Institute of Soil and Water Conservation,Chinese Academy of Sciences and Ministry of Water Resources
Not a member yet
7916 research outputs found
Sort by
Mulching improves yield and water-use efficiency of potato cropping in China: A meta-analysis
No full textChina is the world's largest producer of potato (Solarium tuberosum L.). Potato productivity in China is limited by water shortage. Mulching applications can effectively modify the plant hydrothermal micro-environment. However, the impacts of mulching on potato yield vary with climatic conditions and field managements. Here, we conducted a meta-analysis to evaluate the effects of plastic mulching and straw mulching on the yield and water-use efficiency (WUE) of potato cropping in China using data obtained from 131 peer-reviewed publications. The results showed that plastic mulching and straw mulching increased potato yield in average by 24.3% and 16.0%, respectively. The effects of mulching on the WUE of potato were also improved by 28.7% (plastic mulching) and 5.6% (straw mulching). At regional scale, plastic mulching performed better in Northeast China and Northwest China, while straw mulching performed better in Southwest China and South China. The yield and WUE of potato in response to mulching were affected by the mean growing season air temperature, water input, soil basic fertility and fertilizer applications. When compared to non-mulching control, the improvements of yield and WUE in potato were higher at mean air temperatures of 15-20 C-degrees than at temperatures below 15 degrees C or above 20 degrees C during the growing season for both mulching practices. Increase in potato yield under black film was significantly higher than that under transparent film when air temperature was over 20 degrees C. Potato yield and WUE increases in mulching treatments were greater in areas with a water input of 400 mm. The mean effects of mulching on the yield of potato were greater at relatively low ( 200 kg ha(-1))N rates. Similar trends were observed for P and K rates. In conclusion, this meta-analysis demonstrated that mulching increases the yield and WUE of potato in China and that the adoption of mulching practices should be site specific
Distinguishing transport-limited and detachment-limited processes of interrill erosion on steep slopes in the Chinese loessial region
No full textDistinguishing transport- and detachment-limited processes of interrill erosion on the basis of the ratio of interrill erosion rate (Q) to splash detachment rate (D) was investigated to fully understand interrill erosion processes. A modified experimental device was used to measure interrill erosion and splash detachment rates simultaneously at 12.23%, 17.63%, 26.8%, 36.4%, 40.40% and 46.63% slope gradients under rainfall intensities of 48 and 120 mm h(-1). Results showed that the transport-limited (Q D), and transport- and detachment-limited (Q D) processes were respectively included in individual rainfall event, which were influenced by slope gradient and rainfall intensity, and the transport-limited process changed to a detachment-limited process early when the slope gradients were steep. Furthermore, the ratio of interrill erosion rate to splash detachment rate under rainfall intensities of 48 and 120 mm h(-1) increased from 0.006 to 36.91 and from 0.14 to 15.65 as the slope gradient increased from 12.23% to 46.63%, respectively. The research findings emphasise the importance of quantifying transport- and detachment-limited processes on steep slopes
Nitrogen fertilization improved water-use efficiency of winter wheat through increasing water use during vegetative rather than grain filling
No full textWater availability is a major constraint for wheat production in many semiarid regions of the world, including the Loess Plateau of China, and thus improving the water use efficiency (WUE) becomes a main research target. The impact of nitrogen (N) fertilizer on root growth, water use and WUE were examined for winter wheat grown in a semiarid farm on the Loess Plateau of China. A four-growing season field study (2011-2015) at the Changwu Agri-ecological Station, Changwu, Shaanxi, China with four rates of N fertilizer (0,60,120 and 180 kg N ha(-1)) were conducted to determine soil water balance, root growth, yield and WUE in each growing season. Soil water content at final harvest in each growing season was lower and evapotranspiration (ETg) was higher under N supply than under non-N fertilization. N supply increased root growth and root length density (RLD) in deeper layers of the soil profile (80-140 cm), and improved water uptake, above-ground biomass and WUEb during vegetative growth stage. Grain yield under 60, 120 and 180kg N h a(-1), increased by 12.8, 25.4 and 34.8%, respectively, with corresponding improvements in WUEg of 5.1,13.8 and 29.3%, respectively, when compared to the non-N treatment. Our results demonstrated that N applications improved dryland winter wheat WUEg by increasing deep root growth and water use during vegetative. (c) 2017 Published by Elsevier B.V
