Based on a light-use efficiency model and MODIS data, the net primary productivity (NPP) of grassland during the growing seasons from 2000 to 2018 in native grassland in Inner Mongolia was continuously estimated, and the spatial-temporal change trend of NPP over the past 20 years was also analyzed using a least square method at pixel scale to determine the degree of grassland degradation. It was found that NPP increased from west to east across Inner Mongolia, with an annual average of 198.04 g C·m^-2·yr^-1. An area of potential grassland degradation of 162200 km² was identified. The areas of severely and heavily degraded grassland identified were 2000 and 11100 km², respectively. The latter were mainly distributed in areas with intensive human activities, such as mining areas, or construction land and its surrounding areas. In terms of grassland types, the potentially degraded areas of temperate steppe, temperate meadow, temperate desert and temperate desert-steppe were 52200, 14000, 40400 and 22100 km² respectively. Through analyzing the correlation between NPP and climate factors in the last two decades, it was found that NPP is significantly correlated with precipitation, but has no correlation with temperature. The response of NPP to precipitation was the most sensitive in temperate meadow, that of temperate desert steppe was the second, and that of temperate steppe was the lowest. Based on the above results, this paper puts forward some suggestions for grassland ecological protection.

This research investigated the effects of fertilizer application and soil-plastic mulching on soil water storage, periodic evapotranspiration (ET), plant development, yield and water use efficiency (WUE) of Tartary buckwheat crops grown in a semiarid rain-fed area, in order to identify cultivation techniques that enhance crop drought resistance and efficient resource utilization. A field experiment comprising three treatments was conducted from 2015 to 2017 at Dingxi Experimental Station of Gansu Academy of Agricultural Sciences. The three treatments were: traditional planting without fertilization application (TNF), whole field soil-plastic mulching without fertilization application (MNF), and whole field soil-plastic mulching with fertilization application (MF). The soil water content for the 0-300 cm soil depth, crop dry matter, leaf area index and yield of Tartary buckwheat were recorded. The soil water storage, periodic measurements of ET, harvest index, rainwater use efficiency (RUE) and water use efficiency (WUE) were calculated, to determine the effects of fertilizer application and soil plastic mulching and bunch seeding on water utilization and yield. It was found that MF increased soil water storage by 18.9-42.4 mm in the 0-140 cm soil layer during the seedling stage, and the ET in the pre-flowering period, as compared with TNF and MNF. Compared to TNF and MNF, respectively, MF increased the dry matter quality at maturity by an average of 96.3% and 3.7%, the leaf area index by 123.7% and 7.6%, the number of ears by 9.3% and 3.9%, the grain weight per plant by 139.2% and 12.1%, the grain plumpness by 14.5% and 4.4%, and reduced the ear height by 34.0% and 26.8%. Compared to TNF, MF significantly promoted the population-level statistics of Tartary buckwheat, with a yield increase of 33.6%-130.4%, a biomass increase of 62.8%-182.5%, an enhancement of WUE of 34.5%-106.4%, and these effects were more pronounced in dry seasons. Therefore, the cultivation practice comprising whole-field soil plastic mulching with fertilizer application improves the yield and WUE of Tartary buckwheat, can be recommended as a suitable planting mode for drought amelioration and yield increase of Tartary buckwheat in the semi-arid area of the northwest Loess Plateau.

This research investigated the effect of lactic acid bacteria (LAB) preparations on microbial population counts and silage quality of whole maize silage during fermentation and on aerobic exposure after fermentation. The aim was to test if inoculation with LAB preparations can improve silage quality and aerobic stability. Three different LAB preparations [Homofermentative (Homo), Heterofermentative (Hetero), combined Homo+Hetero] were added to whole maize during ensiling. A blank control treatment was also included. Data on microbial population count, fermentation quality and nutrient contents of silage were evaluated during fermentation at 3, 7, 15, and 30 days after ensiling, and on completion of fermentation, after 1, 3, 7, 15 and 30 days of aerobic exposure. It was found that both during maize silage fermentation and during subsequent aerobic exposure, the LAB population counts, the lactic and acetic acid concentrations were significantly increased compared with the blank control treatment, while the numbers of aerobic bacteria, yeasts and molds and crude protein loss were significantly reduced and the concentrations of NH₃-N and the pH were obviously reduced by addition of the three LAB preparations. These results indicate that LAB preparations improve maize silage nutritional quality and inhibit secondary fermentation after aerobic exposure. The combination treatment Homo+Hetero performed best, and Homo performed better than Hetero.

