Strength criterion for crystalline rocks considering grain size effect and tensile-compressive strength ratio

The macroscopic mechanical properties of rocks are significantly influenced by their microstructure.As a material bonded by mineral grains,the grain morphology of crystalline rock is the primary factor influencing the strength.However,most strength criteria neglect the strength variations caused by different grain characteristics in rocks.Furthermore,the traditional linear criteria tend to overestimate tensile strength and exhibit apex singularity.To address these shortcomings,a piecewise strength criterion that considers the grain size effect has been proposed.A part of an ellipse was employed to construct the envelope of the tensive-shear region on the meridian plane,to accurately reproduce the low tensile-compressive strength ratio.Based on the analysis of experimental data,both linear and exponential modification functions that account for grain size effects were integrated into the proposed criterion.The corresponding finite element algorithm has been implemented.The accuracy and applicability of the proposed criterion were validated by comparing with the experimental data.

No-tillage with straw mulching boosts wheat grain yield by improving the eco-physiological characteristics in arid regions

Straw returning to the field is a technical measure of crop production widely adopted in arid areas. It is unknown whether crop yield can be further increased by improving the eco-physiological characteristics when straw returning is applied in the crop production system. So, a three-year field experiment was conducted with various straw returning treatments for wheat production:(i) no-tillage with straw mulching(NTSM),(ii) no-tillage with straw standing(NTSS),(iii) conventional tillage with straw incorporation(CTS), and(iv) conventional tillage with no straw returning(CT, control). The eco-physiological and yield formation indicators were investigated to provide the basis for selecting the appropriate straw returning method to increase wheat yield and clarifying its regulation mechanism on eco-physiology. The results showed that NTSM and NTSS treatments had better regulation of eco-physiological characteristics and had a higher yield increase than CTS and CT. Meanwhile, NTSM had a relatively higher yield than NTSS through better regulation of eco-physiological characteristics. Compared to CT, the leaf area index of NTSM was decreased by 6.1–7.6% before the Feekes 10.0 stage of wheat, but that of NTSM was increased by 38.9–45.1% after the Feekes 10.0 stage. NTSM effectively regulated the dynamics of the photosynthetic source of green leaves during the wheat growth period. NTSM improved net photosynthetic rate by 10.2–21.4% and 11.0–21.6%, raised transpiration rate by 4.4–10.0% and 5.3–6.1%, increased leaf water use efficiency by 5.6–10.4% and 5.4–14.6%, at Feekes 11.0 and 11.2 stages of wheat, compared to CT, respectively. NTSM had higher leaf water potential(LWP) by 7.5–12.0% and soil water potential(SWP) by 8.9–24.0% from Feekes 10.3 to 11.2 stages of wheat than CT. Meanwhile, the absolute value of difference on LWP and SWP with NTSM was less than that with CT, indicating that NTSM was conducive to holding the stability of water demand for wheat plants and water supply of soil at arid conditions. Thus, NTSM had a greater grain yield of wheat by 18.6–27.3% than CT, and the high yield was attributed to the synchronous increase and cooperative development of ear number, grain number per ear, and 1 000-grain weight. NTSM had a positive effect on regulating the eco-physiological characteristics and can be recommended to enhance wheat grain yield in arid conditions.

Preparation of activated carbon from sunflower straw through H_(3)PO_(4) activation and its application for acid fuchsin dye adsorption

With the development circular economy, the use of agricultural waste to prepare biomass materials to remove pollutants has become a research hotspot. In this study, sunflower straw activated carbon (SSAC) was prepared by the one-step activation method, with sunflower straw (SS) used as the raw material and H3PO4 used as the activator. Four types of SSAC were prepared with impregnation ratios (weight of SS to weight of H3PO4) of 1:1, 1:2, 1:3, and 1:5, corresponding to SSAC1, SSAC2, SSAC3, and SSAC4, respectively. The adsorption process of acid fuchsin (AF) in water using the four types of SSAC was studied. The results showed that the impregnation ratio significantly affected the structure of the materials. The increase in the impregnation ratio increased the specific surface area and pore volume of SSAC and improved the adsorption capacity of AF. However, an impregnation ratio that was too large led to a decrease in specific surface area. SSAC3, with an impregnation ratio of 1:3, had the largest specific surface area (1 794.01 m2/g), and SSAC4, with an impregnation ratio of 1:5, exhibited the smallest microporosity (0.052 7 cm3/g) and the largest pore volume (2.549 cm3/g). The adsorption kinetics of AF using the four types of SSAC agreed with the quasi-second-order adsorption kinetic model. The Langmuir isotherm model was suitable to describe SSAC3 and SSAC4, and the Freundlich isotherm model was appropriate to describe SSAC1 and SSAC2. The result of thermodynamics showed that the adsorption process was spontaneous and endothermic. At 303 K, SSAC4 showed a removal rate of 97.73% for 200-mg/L AF with a maximum adsorption capacity of 2 763.36 mg/g, the highest among the four types of SSAC. This study showed that SAAC prepared by the H3PO4-based one-step activation method is a green and efficient carbon material and has significant application potential for the treatment of dye-containing wastewater.

