Northeast Institute of Geography and Agroecology, Chinese Academy Of Sciences
Not a member yet
4476 research outputs found
Sort by
Interactive effects of pH, EC and nitrogen on yields and nutrient absorption of rice (Oryza sativa L.)
No full textSoil salinity and sodicity can not only directly restrain crop growth by osmotic and specific ion stresses, it also may reduce grain yield indirectly by impacting plant absorption of essential nutrients. Ensuring adequate nitrogen is an important management aspect of rice production in saline-sodic soils. The objective of this study was to investigate the interaction of soil pH, salinity and nitrogen application on rice yield and nutrient absorption. We conducted a rice experiment in containers in a greenhouse. The soils were first leached with 9 target salt solutions of pH 7,8 arid 9 and electrical conductivity (EC) of 2,6 and 10 dS m(-1). Nitrogen application rates were 100,200 and 300 kg N ha(-1). Rice grain yield and shoot weight significantly decreased with increasing soil pH and increasing soil EC, and significantly increased with increasing nitrogen application (P<0.001). However, at high EC and/or high pH yield was not significantly increased by increased N. High pH and high EC in soil significantly influenced the mineral nutrient content of rice shoots (P<0.05). High soil pH and soil EC stresses were superimposed on each other, the negative effects on rice were compounded. The results by stepwise regression analysis showed that soil pH very significantly and adversely impacts grain yield and was the major factor impacting rice grain yield (R-2 = 0.565, P<0.001). Nitrogen application provided a positive response under control and pH 7 at all salinity values, and at pH 8 under low salinity only. There was no significant response to additional N under pH 8 and elevated EC and no significant response at pH 9 for all EC values. Thus, adequate nitrogen application is an important technical measure for improving rice yield and promoting nutrient absorption in rice of high EC soils but not of high pH soils where pH is the major limiting factor for rice production in saline-sodic soils. (C) 2017 Published by Elsevier B.V
Winter wheat yield estimation based on multi-source medium resolution optical and radar imaging data and the AquaCrop model using the particle swarm optimization algorithm
No full textTimely and accurate estimation of winter wheat yield at a regional scale is crucial for national food policy and security assessments. Near-infrared reflectance is not sensitive to the leaf area index (LAI) and biomass of winter wheat at medium to high canopy cover (CC), and most of the vegetation indices displayed saturation phenomenon. However, LAI and biomass at medium to high CC can be efficiently estimated using imaging data from radar with stronger penetration, such as RADARSAT-2. This study had the following three objectives: (i) to combine vegetation indices based on our previous studies for estimating CC and biomass for winter wheat using HJ-1A/B and RADARSAT-2 imaging data; (ii) to combine HJ-1A/B and RADARSAT-2 imaging data with the AquaCrop model using the particle swarm optimization (PSO) algorithm to estimate winter wheat yield; and (iii) to compare the results from the assimilation of HJ-1A/B + RADARSAT-2 imaging data, HJ-1A/13 imaging data, and RADARSAT-2 imaging data into the AquaCrop model using the PSO algorithm. Remote sensing data and concurrent LAI, biomass, and yield of sample fields were acquired in Yangling District, Shaanxi, China, during the 2014 winter wheat growing season. The PSO optimization algorithm was used to integrate the AquaCrop model and remote sensing data for yield estimation. The modified triangular vegetation index 2 (MTVI2) x radar vegetation index (RVI) and the enhanced vegetation index (EVI) x RVI had good relationships with CC and biomass, respectively. The results indicated that the predicted and measured yield (R-2 = 0.31 and RMSE = 0.94 ton/ha) had agreement when the estimated CC from the HJ-1A/B and RADARSAT-2 data was used as the dynamic input variable for the AquaCrop model. When the estimated biomass from the HJ-1A/B and RADARSAT-2 data was used as the dynamic input variable for the AquaCrop model, the predicted yield showed agreement with the measured yield (R-2 = 0.42 and RMSE = 0.81 ton/ha). These results show that using the biomass as the dynamic input variable provides a better yield estimation than using the CC as the dynamic variable. The predicted biomass and yield were more accurately estimated by combining the HJ-1A/B and RADARSAT-2 data with the AquaCrop model than by combining the only HJ-1A/B or RADARSAT-2 data with the AquaCrop model using the PSO algorithm. The results indicated that the PSO-based assimilation method could be used to estimate the winter wheat yield from the spot to the regional scale. (C) 2017 International Society for Photogrammetry and Remote Sensing, Inc. (ISPRS). Published by Elsevier B.V. All rights reserved
