Loess Plateau Region Of China Research Articles

Soil labile organic carbon and nitrate nitrogen are the main factors driving carbon-fixing pathways during vegetation restoration in the Loess Plateau, China

Although the microbial fixation of CO2 is a key process in regulating soil carbon cycling, the effects of vegetation type on microbial carbon-fixing pathways and their driving factors in soils have yet to be sufficiently established. In this study, based on macro-genome sequencing and other analytical methods, we sought to determine the soil physicochemical properties, soil organic carbon contents, carbon-fixing microorganisms, and carbon-fixing genes in areas of farmland (FL), grassland (GL). Robinia pseudoacacia (RP), Caragana korshinskii (CAK), and Prunus sibirica (PS) in the Wuliwan watershed of the Loess Plateau region of China. Our findings revealed that the organic carbon contents of the assessed soils increased in the following order: FL < GL∼PS < CAK < RP (P < 0.05). Re-vegetation-based restoration was found to enhance soil organic carbon pool stability. Compared with farmland soil, the proportions of recalcitrant organic carbon had increased by 6 % and 9 % in the soil at sites that had undergone restoration with C. korshinskii and R. pseudoacacia respectively. Among the identified carbon fixation pathways, the DC/4-HB cycle had the highest relative abundance of 25.10–25.52 %. The dominant groups of carbon-fixing microorganisms were identified as Actinobacteria and Proteobacteria, accounting for over 60 % of the total abundance. Furthermore, analysis based on a partial least squares path model revealed labile organic carbon and soil nitrate nitrogen as the primary drivers of carbon fixation pathways. Collectively, our findings in this study provide evidence to indicate that restoration of vegetation on the Loess Plateau can contribute to increases in soil organic carbon content and stability and the abundance of carbon-fixing microorganisms, with R. pseudoacacia and C. korshinskii having the most significant effects in this regard. These findings have important implications for restorative vegetation carbon pool management and provide additional perspectives for understanding global carbon cycling.

Grass (Poa annua L.) cover for eight years as an effective strategy for recovering soil moisture

Deep soil desiccation has become a major obstacle to restoring vegetation in the Loess Plateau region of China. The restoration of deep soil water plays an important role in ecosystem health. In the present study, we compared the effects on moisture variations in deep dry soil of grass cover and clean tillage treatments based on in-situ soil column monitoring for eight years. The results showed that the dry soil layers could temporarily disappear and reappear again with rainfall under clean tillage. However, grass cover effectively increased the deep soil moisture. Grass primarily consumed soil moisture from the shallow layer (0–2 m), and the total amount of water consumed during the whole growth period was less than the annual rainfall in dry years. The average soil desiccation index decreased by 24.20 % and the deep soil water moisture (2–10 m) recovered from 7.5 % to 12.8 % after eight years, with an annual average recovery of 0.66 %. Thus, it would take half a year to recover to the stable field capacity and 14 years to reach the field capacity. Recovery of the soil moisture also depended on the rainfall supply. We found that precipitation had an obvious lagged effect of approximately two years on the supply of deep soil moisture. Our findings contribute to understanding how to alleviate dry soil layer, with potentially helpful implications for the ecological health in arid and semiarid regions.

Marriage squeeze in the Loess Plateau Region, Northwestern China: A case study of two villages

The quest for spouses among rural men in China has become increasingly arduous, resulting in a growing number of older bachelors. However, the mechanisms driving the marriage squeeze in underdeveloped rural areas remain poorly understood. This study analyzes time-series data from 70 marital unions across 58 households in two geographically distinct villages in the Loess Plateau Region of China. The results indicate that marriage expenses and the subsequent financial burden on the bridegroom's household increased substantially from 1969 to 2018, particularly in the most recent decade, while the bride's household received the majority of marriage-related income. There has been an overall increasing trend in economic pressure induced by marriage expenses in both villages since 1979. A cohort of older bachelors has emerged in the hilly village, where rural males traditionally marry women from more remote, underdeveloped areas. Conversely, rural males in the tableland village can consistently find spouses from comparable geographical settings and have not yet emerged as older bachelors. This study concludes that the marriage squeeze manifests as dual pressures from economic and living conditions, and excludes economically disadvantaged males in harsh environments from the marriage market within the context of rural out-migration and the sex ratio imbalance.

