Application of Chinese milk vetch affects rice yield and soil productivity in a subtropical double-rice cropping system

Green manure can be used as a substitute for chemical fertilizer without reducing rice yield.We studied the responses of soil fertility and rice yield to different combinations of Chinese milk vetch(CMV;Astragalus sinicus L.)and chemical fertilizer in a subtropical double-rice cropping system.Our goal is to reduce chemical fertilizer use and decrease environmental contamination.Compared with the recommended rate of chemical fertilizer(CF),both early-and late-rice yields in the two treatments supplied with 15 and 22.5 Mg CMV ha^-1 plus 60%CF(represented as 60 A and 60 B,respectively)showed no significant differences while the two treatments supplied with 30 and 37.5 Mg CMV ha^-1 plus 60%CF(represented as 60 C and 60 D,respectively)showed significantly higher values.The sustainable yield index(SYI)values in the 60 C and 60 D treatments with double-rice croppong system were significantly higher than those in other treatments(P<0.05).Early-rice yield showed a significant positive relationship with the Chinese milk vetch incorporation rate.The coefficients increased annually from 2009 to 2013 and then decreased in 2014.Soil organic matter increased over time by the end of the experiment in all of the treatment groups.Soil organic matter in 60 A,60 B and 60 C showed no significant difference compared with that in CF,while soil organic matter in 60 D was significantly higher than that in CF.The slopes of soil organic matter and total nitrogen over six years were the highest in 60 C and 60 D.The soil total nitrogen content in 60 A,60 B,60 C and 60 D was higher than that in CF,but the differences were not significant(P>0.05).Therefore,a relatively high Chinese milk vetch incorporation rate(≥30 Mg ha^-1)was more effective in improving the productivity and sustainability of paddy soil.The decreased coefficients of early-rice yield and the Chinese milk vetch incorporation rate in 2014 implied that the benefits of soil fertility and rice yield created by Chinese milk vetch input may decline after five years under a continuously high rate of Chinese milk vetch incorporation.

Management of rice straw with relay cropping of Chinese milk vetch improved double-rice cropping system production in southern China

Improved utilization of rice(Oryza sativa L.)straw and Chinese milk vetch(Astragalus sinicus L.,vetch)has positive effects on rice production.So far,few studies have investigated the productivity of vetch under different residue management practices in double-rice cropping system.The effects of rice straw on the growth and nutrient accumulation of vetch across seven years(2011–2017)and the subsequent effects of rice straw and vetch on two succeeding rice crops in a vetch–rice–rice cropping system,with the vetch established by relay cropping,were examined.The seven-year double-rice experiment consisted of the following treatments:(1)100%chemical fertilizer(F-F100);(2)only vetch without chemical fertilizer(M-Con);(3)80%chemical fertilizer plus vetch plus a low-cutting height(low-retained stubble)with the removal of straw(M-F80);(4)80%chemical fertilizer plus vetch plus a low-cutting height with the retention of straw(M-F80-LR);(5)80%chemical fertilizer plus vetch plus a high-cutting height(high-retained stubble)with the retention of straw(M-F80-HR);and(6)no fertilizer(F-Con).The yields of the two rice crops after vetch were not affected by either the cutting height of stubble with retention of straw or by the management of straw(retention vs.removal)with low-cutting height of stubble.The yields of the two rice crops after vetch were significantly higher for M-F80-HR than for M-F80-LR,but the relative contributions of the high-cutting height and straw retention to the higher rice yield could not be determined in this study.The yield stability of the double-rice grain in M-F80-HR was also increased,as determined by a sustainable yield index.Significant increases in vetch biomass and nutrient uptake were observed in the fertilized treatments during the rice season compared with the unfertilized treatments.In M-F80-HR plots,improvements in the growing environment of the vetch by conserving soil water content were associated with the highest vetch biomass,nutrient uptake,and yield stability of vetch biomass.These increased nutrient inputs partially replaced the demand for chemical fertilizer and stimulated the rice yields.It can be concluded that retaining higher-cutting stubble residues with straw retention could be the best straw management practice for increasing the vetch biomass and nutrient use efficiency,thereby allowing utilization of high-cutting height with retention of straw and vetch to improve the stability of rice productivity in a double-rice cropping system.

Effects of Long-term Return of Milk Vetch(Astragalus sinicus)on Soil Nutrients and Microorganism Communities in Double-rice Cropping Field

[Objectives]This study was conducted to investigate the effects of milk vetch(Astragalus sinicus)on soil nutrients and microorganisms in paddy fields after returning to the field.[Methods]Three treatments,no fertilization,single application of chemical fertilizers and milk vetch return combined with chemical fertilizers,were set up to determine soil nutrient contents and the quantity of microorganisms,respectively.[Results]The return of milk vetch combined with chemical fertilizers could significantly increase the contents of organic matter and total nitrogen in the paddy soil,while the contents of available potassium and available phosphorus decreased.Milk vetch return combined with chemical fertilizers could significantly increase the quantity of soil microorganisms in the paddy field.[Conclusions]The return of milk vetch can be used as a feasible measure to improve soil fertility.