Maize straw application as an interlayer improves organic carbon and total nitrogen concentrations in the soil profile: A four-year experiment in a saline soil

Soil salinization is a critical environmental issue restricting agricultural production.Deep return of straw to the soil as an interlayer (at 40 cm depth) has been a popular practice to alleviate salt stress.However,the legacy effects of straw added as an interlayer at different rates on soil organic carbon (SOC) and total nitrogen (TN) in saline soils still remain inconclusive.Therefore,a four-year (2015–2018) field experiment was conducted with four levels (i.e.,0,6,12and 18 Mg ha~(–1)) of straw returned as an interlayer.Compared with no straw interlayer (CK),straw addition increased SOC concentration by 14–32 and 11–57%in the 20–40 and 40–60 cm soil layers,respectively.The increases in soil TN concentration (8–22 and 6–34%in the 20–40 and 40–60 cm soil layers,respectively) were lower than that for SOC concentration,which led to increased soil C:N ratio in the 20–60 cm soil depth.Increases in SOC and TN concentrations in the 20–60 cm soil layer with straw addition led to a decrease in stratification ratios (0–20 cm:20–60 cm),which promoted uniform distributions of SOC and TN in the soil profile.Increases in SOC and TN concentrations were associated with soil salinity and moisture regulation and improved sunflower yield.Generally,compared with other treatments,the application of 12 Mg ha~(–1) straw had higher SOC,TN and C:N ratio,and lower soil stratification ratio in the2015–2017 period.The results highlighted that legacy effects of straw application as an interlayer were maintained for at least four years,and demonstrated that deep soil straw application had a great potential for improving subsoil fertility in salt-affected soils.

Effect of Strain Ratio on Fatigue Model of Ultra-fine Grained Pure Titanium

The ultra-fine grained(UFG)pure titanium was prepared by equal channel angular pressing(ECAP)and rotary swaging(RS).The strain controlled low cycle fatigue(LCF)test was carried out at room temperature.The fatigue life prediction model and mean stress relaxation model under asymmetrical stress load were discussed.The results show that the strain ratio has a significant effect on the low cycle fatigue performance of the UFG pure titanium,and the traditional Manson-coffin model can not accurately predict the fatigue life under asymmetric stress load.Therefore,the SWT mean stress correction model and three-parameter power curve model are proposed,and the test results are verified.The final research shows that the threeparameter power surface model has better representation.By studying the mean stress relaxation phenomenon under the condition of R≠-1,it is revealed that the stress ratio and the strain amplitude are the factors that significantly afiect the mean stress relaxation rate,and the mean stress relaxation model with the two variables is calculated to describe the mean stress relaxation phenomenon of the UFG pure titanium under different strain ratios.The fracture morphology of the samples was observed by SEM,and it was concluded that the final fracture zone of the fatigue fracture of the UFG pure titanium was a mixture of ductile fracture and quasi cleavage fracture.The toughness of the material increases with the increase of strain ratio at the same strain amplitude.

OsDA1 positively regulates grain width in rice

The size and shape of rice grains influence their yield and commercial value.We investigated the role of OsDA1,a rice homolog of the Arabidopsis DA1 gene,in regulating grain size and shape.OsDA1 was highly expressed in young spikelets and glumes.Its overexpression led to enlarged seeds with increased width and decreased length/width ratio(LWR)and knocking out OsDA1 reduced grain width and increased grain length and LWR.A R310K point mutation in the DA1-like domain is a potential target for breeding for increased grain width and length.OsDA1 interacted with TCP gene-family proteins to regulate grain size and shape.Our findings deepen our understanding of the molecular mechanisms underlying grain size regulation and provide useful information for improving grain yield.

Effects of Regulation of C/N Ratio Wheat Straw Application on Nitrogen,Phosphorus and Potassium Uptake in Tobacco

