中国生态农业学报(中英文)

Agricultural water issues in China - Discussions on research highlights

LIU Changming

2014, 22(8): 875-879. doi: 10.13930/j.cnki.cjea.140649

Abstract(1212) PDF(2343)

Abstract:
Agricultural water use is a major consuming way of water resources, especially in the North China where irrigation has induced severe over-exploitation of groundwater as surface water systems are lacking. With rapid socio-economic development, shortage of water resources intensified over the years. Water cycle remained the scientific basis of research on agricultural water-saving in China and around the globe. Clarifying water cycle and exploring transformation among precipitation, plant water, surface water, soil water and groundwater laid the critical bases for agricultural water-saving research. The core elements of agricultural water-saving research included the regulation and control of the interfaces of agricultural water processes such as soil- atmosphere, root-soil and vegetation-atmosphere interfaces. Researches on agricultural water-saving and systems engineering (which involved studies on rational utilization of water resources, water-saving technology, water-saving agricultural practices and water- saving management measures) ensured the realization of high-production, water-saving agriculture. The paper argued that among the effective ways, meeting agricultural water issues in China were paying more attention on scientific management of water resources, improving water use efficiency, establishing market mechanism for water-saving agriculture and promoting construction of water- saving facilities. Meanwhile, intensive research on water cycle and full utilization of inferior water resources were other vital ways easing water shortage in China.

Towards water and food security in China

KANG Shaozhong

2014, 22(8): 880-885. doi: 10.13930/j.cnki.cjea.140715

Abstract(1659) PDF(2992)

Abstract:
Sustained supply of sufficient water resources and quality food is essential for the continuity of human being society. Water security is fundamental for food security. Continuously increasing the utilization efficiency of agricultural water resources is the only way to ensure future water and food security. This paper focused on the basic issues of water and food security, including the definitions, present and future states at global and national scales, water resources supporting strategies for national food security, and development of water-saving agriculture in China. The key issues of water and food security were reviewed and discussed, including efficient crop water consumption, high-efficiency control and management of water resources, ecological and environmental effects of agricultural water consumption processes and responses to flood and drought events. Then four major research fields were summarized, including: 1) ideal crop water consumption mechanisms and multi-process synergy control mechanisms, 2) multi-scale water cycle and accompanying processes at irrigation district scales with highly intensive human activity, 3) mutual feedback mechanisms of food production-water resources-ecological process systems, and 4) disaster-causing mechanisms and early-warning mechanisms of agricultural drought and flood disasters.

Water-use efficiency and water use effectiveness: A stomatal perspective using stable isotopes

Graham Farquhar, (translated by ZHANG Yucui)

2014, 22(8): 886-889. doi: 10.13930/j.cnki.cjea.140710

Abstract(1333) PDF(2251)

Abstract:
Rainfall is stochastic in Australia and always appears an uneven distribution. As in the North China Plain (NCP), water shortage is the key limiting factor for the food production and crop yield. Agricultural water usage accounts for the largest proportion in the total water consumption. It is meaningful to improve the water-use efficiency and water use effectiveness of the plant/crop for the sustainable development of water resources and agricultural production. Based on the conditions of agricultural production and water shortage in Australia and the NCP, this research concerned the following three aspects from a stomatal perspective: first, the conception of water-use efficiency and water use effectiveness; secondly, research on the water-use efficiency in the stomatal scale; thirdly, the varieties differences of carbon stable isotope discrimination and transpiration rate. In addition, this paper also gave some advices on the agricultural water use in the NCP.

Sustainable exploitable potential of shallow groundwater in the North China Plain

QIAN Yong, ZHANG Zhaoji, FEI Yuhong, CHEN Jingsheng, ZHANG Feng'e, WANG Zhao

2014, 22(8): 890-897. doi: 10.13930/j.cnki.cjea.140704

Abstract(1245) PDF(2328)

