RS Treatments Research Articles

Straw type and nitrogen-water management balance rice yield and methane emissions by regulating rhizosphere microenvironment

Context or problemStraw incorporation improves soil fertility but also poses environmental challenges due to increasing methane (CH4) emissions in paddy fields. Whether nitrogen (N) and water management can balance rice yield and CH4 emissions under different crop straw incorporation is still not well-documented. ObjectiveA three-year field experiment was conducted to probe the comprehensive effects of N application ratios and irrigation regimes on rice yield, rhizosphere soil properties, and CH4 emissions, along with the underlying mechanisms of CH4 emission variations among different straw types. MethodsA two-factor randomized block design was used with two Japonica rice cultivars as materials in 2020 and 2021. The straw incorporation treatment included no straw incorporation (NS), wheat straw incorporation (WS), and rape straw incorporation (RS). The N fertilizer application treatments included local farmers' fertilizer practice (LFP) and increasing basal fertilizer rate (IBF). Two irrigation practices, continuously-flooded irrigation (CF) and alternate wetting and drying irrigation (AWD), were designed under the WS and RS treatments in 2022. Results1) WS-IBF and RS-IBF enhanced yield by 6.70∼9.03 % and 8.13∼9.50 % compared to WS-LFP and RS-LFP, respectively. AWD further increased yield by 6.28∼7.76 % compared to CF. 2) WS-IBF and RS-IBF enhanced dissolved organic carbon (DOC) content, synchronously boosted the methanogens (mcrA) and methanotrophs (pmoA) abundances, but decreased the pmoA/mcrA ratio, which significantly promoted CH4 emission flux in early growth stage. This resulted in a 5.04∼8.01 % and 4.60∼7.88 % increase in CH4 emissions compared to WS-LFP and RS-LFP, respectively, but a decrease in yield-scaled CH4 emissions. AWD reduced DOC content, facilitated the conversion of ammonium N to nitrate N, increased dissolved oxygen content, and hence decreased CH4 emissions by 23.41∼24.38 % compared to CF. 3) RS significantly increased microbial biomass C, N, and related metabolites, leading to a 1.29∼2.73 % increase in yield compared to WS. Meanwhile, RS promoted Nitrospira abundance as well as pterin and flavonoid metabolites associated with mcrA inhibition, while decreasing Anaeromyxobacter abundance, ammonium N, and DOC content, resulting in an increase in the pmoA/mcrA ratio and a noticeable drop in CH4 emissions compared to WS. ConclusionsRS combined with IBF and AWD is a more sustainable integrated practice in light of the synergistic improvement in rice production and environmental benefits. ImplicationsThe results reveal that optimizing N and water management can synergize high-yield and low-carbon by regulating rhizosphere microenvironment in rice production under crop straw incorporation.

Diversity and function of soil microorganisms in response to paddy–upland rotation system in sustainable restoration of saline-sodic soils

Context Rapid desalination by planting rice in saline soil consumes large amounts of water, which is not environmentally friendly. Aims Herein, we propose rapid desalination by planting rice, then shifting to cultivating upland plants to attain substantial resource-saving and higher yield simultaneously with restoration of saline-sodic soil. Methods Field experiments were run for two consecutive years with five treatments: unreclaimed wasteland (WL) as control, rice cultivation followed by fallow (RF), rice–rice continuous cropping (RR), rice–ryegrass rotation (RG), and rice–sorghum rotation (RS). Physicochemical properties, including pH, electrical conductivity, and exchangeable sodium percentage were determined, and 16S rRNA sequences were used to evaluate soil microbial composition and stability. Key results The soil total organic carbon, total nitrogen, available phosphorus, and biomass in RR, RG, and RS treatments were all higher than RF and control. Notably, RR, RG, and RS increased the soil microbial biomass carbon and nitrogen, and significantly reshaped the soil communities of bacteria, fungi, and archaea relative to RF and WL. Conclusions Despite the lower efficiency of RG and RS in ameliorating saline-sodic soil, there were dramatic savings in irrigation water, and the improvements in microbial diversity and functionalities indicated that the paddy–upland crop rotation system had substantial influence on sustainability of soil quality. Implications Providing a balance between salt desalination performance with irrigation water input and yield, the paddy–upland rotation system is a robust, replicable, and environmentally friendly practice in saline-sodic soil remediation.

