Time filter

Source Type

Liu X.,Key Laboratory of Dryland Agriculture | Liu X.,Chinese Academy of Agricultural Sciences | Xu Y.,Key Laboratory of Dryland Agriculture | Xu Y.,Chinese Academy of Agricultural Sciences | And 6 more authors.
Applied Energy | Year: 2012

Application of the ångström-Prescott (A-P) model, one of the best rated global solar irradiation (. Rs) models based on sunshine, is often limited by the lack of model parameters. Increasing the availability of its parameters in the absence of . Rs measurement provides an effective way to overcome this problem. Although some models relating the A-P parameters to other variables have been developed, they generally lack worldwide validity test. Using data from 80 sites covering three agro-climatic zones in China, we evaluated seven models that relate the parameters to annual average of relative sunshine (. n/N) (models 1-2), altitude (model 7), altitude and . n/N (model 3), altitude, . n/N and latitude (model 4), altitude and latitude (model 5) and annual average air temperature (model 6). It was found that model 7 performed best, followed by models 6, 1, 3, 2 and 4. The better performance of models 7 and 6 and the fact that they used fewer sites and variables in their establishment demonstrated that using a large dataset in developing the A-P parameter model or having more variables included is no guarantee of wider applicability, and that the local climatic regime may override other factors in the parameter modeling. This also suggests that applicability of a . Rs model is not proportional to its complexity. The common feature of the better performing models suggests that accurate modeling of parameter . a is more important than that of . b. Therefore, priority should be given to parameter models having higher accuracy for . a. Comparison of predicted against the calibrated A-P parameters revealed many unrealistic predictions by model 5, with which it was possible to obtain meaningful . Rs estimates. To ensure that a parameter model is conceptually consistent and related to reality, it is necessary to check the modeled parameters against the calibrated ones. Models 1, 6 and 7 showed an advantage in keeping the physical meaning of their modeled parameters due to the small magnitude of . n/N and the use of the relation of (. a+. b) versus other variables as a constraint, respectively. All models tended to perform best in zone II and poorest in zone I in predicting . Rs, indicating larger errors in humid climates. Since most productive agricultural areas in China are located in zone I, developing parameter models tailored to this zone would be valuable to improve . Rs accuracy. © 2012 Elsevier Ltd.


Yan C.,Chinese Academy of Agricultural Sciences | Yan C.,Key Laboratory of Dryland Agriculture | He W.,Chinese Academy of Agricultural Sciences | He W.,Key Laboratory of Dryland Agriculture | And 8 more authors.
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2015

Plastic mulching film plays an important role in development of agriculture. However, a series of problems such as pollution of plastic film residue left in the field occur. It is required to make a reasonable assessment on film mulching and rationally utilize it. Based on its application, this study proposed a concept of crop safety period of plastic film mulching, and its estimation methods. Crop safety period through plastic film mulching means the appropriate choice of a photo-selective mulch film according to the transplant season, to the pedoclimatic conditions of the area under cultivation and, finally, to the type of crop. In the days before the transplant, the plastic mulching film should be basic whole, and it works to decrease soil moisture evaporation, to warm soil and to prevent weeds. Successively, these functions almost reduce. The selection of crop safety period of plastic film mulching is helpful to manage agricultural activities efficiently; guiding film makers to produce both meet the demand of production and lower cost of plastic products; to help farmers due to the types of crop and production conditions choosing appropriate plastic mulch film. Based on measurement of function of plastic film mulching, and crop canopy density, 2 kinds of method were established. The first one is to continuously monitor soil moisture,temperature and weed control, to build relationship between the function of soil temperature, moisture, weed suppression and mulching treatments, with that to seek the intersection of them. The coincidence point means functions disappear of plastic mulching and the days from starting mulching to this date is a certain crop safety period in a certain site. The second is crop canopy density to determine crop safety of plastic film mulching period, which includes 2 steps: to measure the change of crop canopy density, and the functions (soil temperature and moisture etc.) of mulching under no mulching and mulching at same time, to establish the curve of crop canopy density and the main function of plastic film in order to cross the best condition between crop canopy density and the contribute of mulch films aimed to the determination of the ideal crop safeguard period. All in all, plastic mulching film has been widely used in global, especially in China, in the past 30 years, and its application area and efficacy works better than any other agronomic practices. Concept of crop safety period of plastic film mulching has been firstly proposed in this paper, and further research in the connotation and extension of its definition still need to be developed. Moreover, the mentioned estimation methods around crop safety period of plastic film mulching showed some usefulness in cotton in Xinjiang, corn in Northeast and tobacco in southwest planting, but more extensive research, application and improvement were needed by far. The findings from this research provide an important information base for improving adaptability evaluation system of plastic mulching film, investigating the spatial pattern of plastic mulching film utilization, and biodegradable plastic film production and application. ©, 2015, Chinese Society of Agricultural Engineering. All right reserved.


