添加锰离子对秸秆还田土壤释放甲烷气体的影响

针对我国每年近2亿吨二氧化碳当量的水稻田甲烷排放现状,研究不同锰盐浓度对模拟水稻秸秆还田后沼气减排效果的影响。本研究以模拟水稻田土壤混合秸秆环境为研究对象,调控不同的初始锰离子浓度,研究厌氧发酵过程中累计沼气和甲烷排放量。研究发现,初始锰盐质量浓度范围为1.75 mg/g~7.00 mg/g秸秆时,累计沼气排放量比无锰试验组降低4.36%~8.67%,特别是温室效应显著的甲烷排放量比无锰试验组降低了2.38%~5.34%。研究结果表明,调控模拟水稻田土壤混合秸秆中初始锰盐浓度,能显著降低稻田中温室气体的排放量,特别是有效降低甲烷的排放量。该研究成果,对于实现我国大面积水稻田温室气体减排和碳中和碳达峰战略目标,有一定的理论意义和实用价值。

Effect of Direct-seeding with Non-flooding and Wheat Residue Returning Patterns on Greenhouse Gas Emission from Rice Paddy

[Objective] This study aimed to investigate the effect of direct-seeding with non-flooding and wheat residue returning patterns on greenhouse gas emission from rice paddy. [Method] Two rice cultivars currently used in the production, Yangdao 6 （an indica） and Yangjing 4038 （a japonica）, were field grown using a direct-seeding method, and four treatments, wheat straw incorporation into soil and traditional flooding （SlF）, non-flooding and wheat straw mulching （NSM）, non-flooding and wheat straw incorporation into soil （NSl） and traditional flooding （no straw returned, Control, TF）, were imposed after sowing to maturity. Effects of direct-seeding with non-flooding and wheat residue returning patterns on CH4, N20 and CO2 emissions were investigated by using the method of static chamber-gas chromatographic tech- niques. [Result] Grain yield showed no significant difference between non-flooding and flooding treatments, but was significantly higher under the SlF than under any other treatments. The emission flux of CH4 and CO2 under TF and SlF exhibited a single peak curve, while changed little under the NSl and NSM The emission flux of N2Oshowed multiple perk curves for all the treatments. Compared with TF, SlF significantly increased mean emission flux of CH4 or N2O, decreased emission of N20, while NSl and NSM significantly decreased the mean emission flux of OH4, and increased emission flux of N2O and CO2. SIF also increased Green Warm Potential （GWP） of CH4, N2O and CO2 and the GWP per unit grain yield by 47.3%- 53.7% and 32.2%-39.4%, respectively. Both NSl and NSM decreased GWP by 24.2%-29.6% and 30.1%-35.5%, and the GWP per unit grain yield was decreased by 21.7-27.2% and 25.6%-31.1%, respectively. [Conelusion] both NSl and NSM could significantly reduce greenhouse effect of CH4, N2O and CO2 meanwhile maintain a high grain yield.

Field Experiment for the Effects of Rice Straw Returning and Seeding Pattern on Wheat Seedling Emergence and Grain Yield

In order to study the effect of rice straw returning and seeding patterns on seedling emergence and grain yield, field experiment was conducted to investi- gate the effects of straw mechanized returning and different seeding patterns on e- mergence rate, emergence uniformity and yield traits of wheat after rice. The results were as follows： in rice straw removal treatments, the emergence rate of mechani- cal seeding in drill was lower than that of mechanical uniform planting and manual broadcast sowing, which were 51.84%, 90.89% and 88.87%, respectively; the emer- gence uniformity of manual broadcast sowing was inferior to mechanical seeding in drill and mechanical uniform planting, which were 0.49, 0.26 and 0.23, respectively. As for the treatments with rice straw returning to the field, the emergence rate and emergence uniformity all decreased in the three seeding patterns, of which mechan- ical seeding in drill dropped markedly with emergence rate decreased by 36.54%. The emergence rate and emergence uniformity affected grain yield by affecting pan- icle, grains per spike and 1 000-grain weight. The grain yield for the treatment with rice straw removal was 6 091.34 kg/hm2, while that with rice straw returning to field was 6 476.20 kg/hm2, and both were higher than the yields of the other two seed- ing patterns. Therefore, mechanical uniform planting was？recommended for its higher emergence rate, better emergence uniformity, which was conductive to increase grain yield in wheat after rice production with rice straw returning to field.

Environmental Effects of Returning Rice and Wheat Straw to Fields

Based on advances in returning rice and wheat straw to fields at home and abroad, environmental physical, chemical and ecological effects of returning rice and wheat straw to fields were analyzed. The results show that returning straw to fields can enhance soil porosity, reduce soil bulk density, and increase the ca- pacity of soil to preserve water, fertilizer and temperature. Besides, it can improve the content of organic matter, nitrogen, phosphorus and potassium in soil, of which the increase of potassium content is the most obvious. Meanwhile, it can provide energy and nutrients for microorganisms in soil and change the activity of soil enzymes, of which it affects invertase most greatly and enhances the activity of ure- ase but has no effect on neutral phosphatase. In addition, it can enhance the total quantity of microorganisms in soil obviously, and the increase correlates positively with the quantity of straw returning to fields. Finally, returning straw to fields can promote the sustainable development of agriculture.