Large-scale soil organic carbon mapping based on multivariate modelling: The case of grasslands on the Loess Plateau
No full textThe Loess Plateau is considered one of the world's regions with severe soil erosion. Grasslands are widely distributed on the Loess Plateau, accounting for approximately 40% of the total area. Soil organic carbon (SOC) plays an important role in the terrestrial carbon cycle in this region. We compiled more than 1,000 measurements of plant biomass and SOC content derived from 223 field studies of grasslands on the Loess Plateau. Combined with meteorological factors (precipitation and air temperature) and the photosynthetically active radiation factor, the topsoil SOC contents of grasslands were predicted using the random forest (RF) regression algorithm. Predicted grassland SOC content (1.70-40.34gkg(-1)) decreased from the southeast to the northwest of the Loess Plateau, with approximately 1/5 of the grassland exhibiting values lower than 4gkg(-1). Observed SOC content was positively correlated with observed plant biomass, and for predicted values, this correlation was strong in the desert steppe and the steppe desert of rocky mountains. Air temperature was the most important factor affecting SOC contents in the RF model. Moreover, the residual error of observations and predictions increased as the grazing intensity varied from none to very severe in the temperate desert steppe, and this RF model may not perform well in plains. The use of the RF model for SOC prediction in Loess Plateau grasslands provides a reference for C storage studies in arid and semi-arid regions, and aboveground biomass and temperature should receive more attention due to increasing C sequestration
尿素对浑水水肥一体化滴灌滴头堵塞的影响
No full text为确定水肥一体化灌溉过程中，尿素对滴头堵塞的影响，分别配置了 3 种泥沙浓度( 1． 0、 1． 5 g·L － 1
和 2． 0 g·L － 1 ) ，3 种肥料质量浓度( 1% 、 2% 和 3% ) ，进行了间歇灌水堵塞试验，分析了滴头流量和排出泥沙量。
结果表明: 施加尿素对浑水滴灌具有缓解滴头堵塞的作用，在一定的尿素浓度范围内，施肥浓度越大，减缓作用越
明显; 施肥浓度对滴头的堵塞形式和主要堵塞物淤积位置的影响很小。滴头出流泥沙含量随灌水次数的增加呈现
先快速增加，后逐渐变缓并趋于下降的趋势。施加尿素提高了滴头泥沙输送能力，施肥浓度越大，滴头输送泥沙的
能力越大，泥沙排出率越大。浑水中施加尿素具有减缓滴头堵塞，延长滴头有效灌水次数的作用，当含沙量为 2． 0
g·L － 1 时，尿素浓度为 1% ，2% 和 3% 的水肥一体化滴灌有效灌水次数比未添加尿素的可分别提高 11% ，89% 和
100% 。可尝试通过尿素水肥一体化滴灌，缓解黄河水滴灌滴头堵塞危险，提高滴灌系统使用效率。</p
Relationships of the hydraulic flow characteristics with the transport of soil organic carbon and sediment loss in the Loess Plateau
No full text
Erosive power is characterized by the hydraulic forces of moving water and determines the water transport capacity of soil organic carbon (SOC) and sediment. Understanding the relationships of hydraulic flow characteristics (flow velocity and depth, shear stress and stream power) with the transport of sediments and SOC will improve the understanding of the transport mechanism of sediment and SOC, which in turn will improve SOC prediction. To address this issue, two loess soils (one silt loam and one silty clay) were selected, and 32 simulated rainfall experiments were conducted in a 1 m by 5 m soil pan at a varying slopes (10°, 15°, 20°, and 25°) and two rainfall intensities (90 mm h−1 and 120 mm h−1). The results showed that the flow velocities had significant
positive linear relationships with the SOC concentrations (P < 0.001) under the rainfall intensity of 90 mm h−1 and that the flow velocities also had close relationships with the suspension transport of clay particles in the fine-textured soil and the rolling transport of light large aggregates in the coarse-textured soil. Under the rainfall intensity of 120 mm h−1, the runoff depth was positively correlated with the SOC concentrations due to the