Xu J.W.,Chinese Academy of Agricultural Sciences | Xu J.W.,Key Laboratory of Agricultural Environment | Ju H.,Chinese Academy of Agricultural Sciences | Ju H.,Key Laboratory of Agricultural Environment | And 4 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2014

It is widely recognized that the frequency and intensity of extreme weather events and climate disasters have strongly increased with global warming. The area of influence of climate disasters has also increased, which has had adverse effects on sustainable social and economic development. Drought is a recurring natural phenomenon, and is associated with a deficit of water resources over a large geographic area and long duration. Drought is attracting increased attention from scholars, with a focus on its intensity, duration and areal extent in northern China within the context of global change. Investigation of the variation of drought and regional response to climate change is very important to agricultural production, and can provide a reference fordeveloping appropriate measures to reduce droughts on the Huang-Huai-Hai(3H) Plain. At present, relevant research is more inclined to study meteorological drought itself, without consideration of drought characteristics in different phases in crop-growing seasons and the climate background of global change. In this paper, we determine drought characteristics in all four seasons and the winter wheat growing season on the 3H Plain, together with the effects of climate change. Based on data of 34 meteorological stations from 1961 to 2011, a relative moisture index was calculated to investigate the spatial pattern and temporal variability of drought characteristics on the 3H Plain. The results show varying degrees of drought in spring, winter and the winter wheat growing season. Drought frequency exceeded 90% over the past 50 years on the plain, with spring and winter the driest seasons. There were high-frequency drought areas in central and northern parts of the plain during spring, winter and the winter wheat growing season. The regional distribution of drought intensity and frequency showed an increasing tendency from south to north. A wet trend was detected on the plain in the winter wheat growing season over the last 50 years. However, the relative moisture index changed since 1978. That is to say, the index had an increasing trend from 1961 to 1980 when the plain was wetter; the index decreased from 1980 to 2011 when it was drier. Overall, although drought eased over the entire analysis period, a serious drought tendency has emerged over the last 20 years. In addition, temporal variability of the relative moisture index was significantly correlated with precipitation, solar radiation and relative humidity. This indicates that drought characteristics of the plain were more sensitive to these three climate variables. This has received increased attention in recent years with respect to addressing climate change. The results of our study indicate an arid trend, with increase of temperature in spring and summer on the 3H Plain. Therefore, relevant agencies should create an early warning system of extreme weather events and natural disasters, toward improvement of future regional agricultural scientific management and decision support systems in agricultural production. These agencies should also adapt to climate change by selecting strongly drought-resistant crop varieties and by adjusting cultivation methods and management measures, especially irrigation measures aimed at spring drought on the 3H Plain.


Hu W.,Chinese Academy of Agricultural Sciences | Hu W.,Key Laboratory of Dryland Agriculture | Yan C.R.,Chinese Academy of Agricultural Sciences | Yan C.R.,Key Laboratory of Dryland Agriculture | And 4 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2014