Effects of over 30-year of different fertilization regimes on fungal community compositions in the black soils of northeast China
No full textIn this study, we investigated the effects of four long-term fertilization regimes that were performed over 30 years, namely, non-fertilization (NoF), chemical fertilization (CF), manure fertilization (M) and chemical fertilization plus manure (CFM), on a range of soil properties and fungal communities at three locations which located in the northern, middle and southern parts of the black soil region of northeast China. The fungal communities were primarily analyzed by Illumina MiSeq sequencing targeting fungal rRNA operon ITS1 region. The results showed that the fertilizers (organic or inorganic) generally increased the soil nutrient contents and fungal abundances. Principal coordinate analysis (PCoA), revealed that all fungal communities were separated into three groups according to their sampling locations, and the soil pH was the most influential factor in determining the total fungal communities across the three locations. Similar fertilization treatments had inconsistent influences on the fungal community compositions and the most influential soil factor in shaping fungal community structures varied among the three locations. Amending with inorganic fertilizers increased the relative abundances of potentially pathogenic fungi in the southern location, while the addition of manure suppressed possible pathogenic fungal growth and enhanced the growth of beneficial fungi in the three locations. Our findings highlighted that the influences of geographical separation along with fertilization regimes should be considered when examining the responses of fungal communities to fertilization regimes in agricultural management
A systematic examination of the relationships between CDOM and DOC in inland waters in China
No full textChromophoric dissolved organic matter (CDOM) plays a vital role in the biogeochemical cycle in aquatic ecosystems. The relationship between CDOM and dissolved organic carbon (DOC) has been investigated, and this significant relationship lays the foundation for the estimation of DOC using remotely sensed imagery data. The current study examined samples from freshwater lakes, saline lakes, rivers and streams, urban water bodies, and ice-covered lakes in China for tracking the variation of the relationships between DOC and CDOM. The regression model slopes for DOC vs. a CDOM (275) ranged from extremely low 0.33 (highly saline lakes) to 1.03 (urban waters) and 3.01 (river waters). The low values were observed in saline lake waters and waters from semi-arid or arid regions, where strong photobleaching is expected due to less cloud cover, longer water residence time, and daylight hours. In contrast, high values were found in waters developed in wetlands or forest in Northeast China, where more organic matter was transported from catchment to waters. The study also demonstrated that closer relationships between CDOM and DOC were revealed when a CDOM (275) were sorted by the ratio of a CDOM. 250/ aCDOM (365), which is a measure for the CDOM absorption with respect to its composition, and the determination of coefficient of the regression models ranged from 0.79 to 0.98 for different groups of waters. Our results indicate the relationships between CDOM and DOC are variable for different inland waters; thus, models for DOC estimation through linking with CDOM absorption need to be tailored according to water types
A 4000-yr multi-proxy record of Holocene hydrology and vegetation from a peatland in the Sanjiang Plain, Northeast China
No full textReconstructing historical hydrologic and vegetation conditions can provide useful insights into the mechanisms underlying peatland development and can be used to construct baselines for peatland restoration. In this study, we present numerous physical and biological indices for a 4000-year core from the Honghe National Natural Reserve (HE), a dish-like depression peatland in the Sanjiang Plain of Northeast China. The history of vegetation change was reconstructed by combining plant macrofossils and pollen data from the core, and the water level changes were reconstructed through a multi-proxy study of plant macrofossils, charcoal, stable carbon isotopes, testate amoebae, sediment grain size, loss on ignition, humification degree and magnetic susceptibility. We found that the HE peatland featured wet condition from 4000 to 3600 cal yr BP, which was in accordance with the extreme flooding event at 4.0 lea in northern China. Significant drier shifts were recorded at 3600 and 1200 cal yr BP, while significant wetter shifts were recorded at 2600 and 500 cal yr BP. Factor analysis were applied to all of the proxies to reduce the seven variables to two factors, and the biological indicators, such as plant macrofossils, charcoal and stable carbon isotopes, were found to be more sensitive than the other parameters to water level changes over the last 4000 years. Furthermore, the multi-proxy reconstruction of the wetness of the HE peatland resembles the pattern observed at other sites in Northeast China. (C) 2016 Elsevier Ltd and INQUA. All rights reserved