Abstract:
As the most important water resource in the North China Plain (NCP), agricultural, economic and social development has heavily relied on shallow groundwater. Supported by data and results of the project of Investigation and Evaluation of Sustainable Utilization of Groundwater, the paper calculated the exploitable amount of shallow groundwater, and evaluated the exploitable potential and sustainable utilization potential of shallow groundwater in the NCP. The total exploitable amount of shallow groundwater in the NCP was 202.94 × 10⁸ m³ a^-1, with a modulus of 14.58 × 10⁴ m³ a^-1 km^-2. Shallow groundwater was unevenly distributed in the NCP, abundant in the piedmont plain and along the Yellow River, and scarce in the middle and eastern plain regions. The estimated exploitable potential coefficient was 1.15, suggesting equilibrium between exploitation and recharge with high exploitable potential in the whole NCP region. But the exploitable potential distribution was very uneven, with the maximum value in Binzhou of Shandong Province (5.16), followed by Tianjin (4.18), and the minimum value in Shijiazhuang (0.72), followed by Langfang (0.75) in Hebei Province. The evaluation results suggested that the exploitable potential of shallow groundwater was almost exhausted. Specifically, freshwater had been over-exploited in several sections with no sustainable utilization potential. On the contrary, some 35 × 10⁸ m³ a^-1 brackish water and saline water resources in the Hebei Plain alone could be exploited to improve sustainable utilization potential of shallow groundwater in the NCP. This, however, required solving the exploitation and utilization difficulties associated with saline water. This research provided guidance for optional water resources allocation and development of the agricultural, economic and social sectors in the NCP.

Impact of climate change on water resources and adaptation strategies in the main grain production belt of the North China

WANG Guoqing, JIN Junliang, BAO Zhenxin, LIU Cuishan, YAN Xiaolin

2014, 22(8): 898-903. doi: 10.13930/j.cnki.cjea.140676

Abstract(1241) PDF(2202)

Abstract:
Climate change, as one of the important global environmental issues, distorts the hydrologic cycle and therefore has significant implications for regional water resources. The grain production belt of the North China mainly consisting of the Yellow River Basin, Hai River Basin and Huai River Basin is the region most vulnerable to climate change in China. The major water issues in this region (including severe shortage of water resources and increasing regional flooding) have attracted significant attentions from both the central government and local communities. It is therefore critical to analyze future trends in water resources and seek for adaptive strategies to climate change in the region. Using statistical methods such as the Mann-Kendall test, variations of historical runoff recorded during the period 1950-2010 at ten key hydrometric stations on the main streams of the Yellow River, Hai River and Huai River were analyzed. Based on seven GCM projects under the three emission scenarios of RCP2.6, RCP4.5 and RCP8.5, the VIC (Variable Infiltration Capacity) model was used to simulate future water resources in these basins. Using 1961-1990 as the baseline period, changes in future water resources were analyzed for each decade. The results suggested that the recorded runoffs in the middle and lower reaches of both the Yellow River Basin and the Hai River Basin significantly decreased in the last 50 years. There was a insignificant change in the Huai River Basin and in the upper Yellow River Basin. For the Hai River Basin in particular, recorded runoff after 1980 deceased by over 50% compared to the value in 1961. While projected temperature steadily rose in the next 30-50 years, precipitation slightly increased over the period. Changes in water yields under the RCP2.6, RCP4.5 and RCP8.5 climate scenarios were estimated to change by ?1.3%, 1.0% and ?2.3%, respectively, distorting the spatial distribution of water resources in the region. Water resources in the middle Yellow River Basin increased while those in both the Hai River Basin and the Huai River Basin decreased, particularly under the RCP8.5 climate scenario. The degree of water shortage in the main grain production belt of the North China was aggravated by the simulated climate change. The core activities of adaptation to climate change included enhancement of the construction of water-saving society, the full use of non-traditional water resources and also the speeding up of the planning and implementation of water conservancy projects in the region.

Correlation among farmland water consumption, grain yield and groundwater dynamics in the Hebei Plain

YUAN Zaijian, XU Yuanze, XIE Luyue

2014, 22(8): 904-910. doi: 10.13930/j.cnki.cjea.140754

Abstract(1225) PDF(2196)

