In this research two experiments were conducted to investigate the effects of slope and cultivation system on soil erosion control. In Experiment 1, a completely random design was used to study the runoff efficiency and the rainfall threshold to produce runoff for ridges along different slopes (0°, 5° and 10°). In Experiment 2, a split-plot design with slope (5° and 10°) as the main plot factor and tillage method (traditional planting, open ridging and tied-ridging) as the split-plot treatment was adopted to study the effect of tied-ridging rainwater harvesting on soil moisture, runoff, sediment yield, nutrient loss, alfalfa fodder yield and water use efficiency (WUE). The mean runoff efficiencies for ridges along slopes of 0°, 5° and 10° were 88.2%, 91.1% and 92.7%, respectively. The threshold precipitation to produce runoff for the respective treatments was 1.55, 1.33 and 1.00 mm, respectively. Compared with traditional planting, the decreases in runoff, runoff efficiency, sediment yield, total nitrogen loss, total phosphorus loss and organic matter loss for open ridging were 62.3%-67.9%, 51.0%-54.5%, 95.6%-96.4%, 95.3%-96.2%, 95.3%-96.1% and 94.1%-95.6%, respectively, whereas the corresponding decreases for tied-ridging were 76.4%-79.9%, 67.8%-68.2%, 98.4%, 98.1%-98.2%, 98.2% and 97.8%-97.9%, respectively. The open ridging and tied-ridging increased shallow-layer (0-60 cm) soil moisture. The increase in alfalfa forage yield and WUE for open ridging were 40.3%-50.4% and 4.4-11.5 kg·ha^-1·mm^-1, respectively. The corresponding increases for tied-ridging were 16.0%-18.7% and 2.0-5.3 kg·ha^-1·mm^-1. The runoff, runoff efficiency, sediment yield, total nitrogen loss, total phosphorus loss and organic matter loss for the 10° slope were 1.44, 1.40, 2.34, 2.24, 2.39 and 1.97 times greater than those for the 5° slope. Lastly, average soil water storage, alfalfa fodder yield and WUE for the 5° slope were 1.05, 1.28, and 1.41 times greater than those for the 10° slope. Tied-ridging rainwater harvesting was particularly beneficial for reducing runoff, sediment yield and nutrient loss. Open-ridging was offered particular effects on increase of alfalfa fodder yield and WUE.

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.

To explore the effects of drought and salt stress on germination characteristics of halophytes, this study simulated drought stress with different concentrations of PEG-6000 and four sodium salts (NaCl, Na₂SO₄, NaHCO₃, Na₂CO₃) to evaluate the effects of those treatments on the seed germination characteristics of Halogeton glomeratus. It was found the germination percentage and germination energy decreased with increasing PEG-6000 concentration, while the seedling fresh weight, dry weight, plant height and root activity initially increased and then decreased at higher PEG-6000 concentration. Cluster analysis and principal component analysis showed that the different PEG-6000 concentrations could be divided into two groups with 6% PEG-6000 as the point of separation. Fresh weight appeared to be an important parameter. In addition, germination percentage germination energy, seedling fresh weight, dry weight, plant height and root activity declined with increase in concentration of the four sodium salts. This indicated that salt stress inhibited seed germination and seedling growth, with the effects of the four tested sodium salts ranked: Na₂CO₃>NaHCO₃>NaCl>Na₂SO₄. Cluster analysis and principal component analysis showed that the sodium salt concentrations were divided into two groups with the separation points falling at 50.00 mmol·L^-1 NaHCO₃, 62.50 mmol·L^-1 Na₂SO₄, 25.00 mmol·L^-1 Na₂CO₃ and 100.00 mmol·L^-1 NaCl. Among the plant traits evaluated as indicators of H. glomeratus stress tolerance in the germination stage, the germination index was the key indicator of NaHCO₃ and Na₂SO₄ stress, root activity emerged as the primary indicator of Na₂CO₃ stress and dry weight was the major indicator of NaCl stress in H. glomeratus.

The effect of nitrogen fertilizer application rate on chlorophyll fluorescence characteristics and dry matter accumulation of switchgrass (Panicum virgatum) is of great significance for the improvement of light use efficiency and biomass yield of switchgrass in saline-alkali land. In this research, the patterns of variation in chlorophyll fluorescence parameters and dry matter accumulation in switchgrass were studied in field conditions with a range of nitrogen application treatments: no nitrogen (0 kg·ha^-1, N₀), low nitrogen application (60 kg·ha^-1, N₆₀), medium nitrogen application (120 kg·ha^-1, N₁₂₀) and high nitrogen application (240 kg·ha^-1, N₂₄₀), and the comprehensive effect of nitrogen application on chlorophyll fluorescence and dry matter accumulation in switchgrass was evaluated using a multivariate Grey relational analysis procedure. It was found that: under N₆₀, N₁₂₀ and N₂₄₀ treatments, the PSⅡ maximum photochemical efficiency (F_v/F_m), PSⅡ actual photochemical quantum efficiency (Φ_PSⅡ), potential activity (F_v/F_o), photochemical quenching (qP), non photochemical quenching (NPQ) and biomass yield were significantly higher, and the heat dissipation of quantum ratio (F_o/F_m) was significantly lower than for the N₀ treatment during the flowering and seed maturation stages of switchgrass development. During the flowering period of switchgrass, the PSⅡ potential activity (F_v/F_o) was initially increased and subsequently decreased across the range of nitrogen application rates, with a maximum observed value of 3.13 at N₁₂₀ (increased 16.26% compared with N₀). The effect of nitrogen application rate on dry matter accumulation differed between the crop growth stages. Dry matter accumulation was high during jointing and booting periods, reached its maximum at the seed filling stage, and decreased slightly thereafter. The maximum observed dry matter accumulation (378.13 g·hole^-1) occurred under the N₂₄₀ treatment during the post-flowering stage and was, respectively, 24.33%, 20.09% and 7.24% higher than that of the N₀, N₆₀ and N₁₂₀ treatments. Grey relational analysis showed that the association between the weighted correlation index and the ideal fertilization level was the highest under the N₂₄₀ treatment. In summary, the N₂₄₀ treatment in this study in the Yinbei saline-alkali area of Ningxia optimized the photochemical activity of PSⅡ and dry matter accumulation of switchgrass.