This paper investigated impacts of climate change on irrigation water requirement for winter wheat with consideration to growing period in the North China Plain(NCP), benefitting to make irrigation scheduling and adaptive strategy. Based on data from 4 typical meteorology stations including Beijing Miyun and Shijiazhuang Nangong stations in the west and Tianjin Baodi and Xingtai Nangong stations in the east and phenology data of winter wheat during 1981 to 2010, the objective of this study is to investigate impacts of climate change on winter wheat irrigation water requirements in growth stages. The results showed that the dates of sowing stage and seeding stage delayed and the more variation of trend was at high latitudes, while the others showed an advanced trend. Then the spatial variation of irrigation water requirement in the NCP was decreasing from south to north in the past 30 years. And in temporal distribution study, there was a marked increase in east, but it was opposite in west area. The irrigation water requirement during the different growth stages made a different change with time. Except for a slight rise during the seeding to jointing stage in two stations and milky to maturity, the irrigation water requirements were reduced during the other growth periods. In the whole growth stages, the west sites were decreased by 6. 72 mm/ 10a and 8. 3 mm/ 10a, respectively. However, in the east sites, there was an increasing tendency of irrigation water requirements with 2. 6 mm/ 10a and 7. 08 mm/ 10a, respectively. Besides the order of annual fluctuation was: sowing to seeding stage>milky to maturity>heading to milk stage>jointing to heading stage>seeding to jointing stage > sowing to maturity. The influence of different meteorological elements on irrigation water requirement was relatively various. The relationship between irrigation water requirement and effective precipitation and related humidity was negative significant, to the contrary, the impact of wind speed, sunshine duration and mean temperature was positive. And correlation was slightly negative between irrigation water requirement and growth period length. The consequence would be more precise if growth period length was taken into consideration in the formula. Therefore, the main climatic factors influencing the irrigation water requirements were different in each growth stage. The prior impact factor was related humidity in jointing to heading stage, while the main factors were different between Beijing Miyun station and others even during the same period of heading to milky stage due to the different districts, which were mean temperature and related humidity, respectively. But for other growth stages, the influence of effective precipitation on irrigation water requirement was more important than other factors. Thus the results could become more realistic, which provided theoretical basis for the reasonable irrigation system and strategies of adapting to climate change.


Xu J.W.,Chinese Academy of Agricultural Sciences | Ju H.,Chinese Academy of Agricultural Sciences | Ju H.,Key Laboratory of Agricultural Environment | Liu Q.,Chinese Academy of Agricultural Sciences | And 3 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2014

With the purpose of probing the drought characteristic in growth stages and its possible climate factors of winter wheat in Huang-Huai-Hai plain (3H plain) under climate change,based on meteorology data of 5 selected meteorological stations from 1981 to 2010, relative moist index has been calculated to investigate the temporal variability of drought characteristic in five growth stages of winter wheat in 3H Plain in recent 30 years.The results indicated that on the temporal variation, an increasing drought trend was detected in sowing to seeding stage in southern of 3H plain while a contrary trend was found in northern of 3H plain, and the same slight tendency was detected in whole growth period. The drought of growth stages except seedling stage was reduced from north to south. The most severe drought occurred in the seeding to jointing stage and a slight increasing drought trend was detected in north while a decreasing drought trend in south in this stage. A drought trend was detected in heading to maturity, with higher magnitude in south than in north. Tianjin and Shijiazhuang stations were observed to be medium drought and serious drought primarily in whole growth period, the frequency of varying degrees of droughts in Shenxian station was equivalent while Xuzhou and Zhumadian stations were observed to be primarily slight drought from 1981 to 2009. Continuous drought of Tianjin and Shijiazhuang station was serious while sustained drought was not found in Zhumadian station in recent 30 years. With the temperature increasing, aridification might be enhanced in Tianjin and Shijiazhuang stations while a contrary trend was found in Shenxian, Xuzhou and Zhumadian stations in whole growth period of winter wheat. The trend of drought will be alleviated with the temperature decreasing in jointing to heading stage and heading to maturity statge. Drought in sowing to seeding stage will be more obvious in Tianjin and Xuzhou stations with the solar radiation increasing. There was a drought trend detected in Shijiazhuang and Zhumadian stations with the relative humidity decreasing in growth stages. Besides, with the wind speed decreasing, moisture tendency will be found in whole growth period and heading to maturity in southern of 3H Plain. The research results can provide a reference for the simulation study on the impact of drought on yield of winter wheat and developing appropriate measures to reduce droughts in the 3H plain.