Effects of Early Rice Straw Returning with Reducing Potassium Fertilizer on Late Rice Yield and Soil Fertility

Rice straw is an important organic fertilizer in the region for double-cropping rice in South China. To reveal the effects of early rice returning with reducing potassium fertilizer on the yield of late rice and soil fertility, field experiments were carried out in Baiyun and Huiyang district in Guangdong province. The biomass, K content, and yield of late rice and the soil fertility properties, such as soil available potassium, soil organic carbon, bacterial diversity, and bacterial community structure were analyzed under three treatments (CK, conventional fertilization; RS, straw returning with conventional fertilization; RS-K, straw returning with reducing 20% potassium fertilizer). The results showed no significant differences in the biomass and yield of late rice between the RS-K treatment and CK treatment. Compared with that in CK, the RS treatment significantly increased the K contents of rice by 3.97% (Baiyun) and 6.91% (Huiyang). The K contents of late rice under the RS-K treatment were significantly lower than that under the CK treatment during the early growth period in rice, but there was no significant difference between them during the late growth period. Compared with that in CK, the soil available K in the RS treatment increased by 13.90% (Baiyun) and 21.67% (Huiyang) (P<0.05), and the soil available K in the RS-K treatment also increased by 3.56% (Baiyun) and 4.23% (Huiyang). Compared with that in the CK treatment, the soil dissolved organic carbon increased significantly in the RS and RS-K treatments (P<0.05). Compared with that in CK, the straw returning treatments (RS and RS-K) significantly improved the Chao1 and Shannon indexes of soil bacteria (P<0.05). Straw returning treatments (RS and RS-K) increased the relative abundance of Proteobacteria, Actinobacteria, and Nitrospirae compared with that in CK, whereas they decreased the relative abundance of Acidobacteria, Bacteroidetes, and Firmicutes. Redundancy analysis showed that the soil bacterial community was mainly influenced by soil organic carbon, dissolved organic carbon, microbial biomass carbon, available P, and available K. In summary, early rice returning could increase soil available K and K content in late rice. Early rice straw returning with reducing potassium fertilizer had no negative impacts on the growth and yield of late rice and could also improve soil organic carbon and the diversity of soil bacteria. Therefore, early rice straw returning with reducing potassium fertilizer can guarantee the grain yield of late rice and improve soil fertility.

Effects of Bacillus fertilizer and agent on growth of young peach tree and soil environment under replant condition.

We analyzed the effects of Bacillus fertilizer and agent supplementation at different concentrations in the replanted soil by examining the growth of young peach trees, soil nutrients, enzyme activities, and fungal commu-nity. The aim of this study was to provide theoretical basis for alleviating peach replant diseases. One-year-old potted 'Yuanmeng' peach trees were subjected to eight treatments: replanted soil without supplementation (RS), non-replanted soil without supplementation (NS), replanted soil with 1%, 4%, 8% Bacillus fertilizer supplementation (BF1, BF2, BF3), and 0.1‰, 0.5‰, 1‰ Bacillus agent supplementation (B1, B2, B3), respectively. The results showed that shoot growth and root biomass under NS treatment were greater than that under other treatments, and the contents of soil organic matter, available nutrients and soil catalase activity were greatly enhanced. Peach trees treated with BF and B treatments showed better root development than RS, among which, BF3 and B1 treatments were the best, and B1 treatment had similar effects as NS treatment. Compared with RS, BF and B treatments significantly increased the activities of soil catalase and urease during new shoot development, while B treatment significantly increased soil sucrase activity after the growth cessation of new shoots. Bacillus fertilizer and agent increased soil fungal diversity and the relative abundance of Ascomycota, Chaetomium and Penicillium, and decreased that of Basidiomycota. Considering the comprehensive parameters, BF3 and B1 showed more significant effects. In summary, our findings indicated that the supplementation of Bacillus fertilizer and agent to replanted soil could improve soil fertility, fungal community, and root development of roots, and thus provided a feasible method to alleviate peach replant diseases.

Biochar amendment pyrolysed with rice straw increases rice production and mitigates methane emission over successive three years

A sustainable biochar strategies on increasing crop yield and mitigating CH4 emissions over successive years is unknown. Thus, on-site equivalent rice straw biochar-returning (ERSC, biochar at 2.8 t ha−1 annual) were compared with on-site equivalent rice straw- returning (RS, rice straw at 8 t ha−1 annual) and high application rate biochar-returning (RSCH, biochar at 22.5 t ha−1 only in the first year). The RS and RSCH treatments increased rice production by 10.1% and 11.8% on average, respectively. The ERSC treatment continually increased rice production by 8.0%, 1.6% and 7.3% in three successive years. The ERSC treatment had a cumulative effect on the soil nutrients phosphorus (P), potassium (K), and magnesium (Mg), as well as increasing total carbon (TC) and total nitrogen (TN) and continuously reducing the effect of soil available aluminum (Al). The RS treatment significantly promoted CH4 emissions while the ERSC treatment reduced methane emissions by 43%, 31% and 30% and the RSCH treatment reduced methane emissions by 52%, 22% and14% in three successive years. Compared with RSCH, ERSC showed the best long-term stable effect on methane emission mitigation in three successive years. This might result from the fact that fresh biochar promoted anaerobic oxidation of methane. This research gives us scientific evidence that an on-site equivalent rice straw biochar-returning strategy may be a promising method for sustaining rice production and mitigating methane emissions.

