Rice Rotation Research Articles

Residual zinc improves soil health, productivity and grain quality of rice in conventional and conservation tillage wheat-based systems

Zinc (Zn) deficiency in rotations of rice (Oryza sativa L.) and wheat (Triticum aestivum L.) impedes the productivity of both component crops. Fertilisation with Zn and switching to conservation tillage systems may help to improve soil health and the productivity of both rice and wheat. However, it is not clear whether, in conservation tillage systems, Zn application to either crop will fulfil the requirement of the following crop through a residual effect. This study was designed to evaluate the influence of Zn applied to wheat on the performance of rice under conventional (puddled transplanted rice, PuTR) and conservation (direct-seeded aerobic rice, DSAR) tillage. As a part of a long-term experiment, Zn was applied as foliage spray (FA, 0.025 M), by seed priming (SP, 0.5 M) and by soil application (SA, 10 kg ha–1) in plough-till wheat (PTW) and no-till wheat (NTW). Controls without Zn application were included (PTW-C, NTW-C). After wheat harvest, rice was planted as PuTR and DSAR in each of the eight Zn application × wheat tillage treatment combinations. Compared with PuTR, DSAR significantly improved soil fertility (nitrogen, phosphorus, Zn), soil organic matter (1.5–4.5%), soil organic carbon (3%), soil microbial biomass carbon (2.5%) and grain yield (5.6%). Overall, DSAR preceded by NTW had higher soil organic carbon (4.3%), soil microbial biomass nitrogen (1.6%) and soil microbial biomass carbon (3.7%) than PuTR sown after either PTW or NTW. Residual Zn enhanced grain Zn concentration by 15% in rice planted after PTW-SA and 12% after NTW-SA. Overall order of improvement in rice-grain Zn concentration was PTW-SA = NTW-SA > NTW-C = NTW-SP. Likewise, higher grain yield with residual Zn availability was in the order DSAR-NTW-SA > PuTR-PTW-SA during 2018. Highest economic return with high benefit:cost ratio was recorded for DSAR-NTW-SA. Zinc application to the wheat crop effectively improved crop performance and grain quality of the following rice crop in both conventional and conservation tillage systems. However, the conservation system DSAR-NTW-SA may be chosen for improved soil health, and for increased harvest grain yield with better grain quality.

Effects of Italian ryegrass residues as green manure on soil properties and bacterial communities under an Italian ryegrass (Lolium multiflorum L.)-rice (Oryza sativa L.) rotation

Green manure shows promise for the relief of the environmental pressure caused by successive farming and excessive applications of fertilizers. Soil microbes play an important role in the decomposition of green manure. However, few studies focused on the relationship between the release of nutrients and bacterial community diversity when different rates of green manure are applied. The aim of this study was to evaluate the dynamic changes in soil bacterial communities and nutrient release during the decomposition of the green manure Italian ryegrass (Lolium multiflorum L.) residues in a new type Italian ryegrass-rice (Oryza sativa L.) rotation (IRR) system in South China. Six different rates (P0–P5) of Italian ryegrass were added to rice-growing red soil (Ferralic Cambisol) and allowed to decompose for 40 d (sampled every 10 d). Nutrient release and soil properties were determined during the decomposition and Illumina reads of the 16S rRNA gene amplicons were used to analyse changes in the bacterial communities. The addition of residues increased both nutrient concentrations (e.g., total nitrogen, available nitrogen and available potassium) and the relative abundance of microbes involved in nutrient cycling (e.g., Proteobacteria, Bacteroidetes, Acidobacteria, and Gemmatimonadetes). Italian ryegrass residues had much faster rates of decomposition at 1–10 d, 11–20 d, and 21–30 d (from 183.2 to 238.1 g kg–1, on average) than that (45.6 g kg–1) at 31–40 d. Overall, the high green manure decomposition rates were accompanied by high similarities in bacterial community structures during decomposition. The nutrient cycle efficiency and bacterial community diversity were higher when the soils were treated with 40,170–44,895 kg ha–1 (P3–4) of green manure than other treatments. The average Shannon index values following the 44,895 kg ha–1 (P4) treatment were the highest among the different rates of residue application, and they were 6.42 at 10 d, 6.37 at 20 d, 6.29 at 30 d, and 6.53 at 40 d. The highest soil total nitrogen concentrations of 1.4–2.0 g kg–1 were obtained following the 40,170 kg ha–1 (P3) treatment, and seedling biomass increased the most under P3 treatment. In addition, soil total nitrogen and available potassium concentrations were significantly correlated with rice seedling biomass. This study demonstrates that the management of green manure application based on the IRR system facilitates rice growth by improving bacterial communities (composition and diversity) and soil fertility, and it provides a new perspective on the links between potential microbial community functions and organic agro-ecosystems.