Effects of Returning Straw and Milk Vetch on Rice Growth and Greenhouse Gas Emissions

The effects of different nitrogen application levels on rice yield and greenhouse gas(NO2,CH4)emissions from rice fields under the combined action of straw and milk vetch.Two treatments were set up in the main area of this experiment:R0(no straw returned to the field,0);R1(amount of straw returned to the field under normal conditions,6000 kg·hm^(-2)).Before turning the straw back into the field,use a circular knife to cut the straw into 10~13 cm.And 3 kinds of nitrogen application treatments in the sub-district:N1(no nitrogen application,0),N2(nitrogen application,15 kg·hm^(-2)),N_(3)(nitrogen application,30 kg·hm^(-2)),two-factor cross-combination,and a non-nitrogen control CK,total of 7 treatments.The results showed that in 2017,early rice R1N2 treatment increased the most obvious yield,which was 32.44%higher than CK,and late rice R_(1)N_(1)treatment increased the most significantly,which was 17.91%higher than CK.CH_(4)emission is positively correlated with the straw returned to the field.N_(2)O is the opposite.The N_(2)O emission flux was highest in the treatment of R1N3,and the CH_(4)emission flux was the highest in the treatment of R1N2.

Integration of Growing Milk Vetch in Winter and Reducing Nitrogen Fertilizer Application Can Improve Rice Yield in Double-Rice Cropping System

To study whether integrative fertilization [growing milk vetch in winter and reducing the dose of chemical nitrogen(N) fertilizer] can improve rice yield, and to reveal the underlying regulatory mechanisms for integrative fertilization, a three-year field trial including two treatments, milk vetch-rice-rice(MRR) and winter fallow-rice-rice(FRR), was conducted in 2010, 2011 and 2012.Our results demonstrated that the MRR treatment could significantly improve rice yield compared with the FRR treatment, especially when the application ratio of milk vetch and chemical fertilizer was 1:2.MRR treatment increased the effective panicle number and the spikelet number per panicle.In addition, a higher tillering number, leaf area index, photosynthetic-potential and photosynthetic-potential to grain ratio were observed in MRR treatment, which could provide enough dry matter for yield formation.Moreover, in MRR treatment, we discovered a higher transportation ratio and transformation ratio of dry matter in culm and leaves, and a stronger total sink capacity and spikelet-root bleeding intensity at the heading stage and 15 d after heading.Furthermore, the MRR treatment showed higher total N, phosphorus and potassium uptakes than FRR treatment, which was associated with the higher root dry weight in each soil layers.These results suggest that growing milk vetch in winter can improve rice yield under less chemical N fertilizer application, which is due to the improvement of soil nutrient status and the increased of rice root growth and development.

Substitution of chemical fertilizer by Chinese milk vetch improves the sustainability of yield and accumulation of soil organic carbon in a double-rice cropping system

The double-rice cropping system is a very important intensive cropping system for food security in China. There have been few studies of the sustainability of yield and accumulation of soil organic carbon (SOC) in the double-rice cropping system following a partial substitution of chemical fertilizer by Chinese milk vetch (Mv). We conducted a 10-year (2008–2017) field experiment in Nan County, South-Central China, to examine the double-rice productivity and SOC accumulation in a paddy soil in response to different fertilization levels and Mv application (22.5 Mg ha^–1). Fertilizer and Mv were applied both individually and in combination (sole chemical fertilizers, Mv plus 100, 80, 60, 40, and 0% of the recommended dose of chemical fertilizers, labeled as F100, MF100, MF80, MF60, MF40, and MF0, respectively). It was found that the grain yields of double-rice crop in treatments receiving Mv were reduced when the dose of chemical fertilizer was reduced, while the change in SOC stock displayed a double peak curve. The MF100 produced the highest double-rice yield and SOC stock, with the value higher by 13.5 and 26.8% than that in the F100. However, the grain yields increased in the MF80 (by 8.4% compared to the F100), while the SOC stock only increased by 8.4%. Analogous to the change of grain yield, the sustainable yield index (SYI) of double rice were improved significantly in the MF100 and MF80 compared to the F100, while there was a slight increase in the MF60 and MF40. After a certain amount of Mv input (22.5 Mg ha^–1), the carbon sequestration rate was affected by the nutrient input due to the stimulation of microbial biomass. Compared with the MF0, the MF100 and MF40 resulted in a dramatically higher carbon sequestration rate (with the value higher by 71.6 and 70.1%), whereas the MF80 induced a lower carbon sequestration rate with the value lower by 70.1% compared to the MF0. Based on the above results we suggested that Mv could partially replace chemical fertilizers (e.g., 40–60%) to improve or maintain the productivity and sustainability of the double-rice cropping system in South-Central China.