Abstract:
Farmland water consumption accounts for most of the groundwater consumption in the Hebei Plain. Research on the interaction mechanism of farmland water consumption, groundwater dynamics and grain production could provide critical evidence for water-saving agriculture. Based on Hebei Province economic statistical data, groundwater exploitation data, groundwater level data and conventional meteorological data for 1981?2010, this paper analyzed the changes in farmland water consumption, grain production, precipitation and groundwater level in the Hebei Plain in the recent 30 years. Their correlation was also discussed. The results showed that in the past 30 years, the Hebei Plain consumed 722.4 km³ of water for agriculture, produced 5.9×10⁸ tons of grain and exploited 440 km³ of groundwater (330 km³ of which was used for agricultural irrigation). This led to groundwater level decline of 11.5 m over the period. In general, farmland water consumption and grain yield in the Hebei Plain increased yearly while groundwater level declined against decreasing exploitation trends since 2000. There was a close correlation among farmland water consumption, groundwater exploitation, groundwater depth and grain yield. In the study area producing 1 ton of grain required 1 224.4 m³ of water (including 597.1 m³ of groundwater). Also for every 1 km³ of groundwater exploitation, groundwater level dropped by 0.03 m. Over-exploitation was the direct cause of groundwater level loss in the plain. This was because of insufficient precipitation to replenish the groundwater in volumes commensurate to exploitation. Although groundwater exploitation in the Hebei Plain slowed down since the beginning of this century, groundwater level still continued to decline. Therefore, the further development of water-saving agriculture was necessary to improve the efficiency of irrigation and to promote sustainable development of agriculture in the Hebei Plain.

Estimation of regional evapotranspiration over the Hufu Plain using STME and MODIS data

LI Fang, SHEN Yanjun, ZHANG Yucui

2014, 22(8): 911-919. doi: 10.13930/j.cnki.cjea.140792

Abstract(2485) PDF(8850)

Abstract:
The Hufu Plain is a vital grain production base, with sufficient solar radiation, energy, fertile soils as well as intensive agricultural management. In the region, irrigation has ensured stable and high crop yields over the years. The continuous extraction of groundwater and surface water has induced severe water shortage in the Hufu Plain region. Therefore reasonable and efficient use of the limited water resources was necessary for sustainable agricultural production. Here in this study, we developed a remote sensing evapotranspiration (ET) model, STME (a single-source trapezoid model for evapotranspiration), and took 115 MODIS (moderate resolution imaging spectrometer) images (local surface temperature and reflectance) for October 1, 2011 to September 30, 2012 to estimate regional surface water deficit index (WDI) and evapotranspiration in the Hufu Plain. Two typical farmland ecosystems were selected as the investigated objectives, one was cropland ecosystem in Luancheng, the other one was orchard ecosystem in Zhaoxian. We compared the estimated ET by STME with observations by the eddy covariance system. Results suggested that the STME model well estimated daily ET. The average observed net radiation (Rn) was 4.10 mm and the average estimated Rn was 4.69 mm, with a root mean square difference (RMSD) of 0.80 mm for Zhaoxian orchard ecosystem. The average observed daily ET was 2.86 mm and the average estimated daily ET was 3.01 mm, with RMSD = 0.95 mm for Zhaoxian orchard ecosystem. Also the average observed daily ET was 2.67 mm and the average estimated daily ET was 2.44 mm, with RMSD = 0.87 mm for Luancheng cropland ecosystem. To interpret the temporal and spatial variations in regional ET, we used the STME model to estimate regional ET in the Hufu Plain study area. Furthermore, the water deficit index (WDI) reflected the severity of drought in the region. ET for orchard ecosystems in October was more than that for cropland ecosystems. The regional ET was less than 1 mm in November. In April, ET for cropland ecosystems was more than that for orchard ecosystems. Then in May, ET for cropland and orchard ecosystems was somehow similar as there was vigorous vegetation growth. In June, ET for cropland ecosystems was less than that for orchard ecosystems because wheat of cropland was harvested and maize just planted. In July, ET for the whole region was the maximum. This suggested that ET was not only related to vegetation growth, but also associated with soil moisture. In the months of August and September, ET decreased as crops matured and were harvested. WDI varied with time and place and it was practicable in guiding irrigation. STME, a mathematically-based model for calculating the vertex of trapezoid framework and water deficit index, simplified and clarified ET estimation process.

