• Authors:
    • Wang, J. Y.
    • Yan, X. Y.
    • Gong, W.
  • Source: PLANT AND SOIL
  • Volume: 353
  • Issue: 1-2
  • Year: 2012
  • Summary: Background and Aims Previous studies have clearly shown substantial increases of soil organic carbon (SOC) in agricultural soils of Yellow River reaches. Those soils did not receive organic fertilizer input, but did receive chemical fertilizer inputs. Thus, to investigate the hypothesis that the observed SOC increases were driven by chemical fertilizer additions, a maize pot experiment was conducted using a Fluvisol that developed under C-3 vegetation in the Yellow River reaches. Methods Using the natural C-13 abundance method we calculated the SOC renewal ratio (C-renewal), and separated total soil organic carbon (TOC) into maize-derived soil organic carbon (SOCmaize) and original soil organic carbon (SOCoriginal). Carbon dioxide fluxes and microbial biomass carbon (MBC) were determined by closed chamber method and fumigation-extraction method, respectively. The experiment included five treatments: (1) NPK: application of chemical fertilizer NPK; (2) NP, application of chemical fertilizer NP; (3) PK: application of chemical fertilizer PK; (4) NK, application of chemical fertilizer NK; and (5) CK: unfertilized control. Results Fertilization increased maize biomass (including grain, straw and root), TOC, C-renewal, SOCmaize, maize-derived carbon (MDC: including SOCmaize, and root and stubble biomass carbon) and MBC, and these values among the treatments ranked NPK>NP>PK>NK>CK. The C-renewal was 5.548.50% across the treatments. Fertilization also increased soil CO2 emission (including root respiration and SOCoriginal decomposition), while the SOCoriginal decomposition during the maize growing season only amounted to 74.0-93.4 and 33.5-46.1% of SOCmaize and MDC among the treatments, respectively. Thus input was larger than export, and led to SOC increase. Maize grain and straw biomass were positively and significantly correlated with soil delta C-13, TOC, C-renewal, SOCmaize, MDC and MBC. Conclusions The study suggests that chemical fertilizer application could increase C-renewal by increasing crop-derived C and accelerating original SOC decomposition, and that as long as a certain level of crop yield or aboveground biomass can be achieved, application of chemical fertilizer alone can maintain or increase SOC level in Fluvisol in the Yellow River reaches.
  • Authors:
    • Chang, H.
    • Ferguson, D. K.
    • Hao, H.
    • Li, C. S.
  • Source: CLIMATIC CHANGE
  • Volume: 113
  • Issue: 2
  • Year: 2012
  • Summary: Lop Nur in Xinjiang, Northwest China, is located in the lowest part of the Tarim Basin at an altitude of 780 m and experiences an extremely dry climate with an annual precipitation of only 17 mm and a high evaporation rate of 2,728 mm. The pollen and spores from the Late Miocene strata of a borehole in Lop Nur were analyzed with a view to interpreting the paleoenvironmental evolution of Lop Nur. Main types of pollen such as Chenopodiaceae, Nitraria, Ephedra and Artemisia reflect an arid climate. By collating the palynological data in this area as recorded in other literature and by applying the method of Coexistence Analysis, we have obtained the paleoclimatic parameters from Late Miocene to Holocene in Lop Nur. These suggest that temperatures increased from the Late Miocene (10.2A degrees C) to the Pliocene (13.4A degrees C), decreased from Pliocene to Pleistocene (4.7A degrees C), and were more stable from Holocene (12.1A degrees C) until now (11.5A degrees C). The precipitation was stable (about 900 mm) from Late Miocene to Early Pleistocene, then decreased markedly (to about 300 mm) in Middle and Late Pleistocene, and reached its lowest value (17.4 mm) in the Holocene. The changes in paleoclimate at Lop Nur provide new evidence for understanding the uplift of the Qinghai-Tibetan Plateau.
  • Authors:
    • Quiroga, S.
    • Garrote, L.
    • Iglesias, A.
    • Moneo, M.
  • Source: PLOS ONE
  • Volume: 112
  • Issue: 1
  • Year: 2012
  • Summary: The effects of climate change will be felt by most farmers in Europe over the next decades. This study provides consistent results of the impact of climate change on arable agriculture in Europe by using high resolution climate data, socio-economic data, and impact assessment models, including farmer adaptation. All scenarios are consistent with the spatial distribution of effects, exacerbating regional disparities and current vulnerability to climate. Since the results assume no restrictions on the use of water for irrigation or on the application of agrochemicals, they may be considered optimistic from the production point of view and somewhat pessimistic from the environmental point of view. The results provide an estimate of the regional economic impact of climate change, as well as insights into the importance of mitigation and adaptation policies.