Innovative fertilizer management system maintains higher maize productivity with lower environmental costs in the Loess Plateau region of China

ContextInnovative fertilizer management is the most effective strategy for increasing crop yields and reducing environmental pollution. ObjectivesDeep fertilization reduces NH3 emissions and increases crop yield, but its effects on N2O emissions are still unclear. Nitrification or urease inhibitors trigger cross-contamination of N2O and NH3. Little is known about whether innovative fertilizer management strategies can reduce nitrogen emissions while maintaining higher yields. MethodsWe conducted field experiments using maize in the semi-humid and drought-prone areas of the Loess Plateau in China from 2019 to 2021. To further verify the research results, experiments were conducted in semi-arid and drought-prone areas in 2022 and 2023 using surface fertilization (SF), surface fertilization with nitrification (SNI) or urease inhibitor (SUI), deep fertilization (DF), and deep fertilization with urease and nitrification inhibitor (DUN) as experimental treatments. ResultsThe trends were similar at the three experimental locations over five years, where the ability of DF to reduce emissions was equivalent to those of SNI for N2O and SUI for NH3. However, the increase in the crop productivity was significantly higher under DF than SUI and SNI. Compared with SF, DF significantly reduced the N2O and NH3 emissions by 39.85 % and 46.08 %, respectively, and significantly the increased maize yield, N uptake, and nitrogen use efficiency (NUE) by 16.86 %, 15.83 %, and 32.79 %. The innovative fertilizer management strategies combined the advantages of inhibitors and deep fertilization, and they obtained the highest maize yield and NUE, as well as the lowest N2O and NH3 emissions and gaseous nitrogen loss intensity (GNLI) among all treatments. Compared with SF, DUN reduced the urease, nitrate reductase, nitrite reductase, and hydroxylamine reductase activities by 22.03 %, 58.81 %, 52.72 %, and 50.27 %, respectively, the soil NO3–-N and NH4+-N contents by 82.94 % and 53.71 %, and N2O and NH3 emissions by 80.79 %, and 79.33 %. DUN increased the maize yield and NUE by 23.30 % and 46.91 %, respectively, and decreased the GNLI by 84.69 %. ConclusionsDUN reduced the concentration of substrates for producing gaseous nitrogen by regulating the activities of soil nitrogen circulating enzymes to significantly reduce the nitrogen loss, and it achieved the highest maize yield (11,818.10 kg ha–1) and NUE (46.62 %) with the lowest GNLI (0.71 g N kg–1 grain). Innovative fertilizer management strategies can help to balance economic and environmental benefits in the Loess Plateau region of China. ImplicationsOur findings provide a reference for obtaining higher maize productivity with low environmental pollution in the Loess Plateau region of China.

Soil moisture and soil organic carbon coupled effects in apple orchards on the Loess Plateau, China

A large number of economic forests, especially apple orchards (AOs) in the Loess Plateau region of China, have been planted to develop the local economy and increase the income of farmers. The two main constraints preventing AOs on the Loess Plateau from developing sustainably and producing a high and steady yield are soil moisture content (SMC) and soil organic carbon (SOC). Nevertheless, little is currently known about the contributions of roots to these changes in the soil profile and the temporal modes of the SMC-SOC coupled effects. In our research, we analyzed the dynamic changes in SMC and SOC in AOs of various years in northern Shaanxi Province, as well as the coupled relationship between the two, and attempted to describe the function of roots in these changes. Research have shown: (1) As the age of the AOs increased, the SMC continued to decline throughout the 0–500 cm profile, especially at depths of 100–500 cm. SMC depletion mainly occurred in AOs aged 20 years (30.02%/year) and 30 years (31.18%/year). (2) Compared with abandoned land (AL), all the AOs except for the 6-year-old AO showed a carbon sequestration effect, and the carbon sequestration effect increased with age. The carbon sequestration rate of the 12-year-old AO was the highest and then decreased with age. Both surface and deeper soils showed better carbon sequestration, with a large amount of SOC being sequestered in deeper soil layers (> 100 cm). (3) The coupled effects of SMC and SOC varied with age and depth. The SMC in the deeper layers was significantly negatively correlated with SOC. Root dry weight density (RDWD) was significantly negatively correlated with SMC and significantly positively correlated with SOC. Path analysis suggested that SMC directly affects SOC at different soil depths, and regulates SOC by affecting RDWD, but these effects are significantly different at different depths. Therefore, we propose that management of AO should focus on the moisture deficit and carbon sequestration capabilities of deeper soils to ensure the sustainability of water use in AOs and the stability of agricultural carbon sequestration on the Loess Plateau.