Modeling crop evapotranspiration using remotely sensed vegetation data: A case study of winter wheat in the North China Plain

WU Xifang, SHEN Yanjun, ZHANG Cong, PAN Xuepeng

2014, 22(8): 920-927. doi: 10.13930/j.cnki.cjea.140753

Abstract(1322) PDF(2732)

Abstract:
The North China Plain (NCP) is a vital granary of China, with an area of 140 000 km² of arable land which produces some 20% of the nation's grain. As local precipitation is not enough to meet crop water requirements in the NCP, irrigation is widely used to increase yields and to ensure food supply. Agriculture accounts for about 70% of water consumption in the NCP, over 75% of which is from groundwater. Groundwater resource has steadily been depleted due to persistent over-pumping, posing tremendous challenges for sustainability. Meanwhile, excessive use of groundwater has resulted in severe environmental problems in the region. Thus, in order to achieve sustainable agricultural water management in the NCP, it is extremely important to explicitly estimate crop evapotranspiration in recent decades. In this paper, a model based on crop coefficient and vegetation remote sensing data was developed to estimate crop evapotranspiration in the NCP. The model not only estimated crop evapotranspiration, but also the spatial distribution of crops and soil moisture in the region. Moreover, the model was applicable to other studies such as water use efficiency and estimation of water footprint. With the model, winter wheat evapotranspiration was estimated for 2000?2013 in the NCP. The results of the model were consistent with those of ETWatch, a remote sensing evapotranspiration estimation product (R2=0.952, RMSE=1.3×10⁷ m³). The results were as follows: 1) Winter wheat evapotranspiration was higher in the southern than in the northern region of the NCP. Evapotranspiration was in excess of 400 mm in the piedmont region of Taihang Mountains and in the irrigation region of Henan-Shandong Yellow River. It was less than 350 mm in the middle plains and even less than 200 mm in coastal areas. 2) Irrigation water consumption by winter wheat was higher in the southern than in the northern region of the NCP. Irrigation was in excess of 250 mm in the piedmont region of Taihang Mountains and in the irrigation region of Henan-Shandong Yellow River. It was less than 100 mm in northern Hebei Plain. 3) There was a significant declining trend in the cultivated area of winter wheat and in irrigation water consumption in northern Hebei Plain in recent 14 years. Along with declining irrigation water consumption was also the slowing in the downward trend in regional groundwater level. Thus the effect of water-saving on the regional groundwater level was obvious. The proposed model in this study was applicable in estimating regional crop water consumption and irrigation water management.

Comprehensive research on the state of agricultural drought in five main grain producing areas in China

KANG Lei, ZHANG Hongqi

2014, 22(8): 928-937. doi: 10.13930/j.cnki.cjea.131227

Abstract(1536) PDF(2047)

Abstract:
Affected by climate change, drought disaster has intensified in China in recent years and it has become a major threat to national food security. The comprehensive evaluation and analysis of the agricultural drought state could contribute to the efforts to clearly grasp the extent and spatial difference of agricultural drought. It could also form the foundation to further strengthen drought management and improve drought resistance in China and elsewhere. To comprehensively evaluate the state of agricultural drought in five major grain producing areas in China, this study put forward a comprehensive crop drought index and the calculation method. The comprehensive crop drought index reflects both the overall area of a region affected by agricultural drought and the difference in the extent of comprehensive agricultural drought under the influence of different levels of drought. Five main grain producing areas were selected for the study, which were Sanjiang Plain, Songnen Plain, Huang-Huai-Hai Plain, Yangtze River Middle Plain and Jianghuai Plain, Sichuan Basin. In the first step, the water-sensitive stages during the growth period were determined in relation to crop phenological data. Then based on national daily meteorological data for 1982-2011 and the spatial distribution data for major crops in the region, the crop aridity index during sensitive stages was calculated along with comprehensive crop drought index. Next, the crop drought level was analyzed along with the state of comprehensive agricultural drought in the study area. The results showed that the states of comprehensive agricultural drought in Sanjiang Plain and Songnen Plain were more serious and the degree of drought in Songnen Plain was more significant. The degree of drought during spring wheat, maize and rice in the two areas was also non-negligible. Also the extent of droughts during spring wheat in Sanjiang Plain and during spring wheat, maize and rice in Songnen Plain were clearly noticeable. The state of drought in Huang-Huai-Hai Plain was the worst in the five investigated areas, especially the drought extent during winter wheat growing season. And extent of maize drought was also obvious and that of single-season rice was relatively small. The state of comprehensive agricultural drought in Yangzi River Middle Plain and Jianghuai Plain was mild. Early rice, late rice and winter wheat showed varying degrees of drought, and were given priority as moderate and lower- degree droughts. The extent of drought for late rice in Yangtze River Middle Plain and Jianghuai Plain was the most obvious. The state of comprehensive agricultural drought in Sichuan Basin was the lowest of the five studied areas. In the area, the degree of droughts for single-season rice and maize was lower while that for winter wheat was somehow more serious.

