source and carbon source for mycelial growth of C. americae-borealis were PDA, peptone, soluble starch and sucrose, with 1.02, 0.91 and 0.82 cm·d–1, respectively; the optimum sporulation conditions were PDA, peptone and glucose, with 1.3 × 106, 1.8 × 105 and 3.6 × 106 spore·mL–1, respectively.
The rumen microbial community plays a crucial role in the degradation and utilization of dietary nutrients. As a new unconventional feed resource, the effect of mulberry branches and leaves on rumen microflora of ruminants is still unclear. In this experiment, six healthy 30-month-old Yunling cattle with an average weight of (400 ± 20) kg were selected. The control group (Group C) and mulberry branch and leaf powder treatment group (Group V) were separated by the self-control method. Group C was fed a basic diet and Group V, a diet supplemented with 7.31% mulberry branch and leaf powder (MBLP). The experimental period was 30 days, including 10 days of pre-feeding and 20 days of normal feeding. The composition of rumen fluid microbiota was analyzed by 16S rRNA sequencing and the bacterial functions predicted using PICRUSt. The results showed that 1 342 operational taxonomic units were obtained by 16S rRNA gene sequencing, which belonged to 182 genera of 19 phyla. The dominant bacteria at the phylum level in both Groups C and V were Bacteroidetes and Firmicutes, and the dominant bacteria at the genus level were Prevotella, Bacteroides BS11 and Rikenellaceae RC9. At the phylum and genus levels, the number of bacteria related to fiber degradation increased, and the number of Bacteroidetes and Prevotella related to non-fiber polysaccharide degradation decreased. The main functions of the rumen microbial community, as predicted by PICRUSt, were amino acid and carbohydrate metabolism. Therefore, adding mulberry branch and leaf powder to the diet appears to have a positive effect on the rumen microbial community diversity and metabolic function, especially by increasing of the proportion of fiber degradation bacteria, a change conducive to the degradation of plant cellulose.
The objective of this study was to investigate the effects of enzyme preparations added to corn (Zea mays) stover and wheat (Triticum aestivum) stalk dietary sources on the performance, ruminal fermentation parameters, serum biochemical indicators, and nutrient digestibility in Hu sheep. A 2 × 2 factorial arrangement was used for this experiment. Fifty-two healthy Hu sheep male lambs were selected and randomly divided into four treatments with 13 sheep in each treatment. The four treatments were corn stover with zero (group Ⅰ) and 0.3% (group Ⅱ) enzyme preparation supplement, and wheat straw with zero (group Ⅲ) and 0.3% (group Ⅳ) enzyme preparation supplement. The trial period included 7 d for the preliminary test period and 63 d for the formal trial period. The results showed that: 1) There was a significant increase in average daily gain (ADG) and dry matter intake (DMI) of Hu sheep, and the feed to gain (F/G) was significantly decreased (P < 0.05). 2) The dry matter digestibility (DMD) and organic matter digestibility (OMD) in added enzyme preparation groups of Hu sheep significantly improved (P < 0.05). There was no significant effect on the digestibility of other nutrients, nor was there a significant difference between straw sources and enzyme preparations in the nitrogen metabolism (P > 0.05). 3) Neither the straw source nor the enzyme preparations affected the concentrations of alanine aminotransferase (ALT), cholesterol (CHO), alkaline phosphatase (ALP), urea nitrogen (UN), aspartate aminotransferase (AST), total triglycerides (TG) and lactate dehydrogenase (LDH) in the blood of Hu sheep (P > 0.05), but the enzyme preparation supplements significantly increased the concentration of glucose (GLU) (P < 0.05). 4) Enzyme preparation supplements significantly increased the total volatile fatty acid (TVFA) concentration in rumen fluid (P < 0.05), but had no significant effect on the proportion of individual fatty acids and acetate to propionate (A:P) ratio (P > 0.05). In summary, the enzyme preparations in diets with different straw sources significantly promoted rumen fermentation, effectively improving the digestion and utilization of fibrous substances and the performance of fattening Hu sheep.
The objective of this study was to investigate the effects of 20%, 50%, and 80% replacement of whole corn silage with straw pellets (on an air dried basis; corn straw and alfalfa hay were mixed and granulated in a 1∶1 ratio) on finishing steers. Twenty healthy Simmental crossbreed beef cattle with similar body weight [(410.56 ± 19.27) kg] were randomly divided into four groups using a randomized block design and were fed 100% whole corn silage + concentrate supplementary feed (control group), 20% straw pellet feed + 80% whole corn silage + concentrate supplementary feed (group 1), 50% straw pellet feed + 50% whole corn silage + concentrate supplementary feed (group 2), and 80% straw pellet feed + 20% whole corn silage + concentrate supplementary feed (group 3). The dry matter intake (DMI), average daily gain (ADG), feed conversion ratio (FCR), nutrient apparent digestibility, blood biochemical indexes, carcass traits, and meat quality were measured. The results showed that: 1) Group 1 had significant improvement in DMI (P < 0.05) and reduction in apparent digestibility of dry matter (DM), organic matter (OM) and neutral detergent fiber (NDF) (P < 0.05), whereas group 1 and 2 had no significant effects. 2) Group 1, 2, and 3 had no significant effect on ADG, FCR, blood biological indicators, carcass traits, and meat quality traits (P > 0.05). In conclusion, straw pellets can replace part of whole corn silage for feeding Simmental western hybrid finishing steers. When the replacement ratio is 20%～80%, it has no adverse effect on the finishing steers.
