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Paddy field soil conservation: Indian historical practices  [PDF]
Deepak Bhattacharya
Agricultural Sciences (AS) , 2011, DOI: 10.4236/as.2011.23045
Abstract: India is an ancient land having high seasonal rain fall (4 months rain & 8 months dry), has paddy cultivation. Becauses silt-sand separation; buoyant sand gets carried; silt agglutinates. Rill fluid dissolves agglutinated soil; vectors as silt → degradation. Indian farmer has unique agricultural field conservation; soil cum fertility maintenance/regeneration heritage. Also use the stubble and cow dung (cellulose) as binder cum multi purpose in-field uses. economic; ecologically safe; and not discussed earlier. Good tool for altruistic administrations.
Methane and nitrous oxide emissions from three paddy rice based cultivation systems in Southwest China
Methane and Nitrous Oxide Emissions from Three Paddy Rice Based Cultivation Systems in Southwest China

Changsheng Jiang,Yuesi Wang,Xunhua Zheng,Bo Zhu,Yao Huang,Qingju Hao,

大气科学进展 , 2006,
Abstract: To understand methane (CH4) and nitrous oxide (N2O) emissions from permanently flooded rice paddy fields and to develop mitigation options, a field experiment was conducted in situ for two years (from late 2002 to early 2005) in three rice-based cultivation systems, which are a permanently flooded rice field cultivated with a single time and followed by a non-rice season (PF), a rice-wheat rotation system (RW) and a rice-rapeseed rotation system (RR) in a hilly area in Southwest China. The results showed that the total CH4 emissions from PF were 646.3±52.1 and 215.0±45.4 kg CH4 hm-2 during the rice-growing period and non-rice period, respectively. Both values were much lower than many previous reports from simfilar regions in Southwest China. The CH4 emissions in the rice-growing season were more intensive in PF,as compared to RW and RR. Only 33% of the total annual CH4 emission in PF occurred in the non-rice season, though the duration of this season is two times longer than the rice season. The annual mean N2O flux in PF was 4.5±0.6 kg N2O hm-2 yr-1. The N2O emission in the rice-growing season was also more intensive than in the non-rice season, with only 16% of the total annual emission occurring in the non-rice season. The amounts of N2O emission in PF were ignorable compared to the CH4 emission in terms of the global warming potential (GWP). Changing PF to RW or RR not only eliminated CH4 emissions in the non-rice season, but also substantially reduced the CH4 emission during the following rice-growing period (ca. 58%, P<0.05). However, this change in cultivation system substantially increased N2O emissions,especially in the non-rice season, by a factor of 3.7 to 4.5. On the 100-year horizon, the integrated GWP of total annual CH4 and N2O emissions satisfies PF>RR≈RW. The GWP of PF is higher than that of RW and RR by a factor of 2.6 and 2.7, respectively. Of the total GWP of CH4 and N2O emissions, CH4 emission contributed to 93%, 65% and 59% in PF, RW and RR, respectively. These results suggest that changing PF to RW and RR can substantially reduce not only CH4 emission but also the total GWP of the CH4 and N2O emissions.
Investigation of Spatial Distribution of Radiocesium in a Paddy Field as a Potential Sink  [PDF]
Kazuya Tanaka, Hokuto Iwatani, Yoshio Takahashi, Aya Sakaguchi, Kazuya Yoshimura, Yuichi Onda
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0080794
Abstract: Surface soils, under various land uses, were contaminated by radionuclides that were released by the Fukushima Daiichi Nuclear Power Plant accident. Because paddy fields are one of the main land uses in Japan, we investigated the spatial distribution of radiocesium and the influence of irrigation water in a paddy field during cultivation. Soil core samples collected at a paddy field in Fukushima showed that plowing had disturbed the original depth distribution of radiocesium. The horizontal distribution of radiocesium did not show any evidence for significant influence of radiocesium from irrigation water, and its accumulation within the paddy field, since the original amount of radiocesium was much larger than was added into the paddy field by irrigation water. However, it is possible that rainfall significantly increases the loading of radiocesium.
Effect of Water-Saving Irrigation on the Law of CH4 Emission from Paddy Field

PENG Shi-zhang,LI Dao-xi,XU Jun-zeng,DING Jia-li,HE Yan,YU Jin-yuan,

环境科学 , 2007,
Abstract: Based on rice water-saving irrigation technique and observation in situ with closed static chamber technique, field experiment was carried out to investigate the effect of rice water-saving controlled irrigation on the law of CH4 emission from paddy field. The results show that the diurnal variation of CH4 emission from paddy field under controlled irrigation (PFCI) appears regular afternoon-maximum model, mainly at 13:00, but that from paddy field under flooding irrigation (PFFI) appears random model. The seasonal variation of CH4 emission from PFCI takes on distinct one-peak pattern, occurring at the initial tillering stage of rice, more than 10 days earlier than that from PFFI. So, water regulation and practical irrigation of control irrigation model, especially after rice turning-green stage, is quite important to affect CH4 release from paddy field. The total CH4 emission from PFCI is 24.46g·m-2, the seasonal average of CH4 emission rate is 7.96 mg·(m2·h)-1, reduced by 39% compared with that from PFFI. But the mean emission rate of CH4 from PFCI is higher during rice turning-green and initial tillering stage, and lower than that from PFFI.
Responses of Soil Organic Carbon Content and Fractions to Land-Use Conversion from Paddy Field to Upland