Soil mineralogy and dynamic pedogenic processes in response to redox cycles due to rice and sweet potato rotation

Effect of long-term wet and dry (redox) cycles attributed to seasonally flooded soils in rotation of rice and upland food crops on soil characteristics is not yet available in modern agriculture. The objective of this study was to assess soil morphological features, mineralogical compositions and dynamic pedogenic processes under rotation of rice and honey-taste sweet potato. Four profiles that experienced redox cycles and one that did not (as a control) were sampled for soil analyses. Results showed that all soil profiles, irrespective of redox cycles, derived from similar parent materials as revealed by the same type of weatherable mineral contents (hornblende, labradorite, hypersthene, and olivine or muscovite), ranging within 27–84%. High proportions of easily weatherable minerals corresponded to the high availability of Ca, Mg, Si, Fe, Mn and Cu nutrients, suggesting the release of nutrient reserves from weatherable minerals. In all soils, the clay fraction contained only the one mineral, halloysite. Long-term redox cycles due to rotation of rice–honey-taste sweet potato resulted in a remarkable pedomorphic feature, i.e. discrete large soft black Mn segregation with the highest accumulation in the middle part of soil profiles. Other pedogenic processes were Ca, Mg, and Si translocation from the upper to lower layers of soil profiles, but Fe was retained in the uppermost two horizons. We proposed a new soil classification ‘Manganic Eutrudept’ as a subgroup category to accommodate the soil property of high soft Mn segregation.

Italian ryegrass–rice rotation system for biomass production and cadmium removal from contaminated paddy fields

PURPOSE: Growing energy plants in Cd-contaminated soil to produce bioenergy feedstock and remove excess Cd in the soil is a promising approach to the production of sustainable bioenergy feedstock and safe food. Rice, an important staple food for human beings, is a major source of Cd intake in human beings. Italian ryegrass (Lolium multiflorum Lam) is a potential bioenergy plant with high biomass productivity and high biofuel conversion efficiency. MATERIALS AND METHODS: An Italian ryegrass and rice crop rotation system would be beneficial for the harvest of bioenergy and phytoremediation. An Italian ryegrass–rice rotation system was established in a moderately Cd-contaminated paddy field. The yield of biomass, amount of Cd removal, and transfer factors for three cropping systems (winter fallow, non-cutting, and cutting) were evaluated over 3 consecutive years of field experiments. RESULTS AND DISCUSSION: The total biomass production of the Italian ryegrass–rice rotation system was significantly higher than that of the traditional cropping system. Biomass growth was further promoted by cutting during March. No significant differences were found in yield or Cd concentration of brown rice among the different cropping systems. Total Cd accumulation in rice and Italian ryegrass straw in the rotation cropping system was significantly higher than that in the winter fallow cropping system. Cd was mainly accumulated in the roots, and the ability of Italian ryegrass to transport Cd to the leaves was higher than that of rice. CONCLUSIONS: The Italian ryegrass–rice rotation system is a potential cropping system for Cd-contaminated paddy fields. The average annual yield of biomass was 1656.6 kg km⁻², and the average annual amount of Cd removal was more than 9.8 g Cd km⁻².

Soil chemical and biological fertility, microbial community structure and dynamics in successive and fallow sugarcane planting systems

ABSTRACTSugarcane yields are declining under successive planting (monoculture) compared to other planting systems in Florida Histosols. To evaluate soil properties related to the sugarcane yield decline, an on-farm study was conducted on soil chemical, biological, and microbial indicators variation with soil samples collected from successive green cane or burnt cane harvest, flooded fallow, and rice and sweetcorn rotation planting sites. Overall, harvest residue incorporated in the soil in green cane harvest and corn rotation increased organic matter, total carbon and C:N ratios which resulted in higher microbial biomass parameters and total PLFA biomass. However, successive planting with burnt cane harvest reduced total soil carbon and hence microbial biomass. Findings suggested that these parameters should be considered for further research to determine specific causes of sugarcane yield decline in successive planting.