Liu E.,Chinese Academy of Agricultural Sciences | Liu E.,Key Laboratory of Dryland Agriculture | Teclemariam S.G.,Chinese Academy of Agricultural Sciences | Teclemariam S.G.,Key Laboratory of Dryland Agriculture | And 10 more authors.
Geoderma | Year: 2014

The influence of different tillage practices on soil organic carbon levels is more significant under long-term tillage compared to short-term tillage. Despite the great interest in the effect of no-tillage (NT) management practice on carbon sequestration, the long-term effect of NT practice on soil organic carbon and its fractions in northern China remain unclear. We evaluated the long-term effects (after 17years) of NT and conventional tillage (CT) practices on soil organic carbon and its fractions at different depths ranging from 0 to 60cm using a cinnamon soil in Shanxi, China. A randomised block design with three replications was used to evaluate both the tillage and its effects on the yield performance of winter wheat (Triticum aestivum L.). After 17years, the soil organic carbon (SOC) concentration in the NT soil was greater than that of the CT soil, but only in the layer that was located between 0 and 10cm. There was a significant accumulation of SOC (0-60cm) in the NT soil (50.2MgCha-1) compared to that observed in the CT soil (46.3MgCha-1). The particulate organic matter C (POM-C), dissolved organic C (DOC), and microbial biomass C (MBC) levels in the 0-5cm layer under NT treatment were 155%, 232%, and 63% greater, respectively, compared to the CT treatment. The POM-C, DOC, and MBC in the 5-10cm layer under NT treatment were 67%, 123%, and 63% greater, respectively, compared to the CT treatment. Below 10cm, the labile carbon observed in the NT treatment did not differ from that of the CT treatment. Significantly positive correlations were observed between the SOC and the labile organic C fractions. Moreover, the winter wheat (T. aestivum L.) yield increased 28.9% in the NT treatment compared to the CT treatment. The data show that NT is an effective and sustainable management practice that improves carbon sequestration and increases soil fertility, resulting in higher winter wheat yields in the rainfed dryland farming areas of northern China. © 2013 Elsevier B.V.


Liu E.K.,Chinese Academy of Agricultural Sciences | Liu E.K.,Key Laboratory of Dryland Agriculture | He W.Q.,Chinese Academy of Agricultural Sciences | He W.Q.,Key Laboratory of Dryland Agriculture | And 2 more authors.
Environmental Research Letters | Year: 2014

Plastic film mulching has played an important role in Chinese agriculture due to its soil warming and moisture conservation effects. With the help of plastic film mulch technology, grain and cash crop yields have increased by 20-35% and 20-60%, respectively. The area of plastic film coverage in China reached approximately 20 million hectares, and the amount of plastic film used reached 1.25 million tons in 2011. While producing huge benefits, plastic film mulch technology has also brought on a series of pollution hazards. Large amounts of residual plastic film have detrimental effects on soil structure, water and nutrient transport and crop growth, thereby disrupting the agricultural environment and reducing crop production. To control pollution, the Chinese government urgently needs to elevate plastic film standards. Meanwhile, research and development of biodegradable mulch film and multi-functional mulch recovery machinery will help promote effective control and management of residual mulch pollution. © 2014 IOP Publishing Ltd.


Hao W.,Chinese Academy of Agricultural Sciences | Hao W.,Key laboratory of Dryland Agriculture | Mei X.,Chinese Academy of Agricultural Sciences | Mei X.,Key laboratory of Dryland Agriculture | And 5 more authors.
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2011

Crop area and its spatial distribution are generally considered to be essential data inputs for crop yield estimation, assessment of water productivity and adjustment of cropping structure to support science and policy applications focused on understanding the role and response of the agricultural sector to environmental change issues. The objective of this research was to evaluate the applicability of time-series MODIS 250m normalized difference vegetation index (NDVI) data for large-area crop mapping over Northeast China. Spatial pattern of crop planting was obtained based on 16-day time-series MODIS 250m NDVI data from 2007 to 2008, Landsat enhanced thematic mapper plus (ETM+) images, and ground truth data using Optimal Iteration Unsupervised Classification, spectral matching technique (SMT) and Google Earth. Sub-pixel area fraction estimate was applied to estimate cropland area, rice area, spring maize area and soybean area. We found that the position precision was 85.7%, their correlation coefficient compared with statistic was 0.916, 0.685, 0.746 and 0.681 respectively, and that there was significant difference between these groups by using paired samples test. Results indicated that the method can accurately reflect various crop distributions in Northeast China and be applied for large-area crops classification and crop planting extraction.