Comparative analysis on the mechanism of climate responsiveness strategies on indoor thermal performance of Yaodong dwellings in the Loess Plateau region of China

The vast rural architecture, while contributing significantly to enormous building energy consumption, also brings about substantial energy-saving potential. This underscores the need for a profound understanding of sustainable and intelligent green construction practices for vernacular dwellings. This study focuses on investigating the mechanisms of climate-responsive strategies on the indoor thermal environment of traditional dwellings in the Loess Plateau region, using the cave dwelling, known as Yaodong in Yulin, as a case study. Through on-site measurements, the study examines the effectiveness of climate responsiveness strategies on the indoor thermal conditions of different types of Yaodong (cliff-side style and independent style). Simultaneously, dynamic simulations are employed to analyze energy consumption of heating season (ECHP) and indoor temperature on the coldest day, while adjusting variable parameters of various passive strategies to identify the influences of factors affecting the indoor thermal performance of different types of Yaodong. The results indicate that the traditional Yaodong, employing passive design methods can contribute to enhancing indoor comfort under adverse climate conditions. The average indoor temperatures of cliff-side and independent Yaodong bedrooms are −1.9 °C and −3.2 °C, respectively, compared to the outdoor temperature of −12.8 °C, outperforming modern brick dwellings with an average indoor temperature of −9.3 °C. For cliff-side Yaodong, factors such as orientation, window-to-wall ratio (WWR), the aspect ratio, and sunspace prove to be the four most critical elements influencing indoor thermal performance. For independent Yaodong, the ranking of key factors is orientation, the aspect ratio, wall thermal resistance, and window-to-wall ratio. This study can provide guidance and reference for the preservation and revitalization of cave dwellings in the Loess Plateau region.

Effects of Different N Fertilizer Doses on Phenology, Photosynthetic Fluorescence, and Yield of Quinoa

Quinoa (Chenopodium quinoa Willd.) is gaining recognition as a pseudocereal due to its nutritional attributes and adaptability to challenging conditions and marginal soils. However, understanding the optimal fertilization for quinoa growth remains a challenge. This study investigates the effects of nitrogen fertilization (0, 90, 120, and 150 kg using urea) on quinoa phenology, growth, and photosynthesis in the Loess Plateau region of China, a critical area facing soil erosion and ecological degradation. The results showed that nitrogen fertilization significantly influenced quinoa phenology, prompting early flowering and shorter growth at an optimum rate of 120 kg ha−1. Nitrogen application enhanced growth traits such as plant height, stem diameter, and chlorophyll content, particularly at the heading and flowering stages. Photosynthesis-related parameters, including net photosynthesis rate, transpiration rate, stomatal conductance, and intercellular CO2 concentration, were affected by nitrogen application, with higher values observed at 120 kg ha−1. Non-photochemical quenching was significantly increased by nitrogen application, indicating the efficient dissipation of excess energy. The study demonstrated a positive correlation between grain yield and growth traits, photosynthesis-related traits, and chlorophyll content. In conclusion, quinoa yield could be significantly improved at the Loess Plateau region under rainfed conditions by an optimal nitrogen fertilizer rate of 120 kg ha−1, which reduces the growth duration while increasing photosynthesis traits.

Organic Certification, Online Market Access, and Agricultural Product Prices: Evidence from Chinese Apple Farmers

Motivated by the increasing interest in sustainable agriculture and the potential benefits associated with organic certification, this study employs a multidimensional fixed-effects model to analyze data derived from onsite surveys conducted among 681 apple farmers in the Loess Plateau region of China to explore the influence of organic certification on absolute and relative agricultural product prices given online market access. The findings indicated a significant increase in apple prices among farmers who held organic certifications and engaged in online market sales, with prices rising by CNY1.60 per half kilogram. Additionally, this study highlights that the amalgamation of organic certification with online market access significantly enhances agricultural product prices by facilitating better dissemination of market information among farmers. Furthermore, this research addresses a critical gap in the existing literature by clarifying the differential impact of organic certification across distinct farmer demographics and geographical regions. The more pronounced positive impact of organic certification on prices observed among cooperative members and farmers in the low-altitude areas is particularly noteworthy. These results underscore the crucial role of online market access in achieving premium effects and price stability for organically certified products.