Straw incorporation influences soil organic carbon sequestration, greenhouse gas emission, and crop yields in a Chinese rice (Oryza sativa L.) –wheat (Triticum aestivum L.) cropping system

Crop straw management plays important roles in sustainable agriculture and environmental protection. Straw incorporation has multiple influences on soil organic carbon (SOC) sequestration, greenhouse gas (GHG) emissions, and crop yields, but these influences have rarely been studied simultaneously in a single cropping system. This study was conducted to examine the influence of long-term straw incorporation on the SOC sequestration rate, methane (CH4) and nitrous oxide (N2O) emissions and crop yields in a Chinese rice (Oryza sativa L.) –wheat (Triticum aestivum L.) cropping system in Hydragric Anthrosols under a subtropical monsoon climate. Four straw incorporation treatments were applied: wheat straw incorporation only (WS), rice straw incorporation only (RS), both wheat and rice straw incorporation (WSRS), and no straw incorporation (as a control). The SOC sequestration rate was estimated from the changes in SOC stock in the topsoil (0–20 cm) from 2007 to 2016. The emissions of CH4 and N2O were measured every 7 d when possible using a static chamber method from the 2013 rice season to the 2016 wheat season. Our results showed that the straw incorporation treatments significantly influenced the seasonal CH4 and N2O emissions and rice yield but had no influence on wheat yield. Straw incorporation significantly increased the annual topsoil SOC sequestration rate by 0.24–0.43 t C ha−1 yr−1 and the annual CH4 and N2O emissions by 44–138 kg CH4-C ha−1 yr−1 and 0.68–1.49 kg N2O-N ha−1 yr−1, respectively. Relative to the RS treatment, the WS and WSRS treatments significantly increased annual CH4 emissions by 38% and 61%, respectively. Relative to the RS treatment, the WSRS treatment significantly increased the annual N2O emissions, by 35%. The average annual yields were significantly higher in the WSRS (16.8 t ha−1 yr−1) and RS (16.7 t ha−1 yr−1) treatments than in the WS (15.7 t ha−1 yr−1) and control (15.2 t ha−1 yr−1) treatments. Across the three rotation cycles, the annual net global warming potential and greenhouse gas intensity were similar between the control and RS treatments but were significantly lower in these treatments than in the WSRS and WS treatments. These findings suggest that the RS treatment can simultaneously increase crop yields and environmental sustainability in rice–wheat cropping systems.

Straw strips mulch on furrows improves water use efficiency and yield of potato in a rainfed semiarid area

Potato (Solanum tuberosum L.) production in semiarid regions is always constrained by water availability. This study was to evaluate the effects of straw strips mulch to potato growth, yield and economic benefits. The field experiment was conducted in northwest China in 2016 and 2017, including four treatments: (1), alternating narrow and wide ridges both mulched by black polyethylene film (PM); (2) alternating large ridges and small furrows with maize straw strips mulched only on the furrows (RS); (3) alternating the strips mulched with maize straw and bare plots with no ridges (PS); (4) traditional flat planting without mulching (CK). Results indicated that mulched treatments significantly (P < 0.05) increased tuber yield and WUE of potato compared with CK. The magnitude of yield in mulched treatments increase were 36.9–61.2% in 2016 and 38.7–45.5% in 2017, respectively, compared with CK. PM and RS treatments produced the highest tuber yield and enhanced water use efficiency by up to 74.8%, compared with CK. Soil water storage (0–2 m depth) was 21.5–39.9 mm in 2016 and 16.7–41.2 mm in 2017, respectively, greater in the mulched treatments, which significantly (P < 0.05) reduced evapotranspiration from sowing to seedling stages, compared with CK. Greater water availability was associated with greater biomass accumulation in above- and below-ground components, and plant height gain, during the growing season. PM significantly (P < 0.05) increased soil temperature (5–25 cm depth), which advanced the duration whole growth period by 6 days on average. RS and PM treatments experienced lower soil temperature (5–25 cm depth), which prolonged the duration whole growth period by 10 days on average, and increased the mass and percentage of Grade 1 tubers and the commodity rate (P < 0.05). As straw strips mulch application has lower input and labor costs than plastic film mulch, it produced the greatest economic benefits during this study, and it should be considered as an environmentally-friendly alternative to plastic film mulch for potato production in semiarid areas.