Aquatic fireflies (Coleoptera: Lampyridae: Luciolinae: Aquatica and Luciola) are a group of important ornamental and resource insects. They are also environmental indicator species in water bodies, and are valuable for balance preservation of grass-water ecosystems. Understanding aquatic firefly biological and ecological characteristics is a key prerequisite for the scientific protection and utilization of these insects. Based on worldwide aquatic firefly research, this study summarized existing findings about biological and ecological characteristics of these aquatic insects, focusing on their life history, phenotypic and behavioral aquatic adaptations, flashing and predation behaviour, and the influence of key environmental factors on their survival. The results show that aquatic fireflies produce one generation annually, and the whole life cycle is completed in one year. They primarily inhabit calm and high-quality water bodies, including streams with slow or static water flow, ditches and lakes. Aquatic fireflies are adapted to water environments phenotypically (e.g., breathing gills) and behaviorally (e.g., swimming). Aquatic fireflies primarily prey on small freshwater snails and perform courtship by producing flashes of light. Water deterioration and light pollution are key factors leading to sharply decreasing population sizes of a wide range of aquatic firefly species. This study concluded that further research on predation, artificial feeding, and ecological adaptation of aquatic fireflies should be conducted in future to reveal the evolutionary mechanisms of their population dynamics and ecological adaptability, which will provide a theoretical basis for the protection and utilization of aquatic fireflies and other important environmental indicator insects.
Gynaephora alpherakii is one of the most serious pests of alpine grasslands. Broad-scale monitoring is the foundation for identifying the distribution and controlling the spread of G. alpherakii. However, traditional quadrat-scale monitoring is difficult to implement accurately and effectively at broad scales using long-term fixed-points. In this study, we propose a UAV-based monitoring method (UAVBelt) to improve efficiency and accuracy over larger areas. Results showed that UAVBelt improved field monitoring efficiency, sampling representation, and destruction of the caterpillar. The method overcame sampling obstacles and improved timeliness and predictability compared with traditional methods. Mavic 2 Zoom, which has terrain-following and digital zoom functions (UAVM2) demonstrated more effective sampling uniformity, data extraction, and accuracy. Combined with long-term and cooperative monitoring and analysis of small-scale habitat fragmentation using UAVs (FragMAP), UAVM2 is a promising technique for delivering early warning and effective prevention of G. alpherakii outbreaks, providing theoretical and practical guidance for sustainable development of the livestock industry and grassland ecosystems of the Qinghai-Tibetan Plateau.
To understand the population dynamics of thrips on alfalfa, blue and yellow sticky traps were used in a clover field from late April to late September, 2019. We also utilized different directions (east, south, west, and north) and different hanging heights (mid of alfalfa, top of alfalfa, and 20 cm above the top of alfalfa). Most of the thrips on the alfalfa were collected by both colored sticky traps in early August. The population of Odontothrips loti reached its highest peak in mid-July to early-August. The largest amount of thrips on the alfalfa and O. loti were collected during the third harvest, which showed a significant difference to the other three harvests (P < 0.05). The results showed that the thrips on the alfalfa preferred the blue sticky traps, whereas O. loti had a strong tendency for the yellow sticky traps. The hanging height at the top of the alfalfa was suggested for the sticky cards. In addition, the number of thrips trapped in the east and south was greater than the other two directions. Multi-way analysis of variance showed that the trapped number of thrips was significantly influenced by color, direction, and height (P < 0.01).
To investigate the effect of storage temperature and ensiling period on fermentation quality of high moisture alfalfa (Medicago sativa) silage at 15, 25 and 35 ℃, silage quality and microbial composition were analyzed after ensiling for 14, 28 and 56 days. Storage temperature, ensiling period and their interaction significantly influenced the silage quality and microbial composition (P < 0.05). Silage pH, butyric acid, ammonia nitrogen content and clostridial counts decreased in high moisture alfalfa silage ensiled at 15 ℃ (P < 0.05) compared to 25 and 35 ℃, while lactic acid, crude protein content and dry matter recovery increased (P < 0.05). As the ensiling period continued, lactic acid content significantly increased (P < 0.05) but silage pH decreased in alfalfa silage ensiled at 15 ℃ (P < 0.05). A decrease in lactic acid content was seen in alfalfa silage ensiled at 35 ℃. After 56 days of ensiling, alfalfa silage ensiled at 15 ℃ had the highest content of lactic acid (22.7 g·kg−1) and crude protein (176 g·kg−1) and lowest content of butyric acid (1.86 g·kg−1) and ammonia nitrogen (71.9 g·kg−1). The V-Score of alfalfa silage at 15 ℃ was fair, but it was poor at 25 and 35 ℃. Therefore, after ensiling for 56 days, high moisture alfalfa ensiled at 15 ℃ preserved nutritional value and improved fermentation quality more than ensilage at 25 and 35 ℃.