Influence of the Depth of Nitrogen-Phosphorus Fertilizer Placement in Soil on Maize Yielding and Carbon Footprint in the Loess Plateau of China

Deep fertilization is a beneficial approach for reducing nitrogen losses. However, the effects of various fertilization depths on maize (Zea mays L.) productivity and environmental footprints have not been thoroughly understood. Therefore, a field experiment was conducted to investigate the effects of different fertilization depths of 5 cm (D5), 15 cm (D15), 25 cm (D25), and 35 cm (D35) on maize productivity and environmental footprints. Reactive nitrogen (Nr) losses and greenhouse gas (GHG) emissions were assessed using life cycle analysis. We hypothesized that deep fertilization can obtain lower carbon and nitrogen footprint. The results indicated that deep fertilization decreased the N2O and NH3 emissions while increasing the CH4 uptake. Compared with D5, D15 resulted in an increase in total GHG emissions and carbon footprint (CF), whereas D25 decreased by 13.0% and 23.6%, respectively. Compared with D5, the Nr losses under D15, D25, and D35 conditions was reduced by 11.3%, 17.3%, and 21.0%, respectively, and the nitrogen footprint (NF) was reduced by 16.0%, 27.4%, and 19.0%, respectively. The maize yield under D15 and D25 increased by 5.7% and 13.8%, respectively, compared with the D5 treatment, and the net economic benefits of the ecosystem increased by 7.1% and 17.1%, respectively. In summary, applying fertilizer at a depth of 25 cm can significantly reduce the environmental footprints and increase maize productivity, making it an effective fertilization strategy in the Loess Plateau region of China.

Effects of tillage microrelief units on splash erosion: A case study from the Loess Plateau, in China

A tillage microrelief unit is the smallest spatially discontinuous area unit of tillage microrelief. Understanding the impact of tillage microrelief units on splash erosion is essential for selecting suitable tillage measures and employing soil and water conservation practices. The objective of this study was to investigate the characteristics and mechanisms of splash erosion under different tillage microrelief units in various directions and distances using the rainfall simulation experiment in the soil landscape of the Loess Plateau region in China, characterized primarily by sloping farmland as the main land use type. Three typical microrelief units, namely, artificial digging (AD), contour tillage (CT), and straight slope conditions (SSC) were designed at 0°, 3°, 5°, 10°, 15°, and 20° slopes. Tillage microrelief units with high surface roughness produced more splash erosion than flat lands. Further, the highest surface roughness increased the total splash amount by 102% relative to flat lands. The tillage microrelief unit itself was elevated with a certain slope, which increased the downslope splash of CT, SSC, and AD by 121%, 173%, and 11%, respectively. Different surface roughness values and slopes under different microrelief units were used to determine the amount of splash erosion. The results showed that the total splash amount responded significantly (P < 0.01) to the interaction between surface roughness and slope, and the sensitivity to roughness was higher than that to slope. According to the single-factor analysis, the surface roughness of all slopes significantly influenced the amount of splash erosion. Furthermore, the sensitivity of the tillage microrelief unit to the slope decreased because of the high slope under high surface roughness. Overall, the results of this study showed that in different tillage microrelief units of slopes in the Loess Plateau, SSC and CT significantly increased the outward splash erosion in this area, while AD significantly decreased the outward splash erosion. Moreover, slope did not have a considerable influence.