  • Authors:
    • Zhang, W. J.
    • Peng, C.
    • Gao, H. J.
    • Deng, A. X.
    • Song, Z. W.
    • Peng, X. X.
    • Huang, S.
    • Zhu, P.
    • Kou, T. J.
  • Source: SOIL & TILLAGE RESEARCH
  • Volume: 118
  • Year: 2012
  • Summary: Soybean (Glycine max L.)-maize (Zea mays L.) rotation has been recommended as a good cropping practice for soil quality improvement and crop productivity enhancement. However, its impacts on carbon sequestration in soil are not well documented. The main objective of this study was to learn whether soybean-maize rotation can promote soil organic carbon (SOC) sequestration. Based on a long-term field experiment (started in 1990) in Northeast China, we investigated the differences in soil organic carbon (SOC) and soil aggregate composition between cropping patterns. This experiment included four treatments: continuous maize cropping (CMC), maize-soybean rotation (MSR), continuous soybean cropping (CSC) and farmland fallow (FALL) in a Haplic Phaeozem soil. All treatments showed a sustained trend toward increasing SOC storage since 1990. The contents of SOC in the topsoil and in the profile to the 1m depth were in the following order of CMC>MSR>CSC=FALL, suggesting a greater potential of C sequestration under cropping with manure application than under the farmland fallow without any fertilizer application. In the 1m soil profiles, SOC levels decreased with soil depth with a major part (around 60-71%) being distributed in the 0-40cm layer, whereas different practices led to great differential of SOC distribution. The CMC had the highest SOC levels (47.3Mgha -1) in the topsoil (0-20cm) among the four systems. Meanwhile, maize cropping system (e.g. CMC and MSR) promoted more SOC allocation in >40cm soil layers. Moreover, cropping pattern also differently influenced the formation and transformation of soil aggregates and the distribution of SOC in the aggregates. Macro-sized aggregate and the associated C (18.6Mgha -1) dominated in the FALL, while the micro-sized fractions (44.0% and 52.5%, respectively) and corresponding associated C (14.8Mgha -1 and 19.2Mgha -1, respectively) were maximized in the MSR and CSC. The CMC had the greatest silt+clay-sized aggregate fraction (42.0%) and associated C in the macro- (13.4Mgha -1) and silt+clay-sized aggregate (12.9Mgha -1) fractions when compared with the MSR and CSC. Thus, maize-soybean rotation may be not the best cropping practice for C sequestration in the rainfed farmland Mollisol (Cumulic Hapludoll) in Northeast China, and intensive cropping with manure application can sustain the soil fertility for a long-term with high crop yield. © 2011 Elsevier B.V.
  • Authors:
    • Song, C. K.
    • Kim, J.
    • Ho, C. H.
    • Lee, M. H.
  • Source: CLIMATIC CHANGE
  • Volume: 113
  • Issue: 2
  • Year: 2012
  • Summary: A number of indices have been employed to describe weather extremes on the basis of climate regimes and public concerns. In this study, we combined these traditional indices into four groups according to whether they relate to warm (T-warm), cold (T-cold), wet (P-wet), or dry (P-dry) extremes. Analysis of the combined indices calculated for the daily temperatures and precipitation at 750 meteorological stations in Korea, China, and Japan for 1960s-2000s shows increasing trends in T-warm and P-dry events and decreasing trends in T-cold events in recent decades, particularly in the northern part of East Asia. A notable regional variation is an increase in the P-wet events in the Korean Peninsula. We applied the same analysis to a 200-year global climate model simulation for 1900-2099 using the National Center for Atmospheric Research-Community Climate System Model 3. During the 20th century, the changes in T-warm and T-cold calculated from the model data are largely consistent with those calculated from the observations, especially in northern East Asia. The model projections for the 21st century indicate statistically significant increasing T-warm and decreasing T-cold trends in extreme events over the region. Results obtained from historical archives and model simulations using our combined weather extreme indices suggest that northern East Asia will be subject to increased warm and dry extremes and the Korea Peninsula will experience more wet extremes.
  • Authors:
    • Wang, J. P.
    • Zhang, Z. S.
    • Kou, Z. K.
    • Yue, L. X.
    • Li, C. F.
    • Cao, C. G.