Anti-transpirant studies and applications in agriculture

ZHANG Xiaoyu, ZHANG Xiying

2014, 22(8): 938-944. doi: 10.13930/j.cnki.cjea.140652

Abstract(1333) PDF(3133)

Abstract:
Under drought conditions, stomata is critical for regulating plant metabolism as it regulates both photosynthesis and transpiration. A considerable amount of research has focused on the regulating behavior of stomatal in strengthening the degree of drought resistance of crops. Research results suggested that crop regulatory systems established the appropriate balance between photosynthesis and water loss. While applications of plant anti-transpirants had potential limits on plant water consumption, it hardly restricted leaf photosynthesis. Thus this study reviewed recent advances in physiological mechanisms and agricultural applications of plant anti-transpirants. The action mechanisms of film-forming anti-transpirants and metabolic anti-transipirants were introduced and compared also. The possibility of evaluating the influences of anti-transpirants using environmental factors was discussed. Also discussed was the possibility of integrated environmental factors into the photosynthesis-transpiration-stomatal conductance models so as to establish the mechanisms of selecting more efficient and suitable crop anti-transpirants. The ease of use and portability of infrared thermometry in obtaining instantaneous transpiration data at large spatial scales made it applicable in evaluating the impacts of anti-transpirants and crop water stress index (CWSI). The use of infrared thermometry in calculating infrared dates made it a valuable tool for evaluating changes in crop drought stress. Finally, it was recommended to focus future research on anti-transpirants on the characteristics of crops at different growth phases and production requirements. It was also important to establish a standard procedure for using different combinations of anti-transpirants for expanded applications and optimized functions.

Effects of mulching materials and furrow-to-ridge ratios on oat grain/hay yield and water use efficiency under rainwater harvesting cultivation

REN Xiang, WANG Qi, ZHANG Enhe, SHI Shangli, WANG Heling, LIU Qinglin

2014, 22(8): 945-954. doi: 10.13930/j.cnki.cjea.140243

Abstract(1188) PDF(2347)

Abstract:
In order to improve soil water content and rainwater utilization in the semiarid Northwest China region, a field experiment of a randomized complete block design was conducted in 2012 at Dingxi Arid Meteorology and Ecological Environment Experimental Station of the Institute of Arid Meteorology of China Meteorological Administration. The experiment investigated the effects of different mulching materials [biodegradable mulch film, common plastic film, no mulching (compacted soil with soil crust)] and furrow-to-ridge ratios (60 cm∶30 cm, 60 cm∶45 cm and 60 cm∶60 cm) of rainfall harvesting cultivation with ridge and furrow on soil water storage, hay yield, grain yield, yield components and water use efficiency (WUE) of oat, with the conventional planting as the control. Also the economic benefits of rainfall harvesting cultivation with ridges and furrows were investigated. The results showed that the order of soil water storage was ridge covered with common plastic film (CMR) ≈ ridge covered with biodegradable mulch film (BMR) > ridge with compacted soil (SR) > traditional planting (TP). Also soil water storage increased with increasing ridge width. Hay yield, grain yield and WUE of oat under SR planting were respectively 12%, 18% and 27% lower than those under TP planting. While these variables were respectively 5%, 4% and 14% higher under BMR planting, they were 7%, 9% and 23% higher under CMR planting, compared with TP. In most cases, hay yield, grain yield and WUE of oat decreased with increasing ridge width. Based on regression analysis, oat grain yield under CMR planting reached the maximum of 2 213 kg·hm^-2 under furrow-to-ridge width ratio of 60 cm∶38 cm. The maximum oat grain yield of 2 114 kg·hm^-2 under BMR planting was for furrow-to-ridge width ratio of 60 cm∶34 cm. On average, the economic benefits of oat were respectively 5 194 Yuan·hm^-2, 4 557 Yuan·hm^-2, 4 889 Yuan·hm^-2 and 5 637 Yuan·hm^-2 under TP, SR, BMR and CMR planting systems. Taking grain yield, WUE and environmental protection into account, biodegradable mulch film with ridge-to-furrow width ratio of 60 cm∶34 cm was best for oat planting in the semiarid Loess Plateau regions.