Assessment of suitable areas for afforestation and its carbon sink value in fragile ecological areas of northern China

Afforestation and reforestation are pivotal in mitigating land degradation and bolstering the carbon sink capacity of terrestrial ecosystems. However, the potential economic ramifications of afforestation and reforestation in the context of climate change remain largely unexplored. In this study, we employed an interdisciplinary methodology to establish a framework for assessing future forest potential and carbon sequestration in the Eastern Loess Plateau region of China. Our findings indicate that an estimated 17,392.99 km2 of land suitable for afforestation still existed within the region, exhibiting a propensity to aggregate around existing forests rather than being dispersed randomly. Notably, 4385.36 km2 was prioritized for afforestation initiatives. Projections suggest a significant enhancement of the forest carbon sink within the study area by 2050, ranging from 36.93 Mt to 105.38 Mt. The corresponding economic value for this enhancement is estimated to vary between US$3.25 billion and US$17.68 billion. Of significance is the observed polarization of the region's carbon sink capacity over time, with half of the total carbon sinks concentrated within 10% of the districts. Additionally, approximately 26% of the counties are expected to transition from carbon sinks to carbon sources. These findings underscore the substantial impact of climate change on forest distribution and suggest a targeted approach to combat forest degradation by circumventing ineffective afforestation activities.

The deviation between the behavior and willingness of rural residents to use clean energy and its influencing factors in China

Rural residents who really accept and adopt clean energy make significant sense for long-term sustainability. The purpose of this study was to resolve the limitations of existing studies that only discuss whether there is a deviation between behavior and willingness, and deeply measures the deviation level between behavior and willingness to use clean energy for heating, cooking, and producing hot water, and to identify the factors influencing contrasting levels of deviation for different energy-consumption activities. A survey of 854 rural residents from 62 villages was conducted in the Loess Plateau region of China, and the multinomial logit model was used to investigate the influencing factors. The results showed that the proportion of high-level deviation for heating and low-level deviation for cooking was the highest. Policy cognition and usefulness perception had significant negative impacts on the deviation for heating, cooking, and producing hot water. Herd mentality had a significant positive impact on low-level deviation in hot water production. Males were more likely to have a high-level deviation for cooking. The results of this study provide a basis for scientific policy formulation and guide the transition from the willingness to the actual clean energy adoption behavior of rural residents.

Spatiotemporal change and drivers of ecosystem quality in the Loess Plateau based on RSEI: A case study of Shanxi, China

The fragile ecological environment and intensive human activities in the Loess Plateau region of China have led to serious soil erosion and adverse weather disasters. To address these issues, the Chinese government has implemented a series of large-scale ecological restoration projects with significant investments and broad public participation. Throughout this process, the ecosystems have undergone substantial artificial intervention. This study utilizes MODIS data to establish a remote sensing ecological index (RSEI) for evaluating the ecosystem quality of Shanxi Province, located in the eastern Loess Plateau, over the past 20 years (2000–2020). Furthermore, the study analyzed the natural and socio-economic factors that influence the local ecosystem quality using Geodetector analysis. The research findings revealed the following: 1) Over the 20-year period of large-scale ecological restoration projects, the ecosystem quality in Shanxi has significantly improved, as indicated by the average RSEI index increasing from 0.48 to 0.57. 2) The southern part of the province has experienced relatively better ecosystem recovery, while the ecosystem quality in the northern and western regions, particularly along the Yellow River, remains poor. 3) Overall, the major factors influencing ecosystem quality are natural geographical factors such as temperature and slope. However, with rapid urbanization, the negative impacts from socio-economic factors represented by GDP have intensified, particularly in the northern regions. Additionally, this study demonstrated that the geographically weighted regression model can better explain the local variations affecting the RSEI and exhibits a high degree of reliability. The research findings provide scientific and effective references for evaluating the ecosystem quality in the Loess Plateau and implementing ecological restoration projects.

Long-term anthropogenic field management enhanced wheat productivity and resource utilization in the Loess Plateau region of China

