Legume/maize intercropping has been practiced in many countries as a sustainable cropping system, but the effects of intercropping legumes with maize together with N application rates on biomass yield, quality, water-use efficiency (WUE), and nitrogen use efficiency (NUE) are limited under arid conditions in Northwest China. Field experiments were carried out in arid areas of Northwest China from 2019 to 2020 with three planting patterns (LM: Dolichos lablab (Lablab purpureus L.)/silage maize (Zea mays L.) intercropping; FM: Fodder soybean (Glycine max L.)/silage maize intercropping; M: silage maize monoculture) and four N application levels (N1: 0 kg N ha⁻¹; N2: 120 kg N ha⁻¹; N3: 240 N kg ha⁻¹; N4: 360 N kg ha⁻¹). The results showed that nitrogen fertilizer had a significant (p < 0.01) effect on total yield, WUE, and various nutrient parameters and the interaction between planting mode and nitrogen fertilizer had no significant effect on the above indicators, but had a significant (p < 0.01) effect on NUE. Compared with N1, the N3 and N4 treatments significantly increased fresh and hay yield, crude protein yield, crude protein concentration, and crude fat concentration of maize, legumes, and the whole silage system, and decreased the concentration of neutral detergent fiber (NDF) and acid detergent fiber (ADF). In comparison with N1, the 2-year average total biomass yield of N3 and N4 increased by 60.38% and 56.45%, respectively, and the total crude protein yield increased by 106.71% and 100.00%, respectively. High N input treatments (N3 and N4) significantly increased WUE_B (the WUE of legume and maize biomass), N concentration, N uptake, and NUE than N1, and the 2-year average NUE of N3 was 59.52% greater than that of N4. The results also show that LM and FM increased crude protein concentration and decreased NDF and ADF concentration compared with M, and the forage quality of LM was greater than that of FM. In contrast with M, LM and FM increased biomass yield by 3.70% and 1.72%, crude protein yield by 32.05% and 22.82%, and WUE_B by 10.49% and 6.02%, respectively. Application of 240 kg N ha⁻¹ in the Dolichos lablab–maize intercropping systems produced better dry biomass yield with increased forage qualities than other treatments, but the economic analysis is needed before making a recommendation.

Grazing on cultivated grassland is a green agricultural model. However, in China's Loess Plateau, the type of cultivated grassland suitable for grazing and the amount of nitrogen application is still unclear, which has led to the failure of this model to be widely implemented. In this context, we set up an experiment using three grass planting types, including monoculture of alfalfa (Medicago sativa L.), monoculture of brome (Bromus inermis L.), and mixed planting of the two forages. Under each planting type, there were six management measures: grazing and no nitrogen application (GN1), grazing and 80 kg ha^-1nitrogen application (GN2), grazing and 160 kg ha^-1nitrogen application (GN3), cutting and no nitrogen application (MN1), cutting and 80 kg ha^-1nitrogen application (MN2), and cutting and 160 kg ha^-1nitrogen application (MN3). To explore the impacts of these treatments on pastures, we studied the effects on the yield, quality, and water use efficiency of the three cultivated grasslands. Results showed that alfalfa monoculture and alfalfa-brome mixed sowing grassland resulted in significantly higher hay yield, crude protein yield, water use efficiency (WUE), precipitation use efficiency (PUE), nitrogen use efficiency (NUE), and agronomic efficiency of nitrogen (AEN) as compared to brome monoculture grassland. In addition, the crude protein, ether extract, and crude ash content of alfalfa monoculture and alfalfa-brome mixture were increased significantly while the contents of neutral detergent fiber (NDF) were reduced, thereby increasing the relative feed value (RFV) during the two years. The forage hay yield, crude protein yield, ether extract, crude ash content, RFV, PUE, and WUE were significantly higher with GN1, GN2, and GN3 treatments than that with MN1 treatment. In contrast, the NDF and acid detergent fiber (ADF) content was significantly lower than the MN1 treatment. Furthermore, the fresh forage yield, crude protein yield, PUE, and WUE of GN3 treatment were significantly higher than that of GN1 and GN2 treatments in both years, while the NUE and AEN were significantly higher in GN2 and GN3 treatments than that of MN3 treatment. Based on these results, alfalfa-brome mixed cropping with the application of 160 kg ha^-1nitrogen under grazing conditions is an appropriate management practice for improving the forage yield, quality, and water- and nitrogen utilization efficiency of cultivated grassland in the Loess Plateau of China. This integrated management model is applicable to the cultivation and utilization of mixed grassland on nutrient-poor land in the Loess Plateau.