Effect of inorganic fertilizers with organic amendments on soil chemical properties and rice yield in a low-productivity paddy soil

Integrating inorganic fertilizers (NPK) with organic materials have been common practices for sustainable agriculture production in low-productivity paddy soil. A 4-year field experiment was conducted to investigate the effects of the annual application of inorganic fertilizer in contrast with the combined application of organic manures and NPK on rice grain yield and the soil chemical properties. Six treatments, including control (no fertilizer), NPK alone, NPK plus spent mushroom compost at 1.5 Mg ha−1 (NPK + MC), NPK plus green manure at 3.6 Mg ha−1 (NPK + GM), NPK plus cattle manure at 4.7 Mg ha−1 (NPK + CM), and NPK plus rice straw at 3.0 Mg ha−1 (NPK + RS)—were applied in this study. The results indicated that the rice grain yields for 2014 under the NPK + CM and NPK + RS treatments were 11.4% and 9.3% higher, respectively, compared with the NPK alone treatment. No significant differences in rice yield were observed between the plots using NPK and NPK + MC or NPK + GM treatments. The application of CM to the soil surface led to significantly higher soil pH (0.16–0.29 units), cation exchange capacity (CEC) (17.4%–21.9%), and lower exchangeable acidity and Al3+ concentrations at soil depths of 0–20 cm, compared with the NPK alone treatment. However, no significant differences in pH or concentrations of base cations in the soil were observed in the 0–10 cm soil layer after the application of NPK alone or NPK plus the other three organic amendments. Additionally, the application of NPK + CM at 4.7 Mg ha−1 y−1 showed the highest available P concentration at 0–10 cm depth. Overall, the rice grain yield, soil pH, and available P were effectively improved by NPK in combination with CM at 4.7 Mg ha−1.

不同施肥处理对土壤活性有机碳和甲烷排放的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 不同施肥处理对土壤活性有机碳和甲烷排放的影响 DOI: 10.5846/stxb201606181181 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金（31300413）；国家科技支撑计划课题（2013 BAD11B02） Effects of organic manure application on active soil organic carbon and methane emission in paddy soils Author: Affiliation: Fund Project: 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:通过采集田间试验区连续3a施入有机肥的稻田耕层土壤，分析土壤中微生物量碳（MBC）、水溶性有机碳（DOC）、易氧化有机碳（ROC）和可矿化有机碳（readily mineralizable carbon，RMC）等活性有机碳的含量，稻田甲烷（CH4）的排放通量，探讨施用有机肥的土壤活性有机碳变化及与CH4排放的关系。研究结果显示：（1）施有机肥对土壤中的活性有机碳均有一定的促进作用。3a不同施肥处理土壤中DOC、ROC、MBC和RMC的平均含量分别为383.6、2501.2、640.4 mg/kg和291.7 mg/kg。3a施猪粪（猪粪+化肥，PM）、鸡粪（鸡粪+化肥，CM）和稻草（稻草+化肥，RS）的DOC的含量分别比化肥（CF）处理增加5.6%、6.7%和19.3%，ROC的含量分别比CF增加6.6%、8.4%和9.8%；MBC含量分别比CF增加5.1%、14.8%和21.5%，RMC增加6.8%、22.0%和33.9%。不同施肥处理的稻田土壤活性有机碳为分蘖期高于成熟期。（2）施肥处理显著增加稻田CH4排放，CH4分蘖期的排放通量是成熟期的143倍，3a PM、CM和RS处理的CH4排放分别比CF处理增加37.0%（P < 0.05）、92.7%（P < 0.05）和99.4%（P < 0.05）。（3）不同施肥处理的DOC、ROC、MBC和RMC含量与CH4排放通量均存在显著正相关关系，ROC与CH4排放的相关系数最高，为0.754（P < 0.01），且4种有机碳间关系密切。稻田分蘖期土壤中的活性有机碳与稻田CH4排放呈显著正相关关系。（4）综合分析，在4种有机碳中，土壤中ROC和MBC的含量直接影响CH4排放。 Abstract:Active soil organic carbon (ASOC) is an important component of soil. It plays a critical role in soil organic carbon turnover processes, which potentially contribute to future climate change. The properties of ASOC and its effects on methane (CH4) emission from paddy soils remain unclear, and were therefore investigated in the present study. We determined ASOC, including microbial biomass carbon (MBC), dissolved organic carbon (DOC), readily oxidized organic carbon (ROC), and readily mineralizable carbon (RMC), for 3 consecutive years after application of organic fertilizer. The treatments used were as follows: (1) no fertilizer (NF); (2) chemical fertilizer (CF); (3) pig manure +chemical fertilizer (PM); (4) chicken manure + chemical fertilizer (CM); and (5) rice straw + chemical fertilizer (RS). The results demonstrated that (1): ASOC increased upon application of organic manures. The 3-year average content of ASOC in DOC, ROC, MBC, and RMC was 383.6, 2501.2, 640.4, and 291.7 mg/kg, respectively. The content of soil DOC, ROC, MBC, and RMC under different treatments was in the following order: RS>CM>PM>CF>NF. The content of DOC was 5.6%, 6.7%, and 19.3% higher in PM, CM, and RS, respectively, than in CF. The content of ROC increased by 6.6%, 8.4%, and 9.8% with PM, CM, and RS, respectively, over that in the CF treatment. The PM, CM, and RS treatments showed 5.1%, 14.8%, and 21.5% higher MBC contents and 6.8%, 22.0%, and 33.9% higher RMC contents, respectively, than CF treatment. The ASOC content was higher at the tillering stage than at the maturity stage. (2): The CH4 emissions significantly increased with application of organic manure. The CH4 emissions under different treatments were in the following order: RS > CM > PM > CF > NF. The CH4 emission in PM, CM, and RS treatments increased by 37.0% (P < 0.05), 92.7% (P < 0.05), and 99.4% (P < 0.05), respectively, over those in the CF treatment. The CH4 emission was 142-fold higher at the tillering stage than at the maturity stage. (3): With the increasing duration of application, CH4 emission at rice tillering stage increased in different treatments. Positive correlations were observed among DOC, ROC, MBC, and RMC in all treatments. DOC, ROC, MBC, and RMC contents were strongly correlated with CH4 emission, (e.g., the highest correlation coefficient between ROC and CH4 emission, r=0.754, P < 0.05). The contents in DOC, ROC, MBC, and RMC at the tillering stage had a significant correlation with CH4 emission, with correlation coefficients of 0.537(P < 0.01), 0.754(P < 0.01), 0.728(P < 0.01), and 0.431(P < 0.01), respectively. However, no significant correlation was observed at the maturity stage. In conclusion, ASOC content showed a close correlation with CH4 emission, especially ROC and MBC content, which might be directly associated with CH4 emission. The results of the present study suggest that, among the treatments tested, pig manure is the best organic fertilizer because the soil has lower ROC and MBC contents.Application of pig manure could be an effective measure to improve the quality of the soil, render it suitable for sustainable development, and mitigate CH4 emissions. 参考文献 相似文献 引证文献