Microbial communities in peatlands along a chronosequence on the Sanjiang Plain, China
No full textMicrobial communities play crucial roles in the global carbon cycle, particularly in peatland ecosystems under climate change. The peatlands of the Sanjiang Plain could be highly vulnerable to global warming because they are mainly located at the southern limit of northern peatlands. In this study, the alpha diversity and composition of bacterial communities in three different minerotrophic fens along a chronosequence were investigated. We captured a rich microbial community that included many rare operational taxonomic units (OTUs) but was dominated by a few bacterial classes that have frequently been detected in other peatland ecosystems. Notably, a large diversity of methanotrophs affiliated with Alpha- and Gammaproteobacteria was also detected. Bacterial alpha diversity and composition varied as a function of peat depth and its associated physical-chemical properties, such as total carbon, total nitrogen, pH and bulk density. We also found that bacterial community turnover (beta diversity) to be significantly correlated with soil age, whereas bacterial alpha diversity was not
Short-term response of CO2 emissions to various leaf litters: a case study from freshwater marshes of Northeast China
No full textSoil organic carbon (SOC) mineralization is an important process of carbon (C) cycling and budgeting associated with litter decomposition in terrestrial ecosystems. Research on altered plant-derived C input on soil C stability due to climate change is controversial and there remains considerable uncertainty in predicting soil C dynamics with the techniques currently available. In this study, we conducted a laboratory incubation experiment to test the effects of single- and mixed-Deyeuxia angustifolia (DA) and Carex lasiocarpa (CL) leaf litter addition on cumulative marshland soil CO2 emission under waterlogged and non-waterlogged conditions in Sanjiang Plain, Northeast China. Results showed that the cumulative CO2 emissions were significantly increased after leaf litter addition in both water conditions, and that the effect was more pronounced for DA amendment than CL regardless of water condition. The cumulative CO2 efflux differed considerably between water conditions after DA addition, whereas no significant differences were found after CL addition. Remarkably impact of leaf litter types on cumulative CO2 evolution was observed overall, water condition and interactions between leaf litter types and water conditions had no significant effect on CO2 emissions, however. There were no non-additive effects of individual leaf litter type on total CO2 efflux of the mixed-leaf litter addition treatments. The results of this study indicate that plant litter input to the C-rich marshy soil can induce rapid changes in SOC decomposition regardless of water conditions and that plant residue effects should be taken into consideration when assessing the dynamics of wetland soil system to the future climate scenarios
Lodging in Corn Varies with Tillage and Crop Rotation: A Case Study after Typhoon Bolaven Pummeling over the Black Soil Zeon in Northeast China
No full textCorn lodging can damage corn growth and reduce corn yield, and the degrees of corn yield loss could vary with corn species, soil conditions, agronomic practices as well as the degrees of external forces from strong wind or heavy rain. In August, 2012, Jilin province, China suffered from Typhoon Bolaven and large areas of corn lodged. However, in some no-tillage (NT) fields of this area corn lodging is much less serious than in other fields. We assumed that NT led to less serious lodging. We conducted this study on a long-term tillage trial which was seriously hit by Typhoon Bolaven. The experiment consists of NT, moldboard plow (MP), ridge tillage (RT) with continuous corn (CC), corn-soybean (CS), and corn-corn-soybean (CCS)rotations. The most serious lodging occurred in MP-CC treatment, followed by NT-CCS, NT-CC, NT-CS, MP-CS, and RT-CS. The lower incidence of lodging occurred in CS rotation. Soil bulk density and penetration resistance were not major factors affecting corn lodging except for MP-CC plot where root lodging occurred. The ratio of 2012 to average of 2007-2011 corn yield took the order of MP-CC < NT-CCS < MP-CS approximate to NT-CS < NT-CC < RT-CS approximate to MP-CCS. It suggested that RT has more advantages than NT and MP in preventing yield loss from strong wind and heavy rain. Moreover, adoption of RT combined with CS rotation could be taken into consideration preferentially for lower lodging and higher yield in Black soils in Northeast China