This study explored the effects of fence enclosure on community composition and niche characteristics in temperate meadow steppe. The indexes Levins niche breadth, Pianka niche overlap and species diversity were used to evaluate the degree of resource utilization by species and the intensity of interspecific competition inside and outside the enclosure. It was found that: the fencing enclosure significantly promoted vegetation restoration of degraded grassland. The aboveground biomass and belowground biomass in the enclosure treatments were enhanced by 255.06% and 51.06%, respectively. The species diversity and richness were enhanced in fenced enclosures by 10.36% and 10.34%, respectively. The two species with the highest niche breadth in enclosures were Iris ventricosa and Leymus chinensis, with values of 0.921 and 0.873, respectively. In comparison, the two species with the highest niche breadth in the freely grazed grassland were Taraxacum mongolicum and Carex duriuscula, with values of 0.912 and 0.791, respectively. Our results clearly show that enclosure by fencing is an efficient restoration measure that not only promotes species diversity but also improves grassland productivity. Compared with free grazing, fencing enclosure increases the overall niche overlap value and inter-species competition of plant communities and their component plant populations.

This research investigated seed germination and seedling growth of four species of bioenergy grass (Pennisetum americanum×Pennisetum purpureum, Pennisetum purpureum, Pennisetum hydridum and Sorghum sudanense), grown on electrolytic manganese residue (control) or electrolytic manganese residue after adding one of three amendments (5% diatomite, 5% charcoal or 2.5% charcoal+2.5% diatomite). Germination percentage for the four bioenergy grasses ranked: P. purpureum>P. americanum×P. purpureum>S. sudanense>P. hydridum. The three amendments all significantly improved the germination percentage, germination energy and germination index of P. hydridum, and for the other three grasses the germination energy and germination index in the mixed amendment treatment of diatomite and charcoal were also significantly higher than those of the control group (P<0.05). Compared with the control group, in the amendment treatments, the fresh weights of P. americanum×P. purpureum, P. purpureum, P. hydridum and S. sudanense were increased by 36.54%, 7.69%, 35.71% and 23.88%, respectively. Amendment application also enhanced chlorophyll content and the activities of antioxidant enzymes (superoxide dismutase, peroxidase, catalase), while the malondialdehyde content of leaves was decreased. Based on the germination, growth and physiological parameters, for the tested bioenergy grasses grown on the electrolytic manganese residue, P. purpureum with 2.5% charcoal and 2.5% diatomite amendment performed best, followed by P. americanum×P. purpureum with 5% diatomite amendment.

This study investigated the relationship between soil moisture and vegetation cover in alpine steppe meadow in the Qilian Mountains with the aim of improving the precision of remote sensing estimates of soil moisture and vegetation cover. Six sample areas with different stocking rates of Cervus elaphus kansuensis (1.00, 1.45, 2.45, 3.45, 4.85, 6.90 AUM·ha^-1) in were set up, AUM means animal unit. Through comparing data from monthly field measurement of vegetation cover and soil moisture and SPOT-TM images combining Landsat5 multispectral images and SPOT2 panchromatic images, we analyzed the relationship between soil moisture, vegetation cover and normalized difference vegetation index (NDVI) and quantitatively explored the dynamics of seasonal change in vegetation cover and soil moisture in the sample areas in the Qilian Mountain alpine steppe. Except for Achnatherum inebrians, Convolvulus ammannii and Stragalus leucocephalus, the response of population cover to surface soil moisture was relatively sensitive, with the population cover of species inversely proportional to soil moisture in the range between c. 5% and c. 25%. The response of plant community cover to surface soil moisture was also relatively sensitive. In the soil moisture range from 10.0% to 1.1%, the community cover increased in the inverse proportional function. The results are highly relevant to remote sensing monitoring of the drought resistance and water use efficiency of plant species, populations and communities in arid and semi-arid steppe grassland, and provide scientific data for vegetation and soil moisture management in steppe grasslands.