Study on Water-Soluble Organic Reducing Substances: II. Organic Reducing Substances Produced from Anaerobic Decomposition of Milk Vetch (Astragalus sinicus L.)

The characteristics of electric charge and molecular weight distribution,oxidation-reduction regimes,e.g.Eh and amounts of organic reducing substances produced by milk vetch during anaerobic decomposition process,were studied by using electrochemical methods.Interaction between soils and organic reducing substances was also observed.The results indicate that the organic reducing substances were mainly the organic compounds with negative and amphoteric charges,which were distributed in two groups at anodic peak potentials of 0.25 and 0.69 volt in differential pulse voltammograms,respectively.Their apparent molecular weights are all less than 700 daltons,in which those active in oxidation-reducion reaction were distributed in the fraction with apparent molecular weight less than 200 daltons.The organic reduction substances can be oxidized by manganese oxides in their interaction with soils.

Effects of Nitrogen Application Rate to Late Rice on Greenhouse Gas Emissions and Soil Carbon Pool During the Growing Season of Winter Chinese Milk vetch

It is of important referential values for the further understanding of the effects of fertilization on greenhouse gas emissions and the effects of winter green manure on soil carbon pool to study the effects of fertilization on the greenhouse gas emissions and soil carbon pool during the growing season of winter Chinese milk vetch in the process of rice cultivation.This study investigated the effects of nitrogen application in late rice season on the yield of the succeeding Chinese milk vetch and greenhouse gas emissions as well as the soil carbon pool characteristics after the winter planting of Chinese milk vetch with the winter idling of no nitrogen application as the control.The results showed that the yield of Chinese milk vetch was the highest under the nitrogen application of 225 kg/hm^2 in the late rice season,reaching up to 18 388.97 kg/hm^2,which was significantly different from other treatments( P <0.05).Nitrogen application in late rice season increased the emissions of N_2 O,CH_4,CO_2 and global warming potential( GWP) in the growing season of Chinese milk vetch.Compared with the winter idling treatment,winter planting of Chinese milk vetch significantly increased the soil organic carbon and soil carbon pool management index.The yield of Chinese milk vetch was significantly positively correlated with N_2O and CH_4 emissions( P < 0.05),while it presented extremely significant positive correlations with CO_2 emissions,GWP,active organic carbon,and carbon pool management index( P < 0.01).Nitrogen application in the late rice season increased the emissions of N_2 O,CH_4,CO_2,and enhanced the greenhouse gas emission potential during the growing season of Chinese milk vetch.Therefore,without reducing the yield of rice,reducing the amount of nitrogen fertilizer in rice could reduce the greenhouse gas emissions in the growing season of succeeding Chinese milk vetch.

CH_4 and N_2O emissions from double-rice cropping system as affected by Chinese milk vetch and straw incorporation in southern China

Chinese milk vetch(CMV) and rice straw(RS)were incorporated into soil to substitute for synthetic N fertilizers and to maintain soil fertility. However, little is known about the integrated impacts of CMV and RS incorporation on CH_4 and N_2O emissions in double-rice cropping systems in southern China. A field experiment was conducted to estimate the integrated impacts of CMV and RS incorporation in the early-and late-rice seasons on CH_4 and N_2O emissions. All treatments received uniform N inputs, 6%–37% of which was replaced by CMV and RS crop residue. CMV and/or RS incorporation produced equivalent or slightly more grain yield, while reducing N2 O emissions by 3%–43%. However, both CMV and RS incorporation increased CH_4 emissions. Annual CH_4 emissions ranged from 321 to 614 kg·hm^(–2)from CMV and RS amendment treatments, which were 1.5–2.9 times higher than that from synthetic N. Compared with single synthetic N fertilizer, incorporation of CMV and/or RS increased GWP and yield-scaled GWP by 45%–164% and45%–153%, respectively. Our results demonstrate CMV and RS amendments replacing N fertilizer, maintained stable yield, mitigated N_2O emission, but enhanced CH_4 emission. Further study is needed on crop residue management in double-cropping rice systems.