After China has halted grassland degradation, it will be very important to rapidly improve current grassland management policies, especially those related to determining the grassland-livestock balance and payments for ecosystem services, and to achieve sustainable development goals (SDGs) for ecological conservation and improvement of herders’ well-being. Over the past 90 years, the United States has created and adjusted its public rangeland management systems and the US experience provides much valuable information for the reform of grassland management policies in China. The lessons from American public management suggest that multiple use and ecosystem service of grassland are two key concepts for sustainable management of grassland. These concepts should be firmly confirmed by social consensus, through the legal system, and in administrative management. Furthermore, public ownership rights form the legal premise for establishing multiple ecosystem services of grassland. The other stakeholder industries beyond animal husbandry provide the economic foundation to realize multifunctional grassland systems. Precise and responsive management by administrative agencies will guarantee the balance between livestock production and ecological conservation. The public participation of multiple stakeholders is the engine to drive forward the reform of grassland management systems. Meanwhile, the twists and turns of public rangeland management evolution in the United States suggest that common elements in the historic development of grassland management policy include: failure and adjustment of ecological policies, the flexibility to reconsider grazing prohibition and supervision intensity, and conflict and compromise between interest groups. All these elements may appear in China’s journey to achieve sustainable grassland management. In the next stage, optimization of grassland property rights, refinement of administrative management, coordination between herders and ecological conservation are the core tasks in the drive to achieve sustainable grassland management in China.

Grassland is an important natural resource and plays a key role in maintaining the stability of ecosystems on a regional scale. Confirmation of grassland contracts and property rights provides an institutional guarantee for grassland ecological protection and development, and is a specific measure to implement the relevant central government requirements. Previous research showed that the speed of determining grassland ownership varies from region to region due to unique local factors in the various grassland areas in China, and in some regions the progress towards determining the ownership of grasslands is relatively slow. Based on analysis of the historical background and current situations relating to contract and property confirmation for grasslands, we here summarize the basic work in grassland contract and property confirmation, including data collection, contract content, contract optimization, issuing of certificates of ownership, landholder training, information management and improvement of grassland dispute resolution mechanisms, et al. The thinking of the planning sector in grassland management including the main building blocks, basic function, workflow, key technologies, is put forward. Finally, consideration of and suggestions for the next stage of the work involving ‘three property rights separation’ are put forward. This research is of great significance to furthering the development of the contract and information management of grasslands in China.

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.

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.

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.

This research explored the physiological leaf response mechanisms of sugar beet to re-watering after drought with a focus on photosynthetic physiological traits and photo-responsive parameters. Two cultivars with different drought resistance, ‘XJT9907’ (a drought sensitive type) and ‘XJT9916’ (a drought tolerant type) were studied. A controlled water deficit was imposed on plants in the leafy growth stage, whereby soil moisture content was allowed to fall to 45%-50% of field water holding capacity for 7 days, then irrigation water was added to raise soil moisture to 70%-75% of the field water holding capacity for 48 hours. At this point, the photosynthetic physiological parameters of leaves were determined, and nonlinear regression used to fit sigmoid curves for the relationship between net photosynthetic rate of leaves and light intensity. It was found that drought stress during the leafy growth stage of sugar beet development significantly reduced the SPAD value, net photosynthetic rate (P_n), stomatal conductance (G_s), intercellular CO₂ concentration (C_i), and transpiration rate (T_r) of both sugar beet varieties. After re-watering, the SPAD value, net photosynthetic rate (P_n), stomatal conductance (G_s), intercellular CO₂ concentration (C_i) and transpiration rate (T_r) of sugar beet leaves under drought stress treatments all improved. The values of physiological parameters for drought tolerant XJT9916 were significantly higher than those of drought sensitive XJT9907, although none of the values exceeded those of plants with a normal level of water supply, indicating a degree of compensation effect. After the re-watering treatment, the maximum net photosynthetic rates (P_nmax) of XJT9916 and XJT9907 varieties were, respectively, 6.2% and 17.1% lower than the control, and the apparent quantum efficiency (AQY) was, respectively, 6.5% and 12.2% lower than the control. Similarly, comparing drought tolerant and drought sensitive varieties to control plants. respiration rates (Rd) were, respectively, 19.1% and 14.9% lower than the control, light saturation points (LSP) were 19.6% and 14.1% lower than the control, while the light compensation points (LCP) were, respectively, 15.4% and 17.6% (P<0.05) higher than the control. For the drought sensitive variety, the light energy utilization interval was comparatively narrow, and the light energy utilization efficiency was reduced. Taken together, the results show that when the soil moisture content is 45%-50% of the field water holding capacity during the sugar beet leafy growth period, the photosynthetic potential of sugar beet leaves is not realized, the photosynthetic capacity of the leaves is weakened and cannot be restored to normal levels after re-watering. The drought-tolerant sugar beet variety XJT9916 has strong photosynthetic recovery ability in the context of re-watering after drought.