Understanding of the transformations and recycling processes of carbon, nitrogen and phosphorus in the soil rhizosphere is fundamental to solving the problems currently limiting the sustainable utilization of grassland agricultural ecosystems and improving grassland productivity. Rhizosphere processes in grassland can reflect the soil carbon, nitrogen and phosphorus nutrient turnover rates, affect the competition for and capture of nutrients by plants and soil microorganisms, and also determine the nutrient balance of each component in the rhizosphere microenvironment. Compared with crop systems, the coupling between carbon, nitrogen and phosphorus in grassland is stronger. Therefore, the structure and function of rhizosphere micro-ecosystems play an important role in maintaining nutrient transformation and circulation. Many literature reports indicate that the critical factor that regulates the rhizosphere microenvironment is the key substance of the plant and soil for material exchange and information transmission. The root exudates and rhizosphere exudates are also the key substances that mediate rhizosphere microorganisms and enzyme activities. When the grassland environment changes, the rhizosphere exudates, rhizosphere enzyme activities, and the composition and diversity of rhizosphere soil microorganisms will also change fundamentally, which will cause a change of supply and availability of soil nutrients, and in turn will affect grassland productivity and utilization efficiency of nutrients. So, further research on the regulation mechanism of nutrient cycling in grassland rhizosphere process is very important for revealing the distribution and utilization of nutrients and nutrient exchanges between grassland plants and microorganisms. This article reviews the mechanisms and interactions involving rhizosphere exudates, rhizosphere enzymes, and rhizosphere microorganisms involved in nutrient cycling, summarizes the mechanisms of grassland rhizosphere processes contributing to nutrient cycling and provides a perspective for consideration when formulating future research on rhizosphere microdomains in grassland ecosystems.

The purpose of this study was to evaluate the rumen degradation characteristics of conventional roughage (corncob, soybean pod shell) and unconventional roughage (corn silage, alfalfa hay) for dairy cows. Three Holstein cows with permanent ruminal cannulas were used to evaluate the ruminal degradability of dry matter (DM), crude protein (CP), neutral detergent fiber (NDF) and acid detergent fiber (ADF) using the nylon-bag technique. It was found that: 1) The CP content in alfalfa hay (17.55%) was significantly higher than that in soybean pod shell (11.10%; P<0.05). The CP content in corncob (2.97%) was significantly lower than that in corn silage (8.41%; P<0.05). The NDF and ADF content in corncob (79.98% and 43.35%, respectively) were significantly higher than in the other three feedstuffs (P<0.05). 2) The DM effective degradability of alfalfa hay was the highest (P<0.05) among the tested feedstuffs, which ranked: alfalfa hay>soybean pod shell>corn silage>corncob. The CP effective degradability of soybean pod shell was significantly higher than the other three feedstuffs (P<0.05), which ranked: soybean pod shell>alfalfa hay>corn silage>corncob. The NDF effective degradability of alfalfa hay was significantly higher than soybean pod shell (P<0.05); there was no significant difference in NDF digestibility between corn silage and soybean pod shell (P<0.05). The ADF effective degradability of corncob was the highest (P<0.05) among the tested feedstuffs; there was no significant difference in ADF effective degradability between alfalfa hay, corn silage and soybean pod shell. In conclusion, corncob and soybean pod shell can be used as unconventional forage resources.