Farmyard manure improves phosphorus use efficiency in weathered P deficient soil

Crop production is limited by low soil fertility in sub-Saharan Africa (SSA), particularly by P deficiency due to strong fixation by Fe and Al oxyhydroxides. Organic amendments are known to increase P availability in fertilizer and in such soils by different mechanisms. This study investigated the effect of adding farmyard manure (FYM) versus mineral triple super phosphate (TSP) fertilizer on P availability in different cropping systems. Field experiments were conducted in three succeeding summer seasons to compare two different upland cropping systems: a Bambara (Vigna subterranea)–rice rotation and a rice–rice system on a highly P deficient Ferralsol. Nine treatments including sole TSP at 0, 10, 20, 30 kg P ha−1 year−1, and sole FYM at 0, 10, 20, 30 kg P ha−1 year−1 (i.e. 100% FYM substitution), and combined FYM and TSP (FYM + TSP) at 20, 30 kg P ha−1 year−1 (i.e. 50% and 67% FYM substitution, respectively) were applied. Results showed that FYM treatments increased Bambara and rice grain yields compared to TSP treatment alone particularly in year three. Phosphorus uptake efficiency was higher in FYM treatments combined or not with TSP in year three of the experiment. The notable response to FYM was associated with increased agronomic efficiency resulting from additional C originating from the FYM with a low initial soil C content, (around 2%), and the effect of liming that reduced soil P sorption thereby improving P availability from FYM. Partial (67%) substitution of TSP by FYM increased grain yields of Bambara by 1.67 Mg ha−1 and of rice by 1.01 Mg ha−1 compared to TSP alone in year three at the highest P rate (30 kg P ha−1). The effect of FYM could be linked to inputs of C and nutrients from added FYM and to the indirect effect on soil physico–chemical properties including soil pH, soil moisture, soil biological activity, low P capacity sorption. This study confirms that application of FYM can help minimize rates of TSP applied in smallholder farms in SSA.

Inter-annual variation in P speciation and availability in the drought-rewetting cycle in paddy soils

Successive application of phosphorus (P) fertilizer under different cropping systems could result in remarkable changes in soil P fractions, accompanied by inducing soil P accumulation and increasing eutrophication risks. However, relatively little attention has been paid to annual changes in soil P fractions and P losses via runoff in drought-rewetting paddy fields. In the present study, we explored inter-annual variations in soil P speciation, availability and runoff P in a five-year field trial in a winter wheat and summer rice rotations system, and in different rice-growth stages. Four P fertilization treatments were applied, including P fertilization in both farming seasons (wheat and rice) (PR + W), application of P fertilizer only in rice-growing seasons (PR), application of P fertilizer only in wheat-growing seasons (PW), and no P fertilization (Pzero). Our results showed that P fertilization treatments (PW, PR, and PR + W) significantly altered the proportions of inorganic P (Pi) fractions, while no P fertilization in the wheat-growing seasons (Pzero, PR) significantly decreased NaHCO3-Pi contents in the wheat-growing seasons and decreased NaHCO3-Pi and NaOH-Pi concentrations in the rice-growing seasons (p < 0.05). Application of P fertilizer in the wheat-growing seasons treatments (PW, PR+W) maintained the stability of soil P fractions both in the wheat- and rice-growing seasons. Moreover, compared to the PR+W treatment, the PW treatment reduced total P (TP) losses from runoff. For inter-annual drought-rewetting variation in P speciation and availability, there was a significant correlation between Olsen-P and NaHCO3-Pi and NaOH-Pi contents in the wheat-growing seasons, and Olsen-P was significantly correlated with NaHCO3-Pi, NaOH-Pi, and HCl-P in the rice-growing seasons. Furthermore, we focused on the change in detailed rice-growth stages, and found aeration significantly increased NaHCO3-Pi, NaOH-Pi, NaOH-Po and HCl-P contents, and there was a significant correlation between soil Olsen-P and the P fractions in the A-aeration growth stage in rice, which could be attributed to the short-term drought-rewetting cycle facilitating the release of soil P. The present study revealed changes in soil P speciation and availability in a drought-rewetting cycle in paddy soils, and indicated the optimized agricultural P management strategies had the potential to reduce environmental risks.

Greenhouse gas mitigation potential under different rice-crop rotation systems: from site experiment to model evaluation