Co-composting of Chinese milk vetch with rice straw and using the compost as a peat substitute of seeding substrate of vegetables

Chinese milk vetch(Astragalussinicus L.)is an environment-friendly green manure used for rice with low carbon/nitrogen(C/N)ratio and high moisture.To improve the added values of milk vetch,the feasibility of co-composting of milk vetch with rice straw was evaluated.The probability of using the milk vetch-based compost as a peat substitute in seeding substrate of vegetable was further tested.The changes in physicochemical properties during co-composting of milk vetch and rice straw were evaluated,depending on three treatments:(1)milk vetch alone(MV),(2)co-composting of milk vetch and rice straws with 4:1 ration(w/w)(MV+S)and(3)MV+S with the addition of 3%(w/w)microbial inoculation(MV+S+M).The entire composting durations were 15 d,24 d,and 24 d in MV,MV+S,MV+S+M composts.Compare to MV compost,both the MV+S,MV+S+M composts increased the temperature,pH,organic C,total nitrogen(N),total potassium(K)and the germination index(GI)(over 100)during the cooling/mature phase,and decreased total N loss,and generally,the improvements or reductions were greater in the MV+S+M compost than in the MV+S compost.Additionally,the MV+S+M compost was added at a peat substitute rates of 0%,20%,40%,80%and 100%in a pot experiment to testify the utilization of milk vetch-based compost in substrates.The results showed that the substrate with 40%substitute rate increased the cabbage seeding growth,and that the electrical conductivity was the limiting factor of preventing the substitute rate increase.Another pot experiment demonstrated that the substrate with 40%peat substitute increased the cucumber growth as compared to the substrate without compost.In conclusion,the co-composting milk vetch with rice straw was feasible and quick,and microbial inoculation accelerated the composting process and improved the compost quality.The milk vetch-based composts were nutrient-rich and safe,and thus,can replace part of peat in vegetable seeding substrate.

Fungi dominate denitrification when Chinese milk vetch green manure is used in paddy soil

Fungi play an important role in soil nitrous oxide(N_(2)O)emission in many agricultural soil systems.However,the effect of fungi on N_(2)O emission in Chinese milk vetch(CMV)-containing soils has not been examined sufficiently.This study investigated the contribution of bacteria and fungi to soil N_(2)O emission in CMV-amended soils.We compared soils from an experimental field in the Fujian Academy of Agricultural Sciences that had been treated with 30000 kg of CMV per 667 m2 per year with one that was not treated with CMV.We incubated soil using cycloheximide and streptomycin to differentiate fungal and bacterial N_(2)O emissions,respectively.Quantitative PCR(qPCR)was performed to investigate bacterial and fungal abundances in the two agricultural soil ecosystems.The contribution of fungi to soil N_(2)O emission in CMV-amended soils was greater than that in nonCMV-amended paddy soils,with fungi accounting for more than 56%of the emissions in CMVamended soils.Quantitative PCR showed that the ratio of the internal transcribed spacer to 16S rDNA was significantly higher in CMV-amended soils than in non-CMV-amended paddy soils.Furthermore,soil properties,such as pH(P<0.05)and NH_(4)^(+)concentration(P<0.05),significantly and negatively affected N_(2)O emission by fungi in soil,whereas the total organic carbon(P<0.05)and NO3–concentration(P<0.05)showed significant positive effects.Fungi may be important contributors to N_(2)O production in CMV-amended soils,which may create challenges for mitigating N_(2)O production.

稻秸-紫云英联合还田对水稻光合特性及产量品质的影响

为评价稻秸-紫云英联合还田对水稻光合特性、产量及稻米品质的影响,采用田间随机试验,以不施氮肥为对照(CK),设置常规氮肥(N)、稻秸还田+常规氮肥(RN)、紫云英还田+常规氮肥(MN)、稻秸还田+紫云英还田+常规氮肥(MRN)、稻秸还田+紫云英还田+60%氮肥(MRN60%),共计6个处理。对不同处理下的叶绿素含量(SPAD值)、净光合速率(net photosynthetic rate,Pn)、气孔导度(stomatal conductance,Gs)、胞间CO_(2)浓度(intercellular CO_(2)concentration,Ci)、蒸腾速率(transpiration rate,Tr)和干物质积累量、产量及稻米品质进行比较。结果表明,与CK相比,N、RN、MN、MRN和MRN60%处理均可显著提高水稻剑叶的SPAD值、Pn、Gs、稻谷产量及稻米糙米率、整精米率和蛋白含量,并显著降低直链淀粉含量。与N处理相比,在光合特性方面,MRN处理剑叶的SPAD值、净光合速率、气孔导度分别显著提高2.36%、5.95%、7.80%;在干物质积累量方面,MRN处理分蘖期、孕穗期、乳熟期的干物质积累量分别显著提高14.77%、3.52%、4.95%;在产量及构成因素方面,MRN处理的有效穗数、穗粒数、稻谷产量分别显著提高7.38%、3.08%、15.96%;在稻米品质方面,MRN处理的整精米率显著提高4.63%,直链淀粉含量显著降低6.54%。与N处理相比,MN处理仅净光合速率显著提高4.75%;MRN60%处理仅直链淀粉含量显著降低7.00%。相关分析结果表明,剑叶SPAD值、Pn和Gs均与有效穗数、穗粒数、产量、糙米率、整精米率呈极显著正相关,与直链淀粉含量呈极显著负相关;SPAD值和Pn与蛋白含量呈极显著正相关;Gs与蛋白含量呈显著正相关。综上,在常规施氮下,稻秸-紫云英联合还田可显著提高水稻剑叶的SPAD值、Pn、Gs等光合指标及水稻产量和蒸煮品质;在60%氮肥施用下,稻秸-紫云英联合还田有利于稳定水稻剑叶光合特性,保持水稻增产和品质特征,可应用于优质水稻生产。

