The aim of this study was to evaluate the physiological responses of Leymus chinensis (Trin.) Tzvel exposed to long-term salt, salt-alkali, and alkali stress in order to elucidate how L. chinensis can survive under alkaline-sodic soils. L. chinensis (30 days after germination) were stressed with salt [SS; sodium chloride (NaCl)], mixed salt-alkali [MS; molar ratio of NaCl: sodium carbonate (Na₂CO₃) = 2:1] and alkali salt (AS; Na₂CO₃) at four different levels of sodium (Na⁺) concentration (0, 75, 150, and 300 mM) for 60 days. L. chinensis showed 100% survival rate at all treatments except 300 mM SS (33.3%) and AS (18.9%). The growth and physiological parameters of survival plants were measured. As anticipated, growth of L. chinensis was inhibited after stresses, which reflected in the decline of plant height, dry weight and tiller number following the increased Na⁺ concentration. The content of Na⁺, proline, and soluble sugar in L. chinensis increased with the increasing Na⁺ concentration, suggesting that L. chinensis need to accumulate inorganic and organic solutes for resisting osmotic stress induced by various salt stresses. These processes ensure the water balance that can provide a relative normal physiological environment for L. chinensis. Potassium (K⁺) content of L. chinensis kept at a relative lower level than control to ensure the normal physiological processes. Chlorophyll content of stressed plant increased slightly compared to control plants, which can produce more energy for L. chinensis resisting various stresses. The increased malondialdehyde (MDA) content of stressed plants showed the damage of various stresses. Among the three treatments (SS, MS, and AS), the injury extent for L. chinensis can be expressed by AS>SS>MS, and MS was the most complicated for the counterbalance effects of soil electrical conduction and pH.

Alfalfa (Medicago sativa L.) is an important perennial legume forage that is cultivated in saline soil worldwide. This study aimed to clarify the effects of organic base fertilizer and inorganic topdressing on the productivity of alfalfa growing in saline soil. A three-year field study was conducted in which alfalfa was grown in the saline soil of the Huanghe River Delta with a control (no fertilizer) and three treatments: organic base fertilizer (Base), topdressing with urea fertilizer (Top), and combined base and topdressing fertilizers (BT). The productivity in the BT and Base treatments was 13.21 and 13.82 t·hm⁻² in 3 years, significantly higher than that in the Top treatment and the control. The increased productivity in the BT and Base treatments were because organic matter promoted root growth of alfalfa seedlings in saline soil. The diversity of the soil bacterial community was not affected by the BT treatment, but the Base treatment increased the abundance of Acidobacteria, and the Top treatment increased the abundance of Gemmatimonadetes. Soil bacteria play an important role in improving the productivity of alfalfa growing in saline soil, and the mechanism by which soil microbes increase yield needs to be further studied.

Alfalfa (Medicago sativa L.) and corn (Zea mays L.) are common forage plants for feeding livestock, and their effects on soil bacterial organisms have been extensively studied. However, there is little comprehensive research on soil bacterial organisms and their function in a long-term alfalfa monocropping system after corn insertion and fertilization. The effects of alfalfa–corn rotation (AF: alfalfa monocropping, RA: alfalfa and corn rotation) and nitrogen fertilization (RA0 and RA15) were investigated in a field experiment. The results showed that fertilization significantly increased the aboveground biomass (AGB) and soil nitrate nitrogen, and corn insertion significantly decreased the nitrate nitrogen (${\mathrm{NO}}_3^{-}$-N) (p < 0.05). In addition, the bacterial community structure among the treatments was significantly changed by the rotation and fertilization. The rotational system of RA significantly increased the soil bacterial diversity compared with AF (p < 0.01), and most of the soil bacterial communities were of the phyla Actinobacterota and Proteobacteria. The RA system had a lower relative abundance of Actinobacterota than the AF system. The bacterial function prediction found that the soil carbon and nitrogen cycle processes in RA were more active than those in AF. The RDA analysis revealed that ${\mathrm{NO}}_3^{-}$-N and pH were the main environmental factors affecting the bacterial community structure in the RA system.

Temperate grassland steppe is an important natural ecosystem in the world, which is being degraded under the combined pressure of climate change and human over-utilization. Our objective was to determine the effect of inorganic and organic fertilizer addition and determine the appropriate fertilizer resource and additional rate for temperate grassland restoration. The treatments consisted of an inorganic and organic fertilizer, each with three additional rates. The effect of fertilizer addition on aboveground biomass, community structure, soil properties, and N balance were examined using a 2-year in situ controlled trial at Guyuan Grassland Station, Hebei Province, China. The results showed that inorganic fertilizer treatments increased the aboveground biomass, and decreased diversity and evenness of the plant community. Organic fertilizer treatments increased soil total carbon and the carbon-to-nitrogen ratio, but did not significantly change the aboveground biomass and soil available nutrition during the 2-year experiment. The N quantity of plant harvest output is approximate to that of fertilizer addition input in inorganic fertilizer treatment with 75 kg hm^-2 urea and 45 kg hm^-2 diammonium phosphate. The study demonstrated that using fertilizer addition to restore temperature grassland steppe requires a comprehensive evaluation of the diverse services functions of the present and future.