Effect of nitrogen application on productivity and water use efficiency of wheat/maize intercropping system under straw mulching

WANG Lin, WANG Qi, ZHANG Enhe, LIU Qinglin, YU Hualin

2014, 22(8): 955-964. doi: 10.13930/j.cnki.cjea.131251

Abstract(1218) PDF(2987)

Abstract:
In order to obtain higher grain yields and water use efficiency (WUE), the effects of different nitrogen levels [0 kg(N)·hm^-2, 140 kg(N)·hm^-2, 221 kg(N)·hm^-2 and 300 kg(N)·hm^-2] on the productivity and WUE of wheat/maize intercropping system under straw mulching were studied. A field experiment was conducted in the oasis region of Shiyang River Basin in Gansu Province during the period from March to October 2012. The results showed that grain yield (5 036 kg·hm^-2) and WUE (25.13 kg·hm^-2·mm^-1) reached the maximum at nitrogen application rate of 221 kg(N)·hm^-2 in monoculture wheat. Grain yield (3 078 kg·hm^-2 and WUE (39.76 kg·hm^-2·mm^-1) reached the maximum at nitrogen application rate of 300 kg(N)·hm^-2 in intercropped wheat. Also grain yield (9 921 kg·hm^-2) and WUE (38.96 kg·hm^-2·mm^-1) reached the maximum in monoculture maize, grain yield (6 895 kg·hm^-2) and WUE (46.31 kg·hm^-2·mm^-1) reached the maximum in intercropped maize at nitrogen application rate of 300 kg(N)·hm^-2. Competitive capacity of wheat relative to maize was maximum (0.049) at nitrogen application rate of 0 kg(N)·hm^-2. Land equivalent ratio of wheat/maize intercropping system was maximum (1.33) at nitrogen application rate of 300 kg(N)·hm^-2. Then water competition ratio of wheat relative to maize was maximum (0.98) at nitrogen application rate of 140 kg(N)·hm^-2. The results showed that wheat/maize intercropping system had significant advantage in terms of yield and water use efficiency and wheat competitiveness was greater than that of maize. It was noted that the difference in time of water demand for physiological use by wheat and maize was the driver for the high WUE in wheat/maize intercropping system. Reasonable nitrogen application enhanced the advantages of yield and water use efficiency.

Effects of fertilization practices on infiltration in Shajiang black soils

WEI Junling, JIN Youqian, GAO Hongjian, CHANG Jiang, ZHANG Ligan

2014, 22(8): 965-971. doi: 10.13930/j.cnki.cjea.140017

Abstract(1247) PDF(2114)

Abstract:
Infiltration is an important mechanism by which rain and irrigation water replenishes soil water to support plant growth. As a low-yield soil, the Shajiang black soil has high clay content with strong wedging structures. These structures hinder infiltration and water holding capacity of the soil. This implies that high percentage of water occurring on the soil surface is lost to evaporation or the water in the soil is lost to leaching, which either way results in low plant water use efficiency. Soil structure improvement was considered as the most effective strategy to increase water holding capacity and plant water use efficiency of Shajiang black soils. However, few approaches have been developed to ameliorate soil properties in the region. Returning crop straw to the soil is a recommended approach that is extensively used in China. However, the exact role of straw products after degradation in soil property improvement and water cycle has remained largely unknown. This study investigated how the addition of maize straw and coal fly ash to soils affected soil properties and water infiltration of Shajiang black soils. Using an in situ Lysimeter field device, the effects of fertilization practices on soil properties and soil water infiltration characteristics were investigated. The study used non-fertilization as the control (CK), and formulated fertilization (PF), formulated fertilization plus 7 500 kg·hm^-2 straw returning (PF+JG) and formulated fertilization plus 7 500 kg·hm^-2 coal fly ash application (PF+FMH) as the experimental treatments. Soil properties and water infiltration characteristics were determined using the double-ring infiltration method at the end of the 2-year field experiment. The results indicated that soil organic matter in PF+JG treatment increased by 18.01% and 11.18%, that in PF+FMH treatment increased by 8.92% and 2.61% over those in CK and PF treatments, respectively. Similarly, soil total porosity respectively increased by 13.89% and 12.46% in PF+JG treatment and by 5.87%, 4.56% in PF+FMH treatment over those in CK and PF treatments. But soil bulk density decreased by 12.90% and 4.48% in PF+JG treatment and by 11.29% and 2.98% in PF+FMH treatment over those in CK and PF treatments, respectively. Cumulative soil water infiltration respectively increased by 98.08% and 34.64% in PF+JG treatment and by 90.39% and 29.41% in PF+FMH treatment over those in CK and PF treatments, which was significant. Steady-state infiltration rates of PF+JG (1.18 × 10^-4 m·s^-1) and PF+FMH (1.13 × 10^-4 m·s^-1) treatments were 1.99 and 1.91 times higher than that of CK (5.92×10^-5 m·s^-1) and 1.35 and 1.29 times higher than that of PF (8.73 × 10^-5 m·s^-1), respectively. While significant positive correlations were noted between steady-state infiltration rate and soil organic matter content or total porosity (P < 0.01), steady-state infiltration rate was negatively correlated with soil bulk density (P < 0.05). The results suggested that the application of maize straw and coal fly ash was a useful alternative method for improving soil properties and increasing water infiltration capacity in Shajiang black soils.