To explore the effects of multi-cutting and sheep excrement on greenhouse gas (GHG) emissions from grassland ecosystems which simulate grazing livestock to a certain extent, spring wheat (Triticum aestivum L., var. Yongliang 15) and common vetch (Vicia sativa L., var. Lanjian 3) were planted in pot experiments in an inland arid region in 2019. Four treatments were conducted with eight replicates: plants without sheep excrement and cutting (CK), plants with multi-cutting (MC), plants with sheep excrement (SE), and plants with multi-cutting and sheep excrement (CE). The results showed that the carbon dioxide (CO₂) emission of common vetch with CE significantly was higher than that with MC at the earlier and later branching stages (p < 0.05). That of spring wheat with CE was significantly higher than that with MC at the later tillering stage (p < 0.05). Nitrogen oxide (N₂O) emissions of the two forage crops with SE rose significantly more than those with MC at both stages (p < 0.05). Methane (CH₄) of both forage crops with SE changed from absorption to emission (p < 0.05). Soil NO₃⁻-N content of both forages significantly increased with SE compared with MC (p < 0.05), while soil NH₄⁺-N content did not change significantly. Sheep excrement changed the CH₄ sink into a CH₄ source of the soil growing the two forage crops and increased the emissions of CO₂ and N₂O, whereas multi-cutting significantly reduced the GHG intensity of forage crops mostly by promoting the growth of the two forage crops. Future studies are suggested to identify the spatiotemporal effects of cutting and sheep excrement on GHG emissions to improve the prediction of future climate impacts from grazing activities.

Aim Legume/maize intercropping systems have been used in many developing countries. However, the effects of such systems on crop yield, quality, water-use efficiency (WUE), and N-use efficiency (NUE) were differed with the use of different legume crops and fertilizer application rates. Methods In the present study, field experiments were carried out in arid areas of Northwest China from 2019 to 2020 with three planting patterns (LM: lablab bean/silage maize intercropping; FM: forage soybean/silage maize intercropping; M: silage maize monoculture) and four N application levels (N1: 0 kg ha⁻¹; N2: 120 kg ha⁻¹; N3: 240 kg ha⁻¹; N4: 360 kg ha⁻¹). Results Compared with N1, the N3 and N4 treatments significantly increased fresh and hay grass yield, crude protein yield, crude protein content, and crude fat content of silage maize, legumes, and the whole system, and decreased the content of neutral detergent fibre (NDF) and acid detergent fibre (ADF). Compared with N1, the 2-year average total hay yield of N3 and N4 increased by 60.38% and 56.45%, respectively, and the total crude protein yield increased by 106.71% and 100.00%, respectively. Compared with N1, the N3 and N4 treatments significantly increased WUE_B, N content, N uptake, and NUE, and the 2-year average NUE of N3 was 59.52% higher than that of N4. Compared with M, LM and FM increased crude protein content and decreased NDF and ADF content, and the forage quality of LM was higher than that of FM. Conclusions Compared with M, LM and FM increased hay yield by 3.70% and 1.72%, crude protein yield by 32.05% and 22.82%, and WUE_B by 10.49% and 6.02%, respectively. Among all treatments, LM-N3 had the highest total fresh and hay yield, crude protein yield, N uptake, WUE_B, and NUE in two years.