Greenhouse gas emissions, soil carbon sequestration and crop yields in a rain-fed rice field with crop rotation management

Field experiments of two consecutive years (2010–2011) were conducted to investigate the effect of crop-rice rotation systems on greenhouse gas (GHG) emissions, soil carbon sequestration, and rice yield. Rotation crops were cultivated in the dry season, while rain-fed rice was grown in the wet season. Four different treatments were investigated: fallow-rice (RF), rice–rice (RR), corn-rice (RC) and sweet sorghum-rice (RS). The closed-chamber method was used for flux measurements of methane (CH4), nitrous oxide (N2O) and carbon dioxide (CO2) in the field. Parameters such as soil carbon budgets (SCBs), soil organic carbon (SOC) stocks, and crop yields were also measured. In this study, it was found that RC and RS rotations reduced CH4 emissions by 78–84%, and reduced net CO2 equivalent emissions (CH4 and N2O) by 68–78%, as compared with RR. After two consecutive years of crop cultivation, SCBs were reclaimed by positive values in the RC and RR treatments. The SOC stocks were maintained in the RR, RC and RS treatments, but decreased in the RF. Although RF also reduced the net CO2 equivalent emissions by 72–84% as compared with RR, there were losses in soil carbon sequestration and agricultural land utilization. The rice grain yields of RC and RS were stable in both years, while RF fell slightly by 11%, and RR significantly reduced by 39% from the first year.

Field Nitrogen Losses Induced by Application Timing of Digestate from Dairy Manure Biogas Production.

Anaerobic digestion of dairy manure has environmental benefits, but the impact of effluent (i.e., digestate [DG]) application on environmental nitrogen (N) losses from soils has not been well quantified. Our objective was to evaluate how field application of DG affected nitrous oxide (NO) emissions and nitrate (NO) leaching compared with raw dairy manure (RM) in spring versus fall applications. We measured N losses year-round for 2.5 yr in silage corn on tile-drained clay soil in Alfred, Ontario, Canada. Treatments were: digestate applied in spring (DS) and fall (DF), raw dairy manure applied in spring (RS) and fall (RF), urea applied in spring, and a control. Overall, the source of N had no effect on annual NO emissions (overall average DG and RM, 4.9 kg NO-N ha yr), but more NO leached from DS than RS treatments (8.8 and 4.8 kg NO-N ha yr on average, respectively). Estimated indirect NO emissions from leached NO-N were small (<0.2 kg NO-N ha yr). Timing of application did not affect annual NO emissions but did shift emissions to the non-growing season for fall applications (65% on average) and to the growing season for spring applications (60% on average). Overall environmental N losses (NO-N + NO-N) from DG were similar to RM when applied at the same time. For the conditions of our study, downstream emissions from anaerobic digestion (i.e., emissions induced by applied digestate) do not present an adverse trade-off to the environmental benefits incurred during the biogas production phase.