Crop rotation systems in fields could improve crop production and indirectly affect carbon and nitrogen dynamics due to multiple fertilizer applications. Therefore, it is important to evaluate the impact of these crop rotation systems on greenhouse gas (GHG) emissions. Field experiments were conducted with three different rotation systems, and the DeNitrification–DeComposition (DNDC) model was applied to monitor and estimate crop yields and GHG emissions during three rice-upland crop rotational periods (from June 2013 to May 2016). Low methane (CH4) and nitrous oxide (N2O) emissions were observed in rice-Chinese milk vetch and single rice rotation systems. The simulated crop yields fit the observed data very well (d > 0.80, EF > 0.70) after the model was calibrated by adjusting the crop parameters. The model-simulated daily and annual CH4 emissions agreed well with the field measurements (d > 0.7, EF = 0.41–0.98). The simulated N2O (d = 0.01–0.70, EF < 0 or close to 0) of accumulated emissions and daily fluxes (d = 0.07–0.14, EF < 0) showed low levels of accuracy with field observations. The GHG emissions in Shanghai rice paddy were different under various rotation systems, with the following order: single rice rotation system < rice-Chinese milk vetch rotation system < baseline rotation system of Shanghai paddy < 1/3 (rice-Chinese milk vetch + single rice + rice-winter wheat rice-winter) rotation system < rice-winter wheat rotation system under the same nitrogen loading. The DNDC was able to predict rice yields and GHG emissions under different crop rotation systems. The results provide positive reliable indications that crop rotation systems have the potential to reduce GHG emissions; e.g., the rice-Chinese milk vetch rotation system could mitigate the CH4 and N2O emissions.

Variable effects of 2°C air warming on yield formation under elevated [CO2] in a Chinese double rice cropping system

Elevated atmospheric CO2 concentration ([CO2]) and temperature can strongly affect rice (Oryza sativa L.) production. However, the impact of warming is variable depending on ambient temperature and cropping system. Little is known about the effect of elevated temperature and its interaction with elevated [CO2] in the Chinese double rice cropping system. To study this issue, field experiments were conducted using open-top chambers (OTC) with varying [CO2] (ambient, ambient+60 μmol mol−1) and varying temperature (ambient, ambient+2 °C) for 4 rotations of double rice from 2013 to 2016. Elevated [CO2] significantly increased grain yield in both early rice and late rice. This could be attributed to greater aboveground biomass, higher panicle number (m-2), spikelet number (per panicle) and 1000-grain weight. Elevated temperature decreased yield in early rice (except for 2016) due to decreases in % filled grains and 1000-grain weight. Elevated temperature increased yield in late rice due to increases in aboveground biomass, number of panicles and spikelets, although % filled grains decreased. We found that warming had positive effects on tiller development and dry matter accumulation during the pre-heading period both in early and late rice, which contributed to yield formation. When elevated temperature and [CO2] were combined, yield changed by −1.9–23.7% in early rice compared with ambient condition as warming partly offset the benefits of CO2 enrichment, while yield increased by 14.3–18.8% in late rice due to a synergy between warming and CO2 enrichment. The benefits of CO2 enrichment for fertile spikelets (m-2) and aboveground biomass could reduce or eliminate the negative impacts of warming. However, there were no significant interactions between elevated temperature and [CO2] in most rice seasons. Our findings indicate that warming by 2 °C is not detrimental to yield formation under CO2 enrichment, and suggest that grain yield may not decrease under future climate change in the Chinese double rice cropping system.

Rice Rotation System Affects the Spatial Dynamics of the Diazotrophic Community in Paddy Soil of the Yangtze Delta, China

Rice-wheat (RW), rice-fallow (RF), and rice-Chinese milk vetch (RM) are the three major rice rotation systems currently used in the Yangtze Delta of China. However, it remains poorly understood how these systems affect microbial communities in soils. Quantitative polymerase chain reaction (qPCR) and denaturing gradient gel electrophoresis (DGGE) were used to analyze the composition, abundance and diversity of diazotrophic community at different depths in soils under RW, RF and RM treatments. The results showed that rice yields were significantly higher in RM as compared to those in RF and RW in all years from 2011 to 2016. Diazotrophic communities at soil depths of 10–20 cm and 40–80 cm under RM were significantly more diverse than those under the other treatments. Sequences affiliated with Geoalkalibacter spp. showed the greatest abundance under RW at all soil depths, while Desulfovibrio and Pseudacidovorax spp. were both more abundant under RM at the 40–80 cm depth. Redundancy analysis (RDA) identified that the diazotrophic community within the 40–80 cm layer of soil under RM was positively associated with soil macro-aggregates. In conclusion, the RM treatment was characterized by significantly higher diversity of diazotrophic community in subsoil and increased rice yields as compared to the other treatments.