To study the application of steam blasting technology in straw processing, different moisture contents (50%～60%, 60%～70%, and 70%～80%) of corn straw and steam explosion pressures (0.8, 1.0, and 1.25 MPa) of a steam explosion device were applied. The nutritional value, in vitro gas production, and fiber structure were analyzed to study the effect of different steam explosion parameters on the corn straw value. The results showed that the contents of neutral detergent fiber (NDF), acid detergent fiber (ADF), and acid detergent lignin (ADL) of corn stalks decreased significantly after steam explosion (P < 0.05). The relative feeding value (RFV), dry matter intake (DMI), digestible dry matter (DDM), total digestible nutrient (TDN), and lactation net energy (NEL) of corn straw after explosion increased significantly (P < 0.05). Under 1.25 MPa pressure and 50%～60% moisture content, the RFV and DMI were 95.65% and 70.64% higher, respectively, than that of the non-explosion corn. DDM, TDN, and NEL increased by 25.41%, 60.18%, and 44.57% under 1.25 MPa and were 50%～60% compared to those of the untreated samples. The cumulative as production for 48 h at an explosion pressure of 1.0 MPa and straw moisture of 70%～80% was significantly higher than that of the other treatments (P < 0.05) and was the lowest for the non-steam explosion. The steam explosion treatment also significantly increased the in vitro dry matter digestibility (IVDMD) of corn straw (P < 0.05), which showed the same trend as that of the in vitro gas production. The extent of the degree of straw fiber structure degradation increased with the pressure of the steam explosion chamber and the moisture content of the raw straw material, and the straw changed from block or schistose into filiform. Under an explosion pressure of 1.25 MPa and a corn straw moisture of 50%～60% and 60%～70%, the fiber structure of the straw was obviously damaged. Therefore, a pressure of 1.0 MPa with a moisture content of 70%～80% were the optimal parameters for corn straw steam explosion.
Livelihood risk is an important perspective for studying the livelihood of farmers. The main goal of such research is to improve the resilience of farmers to livelihood risk by assessing common risks and their influencing factors. In this study, we used Participatory Rural Appraisal (PRA) and a binary-logistic model to investigate the main livelihood risks and the coping strategies of different types of farm households in Xiahe County, Gannan Prefecture, China. We also quantitatively analyzed the main factors affecting the choice of risk response strategy, and explored countermeasures to improve the ability of farm households to defend against risk. The results showed: 1) Employment, health and education risks were the main livelihood risks that farmers faced in the development process. Health risks had the greatest impact on the sustainable development of farmers. 2) From the perspective of coping strategies, becoming a migrant worker, asking relatives and friends for help, getting bank loans and waiting for government relief were the main coping strategies adopted by farmers, but becoming a migrant worker was also affected by the health risk and education risk. 3) According to the impact factors of farmers’ risk coping strategies, becoming a migrant worker was the most important risk coping strategy adopted by all types of farmers. Farmers’ livelihood capital had no significant influence on risk coping. Natural capital was a key factor influencing the strategy of asking relatives and friends for help, and had a significant positive influence. Financial capital, natural capital and social capital were important factors influencing the strategy of borrowing from banks. Among these, financial capital and natural capital had significant positive influence, while social capital had significant negative influence. Financial capital was a key factor affecting the strategy of waiting for relief: farmers with lower financial capital were more eager to wait for relief. Based on the above findings, this study proposed the following countermeasures and suggestions to improve the ability of farmers to resist livelihood risk in alpine pastoral areas: 1) Construction of a community financial mutual assistance platform, which can be an effective way to improve the financial capital of farmers. 2) Development of basic education and career training, which are important to improve farmers’ education and thus to reduce the unemployment risk. 3) Development of public medical and health services in rural areas and rural medical insurance to improve farmers’ ability to cope with health risks.
With increasing use of green manure in cultivation, the mechanization of green manuring is developing rapidly. However, at present, the agricultural machinery and equipment used in green manure planting is inadequate to meet the needs of the rapidly developing green manure industry. Owing to the stagnation of green manure planting and related research in China in previous years, suitable types and functions of green manure rolling machinery are lacking, the division methods and related concepts and terms are not standardized, and the concepts related to green manure rolling mechanization in different regions are vague and confusing. From the perspective of agricultural mechanization for production of green manure, this review summarizes the technological processes and relevant mechanical equipment used for the incorporation of green manure in dry land and orchards in North China, considering particularly grain fertilizer rotation, grain fertilizer multiple cropping, grain fertilizer intercropping and Orchard Green fertilizer intercropping. In view of the confusion associated with naming machines and tools, and the problems of multiple machines, this review systematically names and classifies the types of green manure incorporation machines according to their tipping technology and operation characteristics, and puts forward the corresponding research and development countermeasures and suggestions according to the current use status of incorporation machines and equipment. This review is of great significance for scientific and accurate understanding of the mechanized green manure incorporation process, the rational selection of relevant machinery and associated incorporation processes, and the further development of special incorporation machines for green manure usage in various green manure planting areas (especially for grass-roots production).