The amounts of nitrogen, phosphorus and potassium applied and the ratio of legume to grass in mixed sowings are key factors affecting the yield and fertilizer use efficiency of mixed grassland. The forage yield and utilization efficiency of nitrogen, phosphorus and potassium under different application ratios of those nutrients were analyzed to provide a scientific basis to manage cultivation of mixed grass-legume grassland for high yield. Field experiments were conducted on mixed swards of alfalfa and smooth brome. The experiment comprised two row configurations (legume:grass inter-row pattern 2:2 and 1:2) and seven nitrogen, phosphorus and potassium combinations: N₂₈₀P₁₅₀K₀ (A₁), N₃₅₀P₁₀₀K₃₆₀ (A₂), N₁₄₀P₃₀₀K₃₀₀(A₃), N₄₂₀P₂₅₀K₁₂₀ (A₄), N₇₀P₅₀K₆₀ (A₅), N₂₁₀P₀K₂₄₀ (A₆) and N₀P₂₀₀K₁₈₀ (A₇), where subscripts after each element indicate the application rate as kg·ha^-1 N, P₂O₅, and K₂O, respectively. The highest value for annual total yield of mixed legume-grass forage (11.68 t DM·ha^-1) occurred in the A₂ treatment, and yield in this treatment was significantly higher than in other treatments (P<0.01). Alfalfa yield in the A₂ treatment was 8.60 t DM·ha^-1, and it was significantly higher than A₁, A₅, A₆ and A₇ treatments (P<0.01). Grass yield in the A₁ treatment was 3.80 t DM·ha^-1, and it was significantly higher than in other treatments (P<0.01). Yields of grass and grass-legume forage were lowest in the zero nitrogen treatment, A₇. The combined grass-legume yield was significantly related to the rate of N fertilizer. Both combined grass-legume yield and alfalfa yield displayed a N×K interaction (P<0.05). The NPK partial productivity, and uptake efficiency of grass, alfalfa and grass-legume forage all showed a downward trend with increase in NPK level, and the A₅ treatment was significantly superior to other treatments (P<0.01). The nitrogen utilization efficiency of alfalfa decreased significantly in the zero potassium (A₁) and low potassium (A₅) treatments, and the potassium utilization efficiency of grass, alfalfa and grass-legume forage decreased significantly in the zero phosphorus (A₆) and high phosphorus (A₃) treatments. The annual total yield of alfalfa and legume-grass forage in the 2:2 row configuration were significantly higher than in the 1:2 configuration, with extreme significance (P<0.01). Also, the partial productivity, uptake rate and uptake efficiency of alfalfa NPK, and partial productivity of NPK, N uptake rate and N uptake efficiency of grass-legume forage in the 2:2 row configuration mixture were significantly higher than in the 1:2 configuration with extreme significance (P<0.01), and the partial productivity, uptake amount and absorption efficiency of grass NPK were significantly lower in the 2:2 than in the 1:2 configuration with extreme significance (P<0.01). Considering forage yield and nutrient utilization efficiency, alfalfa-smooth brome mixed sowing in a 2:2 row configuration, and fertilizer application of 140 kg·ha^-1 N, 100 kg·ha^-1 P₂O₅, and 120 kg·ha^-1 K₂O can be recommended, based on these results.

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 research aimed to clarify the effects of fungicides applied in Medicago sativa production on the safety of an important pollinating insect, the honeybee (Apis mellifera), One-day-old adult honeybees were fed a diet containing dimetachlone, prochloraz, iprodione, at a range of concentrations (diluted with water 1:500, 1:1000, 1:1500, 1:2000 and 1:2500) or no fungicide (Control). Subsequently, the activities of three protective enzymes, superoxide dismutase (SOD), guaiacol peroxidase (POD), catalase (CAT), and three detoxifying enzymes, carboxylesterase (CarE), glutathione S-transferase (GST), cytochrome P450 (P450) in the honeybees were measured. It was found that different concentrations of all the three fungicides could induce increased activities of SOD and POD in the honeybees. In particular, treatment with prochloraz solution at the 1:1500 dilution (0.17 mg·L^-1) induced a 1.82-fold SOD activity and a 5.40-fold POD activity compared to the Control treatment. All three fungicides showed low concentration induction and high concentration inhibition of CAT, CarE and GST activities, and showed inhibition (prochloraz) or induction (dimetachlone and iprodione) of P450 activity. With extended treatment time, the 1:1000 dilution of all three fungicides (0.40, 0.25 and 0.50 mg·L^-1 of dimetachlone, prochloraz, and iprodione, respectively) showed an overall induction effect on the activities of the three protective enzymes in Italian bees, but a variable effect on the activities of detoxifying enzymes. Specifically, dimetachlone initially increased the activities of the three protective enzymes and then inhibited activity after 6 h; iprodione induced P450 activity at all times, but inhibited the activities of CarE and GST in the first 12 h, then induced their activity thereafter; prochloraz elicited a gradual decrease in P450 activity with time, but initially induced then later inhibited the activities of CarE and GST. The results indicate that Italian bees can reduce the negative effects of fungicides by regulating the activities of protective and detoxifying enzymes in their bodies, but the fungicides have an impact on the normal physiology and metabolism of bees, even so. Therefore, care should be taken when applying fungicides to protect bees and ensure their safety while pollinating agricultural crops.

This research studied the distribution of plant communities in response to soil environmental factors in desert steppe. We selected a soil habitat transition gradient from sierozem to sandy soil in Yanchi, Ningxia, China. Within, at the edge of, and outside of the sierozem habitat, vegetation characteristics and soil sampling were conducted using a line transect method. Based on the soil environmental factors and community species composition data, we quantitatively classified the plant communities using multivariate regression trees and redundancy analysis. Then we analyzed the differences between the different plant communities using principal component analysis. It was found that dominant species of the plant communities changed from Stipa breviflora+Cleistogenes squarrosa+Thermopsis lanceolate to Sophora alopecuroides+Pennisetum centrasiaticum and to Artemisia scoparia+Salsola collina across the soil gradient. Key soil factors associated with the shift of plant community species dominance included soil coarse sand, soil organic carbon and soil total phosphorus contents. Across the habitat gradient from sierozem to sandy soil, height, cover and biomass of the plant communities showed a statistically significant increase, community species abundance showed a significant decrease, and plant community diversity showed an increase and then a decrease. As soil texture became coarser and soil nutrient content decreased along the gradient, perennial plant communities were replaced by annual plant communities. Compared with the plant communities in the sierozem habitat, the proportion of perennial plant species, plant species diversity and biomass were low in sandy habitats.

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.

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.

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.

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.

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 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.