  • Source: SOIL & TILLAGE RESEARCH Volume: 119 Pages: DOI:
  • Volume: 119
  • Year: 2012
  • Summary: Conservation management practices, such as no-tillage (NT) or crop residue mulch, alter soil organic carbon (C) lability, thus affecting soil quality. However, inconsistent effects of conservation management practices on soil labile organic C have been commonly reported. We hypothesized, however, that conservation management practices can improve soil labile organic C fractions and then C management index (CMI) and soil quality. Thus, our objective was to quantify labile organic C contents on a clay loam soil (Anthrosols, World Reference Base for Soil Resources) 3 years after implementing four tillage/crop residue management treatments under a rice Liangyoupeijiu (Oryza sativa L.)-rape Huayouzaliuhao (Brassica napus) rotation in Wuxue City of central China. The experiment included four treatments: (1) single conventional tillage (CT) without crop residue (rape with NT-rice with CT); (2) double CT without crop residue (rape with CT-rice with CT); (3) double NT without crop residue (rape with NT-rice with NT); and (4) double NT plus crop residue (rape with NT. +. rice residue mulch-rice with NT. +. rape residue mulch). Five soil organic C fractions were determined from 0 to 30. cm layer in October 2009 (3 years after a rape-rice double crop rotation). Total organic C, microbial biomass C, dissolved organic C, particulate organic C, easily oxidizable C, and water stable aggregation were measured. A CMI was also calculated. The concentrations of total organic C, microbial organic C, dissolved organic C, and particulate organic C under the double NT plus crop residue treatment were 1.07-1.17, 1.20-1.26, 1.08-1.30 and 1.17-1.76 times higher than those under the other three treatments. The total organic C and labile organic C contents under the double NT with or without crop residue treatment were generally higher at 0-5. cm than at greater sampling depths. The proportions of 0.5-2. mm water-stable aggregates at the 0-5. cm depth under the double NT with or without crop residue treatment were significantly greater (P< 0.05) than those under the single or double CT without crop residue treatment, but lower (P< 0.05) at the 5-30. cm depth. Soil labile organic C fractions were positively correlated with each other. The greater C pool index (CPI) at the 0-5. cm depth observed under double NT with or without crop residue treatment compared to single or double CT without crop residue treatment led to greater CMI at the same depth. However, CMI at the 5-30. cm depth was lower for the double NT with or without crop residue treatment compared to the single or double CT without crop residue treatment. Thus, our results indicated that soil labile organic C fractions were only sensitive to changes in management practices in the upper soil profile, and that short-term effects of continuous NT or NT with crop residue mulch in a rape-rice rotation system appeared to only improve soil quality in the upper soil profile. Based on these results, we suggested that greater quantities of labile organic C can be concentrated in the 0-30. cm soil layer of a soil under rape-rice rotation by more sustainable practices than those currently being used in central China. © 2011 Elsevier B.V.
  • Authors:
    • Li, Y.
    • Han, L.
    • Chen, W.
    • Chen, S.
    • Peng, Z.
    • Chen, X.
    • Li, D.
  • Source: SOIL & TILLAGE RESEARCH
  • Volume: 123
  • Year: 2012
  • Summary: An important drawback of the partial least squares regression (PLSR) method is the complexity of the transfer of spectral prediction models from one sensor to another. The performance of four visible and near infrared (VNIR) spectral indices in predicting the soil organic matter (SOM) content was compared to that of PLSR model using 30 soil samples collected from inside and outside the litchi canopy area of 15 different orchards in South China. The four types of spectral indices are the sum of the first derivative data at spectral region of high correlation (Sum), the maximum band depth magnitude (BDmax), total area (TA), and left area (LA) of characteristic absorption feature. The linear regression method was applied to correlate the spectral indices and SOM contents. The results showed that the left area below the profile of absorption spectrum at 2140-2240nm (LA_2140-2240) was positively correlated with SOM contents (F value=82.46), which presented the best performance in the examined spectral indices for the prediction of SOM with the highest coefficient of determination (Rcv2) and residual prediction deviation (RPD), and the lowest root mean square error of cross-validation (RMSECV) (Rcv2=0.81, RPD=2.11, and RMSECV=0.27%). The accuracy of this LA_2140-2240 index-based model was comparable to that of the PLSR method (Rcv2=0.81, RPD=2.11, and RMSECV=0.27%). We concluded that the absorption area index in near infrared spectral range can provide an effective way to estimate the SOM content in litchi orchard of South China. The SOM prediction model based on LA_2140-2240 spectral index can also be transferred from one sensor to another conveniently, which cannot be accomplished with the conventional PLSR method. The calibration method in this study was applied to the largest litchi plantation area of South China and even in the world. It has the potential to be used in other litchi orchards worldwide. © 2012 Elsevier B.V..