Effects of Rice Straw Incorporation and Soil Pre－Flooding on the Fate of Applied （^（15）NH_4）_2SO_4－N and Growth of Rice

A pot experiment was conducted to investigate the effects of straw incorporation and soil pre-flooding on the fate of (￣(15)NH_4)_2SO_4-N and the growth of rice. Excessive application of rice straw when incorporated with (￣(15)NH_4)_2SO_4 at the C/N ratio of 40 reduced the loss of (￣(15)NH_4)_2SO_4-N and retarded the growth and development of rice significantly, while no adverse effects were observed on dry weight of panicle and the total recovery of (￣(15)NH_4)_2SO_4-N when rice straw was incorporated with (￣(15)NH_4)_2SO_4 at a C/N ratio less than 25. There were no significant effects of duration of soil pre-flooding within 6 weeks on (￣(15)NH_4)_2SO_4-Nuptake by rice and on rice growth, but, less loss of (￣(15)NH_4)_2SO_4-N was observed in the soil with a longer period of pre-flooding.

Effects of Winter Planting Milk Vetch on Yield and PartialProductivity of Nitrogen Fertilizer of Machine-transplantedDouble-cropping Rice under Straw Returning to the Field

From 2017 to 2018,the effects of winter planting of milk vetch on yield and partial productivity of nitrogen fertilizer of machine-transplanted double-cropping rice under straw returning were studied in Ningxiang city,Hunan Province.The results showed that the dry matter accumulation,effective panicle,yield and partial productivity of nitrogen fertilizer in the stem,leaf,panicle and aboveground parts of early and late rice treated with winter planting milk vetch and straw returning were signi ficantly higher than those treated with straw returning only.Among them,the effective panicles of early and late rice increased by 2.58%,3.18%(2017)and 5.22%,6.32%(2018),respectively.Yield increased by 11.85%,10.07%(2017)and 12.42%,10.92%(2018),annual partial productivity of nitrogen fertilizer increased by 10.90%(2017)and 11.66%(2018),respectively.In conclusion,winter planting milk vetch under straw returning is beneficial to increase dry matter accumulation,rice yield and partial productivity of nitrogen fertilizer in mechanized double cropping rice.

水稻麦秸还田机插秧农机农艺要求对秧苗生长?及产量构成的影响探究

在江苏省如东县丰利镇稻麦二熟制地区,通过研究不同农机农艺对秧苗生长及产量构成的影响,逐步形成了成熟的水稻麦秸机插秧农机农艺配套技术,成效显著.试验示范结果表明,麦秸秆粉碎还田改进工艺和肥水科学运筹,提高了埋草率,减少了尿素的使用,节约了人工补秧及秧苗成本,增加了稻谷产量和纯收益率,达到了节本增效的目的.

Production Benefits of Double-Cropping Rice Under Optimized Application of Nitrogen and Potassium Fertilizers Combined with Chinese Milk Vetch and Straw Co-Returning to Fields

In order to explore the technology and effects of reducing nitrogen and potassium fertilizer applications in double-cropping rice,a field plot experiment was conducted to study the effects of optimized application of nitrogen and potassium fertilizers combined with returning Chinese milk vetch and straw to fields on yield,fertilizer utilization efficiency,net photosynthetic rate(Pn),stomatal conductance(Gs),intercellular CO_(2) concentration(Ci),chlorophyll content(SPAD value)and soil physical and chemical properties in late rice harvest period.The results showed that the optimized application of nitrogen and potassium fertilizers combined with the integrated technology of Chinese milk vetch and straw co-returning to the field could enhance the photosynthetic efficiency of double-cropping rice,increase rice yield,and enhance soil biological activity,especially T4 treatment involving the returning of Chinese milk vetch and straw to the field instead of 30%nitrogen fertilizer achieved the highest rice yield,fertilizer use efficiency,net photosynthetic rate and soil biological activity.Compared with the conventional fertilization treatment T2,the total rice yield of T4 treatment increased by 4.1%,among which the early rice and late rice increased by 6.3%and 2.4%,respectively;Pn,Gs and SPAD values of flag leaves at full heading stage significantly increased,and the contents of soil active organic carbon,alkali hydrolyzed nitrogen,available phosphorus and readily available potassium significantly increased.

Straw Application Altered CH_4 Emission,Concentration and ^(13)C-Isotopic Signature of Dissolved CH_4 in a Rice Field

CH4 emission and the concentration of dissolved CH4 in soil solution and floodwater in a rice field and their stable carbon isotopic signatures as affected by straw application were investigated in 2009 in a field experiment at Jurong, Jiangsu Province, China. Straw application increased CH4 emission and CH4 concentration in the soil solution and floodwater. A positive seasonal correlation was also observed in the variation between CH4 flux and CH4 concentration in soil solution. The seasonal total CH4 emission （51.6 g CH4 m^-2） in Treatment WS （straw applied） was about 168% higher than that in Treatment CK （without straw）. The emitted CH4 and CH4 in soil solution were initially relatively enriched, then depleted and finally enriched again in 13C in both treatments, while CH4 in floodwater became isotopically heavier. The carbon isotopic signature of emitted CH4 and CH4 in floodwater averaged around -62%o and -45%0 for both treatments, respectively, and was not significantly influenced by the application of straw. However, straw application caused the CH4 in soil solution to be significantly depleted in lac during the middle of the rice season, and the mean δ13C value was lower in WS （-57.5‰） than in CK （-49.9‰）. Calculation from the isotopic data showed that straw application increased the fraction of CH4 oxidized, causing no significant difference in the δ13C value of the emitted CH4 between the two treatments.