稻草和紫云英协同还田下钾肥施用量对水稻产量及土壤供钾能力的影响

[目的]水稻生产对钾素的需求量大,研究稻草和紫云英协同还田条件下不同施肥处理对水稻产量和土壤钾素形态变化的影响,旨在保障我国南方水稻的高产和土壤钾素高效利用。[方法]不同轮作模式钾肥定位试验位于中国农业科学院红壤实验站内(始于2016年)。试验处理包括不施肥和冬闲(CK)、氮磷钾肥和冬闲(F)、氮磷钾肥和冬种紫云英(CM)、氮磷钾肥配合稻草还田和冬种紫云英(RCM)、氮磷减钾50%配合稻草还田和冬种紫云英(50%KRCM)。在试验第3年(2019年)于水稻收获后调查分析水稻产量和钾素含量,以及耕层土壤中速效钾和缓效钾含量,计算水稻钾素吸收量、钾素生理效率和钾素表观平衡,并进一步探讨水稻产量和钾素各指标之间的相关性。[结果]与CK处理相比,紫云英轮作显著提高水稻年产量,增幅以RCM、50%KRCM较高,分别为59.4%和59.7%。两者协同还田和紫云英单独还田均可显著提高有效穗数,相比化肥冬闲处理(F),增幅为53.1%~63.3%,在稻草和紫云英协同还田下,减钾对水稻产量构成因素的影响不明显。和F处理相比,RCM、50%KRCM处理显著提高了土壤速效钾和缓效钾含量,增幅分别为87.6%、41.1%和14.0%、12.1%,紫云英单独还田(CM)可显著提高土壤速效钾含量,对缓效钾含量的影响不显著。与RCM处理相比,50%KRCM处理的土壤速效钾含量显著降低了24.8%,缓效钾含量没有显著变化。和CK处理相比,RCM处理显著提高了稻谷含钾量,增幅为6.7%,4个施肥处理均显著提高了稻草和稻谷吸钾量,钾素表观平衡均表现为盈余,RCM和50%KRCM处理的钾素盈余量高于CM处理,但50%KRCM处理的钾素盈余量比RCM处理降低了119.7 kg/(hm^(2)·a)。钾素盈余量与土壤速效钾含量变化呈显著正相关,钾素盈余量每增加1 kg/(hm^(2)·a),土壤速效钾含量提高0.25 mg/kg。施肥降低了钾素生理效率,CM、RCM和F处理的钾素生理效率比CK降低了10.3%~15.5%。土壤速效钾含量、植株总吸钾量、钾素表观平衡和水稻产量之间均显著正相关,植株总吸钾量每增加1 kg/hm^(2),水稻产量提高30.5 kg/hm^(2),钾素表观平衡每增加1 kg/(hm^(2)·a),水稻产量提高9.5 kg/hm^(2)。[结论]稻草和紫云英协同还田可增加水稻有效穗数进而提高稻谷产量,增加钾素盈余量可提高土壤速效钾和缓效钾含量,两者协同还田提升水稻产量和土壤供钾能力的作用优于紫云英单独还田。稻草和紫云英协同还田条件下减少钾肥施用量,显著降低钾素盈余量,但没有降低土壤钾素的供应能力,因此,可适当减少钾肥的施用量。

不同轮作模式对稻田土壤肥力和微生物群落结构的影响

为了探索不同水稻轮作模式对稻田土壤微生物群落结构的影响,以及与土壤养分供给的关系,本研究采用高通量测序技术对3种不同轮作模式下(水稻-小麦轮作、水稻-紫云英轮作、水稻-休耕)土壤细菌和真菌的群落结构变化进行分析,并进一步探讨了微生物群落结构与土壤养分含量之间的相互关系。结果表明:水稻-紫云英轮作模式能够明显改善稻田土壤的综合肥力,紫云英连续翻压还田后显著提高了土壤中总氮(TN)和有效氮(AN)的含量。土壤微生物群落结构方面,不同种植模式对细菌群落结构的影响大于真菌。水稻-紫云英轮作模式中优势菌群如酸杆菌门(Acidobacteriota)和子囊菌门(Ascomycota)等的富集有助于促进土壤生态系统的养分循环与生态健康。不同种植模式条件下土壤养分的变化如TN、AN、总钾(TK)及速效钾(AK)等可能是导致土壤细菌和真菌群落结构发生变化的主要驱动因素。稻田土壤中细菌群落结构对于土壤养分变化的敏感性要高于真菌。综合来看,水稻-紫云英轮作模式是更加适合水稻生态可持续栽培的种植模式,能够明显改善稻田土壤的综合肥力和土壤微生态环境。