Low precipitation and poor soil quality are the main factors that limit wheat production in the Loess Plateau region of China. Straw incorporation and/or adding organic fertilizer can enhance wheat productivity by improving the soil water content (SWC) and soil fertility, but systematic long-term research has not yet been conducted. Thus, we conducted a 12-year continuous in-situ experiment in the Loess Plateau by testing four treatments: (1) CK: no fertilization and wheat straw removal; (2) FM: straw removal and application of inorganic fertilizer; (3) SI: straw incorporation and application of inorganic fertilizer; (4) SIOM: straw incorporation and application of inorganic fertilizer, with organic fertilizer added to replace 10% of the inorganic fertilizer. Under CK, the soil chemical properties and enzyme activities tended to decrease over the years. The soil fertility was significantly higher under FM than CK, and higher under SI and SIOM than FM (P < 0.05). SIOM significantly improved the soil nutrients and wheat productivity than other treatments (P < 0.05). Compared with FM, the soil bulk density in the 0–20 cm soil layer under SIOM decreased by 4.5%, while SOC, TN, TP, AN, and Olsen-P increased by 4.5%, 6.1%, 4.9%, and 12.3%, respectively. The DOC, DON, MBC, and MBN contents increased by 18.5%, 26.4%, 15.8%, and 16.2%, respectively. The activities of urease, sucrase, and catalase increased by 12.8%, 13.6%, and 22.8%, and the N uptake, nitrogen use efficiency (NUE), water use efficiency (WUE), water productivity, and wheat yield increased by 17.8%, 43.7%, 38.6%, 33.5%, and 22.4%. SIOM obtained the highest NUE, WUE, yield, and economic benefits of 37.83%, 14.34 kg ha–1 mm–1, 4579.16 kg ha–1, and 7990.39 Yuan ha–1, respectively. Linear mixed effects modeling showed that the year and treatment significantly affected the soil fertility and wheat productivity (P < 0.05). Random forest and structural equation modeling showed that the soil and fertilizer management strategies increased wheat productivity (R2 = 0.50) by improving the soil fertility. Therefore, straw incorporation and applying inorganic/organic fertilizers are effective management strategies for improving soil fertility and wheat productivity in semi-arid areas of Loess Plateau regions.

Optimizing Sowing Patterns and Nitrogen Management Strategies Used to Balance Maize Crop Productivity, N2O Emissions, and Economic Benefits in the Loess Plateau Region of China

Understanding the combined effects of sowing patterns and nitrogen (N) management strategies on crop productivity, environmental costs, and economic benefits is important to ensuring the sustainable development of dryland agriculture. Thus, we conducted a three-year field experiment to explore two spring maize sowing patterns (FS, flat sowing; RFPM, ridge and furrow plastic film mulching) and four N management strategies (N0, no N fertilizer; N1, normal urea as base fertilizer; N2, split application of normal urea at sowing and a large flare period at a ratio of 3:2; N3, all controlled-release urea as base fertilizer) on growth, the grain yield, the N uptake and utilization efficiency, N2O emissions, and economic benefits in the Loess Plateau region of China. Our results showed that compared to FS, RFPM promoted growth of the spring maize canopy and increased the grain yield, cumulative N uptake, and N use efficiency. RFPM promoted N2O emissions by improving the soil’s hydrothermal environment, but it reduced the environmental cost (yield-scaled N2O emission). RFPM increased the production cost, but it increased the net income by improving the total output. Compared to traditional N management strategies (N1), N2 and N3 treatments improved the spring maize productivity and net income, and they reduced the environmental costs by improving the synchronization of the nitrogen supply. However, due to the decreasing rural labor force available in China, N3 is more beneficial in terms of reducing labor inputs. Therefore, we suggest that RFPM and N3 can be combined to form an efficient management strategy for spring maize production in the Loess Plateau that balances crop productivity, N2O emissions, and economic benefits.

Optimizing soil and fertilizer management strategy to facilitate sustainable development of wheat production in a semi-arid area: A 12-year in-situ study on the Loess Plateau

