The ratio of transpiration to evapotranspiration in a rainfed maize field on the Loess Plateau of China

Maize (Zea mays L.) is a major crop on the Loess Plateau, and calculating the ratio of transpiration to evapotranspiration (T/ET) of maize is important for estimating field water balance. In this study, the sap flow method was adopted to measure transpiration (T) characteristics of maize. In order to calibrate the sap flow gauge, the sap flow rate was compared to the leaf T determined by the weighing method. The sap flow value was measured per hour for 3 days and the mean of the hourly values for each day was taken as the daily value to avoid the influence of hydraulic capacitance. There was a significant linear relationship between leaf T and sap flow rate. The slope and intercept of linear regression were 0.764 and 4.944, with an R2 of 0.97 (p < 0.01). We also analyzed the T and ET of maize under field conditions. The T/ET of maize was 63.3% from July to September 2012. The T/ET and leaf area index had a good linear relationship. Partitioning of ET into soil evaporation (E) and T may have important implications for analyzing crop water use efficiency, evaluating the crop production potential of precipitation and optimizing field water management.

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Nitrogen Supply Affects Grain Yield by Regulating Antioxidant Enzyme Activity and Photosynthetic Capacity of Maize Plant in the Loess Plateau

Agronomy ◽

10.3390/agronomy11061094 ◽

2021 ◽

Vol 11 (6) ◽

pp. 1094

Author(s):

Kai Yue ◽

Lingling Li ◽

Junhong Xie ◽

Setor Kwami Fudjoe ◽

Renzhi Zhang ◽

...

Keyword(s):

Grain Yield ◽

Antioxidant Enzyme ◽

Loess Plateau ◽

Photosynthetic Capacity ◽

Growth And Yield ◽

Dry Matter Accumulation ◽

The Loess Plateau ◽

Area Index ◽

Leaf Stage ◽

Significant Difference

Nitrogen (N) is the most limiting nutrient for maize, and appropriate N fertilization can promote maize growth and yield. The effect of N fertilizer rates and timings on morphology, antioxidant enzymes, and grain yield of maize (Zea mays L.) in the Loess Plateau of China was evaluated. The four N levels, i.e., 0 (N0), 100 (N1), 200 (N2), and 300 (N3) kg ha−1, were applied at two timings (T1, one-third N at sowing and two-thirds at the six-leaf stage of maize; T2, one-third applied at sowing, six-leaf stage, and eleven-leaf stage of maize). The results show that N2 and N3 significantly increased the plant height, stem and leaf dry weight, and leaf area index of maize compared with a non-N-fertilized control (N0). The net photosynthetic rate, transpiration rate, stomatal conductance, and leaf chlorophyll contents were lower, while the intercellular carbon dioxide concentration was higher for non-fertilized plants compared to fertilized plants. The activities of peroxidase (POD) and superoxide dismutase (SOD) increased with N rate, but the difference between 200 and 300 kg ha−1 was not significant; further, the isozyme bands of POD and SOD also changed with their activities. Compared with a non-N-fertilized control, N2 and N3 significantly increased grain yield by 2.76- and 3.11-fold in 2018, 2.74- and 2.80-fold in 2019, and 2.71- and 2.89-fold in 2020, and there was no significant difference between N2 and N3. N application timing only affected yield in 2018. In conclusion, 200 kg N ha−1 application increased yield through optimizing the antioxidant enzyme system, increasing photosynthetic capacity, and promoting dry matter accumulation. Further research is necessary to evaluate the response of more cultivars under more seasons to validate the results obtained.

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The effects of three micro-catchment practices on erosion and runoff dynamics for a typical soil slope on the Loess Plateau of China

Canadian Journal of Soil Science ◽

10.1139/cjss-2018-0089 ◽

2019 ◽

Vol 99 (1) ◽

pp. 46-59 ◽

Cited By ~ 4

Author(s):

Liquan Sun ◽

Shufang Wu ◽

Robert Lee Hill ◽

Huili Guo ◽

Hao Feng

Keyword(s):