紫云英和石灰配施对水稻镉吸收的影响

通过盆栽试验研究了单纯紫云英翻压(GM),以及紫云英与石灰共施(GM0HL)、紫云英+常量石灰晚施(GM5HL)、紫云英+减量石灰晚施(GM5LL)等处理对土壤性状、水稻根表铁膜及水稻对镉吸收转运的影响。结果表明,相较于对照(CK),翻压紫云英可显著(P<0.05)提高土壤有机质含量2.1~2.7 g·kg^(-1)。相较于GM处理,增施石灰后,土壤pH值显著提高0.38~0.78个pH单位,且土壤有效态Cd含量显著降低21.71%~41.28%。在紫云英快速腐解末期,增施了石灰的处理(GM0HL、GM5HL、GM5LL),土壤Eh显著高于GM处理。与CK相比,GM0HL、GM5HL、GM5LL处理在分蘖期的水稻根表铁膜Fe含量分别显著下降43.34%、38.82%和29.00%,根表铁膜Cd含量分别显著下降43.72%、35.56%和12.72%。主成分分析的结果显示,土壤pH值和有机质含量是影响水稻Cd吸收的关键因子,提高土壤pH值和有机质含量可以降低土壤Cd有效性,增加水稻根表铁膜厚度和根表铁膜Cd含量,从而抑制水稻对Cd的吸收。在试验条件下,紫云英翻压5 d后减量施用石灰,既可以达到较好的降Cd效果,又能在一定程度上减少Cd污染耕地的治理投入。

配施紫云英对不同类型水稻土溶解性有机碳氮淋溶及损失的影响

为探讨配施紫云英对不同类型稻田土壤溶解性有机碳(Dissolved organic carbon,DOC)和溶解性有机氮(Dissolved organic nitrogen,DON)含量的影响程度,阐明稻田土壤DOC和DON的淋溶特性,本研究以亚热带3种典型水稻土(黄泥田、灰黄泥田和灰泥田)为研究对象,通过田间试验,探讨等氮磷钾条件下单施化肥(CK)和紫云英配施化肥(cmv)处理对不同水稻土DOC和DON的动态变化、淋溶特性及损失的影响。结果表明,不同土壤类型水稻土DOC和DON的淋溶特性有所不同。3种供试水稻土中,灰泥田水稻土DOC淋溶损失量最大,其CK处理DOC淋溶损失量较灰黄泥田和黄泥田分别显著提高24.09%和72.15%,cmv处理淋溶损失量较灰黄泥田和黄泥田分别显著提高16.53%和40.55%;而黄泥田水稻土DON淋溶损失量最大,其CK处理淋溶损失量较灰黄泥田和灰泥田分别显著提高18.93%和37.01%,cmv处理3种不同类型水稻土DON淋溶损失量无显著差异。配施紫云英可显著降低水稻土DON的淋溶损失量,每季水稻中cmv处理黄泥田、灰黄泥田和灰泥田DON淋溶损失量较CK处理分别降低了24.67%、14.88%和13.54%;黄泥田cmv处理DOC较CK处理提高了19.19%,而灰黄泥田和灰泥田2种施肥处理无显著差异。供试稻田中DOC和DON在土层间的淋溶具有一定的延迟性,且DOC的延迟时间大于DON。灰色关联分析表明,在土壤性质中有机质是影响水稻土DOC淋溶损失的重要因素,孔隙度是DON淋溶损失的重要影响因素。不同类型水稻土DON的淋失早于DOC,且DON在黄泥田中淋溶损失较高,而DOC在灰泥田中淋溶损失较高;在等氮磷钾的条件下,配施紫云英可减少水稻土DON的淋溶损失,而低肥力水稻土DOC的淋溶损失量有所增加。