suspension transport of the clay particles and was negatively correlated with the sediment concentration. The slope had a greater effect on the sediment and SOC loss of the coarse-textured soil than those of the fine-textured soil. Additionally, the stream power was a better descriptor of the sediment loss in the loess soils than shear stress. Overall, both the soil texture and rainfall intensity changed the relationships of the hydraulic flow
characteristics with the sediment and SOC loss. Finally, the results of our study will provide important knowledge for improving or building hydraulic-based SOC and sediment loss models.</div
Simulating the potential distribution of Elaeagnus angustifolia L. based on climatic constraints in China
No full text
Elaeagnus angustifolia L. has considerable ecological value and plays an important role in windbreak and sandfixation, soil and water conservation, vegetation restoration and afforestation in Asia. Understanding the potential distribution and the limiting climatic factors is the first step for sustainable use of this species at regional scale. Here, we simulated the potential distribution of E. angustifolia and evaluated its limiting climatic factors using a maximum entropy model (MaxEnt) and geographical information system (GIS) in China, based on 190 occurrence grid cells and 13 climatic variables in China. The results show that: (1) annual range of temperature (ART), annual mean temperature (AMT), humidity index (HI), and coldness index (CI) are the dominant climatic
factors limiting its potential distribution range; (2) low temperature is an important climatic factor that limits both southern and northern distribution boundaries, and high rainfall is another climatically limiting factor for them temperate and middle temperate zone with cold and dry winters, and in the arid and semi-arid regions of China between 30°N and 50°N. The simulating results can improve our understanding of the geographical and ecological char- acteristics of E. angustifolia, and provide references for the introduction of this species for control and restoration of degraded land in China.</div
New design of external heat-ratio method for measuring low and reverse rates of sap flow in thin stems
No full textSap-flow techniques had limited application to thin-stemmed woody and herbaceous species and to diverse functional plant organs until the recent development of the external heat-ratio (EHR) method. Existing EHR techniques using miniature gauge configurations, however, are limited to thin stems with diameters of 2–5 mm. This study introduces a new design of an EHR gauge adapted to thin stems with diameters up to 15 mm and sap-flux densities <50 cm h−1. The gauge was calibrated on cut stems of the shrubs Caragana korshinskii and Salix psammophila, with the measured heat-pulse velocity (Vh) compared to gravimetric measurements of sap-flux density (Vs) under controlled conditions. A validation test was also carried out by comparing EHR method with the stem heat-balance (SHB) method through in situ and long-term monitoring of Vs on standing stems of C. korshinskii. Vh in the tested cut stems of both species was linearly correlated with Vs up to approximately 50 cm h−1 (R2 up to 0.96, P < 0.001) in a range of stem diameters of 4.1–15.6 mm. An empirical multiplier for converting the measured Vh to Vs, however, varied between the two species, 2.02 and 1.15 for C. korshinskii and S. psammophila, respectively. The EHR technique sensitively captured the diurnal dynamics of Vs in field tests, within a range from zero to nearly 30 cm h−1 on C. korshinskii stems, and hourly Vs was linearly correlated with the reference evapotranspiration (R2 = 0.70, P < 0.001) over 26 successive days without drought stress. The tested SHB method, however, poorly detected the sap-flux density, especially at low densities. The gauges for the EHR method were easy to build and capable of accurate estimating bidirectional sap flow, especially at low densities. This technique, with variable EHR gauge configurations, has broader applications than SHB methods for understanding plant-water relations in understories, shrubs and ecosystems dominated by herbage.</p
地膜覆盖和施氮量对旱作春玉米农田净温室效应的影响
No full text 以旱作雨养条件下的春玉米为试验对象，在长武黄土高原农业生态试验站进行田间 试验，研究了地膜覆盖和施氮量对农田净温室效应和温室气体排放强度的影响．结果表明: 采 用地膜覆盖与增加施氮量都会影响净温室效应与温室气体排放强度，地膜覆盖条件下( FM) ， 不同施氮量的春玉米产量为 1643 ～ 16699 kg·hm－2，净温室效应( CO2 当量，下同) 为 595 ～ 4376 kg·hm－2·a－1，温室气体排放强度为213～358 kg·t－1; 无覆膜条件下( UM) ，不同施氮量 的春玉米产量为 956～8821 kg·hm－2，净温室效应为 342～4004 kg·hm－2·a－1，温室气体排放 强度为 204～520 kg·t－1．研究表明，对于旱作春玉米农田系统，地膜覆盖可以有效降低温室气 体排放强度，增加作物产量，地膜覆盖下施氮 250 kg·hm－2可以实现高产与降低环境代价的 双赢．</p