Diseño de un sistema de producción de arroz sostenible en Babahoyo, provincia de Los Ríos, Ecuador

Este trabajo se ajusta para la localidad de Babahoyo, en la provincia de Los Ríos (Ecuador), con el objetivo de diseñar un sistema de producción de arroz que haga sustentable a este monocultivo en Babahoyo y establecer indicadores para la evaluación de la sustentabilidad de este sistema de producción de arroz. Se procederá bajo el siguiente esquema metodológico: con el diseño de los cercos forestales propuestos se podrá establecer un sistema de producción de arroz en donde también se realizaría rotación de cultivos. Los cercos forestales se conformarán por la siembra alternada de inga (Inga edulis Martius), guayacán (Guaiacum sanctum L.) y mango (Manguifera indica), sobre los muros perimetrales de las parcela de arroz, mientras que la rotación de cultivos será entre arroz (Oryza sativa L.) y soya (Glycine max L.), en el año se cultivará arroz en estación húmeda y soya en estación seca. Los resultados serían la transformación del monocultivo de arroz en un Sistema Sustentable de producción de arroz, lo que permitirá al productor arrocero no depender solo de la producción y comercialización de esta gramínea; con la soya y la inga el sistema permitirá también la fijación de nitrógeno en el suelo y por la naturaleza de sus raíces la soya evitará la compactación del suelo. Asimismo, se espera que el sistema agroforestal propuesto contribuya de un modo eficiente a la captura de carbono. En términos fitosanitarios, la rotación de cultivos interrumpirá los ciclos biológicos de las plagas propias de los cultivares.

Effect of reduced nitrogen fertilization on carbon footprint in spring maize-late rice production system

With the growing concerns on global climate change and food security, low carbon agriculture in food production attracts more attention. Low carbon agriculture needs to balance higher-level crop yields and lower greenhouse gas emission in production process. Improving nitrogen mana-gement may help mitigate greenhouse gas emission and achieve stable or higher crop yields in crop production systems. In this study, we investigated the effects of nitrogen application rates (150, 225, 300 kg N·hm-2) on the carbon footprint of spring maize-late rice rotation system in paddy field using the life cycle assessment. The results showed that greenhouse gas emission and carbon footprint increased with the nitrogen fertilizer application rates in both crops. Nitrogen fertilizer was the most important contributor to carbon footprint of spring maize ecosystem, accounting for 36.2%-50.2%. Methane emission increased with nitrogen fertilizer input and contributed the most to the carbon footprint of late rice production, accounting for 42.8%-48.0%. When the nitrogen application rate was reduced by 25% (225 kg N·hm-2) and 50% (150 kg N·hm-2), greenhouse gas emission of maize production decreased by 21.9% and 44.3%, and the carbon footprint decreased by 20.3% and 39.1%, respectively. Meanwhile, the greenhouse gas emissions of late rice decreased by 12.3% and 20.4%, and the carbon footprint of late rice decreased by 13.7% and 16.7%, respectively. The reduction of nitrogen fertilizer rate had no significant effect on maize yield, with the treatment of 225 kg N·hm-2 rate holding the highest yield in late rice ecosystem. The treatment of 150 kg N·hm-2 rate in spring maize production and 225 kg N·hm-2 rate in late rice production was the sustainable N fertilizer application rate for achieving high grain yield and reducing the carbon footprint in crop system.

Potential yields, yield gaps, and optimal agronomic management practices for rice production systems in different regions of China

Understanding crop potential yields, yield gaps, and optimal agronomic management practices helps in identifying the limiting factors, scope, and ways to achieve sustainable intensified agricultural production. Here, using detailed field trial data collected from 1981 to 2009 at 11 agro-meteorological experimental stations and the crop model CERES–Rice, we investigated changes in potential yields, water- and nitrogen-stressed yields, and yield gaps of rice in the major rice cultivation regions of China during the collection period. We further identified the optimal nitrogen application rate, transplanting date, and cultivar traits for the sustainable intensification of rice production systems in different regions. Owing to climate change, the potential rice yields declined or changed little in the Middle and Lower Reaches of the Yangtze River (MLRYR), while they increased or changed little in the Northeastern China Plain (NECP) during 1981–2009. Rice yield gaps shrank in the major rice production regions because the actual yields increased and approached the potential yields. The average yield gap was 16.0% in the 2000s, with water and nitrogen stresses being the limiting factors in the NECP and water stress being the major limiting factor in the MLRYR. The nitrogen application rate was suggested to be increased by 47.5% and 21.7% for single rice (i.e., rice cultivated in a single season per year) in the NECP and MLRYR, respectively, and increased by 5.2% for early rice (i.e., rice cultivated in the early season in a rice–rice rotation system per year). However, it was suggested to be reduced by 13.1% for late rice (i.e., rice cultivated in the late season in a rice–rice rotation system per year). Early transplanting could increase the yield, while late transplanting could decrease the yield. The impacts were greater for single rice in the NECP and late rice in the MLRYR than for single rice and early rice in the MLRYR. Cultivars with longer growth durations, and greater spikelet numbers and grain weights, could significantly increase the rice yield by 14.8%–45.6%. The optimal cultivars, combined with advancing transplanting by 10 d, could increase rice yields by 29.2%–68.9%. Our findings provide new approaches, important insights, and effective options for the sustainable intensification of rice production systems in different regions of China.