紫云英及氮肥减量下配施生物质炭对土壤理化性质和水稻产量的影响

【目的】为减少化学氮肥的使用,通过盆栽试验探究在紫云英还田条件下,氮肥减量配施生物质炭对稻田土壤养分提升、水稻增产的作用,旨在明确在紫云英替代部分氮肥的基础上,更有利于培肥和增产的最佳减氮量和生物质炭添加比例,以期为实际生产应用提供科学依据。【方法】采用双因素水稻盆栽试验,以冬闲+常规施肥(CK)为空白对照,设置了4个(0.25%、0.5%、1%、2%)生物质炭添加比例,在追肥时设置3个(减氮10%、减氮20%、减氮30%)减氮比例,共设置13个处理组合,每个处理重复4次,共计52盆,生长周期120 d,水稻成熟后比较各处理对土壤理化性质及水稻产量、性状的影响。【结果】在紫云英还田下,减氮30%配施2.0%生物质炭显著提高了土壤pH(P<0.01)与CK相比提高了12.02%;减氮20%配施2.0%生物质炭对土壤有机质(SOM)、有效磷(AP)、速效钾(AK)含量均具有极显著提升作用(P<0.01),显著提升了土壤全氮含量(P<0.05),比CK分别增加了38.8%、107.2%、25.4%、24.9%;减氮20%配施0.5%生物质炭时碱解氮含量显著提升了49.6%(P<0.01)。紫云英还田下减氮30%配施1.0%生物质炭时产量最高,与CK相比分别显著增产18.7%(P<0.01)。施加低量生物质炭(0.25%生物质炭)更有利于水稻地上部生物量积累,比CK显著增加了90.04%(P<0.01)。相关性分析表明,土壤有机质、有效磷、速效钾是提升水稻产量的主要土壤环境因子(P<0.05、r>0.5)。【结论】紫云英、氮肥减量及生物质炭联合施用的培肥增产效果显著,紫云英还田下减氮20%配施2.0%生物质炭更有利于提升稻田土壤养分含量,减少氮素流失,促进水稻生长增产,但施加过量生物质炭对水稻产量及生物量具有一定的抑制作用,在追肥时减氮30%配施1.0%生物质炭对水稻增产效果最佳。

紫云英压青结合稻秸还田对水稻的节肥增效作用

【目的】紫云英压青结合稻秸还田是降低化肥用量、提高肥料利用率的绿色有效措施。在福建灰(黄)泥田多地开展田间试验,以验证该措施的有效性。【方法】田间试验分别在福建沙县、顺昌县、浦城县进行,沙县供试水稻为头茬再生稻,顺昌和浦城为单季稻。所有试验均设置5个处理:不施肥(CK)、100%常规化肥(100%CF)、80%常规化肥(80%CF)、种植翻压紫云英+80%常规化肥(CMV+80%CF)、稻秸还田+种植翻压紫云英+80%常规化肥(RS+CMV+80%CF)。在水稻成熟期,调查产量和产量经济性状,分析氮磷钾养分积累量,并计算水稻产量的变异系数和可持续指数。【结果】与100%CF处理相比,CMV+80%CF和RS+CMV+80%CF处理三地稻谷平均产量和稻秸平均产量增加不显著,但在沙县稻秸产量显著增加33.7%和26.1%。100%CF处理对产量的贡献率较80%CF处理增加了2.74个百分点;CMV+80%CF、RS+CMV+80%CF处理对水稻产量的贡献率较80%CF处理分别提高了7.73%、11.30%,三地RS+CMV+80%CF处理稻谷平均产量比CMV+80%CF处理提高3.9%。各处理间水稻产量变异系数表现为RS+CMV+80%CFCMV+80%CF>100%CF>80%CF,翻压紫云英、紫云英与稻秸联合还田均有利于水稻持续性高产稳产,且紫云英与稻秸联合还田的效果明显高于紫云英单独翻压。翻压紫云英、紫云英与稻秸联合还田均有利于水稻氮、磷、钾养分的累积,与100%CF处理相比,CMV+80%CF处理的平均氮、磷、钾养分回收率分别增加了19.1、20.1、29.5个百分点,RS+CMV+CMV+80%CF处理分别增加了19.3、8.8、30.6个百分点,RS+CMV+80%CF处理的氮、钾养分回收率高于CMV+80%CF处理。RS+CMV+80%CF处理的氮肥农学利用率和氮肥偏生产力最大,较100%CF处理分别增加了76.38%和8.99%。【结论】无论再生稻还是单季稻,在减施化肥用量20%的条件下,紫云英压青结合稻秸还田有利于水稻稳产和产量的可持续性,同时提高养分回收率,增强节肥增效作用,可作为灰黄泥田水稻绿色高效生产的管理制度。