HUANG Shan~,RUI Wen-yi~,PENG Xian-xian~,LIU Wu-ren~,ZHANG Wei-jian~,

环境科学 , 2009,
Abstract: Natural()~(13)C abundance determination method coupled with physical fractionation of soil organic carbon(SOC) was used to evaluate the responses of SOC and its fractions to long-term land-use conversion from paddy field to upland field(corn cultivation).Results showed that land-use conversion from paddy field to upland field led to significant decreases in the contents of SOC and total nitrogen(TN).Concentrations of total organic carbon(TOC) and TN were respectively greater by 76.7% and 47.6% in the paddy ...
The Influence of Continuous Rice Cultivation and Different Waterlogging Periods on Morphology, Clay Mineralogy, Eh, pH and K in Paddy Soils  [PDF]
M.A. Bahmanyar
Pakistan Journal of Biological Sciences , 2007,
Abstract: The effect of different rice cultivation periods on the properties of selected soils in alluvial plain were studied in Mazandaran province (north of Iran) in 2004. Soils were sampled form 0, 6, 16, 26 and over 40 years rice cultivation fields. In each treatment three soil profiles and six nearby auger holes were studied. The present study results indicated that continuous rice cultivation have changed soil moisture regime from xeric to aquic, soil color from brown to grayish, surface horizons from mollic to ochric epipedon and soil structure changed from granular or blocky to massive. Therefore, the soil order has changed from Mollisols to Inceptisols. No illuviation and eluviation of clay minerals occurred as a consequence of rice cultivation. X-ray diffraction analysis showed that clay minerals in non-rice cultivated field were illite, vermiculite, montmorillonite, kaolinite and chlorite, but in rice field were illite, montmorillonite, kaolinite and chlorite, respectively. In contrast of montmorillonite, the amount of illite and vermiculite have been decreased by increasing periods of rice cultivation. The pH values of the saturated soil surface in six weeks past plantation have shifted toward neutrality. While Eh value of non-paddy soils were about +90 mv, surface horizons of paddy soils at field conditions had Eh value about +40, -12, -84, -122 mv, respectively. The amounts of organic matter and available Fe, Mn, Zn and Cu were increased whereas available K was decreased in paddy soils.
A review of syntrophic fatty acids oxidation in anoxic paddy soil