Spring Safflower Performance under Growth Stage Based Irrigation in the Southern High Plains

Water stress is the most important environmental factor limiting crop yield in the southern High Plains. Drought tolerant crops along with deficit irrigation strategies may be promising for sustainable agriculture in the region. The objective of this study was to assess water relations, photosynthesis, yield‐forming components, and yield of spring safflower (Carthamus tinctorius L.) cultivars under growth stage based irrigation management. A blocked split plot design was used with irrigation treatments (fully irrigated [FI], stress at vegetative stage [VS], stress at reproductive stage [RS], and dryland [DL]) as the main plot and cultivars (PI8311, 99OL and Nutrisaff) as subplot in four replications. Measurements of water potential (Ψl) indicated that irrigation treatments imposed water stress on safflower. Safflower responded to stress by regulating stomata and osmotic adjustment. Water stress significantly reduced photosynthesis (Pn), leaf area index (LAI) and light interception in all stress treatments, resulting in decreased biomass accumulation. Seed yield of safflower was strongly related to biomass production (R2 = 0.61). Among yield‐forming traits, heads per plant were more influential in yield formation than seeds per head and 1000‐seed weight. Compared to the FI treatment, RS treatment reduced seed yield by 19 and 20% in 2013 and 2014, respectively; while the same reduction in VS treatment was 25 and 22%, respectively. However, seed yield differences between RS and VS treatments were not statistically significant.

Winter wheat grain yield, water use, biomass accumulation and remobilisation under tillage in the North China Plain

We conducted a two-year experiment (2007–2009) in the North China Plain with supplemental irrigation to investigate the effects of tillage practices on the water use, biomass accumulation and remobilisation of winter wheat. Five tillage treatments were tested: strip rotary tillage (SR), rotary tillage (R), mouldboard ploughing (P), strip rotary tillage after subsoiling (SRS) and rotary tillage after subsoiling (RS). SRS significantly promoted the changes in soil water storage (ΔS) at soil depths of 60cm to 160cm, and the lowest ΔS level was observed in the SR treatment. The 60cm to 140cm soil moisture content in the SRS treatment was higher by 10.84% than that of the SR treatment before sowing in 2008–2009 and lower by 14.85% at maturity. The lowest dry matter remobilisation during grain filling (DMR) was detected in the SRS treatment. This value was 22.22% and 30.27% lower than those of the SR treatment in 2007–2008 and 2008–2009, respectively. However, the SRS treatment exhibited the highest contribution of dry matter accumulation during grain filling (CDMRG), in which high flag leaf photosynthetic rate (Pn) was observed from anthesis to maturity. The SRS and RS treatments exhibited the highest grain yields (9237.20 and 9261.31kgha−1 for two-year average) with no significant difference between the two treatments. The highest grain yields for the two treatments were 10.76% and 11.05% higher than those of the P treatment, correspondingly. The average water-use efficiency (WUE) for the two growing seasons was 20.49kgha−1mm−1 in the SRS treatment, which was higher than those in the SR, R, P and RS treatments by 17.02%, 13.42%, 8.73% and 3.83%, respectively. Hence, SRS would be a preferable tillage system for planting wheat in this region.

Effects of Tillage Practices on Water Consumption, Water Use Efficiency and Grain Yield in Wheat Field

Water shortage is a serious issue threatening the sustainable development of agriculture in the North China Plain, with the winter wheat (Triticum aestivum L.) as its largest water-consuming crop. The effects of tillage practices on the water consumption and water use efficiency (WUE) of wheat under high-yield conditions using supplemental irrigation based on testing soil moisture dynamic change were examined in this study. This experiment was conducted from 2007 to 2010, with five tillage practice treatments, namely, strip rotary tillage (SR), strip rotary tillage after subsoiling (SRS), rotary tillage (R), rotary tillage after subsoiling (RS), and plowing tillage (P). The results showed that in the SRS and RS treatments the total water and soil water consumptions were 11.81, 25.18% and 12.16, 14.75% higher than those in SR and R treatments, respectively. The lowest ratio of irrigation consumption to total water consumption in the SRS treatment was 18.53 and 21.88% for the 2008–2009 and 2009–2010 growing seasons, respectively. However, the highest percentage of water consumption was found in the SRS treatment from anthesis to maturity. No significant difference was found between the WUE of the flag leaf at the later filling stage in the SRS and RS treatments, but the flag leaf WUE at these stages were higher than those of other treatments. The SRS and RS treatments exhibited the highest grain yield (9573.76 and 9507.49 kg ha−1 for 3-yr average) with no significant difference between the two treatments, followed by P, R and SR treatments. But the SRS treatment had the highest WUE. Thus, the 1-yr subsoiling tillage, plus 2 yr of strip rotary planting operation may be an efficient measure to increase wheat yield and WUE.