Relationship among water use of different plants in Heihe River riparian forests

CHEN Xiaoli, CHEN Yaning, CHEN Yapeng

2014, 22(8): 972-979. doi: 10.13930/j.cnki.cjea.140169

Abstract(1114) PDF(2249)

Abstract:
This paper analyzed the sources of water for desert riparian forests and identified the sources of water for different plant species. In order to explore the relationships among the plant species, the spatial differences in the sources of water for different forest plants were analyzed. The study provided the basis for locating ecological desert river forest oases with mixed plant species and for protecting inter-species interactions by monitoring aggressive water use and competition. A multi-isotope mass balance analysis was used to explore the potential contributions of different sources of water to plant. The xylem water and potential water resources including soil water and groundwater, of Populus euphratica (seedlings), Tamarix karelinii, Sophora alopecuroides, Hippophae rhamnoides subsp. sinensis, Karelinia caspia and Peganum nigellastrum were analyzed by using stable oxygen isotope composition (δD, δ¹⁸O) measurements and analyses. The results showed different δD, δ¹⁸O values in xylem water of different types of plants. This suggested that different plants absorbed water from different depths. The analysis showed that the main soil depth of absorbed water was 0-20 cm for P. euphratica seedlings, 200-300 cm for T. karelinii, 0-20 cm for H. rhamnoides subsp. sinensis, 50-100 cm for K. caspia, 0-20 cm for P. nigellastrum and 0-5 cm for S. alopecuroides. The contribution rates of different potential water resources were different to different plant species. Herbaceous plants mainly used shallow soil water. While shrubs with different plant species had different sources of water, P. euphratica also mainly used the shallow soil water. Based on the results of the study, competitions were noted among P. euphratica seedlings, H. rhamnoides subsp. sinensis and P. nigellastrum in the Heihe River desert riparian forests in terms of water use. P. euphratica and T. karelinii enhanced the water use of each other in the study area. Evaporation of soil moisture was the cause of enriched stable isotopes of hydrogen and oxygen in the lower reaches of Heihe River. However, these enriched stable isotopes were diluted by groundwater with increasing soil depth. This caused corresponding changes in stable isotope values with increasing soil depth.

Characteristics and potential sources of nitrate pollution in surface water and groundwater systems in Taizihe River Basin

ZHANG Yali, ZHANG Yizhang, ZHANG Yuan, LIU Xiangchao, MA Shuqin, TANG Changyuan, LIU Sisi, SUN Lihui

2014, 22(8): 980-986. doi: 10.13930/j.cnki.cjea.131176

Abstract(1344) PDF(2562)