LIU Peng-Fei,LU Ya-Hai,

微生物学通报 , 2013,
Abstract: Flooded rice field is one of major biogenic sources of greenhouse gas CH4. Complex organic matter is degraded to CH4 and CO2 by the co-operation of anaerobic microorganisms of several metabolic guilds involving the syntrophic oxidation of short-chain fatty acids like propionate, butyrate and acetate. Due to the fastidious nature of cultivation, the diversity and ecology of microorganisms involved in syntrophic oxidation in natural environments like paddy soils remain largely unexplored. Stable isotope probing (SIP), which links microbial identity and function, is a powerful tool to investigate the syntrophic oxidation of fatty acids in flooded paddy soils. This article reviews the recent research progresses in the thermodynamic principles, the interspecies interactions in the syntrophic oxidation of fatty acids, and paddy soils employing SIP technology. The knowledge acquired suggests that phylogenetically diverse bacterial groups are active in the syntrophic oxidation: except classic syntrophic bacteria, organisms belonging to uncultivated phylogenetic groups are also detected, which can serve as candidate syntrophs. Among archaea, Methanocella is the major methanogen partner in syntrophic oxidation of different fatty acids, indicating the importance of this group in CH4 production of paddy field soil.
Emissions of CH4 and N2O under Different Tillage Systems from Double-Cropped Paddy Fields in Southern China  [PDF]
Hai-Lin Zhang, Xiao-Lin Bai, Jian-Fu Xue, Zhong-Du Chen, Hai-Ming Tang, Fu Chen
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0065277
Abstract: Understanding greenhouse gases (GHG) emissions is becoming increasingly important with the climate change. Most previous studies have focused on the assessment of soil organic carbon (SOC) sequestration potential and GHG emissions from agriculture. However, specific experiments assessing tillage impacts on GHG emission from double-cropped paddy fields in Southern China are relatively scarce. Therefore, the objective of this study was to assess the effects of tillage systems on methane (CH4) and nitrous oxide (N2O) emission in a double rice (Oryza sativa L.) cropping system. The experiment was established in 2005 in Hunan Province, China. Three tillage treatments were laid out in a randomized complete block design: conventional tillage (CT), rotary tillage (RT) and no-till (NT). Fluxes of CH4 from different tillage treatments followed a similar trend during the two years, with a single peak emission for the early rice season and a double peak emission for the late rice season. Compared with other treatments, NT significantly reduced CH4 emission among the rice growing seasons (P<0.05). However, much higher variations in N2O emission were observed across the rice growing seasons due to the vulnerability of N2O to external influences. The amount of CH4 emission in paddy fields was much higher relative to N2O emission. Conversion of CT to NT significantly reduced the cumulative CH4 emission for both rice seasons compared with other treatments (P<0.05). The mean value of global warming potentials (GWPs) of CH4 and N2O emissions over 100 years was in the order of NT
Effects of Tillage and Nitrogen Fertilizers on CH4 and CO2 Emissions and Soil Organic Carbon in Paddy Fields of Central China  [PDF]
Li Cheng-Fang, Zhou Dan-Na, Kou Zhi-Kui, Zhang Zhi-Sheng, Wang Jin-Ping, Cai Ming-Li, Cao Cou-Gui
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0034642
Abstract: Quantifying carbon (C) sequestration in paddy soils is necessary to help better understand the effect of agricultural practices on the C cycle. The objective of the present study was to assess the effects of tillage practices [conventional tillage (CT) and no-tillage (NT)] and the application of nitrogen (N) fertilizer (0 and 210 kg N ha?1) on fluxes of CH4 and CO2, and soil organic C (SOC) sequestration during the 2009 and 2010 rice growing seasons in central China. Application of N fertilizer significantly increased CH4 emissions by 13%–66% and SOC by 21%–94% irrespective of soil sampling depths, but had no effect on CO2 emissions in either year. Tillage significantly affected CH4 and CO2 emissions, where NT significantly decreased CH4 emissions by 10%–36% but increased CO2 emissions by 22%–40% in both years. The effects of tillage on the SOC varied with the depth of soil sampling. NT significantly increased the SOC by 7%–48% in the 0–5 cm layer compared with CT. However, there was no significant difference in the SOC between NT and CT across the entire 0–20 cm layer. Hence, our results suggest that the potential of SOC sequestration in NT paddy fields may be overestimated in central China if only surface soil samples are considered.
Intra- versus inter-site macroscale variation in biogeochemical properties along a paddy soil chronosequence
C. Mueller-Niggemann, A. Bannert, M. Schloter, E. Lehndorff,L. Schwark
Biogeosciences (BG) & Discussions (BGD) , 2012,
Abstract: In order to assess the intrinsic heterogeneity of paddy soils, a set of biogeochemical soil parameters was investigated in five field replicates of seven paddy fields (50, 100, 300, 500, 700, 1000, and 2000 yr of wetland rice cultivation), one flooded paddy nursery, one tidal wetland (TW), and one freshwater site (FW) from a coastal area at Hangzhou Bay, Zhejiang Province, China. All soils evolved from a marine tidal flat substrate due to land reclamation. The biogeochemical parameters based on their properties were differentiated into (i) a group behaving conservatively (TC, TOC, TN, TS, magnetic susceptibility, soil lightness and colour parameters, δ13C, δ15N, lipids and n-alkanes) and (ii) one encompassing more labile properties or fast cycling components (Nmic, Cmic, nitrate, ammonium, DON and DOC). The macroscale heterogeneity in paddy soils was assessed by evaluating intra- versus inter-site spatial variability of biogeochemical properties using statistical data analysis (descriptive, explorative and non-parametric). Results show that the intrinsic heterogeneity of paddy soil organic and minerogenic components per field is smaller than between study sites. The coefficient of variation (CV) values of conservative parameters varied in a low range (10% to 20%), decreasing from younger towards older paddy soils. This indicates a declining variability of soil biogeochemical properties in longer used cropping sites according to progress in soil evolution. A generally higher variation of CV values (>20–40%) observed for labile parameters implies a need for substantially higher sampling frequency when investigating these as compared to more conservative parameters. Since the representativeness of the sampling strategy could be sufficiently demonstrated, an investigation of long-term carbon accumulation/sequestration trends in topsoils of the 2000 yr paddy chronosequence under wetland rice cultivation restricted was conducted. Observations cannot be extrapolated to global scale but with coastal paddy fields developed on marine tidal flat substrates after land reclamation in the Zhejiang Province represent a small fraction (<1%) of the total rice cropping area. The evolutionary trend showed that the biogeochemical signatures characteristic for paddy soils were fully developed in less than 300 yr since onset of wetland rice cultivation. A six-fold increase of topsoil TOC suggests a substantial gain in CO2 sequestration potential when marine tidal wetland substrate developed to 2000 yr old paddy soil.
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