Effects of Paddy Percolation Rates on Greenhouse Gases Emission from Rotation of Rice and Other Crops with Farm Land Consolidation regarding Volcanic Ash Soil

Effects of Paddy Percolation Rates on Greenhouse Gases Emission from Rotation of Rice and Other Crops with Farm Land Consolidation regarding Volcanic Ash Soil

Morphological and Metabolic Changes in Soybean Plants Cultivated in Irrigated Rice Rotation and as Affected by Imazapyr and Imazapic Herbicides Carryover

ABSTRACT: The appearance of soybean cultivars that are tolerant to herbicides from the imidazolinone group enables irrigated rice rotation conducted on Clearfield® system. The objective of this work was to evaluate the morphological and metabolic changes of soybean cultivars containing Cultivance® (CV), which is tolerant to imidazolinone, sulphonylurea toletant (STS) and Roundup Ready® (RR), which is tolerant to glyphosate as affected by carryover of increasing doses of imazapyr and imazapic herbicides mixture, applied in the management of irrigated rice crop. Thus, experiments were conducted on the field and in greenhouse, evaluating phytotoxicity, height, leaf area, shoot dry matter, as well as variables related to the secondary metabolism of plants like chlorophyll, carotenoids, hydrogen peroxide, lipid peroxidation and electrolytes leakage. Soybean cultivars RR and STS are susceptibles to the carryover of imazapyr and imazapic mixture applied in the management of irrigated rice crop, whereas the CV cultivar is resistant. The rise in the herbicide carryover dose increases the reactive oxygen species (ROS) production in soybean plants. The RR cultivar, in general, shows higher ROS production compared to the other soybean cultivars.

春玉米-晚稻与早稻-晚稻种植模式碳足迹比较

PDF HTML阅读 XML下载 导出引用 引用提醒 春玉米-晚稻与早稻-晚稻种植模式碳足迹比较 DOI: 10.5846/stxb201808021647 作者: 作者单位: 浙江大学环境污染防治研究所 作者简介: 通讯作者: 中图分类号: 基金项目: 国家重大研发计划（2016YFD0300203-4） Comparison of carbon footprint between spring maize-late rice and early rice-late rice cropping system Author: Affiliation: Institute of Environment Pollution Control and Treatment, Zhejiang University Fund Project: The National Basic Research Program of China (973 Program) 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:量化作物生产的碳足迹有助于为农业生态系统温室气体减排提供理论依据。利用生命周期法研究了我国南方地区稻田春玉米-晚稻水旱轮作种植模式和早稻-晚稻连作种植模式下粮食生产的碳足迹，并定量分析粮食生产过程中各种碳排放源的相对贡献。结果表明，与早稻-晚稻的连作模式相比，春玉米-晚稻轮作模式的单位面积碳排放降低了6724 kg CO2-eq/hm2，单位产量的碳足迹降低了0.56 kg CO2-eq/kg。春玉米比早稻少排放6228 kg CO2-eq/hm2；与早稻-晚稻模式中晚稻碳排放相比，春玉米-晚稻轮作模式晚稻碳排放降低了497 kg CO2-eq/hm2。早稻-晚稻种植模式的碳足迹主要来源于甲烷（CH4），其碳排放为9776 kg CO2-eq/hm2（54.8%），氮肥生产和施用的碳排放为2871 kg CO2-eq/hm2（16.1%），灌溉电力消耗的碳排放2849 kg CO2-eq/hm2（16.0%）。春玉米-晚稻轮作模式的碳足迹主要来源于CH4的碳排放4442 kg CO2-eq/hm2（39.9%），氮肥生产和施用的碳排放2871 kg CO2-eq/hm2（25.8%），灌溉电力消耗的碳排放1508 kg CO2-eq/hm2（13.6%）。该模式中晚稻的碳足迹组成情况与春玉米-晚稻模式的碳足迹相似。但是，对于春玉米而言，其碳足迹主要来源氮肥生产和施用的碳排放1436 CO2-eq/hm2（50.1%），氧化亚氮（N2O）的碳排放为579 kg CO2-eq/hm2（20.2%），CH4的碳排放为378 CO2-eq/hm2（13.2%）。同时，相比于早稻-晚稻中晚稻的产量（6333 kg/hm2），春玉米-晚稻轮作模式下的晚稻产量（7270 kg/hm2）提高了14.8%。因此，引入春玉米-晚稻轮作模式有利于提升稻田生产力，降低稻田连作系统碳排放和碳足迹。 Abstract:Quantifying the carbon footprint of crop production can help provide a theoretical basis to mitigate greenhouse gas emissions in agro-ecosystem. In this study, the life cycle assessment was used to assess the carbon footprint of two cropping systems (early rice-late rice continuous cropping system and spring maize-late rice rotation systems) and quantitatively analyze the relative contribution of various carbon sources in grain production in paddy field of Southern China. The results showed that the spring maize-late rice rotation reduced the carbon emissions per unit area by 6724 kg CO2-eq/hm2 and the carbon footprint per unit yield by 0.56 kg CO2-eq/kg compared with the continuous cropping of early rice-late rice. The carbon emissions from the production of spring maize were less 6228 kg CO2-eq/hm2 than in early rice. The carbon emissions of late rice in spring maize-late rice rotation system were decreased by 497 kg CO2-eq/hm2, when compared with that in early rice-late rice system. The main components of carbon footprint in the early rice-late rice planting system were derived from the carbon emission of methane (CH4) from paddy field (9776kg CO2-eq/hm2, 54.8%), nitrogen fertilizer production and application (2871 kg CO2-eq/hm2, 16.1%), and electricity consumption (2849 kg CO2-eq/hm2, 16.0%). While the main part of carbon footprint came from the carbon emission of CH4 (4442 kg CO2-eq/hm2, 40.0%), nitrogen fertilizer production and application (2871 kg CO2-eq/hm2, 25.8%), and electricity consumption (1508 kg CO2-eq/hm2, 13.6%) in the spring maize-late rice rotation system. The composition of carbon footprint of late rice in this system were similar to that in the spring maize-late rice system. However, the main part of carbon footprints of spring maize were mainly derived from the carbon emission of nitrogen fertilizer production and application (1435 CO2-eq/hm2, 50.1%), nitrous oxide (579 kg CO2-eq/hm2, 20.2%), and CH4 (378 CO2-eq/hm2, 13.2%). Meanwhile, compared with the yield of late rice (6333 kg/hm2) in early rice-late rice cropping system, the yield of late rice (7271 kg/hm2) was increased in the spring maize-late rice rotation system. Accordingly, introducing spring maize-late rice rotation system is conducive to improving rice paddy productivity and mitigating carbon emission and carbon footprint in continuous rice systems. 参考文献 相似文献 引证文献