Simulated acid rain changed the proportion of heterotrophic respiration in soil respiration in a subtropical secondary forest

Acid rain is a matter of concern in southern China. We explored how soil respiration (Rs) and heterotrophic respiration (Rh) rates changed when subjected to simulated acid rain (SAR) environment for 3 years (from March 2010 to February 2013) in a secondary forest in subtropical China. The field experiment was arranged in a split-plot design, with 4 main blocks. Each block was split into un-trenched (Rs) and trenched (Rh) treatments. Four SAR treatments of CK (control, deionized water), A1 (pH 4.0), A2 (pH 3.0), and A3 (pH 2.0) were randomly assigned in each of the Rs and Rh treatments. Soil CO2 fluxes as well as soil temperature and moisture at a depth of 5cm were measured weekly. Different SAR treatments exhibited similar seasonal patterns of Rs and Rh. Mean annual Rs rates in CK, A1, A2, and A3 plots were 878.2±100.8, 919.4±33.1, 865.6±62.5, and 925.2±20.5gCm−2yr−1, respectively, over 3 years; SAR had no significant effects on Rs. Rh, however, was significantly (P<0.05) affected by the lowest SAR pH level (A3). On overage of 3 years, annual Rh rates in CK, A1, A2 and A3 plots were 606.7±52.4, 663.5±35.5, 728.2±60.7, and 760.1±42.2gCm−2yr−1, respectively. Statistical analysis showed that SAR significantly (P<0.05) increased the proportion of Rh in Rs. The relationship between residual Rs (or Rh) based on soil temperature and observed Rs (or Rh) and soil moisture could be well fitted in a quadratic model.

Effects of different control measures on cucumber yield, quality and soil microbial diversity under greenhouse cultivation.

In order to research the effects of different control measures on soil microbial diversity by Biolog, the greenhouse soils of cucumber cultivated in Shouguang City, Shandong Prorince were collected and the relationship between the soils and yield and quality of cucumber was investigated. The results showed that, the average well color development (AWCD) of returning straw to field (RS) was the highest and that of no fertilizer (CK) was the lowest. The activity of microbe was vigorous at the time of cultivation of 72 h and AWCD of treatments ranged from 0.494 to 0.881. AWCD of RS was 1.3 times than that of conventional fertilization (CF) and the difference reached significant level at the moment. However, AWCD of drip irrigation (DI) was lower slightly than that of CF. Soil microbial diversity changed in different treatments.CF had the lowest Shannon index(H)and Substrate evenness(E), but these two indices increased significantly through the application of RS and DI. Principal component analysis showed that carbon utilization by soil microbial communities also changed in different treatments. RS concentrated in the positive direction of the first principal component and the score coefficients ranged from 4.91 to 5.50. Conversely, others concentrated in the negative direction and the score coefficients ranged from-3.26 to-0.18. Compared with CF, cucumber yield and quality of RS and DI treatments had no significant changes. Simpson′s dominance (Ds) and Substrate richness(S)were positively correlated with cucumber yield, Vc and soluble sugar content. Comprehensive consideration, RS was more helpful to improve the soil micro-ecological envrion-ment than DI. Therefore, future research of RS is necessary for sustainable development of installation agriculture.

Microcalorimetric evaluation of soil microbiological properties under plant residues and dogmatic water gradients in Red soil

A study of 6 months duration was carried out to investigate the effect of water regimes and organic amendments on the soil microbial biomass and microbial population under Red soil collected from Hunan Providence, China. The soil microbial biomass and population were measured with traditional methods and results obtained by conventional methods, corroborated with microcalorimetry. The incorporation of rice (Oryza sativa L.) straw (RS) and green manure (GM), especially at high rates, enhanced the soil microbial activities. We observed that the use of GM exhibited more significant stimulating effects on microbial activities than RS. Similarly, water regimes, 25% (W1) and 200% (W2) of water holding capacity, also had significant effects on microbial activities. Comparing the effects of water levels, we noticed that W2 had a significant negative influence on soil microbial biomass and population. To compare the results of conventional methods and to check the sensitivity of microcalorimetry, the thermodynamic parameters, microbial growth rate constant (k), total heat evolution (Q), peak height (Pmax) and peak time (tmax) were calculated. Highest Pmax, k and Q were observed in GM treatments at water regime W1, while highest tmax values were recorded in CK (control) and RS treatments at W2. The microcalorimetric parameters, Pmax, k and Q were positively correlated, whereas tmax negatively linked with microbial biomass and population at p < 0.01. Our results suggest that microcalorimetry successfully verified the results obtained from customary methods and microcalorimetric parameters Pmax, tmax, Q and k proved that they are highly sensitive to microbial properties and could be used as indices of microbial community shifts and activities in soil ecosystems.