Abstract:
As one of the main sources of drinking water and important irrigation water for agriculture, groundwater quality influences not only human health but also food security and ecological sustainability. This study attempted to lay the scientific basis for understanding nitrate pollution and groundwater quality evaluation. The study analyzed the composition of ions and concentration of nitrate in surface water and groundwater systems in Taizihe River Basin in the Northeast China. To assess nitrate pollution and identify the potential sources, surface water and groundwater samples were collected in Taizihe River Basin and the ions composition characteristics and nitrate isotopes in the groundwater samples analyzed. The results showed that nitrate was the dominant form of nitrogen pollution, accounting for 78.38% of total nitrogen concentration, with concentration range of 0.75-6.40 mg·L^-1 in surface water systems in Taizihe River Basin. The NO₂^--N was 0.78% of total nitrogen, with concentration range of 0-0.93 mg·L^-1 in surface water respectively. The concentration of NO₃^--N increased from upstream to midstream regions in the basin and the highest value (6.40 mg·L^-1) occurred at site S6, from where it declined gradually along the course of the river. However, NO₂^--N showed less change along the river. Because of extensive use of chemical fertilizers and intensive mineralization of organic nitrogen, the concentration of Cl^- and NH₄⁺ increased in the downstream regions. The concentration of NO₃^- in groundwater was generally higher than that in surface water systems. The average concentration of NO₃^- in groundwater was 20.26 mg·L^-1, suggesting that a severe NO₃^- pollution existed in the groundwater systems in Taizi River Basin. A wide range of studies has used isotropy to trace nitrate pollution sources in aquatic environment. Analysis of environmental isotopes in the study area showed that δ¹⁵N was in the range of -0.74‰-13.27‰ in surface water systems in Taizihe River Basin. Based on the results of nitrate isotope analysis, it was reasonable to conclude that NO₃^- in surface water systems in the upstream regions was mainly from mineralization of soil organic nitrogen. Agricultural fertilizers and livestock manure were the main pollution sources of NO₃^- in surface water systems in the middle and downstream regions of the basin. Higher δ¹⁵N values (5.7‰-17.5‰) were noted in groundwater system in the basin, indicating that NO₃^- in groundwater of Taizihe River Basin was mainly driven by human/animal feces and leakage of agricultural fertilizers.

Health risks of typical soil and groundwater organic pollutants in greenhouse vegetables growing area

LEI Ting, CUI Xiangxiang, ZHANG Zhaoji, FEI Yuhong, LI Yasong, QIAN Yong

2014, 22(8): 987-994. doi: 10.13930/j.cnki.cjea.140724

Abstract(1177) PDF(2160)

Abstract:
Nine groups of groundwater samples and two groups of soil samples were collected in greenhouse areas in Shijiazhuang and analyzed for organic pollutants. Two groups of groundwater samples were sampled from drinking water wells and seven groups from irrigation wells. Soil samples were surface soils inside greenhouse and farmland outside greenhouse respectively. About 20 organic pollutants were detected in the surface soil, 8 of which also occurred in groundwater with PAEs as the main pollutant. There were obvious differences in the pollutant species and content from surface soils between outside and inside greenhouse. There were more OCPs in farmland soils than inside greenhouse soils and the reverse was the general trend for PAEs and PAHs. Based on standard health risk assessments, the target pollutants for health risk were dieldrin, benzo a-anthracene, benzo a-pyrene, indeno 1,2,3-cd-pyrene, dimethyl phthalate and dibutyl phthalate. The test results showed that the characteristics of the above organic pollutants in surface soils and groundwater systems in studying area posed health risks to greenhouse farmers and sensitive population. The exploration assessment of cultivated greenhouse soils followed the four steps of Health Risk Assessment certified by US EPA. The steps include data collection and evaluation, toxicity assessment, exposure assessment and risk attribute. The major exposure pathways included oral ingestion of soil and drinking groundwater. Then oral ingestion of soil was subdivided into oral ingestion of greenhouse surface soil and that of surface soil of farmland outside greenhouse. The results of the health risk assessment showed that in this area, both non-carcinogenic risk and carcinogenic risk of greenhouse farmers were at acceptable levels. The contribution rate of dibutyl phthalate to non-carcinogenic risk, which was the most dangerous non-carcinogenic risk contaminant, was nearly 84.2%, while that of dieldrin was only 15.8%. Also the contribution rate of dieldrin to carcinogenic risk, which was the most dangerous carcinogenic contaminant, was 51.35%. That of benzo a-pyrene, the second largest rate, was about 39.75%. Then those of benzo a-anthracene and indeno 1,2,3-cd-pyrene were the least, with contribution rates of only 4.89% and 4.01%. Drinking groundwater was the main pathway for non-carcinogenic risk, with a contribution rate of about 94.42%. The contribution rates of the other two exposure pathways (oral ingestion of greenhouse surface soil and that of surface soil in farmland outside greenhouse) to non-carcinogenic risk were 5.578% and 0.002%, respectively. Oral ingestion of surface soil in farmland outside greenhouse was the main pathway for carcinogenic risk, with a contribution rate of about 47.14%. The contribution rates of the other two exposure pathways (drinking groundwater and oral ingestion of greenhouse surface soil) to carcinogenic risk were 33.2% and 19.66%, respectively.

2014 Vol. 22, No. 8