Soil Erosion ◽

Loess Plateau ◽

Crop Production ◽

Linear Functions ◽

Fish Scale ◽

Transition Flow ◽

The Loess Plateau ◽

Stream Power ◽

Cumulative Rainfall ◽

Reduction Effect

Three micro-catchment measures that are named fish-scale pits (FSPs), artificial digging (AD), and contour plowing (CP) for soil erosion prevention are widely used in the Loess Plateau. To clarify the effectiveness of these measures in intercepting runoff and reducing erosion and the mechanism of water flow movement, intermittent simulated rainfall events was carried out in the 15° slopes with FSPs, AD, CP, and control slope (CK). The results demonstrated the following. (1) For cumulative rainfall <83 mm, three measures effectively intercepted runoff and reduced sediment compared with the CK. The runoff and sediment reduction effect of three measures gradually disappeared when cumulative rainfall increased to 83, 99, and 108 mm, and the sediment generation of the three measures successively exceeded that of the CK and was more than two times higher. (2) Laminar or transition flow occurred for the CK, and the flow pattern changed from subcritical to supercritical at 101 mm of cumulative rainfall. For three measures, the flow patterns became turbulent within a short time but remained subcritical. (3) A correlation analysis showed that the soil detachment rate, hydraulic shear stress, and stream power in the micro-catchment measures can be described using linear functions, which reduced the rill erodibility and enhanced the soil’s resistance to concentrated flow erosion. This research has important guiding significance on the rational and effective implementation of micro-catchment practices to prevent severe soil erosion and increase water storage for crop production on the Loess Plateau of China.

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Coupling model of ecohydrology and simulation of typical shrub ecosystems on the Loess Plateau

10.5194/egusphere-egu2020-4423 ◽

2020 ◽

Author(s):

Yu Zhang ◽

Xiaoyan Li ◽

Wei Li ◽

Weiwei Fang ◽

Fangzhong Shi

Keyword(s):

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Loess Plateau ◽

Field Experiments ◽

Annual Precipitation ◽

The Loess Plateau ◽

Rainfall Interception ◽

Area Index ◽

Caragana Korshinskii

Shrub is the main vegetation type for vegetation restoration in the Loess Plateau, which plays an important role in the regional ecosystem restoration. Study on the relationships between vegetation and soil water of typical shrub ecosystems are significant for the restoration and reconstruction of ecosystems in the Loess Plateau. Three typical shrub (Hippophae rhamnoides Linn., Spiraea pubescens Turcz., and Caragana korshinskii Kom.) ecosystems were chosen in the Loess Plateau. Field experiments were conducted to investigate the factors that influencing the processes of rainfall interception and root uptake of typical shrubs. S-Biome-BGC model was established based on the Biome-BGC model by developing the rainfall interception and soil water movement sub-models. The model was calibrated and verified using field data. The calibrated S-Biome-BGC model was used to simulate the characteristics of leaf area index (LAI), net primary productivity (NPP), soil water content and the interactions among them for the shrub ecosystems along the precipitation gradients in the Loess Plateau, respectively. The results showed that the predictions of the S-Biome-BGC model for soil water content and LAI of typical shrub ecosystems in Loess Plateau were significantly more accurate than that of Biome-BGC model. The simulated RMSE of soil water content decreased from 0.040~0.130 cm3 cm-3 to 0.026~0.035 cm3 cm-3, and the simulated RMSE of LAI decreased from 0.37~0.70 m2 m-2 to 0.35~0.37 m2 m-2. Therefore, the S-Biome-BGC model can reflect the interaction between plant growth and soil water content in the shrub ecosystems of the Loess Plateau. The S-Biome-BGC model simulation for LAI, NPP and soil water content of the three typical shrubs were significantly different along the precipitation gradients, and increased with annual precipitation together. However, different LAI, NPP and soil water correlations were found under different precipitation gradients. LAI and NPP have significant positive correlations with soil water content in the areas where the annual precipitation is above 460~500 mm that could afford the shrubs growth. The results of the study provide a re-vegetation threshold to guide future re-vegetation activities in the Loess Plateau.