Pang X.,Chinese Academy of Agricultural Sciences | Pang X.,Key laboratory of Dryland Agriculture | He W.Q.,Chinese Academy of Agricultural Sciences | He W.Q.,Key laboratory of Dryland Agriculture | And 8 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2013

The long-term impact of tillage and residue management on soil microbial biomass carbon and, soil moisture and temperature was studied in a cinnamon soil in northern China over the maize (Zea mays L.) growing season in monoculture. Soil microbial biomass, the active fraction of soil organic matter, plays a central role in the flow of C and N in ecosystems, responds rapidly to management practices, and serves as an index of soil fertility. This study was to investigate the effects of different tillage-residue practices on soil microbial biomass carbon dynamics of maize after seven years of conserved tillage practice. Treatments of conventional tillage (CT), no tillage with straw mulch (NTSM), and tillage with all straw return (ASRT) were considered, and a randomized complete block design was used to lay out the experimental plots. The results showed that conservation tillage practices (NTSM and ASRT) had a noticeable positive effect on soil moisture content. The NTSM and ASRT treatments increased the soil moisture content by 18%, 22%, 29%, 21% and 3%, 10%, 12%, 13% at four physiological stages of the maize (seeding stage, jointing stage, filling stage, and maturation stage). However, soil temperature were decreased under NTSM and ASRT compared to CT at both depths, especially at 5-cm depths where significantly lower values were observed (18. 12, 18. 76, and 19. 44°C under NTSM, ASRT, and CT treatment, respectively). The dynamic of microbial biomass carbon in the whole growth period rapidly reaches a peak at the jointing stage and then begins to decline and tend to stabilize. Soil microbial biomass carbon was significantly higher with NTSM and ASRT than with CT in the arable soil layer at different stages. The values under NTSM and ASRT increased by 70%, 40%, 85%, 30%, and 10%, 20%, 15%, 15% at seeding stage, jointing stage, filling stage, and maturation stage, respectively. There is a positive correlation between soil microbial biomass carbon and soil moisture and soil temperature.


Zhang H.,Chinese Academy of Agricultural Sciences | Zhang H.,Key Laboratory of Dryland Agriculture | Zhang Y.,Chinese Academy of Agricultural Sciences | Zhang Y.,Key Laboratory of Dryland Agriculture | And 6 more authors.
Geoderma | Year: 2016

Knowledge about the changes in soil nitrogen pools under different tillage managements is necessary to assess the feasibility of adoption of conservation practices for sustaining productivity and protecting the environment in dryland farming in northern China. We investigated the long-term effects (22 years) of no-till with residue retention (NTR) on total soil N and its fractions in a dry-land winter wheat (Triticum aestivum L.) cropping system in northern China. Compared with conventional tillage without residue retention (CT), significantly higher soil total N (STN) concentrations were observed in the surface soil layer (0-10 cm) under NTR. Meanwhile, more soil N accumulated for the whole soil profile (0 to 60 cm) in the NTR (3.38 Mg ha-1) treatment relative to the CT (3.17 Mg ha-1) treatment. The particulate organic matter N (PON), microbial biomass N (MBN), and water extractable organic N (WEON) levels in the NTR treatments were 52.3%, 116%, and 69.4% greater at a depth of 0-5 cm and 41.6%, 108%, and 44.9% greater at a depth of 5-10 cm, respectively, compared with the CT treatment. However, no differences were observed below the 10 cm layer. At a depth of 0-60 cm, the soil NH4-N content under CT was higher than that under NTR. However, the soil NO3-N contents in the NTR treatments were significantly greater at a depth of 0-10 cm and were not significantly different at a depth of 10-60 cm, relative to the CT treatment. Significantly positive correlations were observed between the STN and the labile organic N fractions. Overall, the results show that no-till coupled with residue retention is an effective management method for improving soil N stocks and increasing soil fertility. Nonetheless, other benefits associated with NT and residue retention present greater challenges regarding their popularization and application in the dryland farming areas in northern China. © 2016 Elsevier B.V.

Loading Key laboratory of Dryland Agriculture collaborators
Loading Key laboratory of Dryland Agriculture collaborators