ContextThe low precipitation and low soil fertility in the Loess Plateau region of China limit the sustainable development of farmland. No-tillage, straw mulching, or planting green manure can improve soil water storage or soil quality. However, further research is needed to optimize these soil and fertilizer management strategies to maximize yield and effectively utilize resources. ObjectiveThe present study aimed to determine the optimal soil and fertilizer management strategies to maximize wheat growth and water/nitrogen utilization efficiency, while minimizing nitrogen fertilizer input. MethodsFive different soil and fertilizer treatments were tested on the Loess Plateau between 2009 and 2021, including traditional tillage followed by bare soil (CK), no-till with straw mulching (NTSM), no-till with straw mulching followed by leguminous green manure (OPT), and reductions in N fertilizer inputs of 10% (OPT10) and 20% (OPT20) under OPT. ResultsThe average results from 12 years of research revealed that the soil water content (SWC) and NO3–-N content in the 0–20 cm soil depth under OPT were higher by 4.3% and 13.4% compared to CK (P < 0.01), and the length and surface area of the wheat roots were higher by 20.9% and 11.0% (P < 0.01), respectively. Optimized soil and fertilizer management delayed leaf senescence and enhanced the antioxidant and photosynthetic capacities of the wheat crop. Compared with CK, the net photosynthetic rate and superoxide dismutase activity were 38.6% and 11.6% higher under OPT, respectively, and no significant differences were observed between OPT and OPT10. Optimized soil and fertilizer management promoted wheat yield formation, water and fertilizer use efficiency, and OPT obtained the highest yield (4497.3 kg ha−1), N uptake (138.7 kg ha−1), and water use efficiency (WUE, 13.3 kg ha−1). Compared with CK, OPT increased the wheat yield, N uptake, WUE, and WP by 21.5%, 16.7%, 16.6%, and 12.6%, respectively, and there were no significant differences between OPT10 and OPT. ConclusionsOptimizing the soil and fertilizer management strategies increased the soil water and NO3–-N contents, delayed leaf senescence, enhanced the leaf antioxidant and photosynthetic capacities, promoted wheat yield formation and efficient resource utilization. A 10% reduction in N fertilizer input based on no-till, straw mulching and green manure planting during the fallow period is an efficient soil and fertilizer management strategy for ensuring sustainable wheat production in semi-arid areas of the Loess Plateau. ImplicationsOur findings provide a reference for wheat production in semi-arid regions similar to the Loess Plateau throughout the world.

The Effect of Empowerment on the Adoption of Soil and Water Conservation Technology in the Loess Plateau of China

Since there is a serious problem of land degradation and soil erosion in the Loess Plateau region of China, soil and water conservation technology (SWC) is necessary to protect land resources and reduce water loss, so as to promote the development of sustainable agriculture. By using the binary probit model, this study analyzes the effect of organizational, economic and self-empowerment on the adoption of soil and water conservation technology in the Loess Plateau region of China. The results indicated that all these empowerments have significant positive effects on the adoption of SWC, and there are significant gender differences in the impact. Organizational empowerment had a more significant impact on the adoption of SWC by male household heads, while economic empowerment and self-empowerment had a more significant effect on the adoption of SWC by female household heads. Therefore, more organizational and financial support for farmers is needed, and farmers themselves should have more confidence in the adoption of new technologies. Furthermore, given the gender differences in the impact, more gender equality should be ensured in the promotion of agricultural technologies.

Effects of Future Climate Change on Spring Maize Yield and Water Use Efficiency under Film Mulching with Different Materials in the LOESS Plateau Region of China

Background: Traditional polyethylene film mulching is widely used in the Loess Plateau region of China to improve crop yields. However, whether long-term polyethylene film mulching can continue to ensure crop yield under future climate change conditions is questionable. First, we conducted a four-year field experiment to calibrate and validate the biogeochemical DeNitrification–DeComposition (DNDC) model. Then, based on the calibrated and validated model, we evaluated the spring maize yield and water use efficiency under different film mulching methods (no mulching, traditional polyethylene film mulching, and biodegradable film mulching) in the Loess Plateau region. Results: The temperature and rainfall in the Loess Plateau region are predicted to increase in the future (2021–2100) under four scenarios due to higher CO2 concentrations. Through 252 simulation results, we found that future climate change will have positive impacts under no mulching, traditional polyethylene film mulching, and degradable film mulching conditions. The yield increase will be greater with no mulching, but in the future, film mulching will continue to reduce crop yields. Additionally, the crop yield reduction under traditional polyethylene film mulching is greater. A sensitivity analysis indicated that rainfall will have a major effect on yield, and polyethylene film mulching will reduce the sensitivity of the yield to rainfall. As the rainfall increases, the differences between the yield and water use efficiency under ordinary plastic film and degradable film will become smaller. In the later period with a warmer and wetter climate under the SSP585 scenario, the water use efficiency will be higher under degradable film than traditional polyethylene film mulching. Conclusion: It can be seen that degradable film is more adaptable to the warmer and wetter climate in the future.