The objective of this study was to evaluate the effects drinking water temperature on production performance, apparent digestibility of nutrients and blood biochemical parameters in fattening sheep in winter, and rumen structure was also observed using a microscope. Information on the ideal temperature of drinking water for fattening sheep might well lead to improved production efficiencies through mechanisms such as alleviation of cold stress. A flock of 135 healthy fattening sheep with similar weight were randomly assigned into three groups, with drinking water supplied at 2, 8 and 20 ℃ for the respective groups. Each treatment contained three pens (15 sheep·pen^-1). The experiment duration was 28 days. It was found that: 1) Compared with the 2 ℃ group, the 8 and 20 ℃ groups had increased daily water consumption (P<0.05). Although there was no statistical difference (P>0.05) in daily feed intake and daily gain between any of the groups, the feed conversion efficiency in the 20 ℃ group was higher than that in 2 ℃ group (P<0.05). 2) There was a difference (P<0.01) between groups in the serum glucose (GLU) contents. The GLU content in 8 and 20 ℃ groups was 1.39 and 1.14 times higher, respectively, than that in the 2 ℃ group, and the 20 ℃ group had decreased the serum cholesterol (P<0.05). The serum urea nitrogen, total protein and serum hormone (triiodothyronine, thyroxine and growth hormone) contents did not differ between groups (P>0.05). 3) The length, width, and surface area of rumen papilla in the 20 ℃ group were increased (P<0.05) compared with the 2 and 8 ℃ groups. The group drinking water at 20 ℃ had reduced rumen muscle layer thickness (P<0.05) and increased submucosal thickness (P<0.05). However, there was no difference (P>0.05) in thickness of mucosal epithelium among groups. 4) With increase in drinking water temperature, the apparent digestibility of crude fat, neutral detergent fiber (NDF) and phosphorus (P) increased (P<0.05), especially P and NDF, while the digestibility of other nutrients did not differ between treatment groups (P>0.05). The results showed that drinking warm water improved the feed conversion efficiency of fattening sheep. In addition, drinking warm water may improve rumen function and promote the digestion and absorption of nutrients.

Petrobia harti is a very serious worldwide pest mite harming Oxalis corymbosa, and pyridaben as a broad-spectrum, contact-killing acaricide that is highly effective against P. harti. To clarify the sublethal effects of pyridaben on P. harti and provide data for developing comprehensive control strategies for this mite with minimal usage of pyridaben, the toxicity of pyridaben against P. harti was determined by a leaf impregnation method. The sublethal doses used were determined by a regression equation of P. harti death rate on pyridaben concentration, in order to identify concentrations predicted to be lethal to 10% or 20% of a test population of mites (LC₁₀ and LC₂₀, respectively). The effects of the LC₁₀ and LC₂₀ sublethal pyridaben doses on the development, fertility and life-history parameters of P. harti were evaluated by establishing a life table. It was found that the fecundity of P. harti was significantly decreased after treatment with the sublethal doses of pyridaben (P<0.05) with the number of eggs laid per female reduced, respectively, by 53.37% and 55.46% in the F₀ generation and 41.34% and 45.24% in the F₁ generation in the LC₁₀ and LC₂₀ treatments, compared to the controls. Similarly, the oviposition duration was significantly shortened, respectively, by 3.11 and 4.75 days in F₀ generation and 3.47 and 2.81 days in the F₁ generation. The average adult longevity was also significantly shortened, respectively, by 1.45 and 2.04 days in the F₀ generation and 3.24 and 4.00 days in the F₁ generation. Compared to the control, after treatment with sublethal pyridaben doses, the net reproductive rate (R₀), intrinsic rate of increase (r_m) and finite rate of increase (λ) of P. harti were all significantly decreased in the LC₁₀ and LC₂₀ treatments (the R₀ from 28.54 to 16.91 and 15.48; the r_m from 0.1650 to 0.1276 and 0.1249; the λ from 1.17941 to 1.1435 and 1.1330; P<0.05), while the mean generation time (T) and the population doubling time (Dt) were both significantly prolonged (the T from 20.31 to 22.17 and 21.94 days; the Dt from 4.20 to 5.43 and 5.55 days, respectively; P<0.05). The results indicated that the sublethal doses of pyridaben at LC₁₀ and LC₂₀ decreased the development rate and fecundity of laboratory populations of P. harti.