  • Authors:
    • Zhu, Y. F.
    • Zhu, C. W
    • Chen, D. L
    • Shan, X. L.
    • Qian, W. H.
  • Source: CLIMATIC CHANGE
  • Volume: 110
  • Issue: 1-2
  • Year: 2012
  • Summary: Historical annual dry-wet index for 1470-2003 combined with instrumental precipitation since 1951 were used to identify extremely dry years and events near the northern fringe of the East Asian summer monsoon in China-the Great Bend of the Yellow River (GBYR) region. In total, 49 drought years, of which 26 were severe, were identified. Composites of the dry-wet index under the drought years show an opposite wet pattern over the Southeast China. The longest drought event lasted for 6 years (1528-1533), the second longest one 4 years (1637-1640). The most severe 2-year-long drought occurred in 1928-1929, and the two driest single years were 1900 and 1965. These persistent and extreme drought events caused severe famines and huge losses of human lives. Wavelet transform applied to the dry-wet index indicates that the severe drought years are nested in several significant dry-wet variations across multiple timescales, i.e., the 65-85 year timescale during 1600- 1800, 40-55 year timescale before 1640 and 20-35 year timescale mainly from 1550 to 1640. These timescales of dry-wet variations are discussed in relation to those forcing such as cycles of solar radiation, oscillation in the thermohaline circulation and the Pacific Decadal Oscillation (PDO). Comparing 850 hPa winds in Asia in extremely dry and wet years, it was concluded that dry-wet variability in the GBYR region strongly depends upon whether the southerly monsoon flow can reach northern China.
  • Authors:
    • Ye, A. H.
    • Liu, B. Y.
    • Dai, Y. J.
    • Shangguan, W.
    • Yuan, H.
  • Source: Geoderma
  • Volume: 171
  • Year: 2012
  • Summary: We developed a multi-layer soil particle-size distribution dataset (sand, silt and clay content), based on USDA (United States Department of Agriculture) standard for regional land and climate modelling in China. The 1:1,000,000 scale soil map of China and 8595 soil profiles from the Second National Soil Survey served as the starting point for this work. We reclassified the inconsistent soil profiles into the proper soil type of the map as much as possible because the soil classification names of the map units and profiles were not quite the same. The sand, silt and clay maps were derived using the polygon linkage method, which linked soil profiles and map polygons considering the distance between them, the sample sizes of the profiles, and soil classification information. For comparison, a soil type linkage was also generated by linking the map units and soil profiles with the same soil type. The quality of the derived soil fractions was reliable. Overall, the map polygon linkage offered better results than the soil type linkage or the Harmonized World Soil Database. The dataset, with a 1-km resolution, can be applied to land and climate modelling at a regional scale. (C) 2011 Elsevier B.V. All rights reserved.
  • Authors:
    • Chen, J.
    • Tang, Y. H.
    • Shen, M. G.
    • Yang, W.
  • Source: CLIMATIC CHANGE
  • Volume: 114
  • Issue: 3-4
  • Year: 2012
  • Summary: A number of studies have reported an extension of the thermal growing season in response to the warming climate during recent decades. However, the magnitude of extension depends heavily on the threshold temperature used: for a given area, a small change in the threshold temperature results in significant differences in the calculated thermal growing season. Here, we specified the threshold temperature for determining the thermal growing season of local vegetation across 326 meteorological stations in temperate China by using vegetation phenology based on satellite imagery. We examined changes in the start, end, and length of the thermal growing season from 1960 to 2009. The threshold temperatures for determining the start and end increased strongly with increasing mean annual temperature. Averaged across temperate China, the start of the thermal growing season advanced by 8.4 days and the end was delayed by 5.7 days, resulting in a 14.1-day extension from 1960 to 2009. The thermal growing season was intensively prolonged (by 0.59 day/year) since the mid-1980s owing to accelerated warming during this period. This extension was similar to that determined by a spatially fixed threshold temperature of 5 A degrees C, but the spatial patterns differed, owing to differences in the threshold temperature and to intra-annual heterogeneity in climate warming. This study highlights the importance of specifying the temperature threshold for local vegetation when assessing the influences of climate change on thermal growing season, and provides a method for determining the threshold temperature from satellite-derived vegetation phenology.