Effects of physical crust on soil detachment by overland flow in the Loess Plateau region of China

Physical soil crust (PSC), a key component of surface soil structure, exists extensively in loess areas. PSC is considered to have a significant effect on soil detachment processes. However, the long-term effects and the corresponding mechanisms of PSC on soil detachment by overland flow are still not well understood, especially in natural environments. To investigate temporal variation in soil erosion resistance and the underlying factors during PSC formation, an 8 × 8-m soil plot was exposed to natural conditions in the Loess Plateau over a 524-day period spanning two rainy seasons and a winter between them. A flume test was conducted to determine soil detachment capacity (Dc) under six designed flow shear stress levels (5.66–22.11 Pa) using crusted (SC) and non-crusted (NSC) soil samples at different PSC development stages. Subsequently, two soil erosion resistance parameters, rill erodibility (Kr) and critical shear stress (τc), were calculated. Over time, in the SC and NSC treatments, Kr decreased from 0.516 to 0.120 s m−1 and 0.521 to 0.223 s m−1, respectively, while τc increased from 0.49 to 4.42 Pa and 0.26–2.46 Pa, respectively. Variation in soil erosion resistance was rapid in the first one to two months, and then slowed down, with slight fluctuations afterwards. In the SC treatment, Kr was 42% lower and τc was 67% greater than those in the NSC treatment. Soil properties changed greatly for both treatments. SCT increased from 0 to 7.09 mm in the SC treatment. Coh increased from 2.91 to 9.04 kPa and 3.01–4.78 kPa in SC and NSC treatments, respectively. Both soil erosion resistance parameters could be well predicted by SCT and Coh in the SC treatment (R2 ≥ 0.82), while their best predictor was Coh in the NSC treatment (R2 ≥ 0.90). The results demonstrate that PSC formation enhances soil erosion resistance in the soil detachment process in the loess region under natural conditions. Our study revealed the important role and complexity of PSC in the process of soil erosion, and provided theoretical and data support for accurate understanding and prediction of soil erosion.

Land Subsidence Monitoring and Building Risk Assessment Using InSAR and Machine Learning in a Loess Plateau City—A Case Study of Lanzhou, China

As a representative city located in the Loess Plateau region of China, Lanzhou is affected by various environmental and engineering factors, such as precipitation, earthquake subsidence, and building construction, which all lead to frequent geological disasters. Obtaining information on land subsidence over a long time series helps us grasp the patterns of change in various types of ground hazard. In this paper, we present the results of using Interferometric Synthetic Aperture Radar (InSAR) to monitor land subsidence in the main urban area of Lanzhou from 26 October 2014 to 12 December 2021. The main influential factors leading to subsidence were analyzed and combined via machine learning simulation to assess the land subsidence risk grade distribution of a building unit. The results show that the annual average deformation rate in Lanzhou ranged from −18.74 to 12.78 mm/yr. Linear subsidence dominated most subsidence areas in Lanzhou during the monitoring period. The subsidence areas were mainly distributed along the Yellow River, the railway, and villages and towns on the edges of urban areas. The main areas where subsidence occurred were the eastern part of Chengguan District, the railway line in Anning District, and the southern parts of Xigu District and Qilihe urban area, accounting for 38.8, 43.5, 32.5, and 51.8% of the area of their respective administrative districts, respectively. The random forest model analysis results show that the factors influencing surface subsidence in Lanzhou were, in order of importance, precipitation, the distribution of faults, the lithology of strata, high-rise buildings, and the distance to the river and railway. Lanzhou experienced excessive groundwater drainage in some areas from 2015 to 2017, with a 1 m drop in groundwater and 14.61 mm surface subsidence in the most critical areas. At the same time, extensive subsidence occurred in areas with highly compressible loess ground and most railway sections, reaching a maximum of −11.68 mm/yr. More than half of the super-tall building areas also showed settlement funnels. The area at a very high risk of future subsidence in Lanzhou covers 22.02 km2, while the high-subsidence-risk area covers 54.47 km2. The areas at greatest risk of future subsidence are Chengguan District and Qilihe District. The city contains a total of 51,163 buildings in the very high-risk area, including about 44.57% of brick-and-timber houses, 51.36% of old housing, and 52.78% of super-tall buildings, which are at especially high risk of subsidence, threatening the lives and properties of the population. The deformation results reveal poor building safety in Lanzhou, providing an essential basis for future urban development and construction.