Diazotroph abundance and community structure are reshaped by straw return and mineral fertilizer in rice-rice-green manure rotation

The nitrogen (N)-fixing community in soil, a key functional player to replenish N pools from atmospheric N2, can be radically changed by the addition of inorganic or organic substrate; however, the response of the diazotroph population to nutrient and residue management in green manure-based wetland rice rotations is poorly understood. Here, we investigated the diazotrophic community to inputs of a leguminous green manure Chinese milk vetch (Mv, Astragalus sinicus) using quantitative PCR and Illumina Miseq sequencing of the nifH gene. Five treatments were compared in a Milk vetch–early rice–late rice rotation: 1) Control, no fertilization and straw return (CK); 2) rice straw incorporation alone (Rs); 3) inorganic fertilizer application alone (F); 4) F plus Rs (FRs); 5) similar with FRs but high-stubble (∼35–40 cm) of late rice straw was remained (FRh). The results showed that cultivation practice affected the magnitude of soil available nutrient pools (N, P and K), but not the soil organic matter and total N pools. The rice straw significantly repressed the nifH gene abundance compared to the control, and increased the number of diazotrophic bacteria species, Chao 1 values, Shannon and Simpson indexes more than other fertilization treatments. Multivariate regression tree analysis revealed that the community diversity and structure of diazotrophs were primarily shaped by soil nitrate and available P status, as well as C/N ratio. The most abundant genus Bradyrhizobium (21%–32%) tended to decrease in rice straw soil in comparison with the control but was significantly enhanced in the FRs treatment at seedling stage and in FRh treatment at flowering stage. Spearman correlation analysis showed that the dominant diazotrophic genera were positively related with soil available phosphorus, but responded differentially to soil total N, nitrate, and pH between the seedling and flowering stages. Overall, the planting and incorporation of vetch under different practices of residue and fertilizer management reshaped the diazotrophic community during the green manure season, highlighting the crucial roles of soil C, N, and P status or their ratios in shaping the population and diversity of diazotrophs.