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Spatial–Temporal Changes and Driving Force Analysis of Ecosystems in the Loess Plateau Ecological Screen

Forests ◽

10.3390/f13010054 ◽

2022 ◽

Vol 13 (1) ◽

pp. 54

Author(s):

Kai Su ◽

Hongjun Liu ◽

Huiyuan Wang

Keyword(s):

Economic Development ◽

Loess Plateau ◽

Soil Conservation ◽

Chinese Government ◽

Total Solar Radiation ◽

Ecosystem Structure ◽

The Loess Plateau ◽

Area Index ◽

Gradual Improvement ◽

Ecological Degradation

The ecological degradation caused by unreasonable development and prolonged utilization threatens economic development. In response to the development crisis triggered by ecological degradation, the Chinese government launched the National Barrier Zone (NBZ) Construction Program in 2006. However, few in-depth studies on the Loess Plateau Ecological Screen (LPES) have been conducted since the implementation of that program. To address this omission, based on the remote sensing image as the primary data, combined with meteorological, soil, hydrological, social, and economic data, and using GIS spatial analysis technology, this paper analyzes the change characteristics of the ecosystem pattern, quality, and dominant services of the ecosystem in the LPES from 2005 to 2015. The results show that from 2005 to 2015, the ecosystem structure in the study area was relatively stable, and the area of each ecosystem fluctuated slightly. However, the evaluation results based on FVC, LAI, and NPP showed that the quality of the ecosystem improved. The vegetation coverage (FVC) increased significantly at a rate of 0.91% per year, and the net primary productivity (NPP) had increased significantly at a rate of 6.94 gC/(m2∙a) per year. The leaf area index (LAI) in more than 66% of the regions improved, but there were still about 8% of the local regions that were degraded. During these 10 years, the soil erosion situation in LPES improved overall, and the amount of soil conservation (ASC) of the ecosystem in the LPES increased by about 0.18 billion tons. Grassland and forest played important roles in soil conservation in this area. Pearson correlation analysis and redundancy analysis showed that the soil conservation services (SCS) in the LPES were mainly affected by climate change, economic development, and urban construction. The precipitation (P), total solar radiation (SOL), and temperature (T) can explain 52%, 30.1%, and 17% of the change trends of SCS, respectively. Construction land and primary industry were negatively correlated with SCS, accounting for 22% and 8% of the change trends, respectively. Overall, from 2005 to 2015, the ecological environment of LPES showed a gradual improvement trend, but the phenomenon of destroying grass and forests and reclaiming wasteland still existed.

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In Situ Sample Dataset of Stem Sap Flow of Robinia pseudoacacia Plantation on the Loess Plateau

GCdataPR ◽

10.3974/geodb.2019.06.17.v1 ◽

2020 ◽

Author(s):

Jun ZHANG ◽

Li DI ◽

Zhini CHEN ◽

Anmin WANG ◽

Fan NI ◽

...

Keyword(s):

Loess Plateau ◽

Sap Flow ◽

Robinia Pseudoacacia ◽

The Loess Plateau

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Characterizing drought in terms of changes in the precipitation–runoff relationship: a case study of the Loess Plateau, China

Hydrology and Earth System Sciences ◽

10.5194/hess-22-1749-2018 ◽

2018 ◽

Vol 22 (3) ◽

pp. 1749-1766 ◽

Cited By ~ 7

Author(s):

Yuan Zhang ◽

Xiaoming Feng ◽

Xiaofeng Wang ◽

Bojie Fu

Keyword(s):

Loess Plateau ◽

Mean Annual Precipitation ◽

Water Yield ◽

Drought Severity ◽

The Loess Plateau ◽

Drought Duration ◽

Continuous Precipitation ◽

Area Index ◽

Limited Region

Abstract. The frequency and intensity of drought are increasing dramatically with global warming. However, few studies have characterized drought in terms of its impacts on ecosystem services, the mechanisms through which ecosystems support life. As a result, little is known about the implications of increased drought for resource management. This case study characterizes drought by linking climate anomalies with changes in the precipitation–runoff relationship (PRR) on the Loess Plateau of China, a water-limited region where ongoing revegetation makes drought a major concern. We analyzed drought events with drought durations ≥ 5 years and mean annual precipitation anomaly (PA) values ≤ −5 % during drought periods. The results show that continuous precipitation shifts are able to change the water balance of watersheds in water-limited areas, and multi-year drought events cause the PRR to change with a significantly decreasing trend (p < 0.05) compared to other historical records. For the Loess Plateau as a whole, the average runoff ratio decreased from 10 to 6.8 % during 1991–1999. The joint probability and return period gradually increase with increasing of drought duration and severity. The ecosystem service of water yield is easily affected by drought events with durations equal to or greater than 6 years and drought severity values equal to or greater than 0.55 (precipitation ≤ 212 mm). At the same time, multi-year drought events also lead to significant changes in the leaf area index (LAI). Such studies are essential for ecosystem management in water-limited areas.

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