紫云英稻秸秆协同还田与氮肥减量配施对水稻干物质积累、氮素转运及产量的影响

研究紫云英稻秸秆协同还田下氮肥减量对水稻关键生育期干物质积累和氮素吸收转运及籽粒产量的影响,为水稻绿色高效栽培提供技术路径。试验于2019—2021年在陕西省汉中市农业科学研究所韩塘试验基地进行,采用随机区组设计,重复3次。供试水稻品种为优质籼稻‘黄华占’。共设5个处理,(1)冬闲水稻秸秆不还田,不施肥(CK);(2)冬闲水稻秸秆不还田,常规施氮(NPK);(3)冬作紫云英水稻秸秆还田,常规施氮(GRN_(100));(4)冬作紫云英水稻秸秆还田,氮肥减量20%(GRN_(80));(5)冬作紫云英水稻秸秆还田,氮肥减量30%(GRN_(70))。分析了水稻齐穗期和成熟期干物质积累、氮素累积量、氮素吸收与利用。结果表明:1)与NPK相比,紫云英水稻秸秆协同还田各处理水稻产量增加3.50%~7.65%;齐穗期茎鞘、叶片、穗干物重分别增加25.54%~44.79%、44.79%~53.74%、33.76%~61.81%,成熟期茎鞘、叶片干物重增加6.87%~25.57%、20.87%~23.46%;且与GRN_(100)相比,GRN_(80)和GRN_(70)水稻产量增加4.00%和2.77%,齐穗期穗干物重增加21.33%、4.56%,GRN_(80)有效穗增加7.77%,千粒重增加2.56%,GRN_(80)成熟期茎鞘、穗干物重增加17.52%、10.91%。2)与NPK相比,紫云英水稻秸秆协同还田各处理齐穗期茎鞘、叶片、穗氮累积量增加34.84%~60.59%、50.41%~69.28%、26.57%~45.35%,成熟期增加48.61%~54.78%、54.67%~91.81%、6.42%~19.96%,茎鞘氮转运量增加16.89%~64.99%,叶片氮转运量增加47.85%~73.05%,氮转运贡献率增加27.75%~41.09%;且与GRN_(100)相比,GRN_(80)穗中氮增量增加19.76%,茎鞘氮转运量、茎鞘转运率、叶片转运率、氮素转运效率分别增加7.46%、2.73%、9.35%、6.86%。3)与NPK相比,紫云英水稻秸秆协同还田各处理氮素干物质生产效率减低10.64%~20.92%,氮肥生理利用率减少17.88%~32.89%,氮肥农学效率增加7.81%~63.03%,氮素回收率增加57.36%~97.19%,氮肥偏生产力增加3.55%~52.00%;且与GRN_(100)相比,GRN_(80)和GRN_(70)氮素干物质生产效率增加13.00%、10.97%,氮肥生理利用率增加12.34%、22.37%,氮肥农学效率显著增加35.66%、51.21%,氮素回收率显著增加21.04%、25.52%,氮肥偏生产力增加30.04%、46.79%。紫云英水稻秸秆协同还田下减氮20%或30%能够显著提高水稻产量,增加氮素吸收转运,提高氮素利用,是适宜汉中地区水稻生产的一种绿色高效栽培模式。

紫云英稻秆联合还田与氮肥减量对水稻产量及氨挥发的影响

为研究紫云英-水稻轮作体系中紫云英稻秆联合还田与氮肥减量配施对水稻产量和氨挥发的影响,连续两个轮作季(2019—2021年)在陕西汉中开展田间试验,试验设置4个处理:冬闲稻秆不还田+常规施氮处理,即对照处理(CK);冬作紫云英稻秆还田+常规施氮处理(GRN_(100));冬作紫云英稻秆还田+氮肥减量20%处理(GRN_(80));冬作紫云英稻秆还田+氮肥减量30%处理(GRN_(70))。采用通气式氨挥发收集装置监测水稻生育期间氨挥发特征。结果表明:与CK相比,紫云英稻秆联合还田各处理可提高“黄华占”籽粒产量,产量由高到低的顺序为GRN_(80)、GRN_(70)、GRN_(100),其中GRN_(80)和GRN_(70)处理相较于CK处理的年均增幅分别为7.66%和6.37%。冠层氨挥发主要发生在水稻施肥30 d以后,其中水稻抽穗期至成熟期挥发速率较大。土壤氨挥发主要发生在水稻施肥后16 d内,在施肥后第2天达到峰值,2020年和2021年分别为0.53 kg·hm^(-2)·d^(-1)和0.58 kg·hm^(-2)·d^(-1)。与CK相比,GRN_(80)处理显著降低水稻全生育期冠层氨挥发累积量和单位产量氨挥发强度,二者分别下降58.73%和57.14%。紫云英稻秆联合还田较CK处理可显著降低水稻全生育期土壤氨挥发累积量和单位产量氨挥发强度,其值由高到低依次顺序为GRN_(100)、GRN_(70)、GRN_(80)。就水稻全生育期氨挥发累积量和单位产量氨挥发强度而言,紫云英稻秆联合还田较CK处理可显著降低2.88%~8.32%和5.26%~13.88%,其中GRN_(80)处理降幅最大。相关分析表明,田面水铵态氮浓度与各处理土壤氨挥发速率呈显著正相关,与GRN_(80)和GRN_(70)处理冠层氨挥发速率呈显著负相关。研究表明,紫云英和稻秆联合还田与氮肥减量20%或30%配施,可显著提高水稻产量,减少稻田氨挥发损失,是适宜汉中地区兼顾水稻高产和环境友好的栽培措施。