Cover Crops as Affecting Soil Chemical and Physical Properties and Development of Upland Rice and Soybean Cultivated in Rotation

Cover crops can provide changes in soil chemical and physical properties, which could allow a sustainable development of soybean and upland rice rotation in Brazilian Cerrado. The objective of this study was to determine the effects of cover crops (cultivated in the offseason) in the soybean-upland rice rotation (cultivated in the summer season) on the soil chemical and physical properties, yield components and grain yield of the cash crops. The experimental design was a randomized block design in factorial scheme 4×2 with six replications. Treatments were composed by four cover crops: fallow, millet (Pennisetum glaucum)+Crotalaria ochroleuca, millet+pigeon pea (Cajanus cajans), and millet+pigeon pea+Urochola ruziziensis in the offseason with one or two cycles of cover crops, with rice (Oryza sativa) or soybean (Glycine max) in the summer season. Cover crops alone provided no changes in soil chemical properties. However, the rotation cover crops/cash crops/cover crops/cash crops reduced pH, Al and H+Al and increased Ca, Mg, K and Fe contents in the soil. The cover crops millet+pigeon pea and millet+pigeon pea+U. ruziziensis improved soil physical properties in relation to fallow, especially in the 0–0.10m soil layer. In spite of the improvement of the soil physical properties after two years of rotation with cover crops and cash crops, the soil physical quality was still below the recommended level, showing values of macroporosity, S index and soil aeration capacity lower than 0.10 m3/m3, 0.035 and 0.34, respectively. Upland rice production was higher under mixtures of cover crops than under fallow, mainly because of soil physical changes done by these mixtures of cover crops. Soybean grain yield was similar under all cover crops tested, but was higher after the rotation cover crops/upland rice/cover crops than after only one cycle of cover crops.

Influence of consecutive integrated rice–crayfish culture on phosphorus fertility of paddy soils

AbstractChina has experienced an increase in integrated rice–crayfish (Procambarus clarkii) culture (IRCC) in rice paddies. However, whether the current regime degrades phosphorus (P) fertility in rice paddies remains unclear. To assess changes in P fertility, the surface soil (0–20 cm) of high‐yield rice paddies with 3, 6, and 10 consecutive years of IRCC was sampled in Honghu County in the Jianghan Plain region, China. Adjacent fields planted with long‐term rotations of rice and dry‐season crops (RRD) were also sampled. Total P (TP), available P (Pa), organic P (Po) compounds, and P fractions in soils were intensively assessed using chemical digestion, NaHCO3 extraction, 31P nuclear magnetic resonance, and sequential chemical extraction. IRCC significantly increased organic matter, total nitrogen, TP, Fe(II), and S2− contents of rice paddy soils and nutrient concentrations in the surface water, with a distinct decrease in total Fe and pH. Consecutive IRCC greatly influenced P fertility. Continuous P accumulation in rice paddy soils accelerated greatly, with a mean increase of approximately 43 mg·kg−1·yr−1. Pa was 67% higher after 3 years of IRCC, compared with RRD, but 78% lower after 10 years. Consecutive IRCC induced a decrease in Po compounds, with a mean decrease in TPo of approximately 20 mg·kg−1·yr−1. Long‐term consecutive IRCC increased transformation of Pa, Fe(II)–P, and Po into Ca–P and Fe(III)–P, increasing mean Ca–P and Fe(III)–P concentrations by approximately 69 and 7 mg·kg−1·yr−1, respectively. Our results suggested that long‐term consecutive IRCC degrades P fertility in rice paddies, and implementing IRCC in high‐yield rice paddies is not recommended.

The role of Chinese Milk Vetch as cover crop in complex soil nitrogen dynamics in rice rotation system of South China

The effect of Chinese Milk Vetch (CMV) residues as a cover crop on the performance of rice plants and nitrogen mobilization and mineralization in paddy soil was evaluated in a pot-culture experiment. Three treatments were included in the trial, i.e. without exogenous-N (Control or CK), urea fertilizer as the sole N-source (N) and urea plus CMV (NM). The results revealed higher amounts of total-N, inorganic-N, acid hydrolysable-N and non-acid hydrolysable-N in the soil under NM, followed by N and CK treatments at tillering, booting and maturity stages of rice. A similar trend was observed for various soil ammonia oxidizing bacteria, aerobic and anaerobic bacteria. Correlation coefficients exhibited a negative correlation of residual exogenous-15N with only amino acid nitrogen (P < 0.01). Moreover, low abundance of the key functional gene amoA in rice was found in CK treatment. From the results it can be concluded that the nitrogen from organic source can improve the availability of total-N, inorganic-N and NH4 in the soil, especially at the later stages of rice growth.