Effects of Resistant Potato Starches on Gastrointestinal Symptoms and Function

The gastrointestinal functions of fiber include stool bulking, increased stool frequency and decreased gastrointestinal transit time. The purpose of this study is to determine the effects of two resistant potato starches (RS4) on bowel movement frequency and gastrointestinal symptoms in healthy individuals. Biscotti and Koolaid , fortified at 30 g/d of fiber from RS4a or RS4b, and control foods, were incorporated into the diets of healthy individuals (n 22) for 15-day periods in a three-phase, randomized, crossover design with 7-day washouts. Participants completed a daily diary of bowel movement frequency andgastrointestinal symptom intensity,with “0” being free of symptoms, “1” mild symptoms and “10” severe symptoms, throughout each treatment period. Daily bowel movement frequency showed a trend to increase from the control period 0.89 0.50 to 1.01 0.58 (p 0.06) for RS4a, and 1.01 0.53 (p 0.11) for RS4b. Mean participant symptom score showed no significant differences in bloating between treatments (Control: 0.47 0.81; RS4a: 0.64 1.26; RS4b: 0.69 0.99). A increase in flatulence was found for both RS4a (1.95 1.69; p 0.05) and RS4b (1.96 1.08; p 0.05) compared to the control (1.25 1.01) with no difference between RS treatments. Cramping was an uncommon symptom (Control: 0.33 0.61; RS4: 0.45 1.14; RS2: 0.36 0.63), aswas intestinal noise (Control: 0.24 0.35; RS1: 0.37 0.87; RS2: 0.22 0.33) with no significant differences between treatments. The intake of resistant potato starch at 30 g per day is well tolerated with only mild flatulence reported as a symptom.

Effects of Soil Tillage Practice on Dry Matter Production and Water Use Efficiency in Wheat

The objective of this study was to understand the effects of tillage practice on water consumption characteristics and dry matter accumulation and distribution in wheat (Triticum aestivum L.) plant under high-yielding and flexible irrigation conditions. In a fixed position experiment across 3 growing seasons from October 2007 to June 2010, only one wheat cultivar, Jimai 22, was planted in the field. In the 2007–2008 wheat season, 5 tillage treatments were designed, which were strip rotary tillage (SR), strip rotary tillage after subsoiling (SRS), rotary tillage (R), rotary tillage after subsoiling (RS), and plowing tillage (P). The same treatments were arranged in the same field plots in the 2008–2009 and 2009–2010 wheat seasons, except that SRS and RS had no subsoiling. All tillage treatments were irrigated at sowing, jointing, and anthesis stages to designed soil water content based on testing soil moisture before watering. The total water consumption was higher in SRS and RS treatments than in SR and R treatments. Treatment SRS increased the amount of soil water consumption in 0–200 cm soil layers but decreased the soil evaporation, compared to other treatments. Treatments SRS and RS gained the highest amount of dry matter accumulation, grain dry matter partitioning at maturity, and contribution to grain of dry matter assimilation after anthesis, followed by treatment P, and treatments R and SR showed the lowest levels in the above parameters, particularly SR. In the experiment across 3 years, SRS obtained the grain yields of 9409.01 kg ha−1 in 2008, 9613.86 kg ha−1 in 2009, and 9698.42 kg ha−1 in 2010, which were equivalent to that of RS but significantly higher than other treatments. Treatments P and R also exhibited higher yield level than SR treatment. In the 2008–2009 and 2009–2010 growing years, the water use efficiencies of SRS treatment were the highest among treatments, which were 21.39 kg ha−1 mm−1 and 22.09 kg ha−1 mm−1, respectively. Treatment RS also had higher water use efficiency than SR, R, and P treatments. Therefore, SRS is recommended as the optimal tillage practice in high-yielding and water-saving production system in the Yellow-Huai-Hai River Valleys Plain.

SU‐GG‐T‐551: Spinal Radiosugery: Comparison between Volumetric Modulated Arc Therapy and Static Gantry IMRT

Purpose: Image Guided Radiosurgery (IGRS) has been used successfully to treat lesions involving the spine. Treatment plans usually involve multiple static Intensity Modulated Radiotherapy (IMRT) fields. Conformality is paramount in spinal RS treatments to maximize the dose to the target while sparing the intimately associated spinal cord. To improve conformality, it is necessary to increase the number of fields, increasing the complexity of the treatment as well as time of delivery. Delivery time is crucial with this group of patients as it is difficult for them to remain on the couch without moving for long periods of time. Volumetric Modulated Arc Therapy (VMAT) can deliver treatment in a shorter time. In this study, we compared the conformality of plans created with VMAT and IMRT. Materials and Methods: Four patients were planned using both RapidArc VMAT and IMRT. The same structure sets were used for both planning methods. Plans were normalized such that prescription dose covered 95% of the planning target volume. Optimization was accomplished with comparable constraints and maximum cord dose was desired. Once acceptable plans had been achieved, the conformality index was calculated. Results: In comparing the plans for the two methods, the Paddick Conformality Index for VMAT ranged from 0.7553 to 0.8938 while for IMRT it went from 0.7315 to 0.8186. Conformality was consistently better for VMAT than for IMRT. Maximum cord dose differed by no more than 5%. Conclusion: Although planning time for VMAT was longer than for IMRT, conformality was consistently better. This study has shown that faster delivery time does not compromise quality of the dose distribution. Shorter delivery time also increases accuracy due to less patient movement during treatment. VMAT is a viable and effective tool for treating patients where spine SRS is indicated. Research supported by Varian Medical Systems