[Objective]The aim was to study the effects of regulation of C/N ratio wheat straw application on tobacco nitrogen,phosphorus and potassium uptake. [Method]Effects of regulation C/N ratio wheat straw application on the flue-cured tobacco yield,output value,nitrogen,phosphorus and potassium content and cumulative uptake of the upper,middle and bottom leaf were studied by using the field plot experiments at Banqiao town,Qujing city,Yunnan Province during the 2008-2009 summer growing seasons. [Result]The results showed that the application of wheat straw alone or after C/N regulation,could significantly increase tobacco production,potassium content,the potassium and nitrogen accumulation amount of leaf,and was more conducive to the potassium uptake of tobacco leaf with wheat straw application after C/N regulation. Compared with non-straw application,the yield of tobacco increased by 6.59%,3.58%,5.98%,8.80% with application of wheat straw alone,wheat straw and vetch,wheat straw and oilseed cake,wheat straw and urea nitrogen,the potassium content in tobacco leaf increased by 3.85%,7.76%,8.82%,11.21%,respectively,the total potassium cumulative amount of leaf increased by 10.71%,11.62%,15.32% ,21.01% and the total nitrogen cumulative amount increased by 9.76%,1.22%,8.14%,14.00%. However,the differences of tobacco leaf nitrogen content among the different treatments were not significant,the phosphorus uptake of tobacco leaf decreased. [Conclusion]application of high C/N ratio wheat straw in flue-cured tobacco production,which should be concerned not only to adjust C/N ratio by adding nitrogen,but also considering additional phosphorus application.

Straw return and appropriate tillage method improve grain yield and nitrogen efficiency of winter wheat

Straw return is an important management tool for tackling and promoting soil nutrient conservation and improving crop yield in Huang-Huai-Hai Plain, China. Although the incorporation of maize straw with deep plowing and rotary tillage practices are widespread in the region, only few studies have focused on rotation tillage. To determine the effects of maize straw return on the nitrogen （N） efficiency and grain yield of winter wheat （Triticum aestivum L.）, we conducted experiments in this region for 3 years. Five treatments were tested： （i） rotary tillage without straw return （RT）; （ii） deep plowing tillage without straw return （DT）; （iii） rotary tillage with total straw return （RS）; （iv） deep plowing tillage with total straw return （DS）; （v） rotary tillage of 2 years and deep plowing tillage in the 3rd year with total straw return （TS）. Treatments with straw return increased kernels no. ear-1, thousand-kernel weight （TKW）, grain yields, ratio of dry matter accumulation post-anthesis, and nitrogen （N） efficiency whereas reduced the ears no. ha-1 in the 2011-2012 and 2012-2013 growing seasons. Compared with the rotary tillage, deep plowing tillage significantly increased the grain yield, yield components, total dry matter accumulation, and N efficiency in 2013-2014. RS had significantly higher straw N distribution, soil inorganic nitrogen content, and soil enzymes activities in the 0-10 cm soil layer compared with the DS and TS. However, significantly lower values were ob- served in the 10-20 and 20-30 cm soil layers. TS obtained approximately equal grain yield as DS, and it also reduced the resource costs. Therefore, we conclude that TS is the most economical method for increasing grain yield and N efficiency of winter wheat in Huang-Huai-Hai Plain.

Changes in Grain Yield of Rice and Emission of Greenhouse Gases from Paddy Fields after Application of Organic Fertilizers Made from Maize Straw

A field experiment was conducted at the farm of Yangzhou University, Yangzhou, China, to study the effects of organic fertilizers made from maize straw on rice grain yield and the emission of greenhouse gases. Four organic fertilizer treatments were as follows： maize straw （MS）, compost made from maize straw （MC）, methane-generating maize residue （MR）, and black carbon made from maize straw （BC）. These organic fertilizers were applied separately to paddy fields before rice transplanting. No organic fertilizer was applied to the control （CK）. The effects of each organic fertilizer on rice grain yield and emission of greenhouse gases were investigated under two conditions, namely, no nitrogen （N） application （ON） and site-specific N management （SSNM）. Rice grain yields were significantly higher in the MS, MC and MR treatments than those in CK under either ON or SSNM. The MS treatment resulted in the highest grain yield and agronomic N use efficiency. However, no significant difference was observed for these parameters between the BC treatment and CK. The changes in the emissions of methane （CH4） carbon dioxide （CO2）, or nitrous oxide （N20） from the fields were similar among all organic fertilizer treatments during the entire rice growing season. The application of each organic fertilizer significantly increased the emission of each greenhouse gas （except N20 emission in the BC treatment） and global warming potential （GWP）. Emissions of all the greenhouse gases and GWP increased under the same organic fertilizer treatment in the presence of N fertilizer, whereas GWP per unit grain yield decreased. The results indicate that the application of organic fertilizer （MS, MC or MR） could increase grain yield, but also could enhance the emissions of greenhouse gases from paddy fields. High grain yield and environmental efficiency could be achieved by applying SSNM with MR.

Yield of Wheat (<i>Triticum aestivum</i>) and Nutrient Uptake in Grain and Straw as Influenced by Some Macro (S &Mg) and Micro (B &Zn) Nutrients

A wheat variety BARI Gom 26 was cultivated with an objective of evaluating the effects of macro/secondary nutrients as S and Mg, and micro nutrients as B and Zn on yield, yield contributing traits and nutrient uptake status by the crop. The field experiment was con-ducted in the “North Eastern Barind Tract Soils” at Kushadaha, Nawabganj, Dinajpur, Bangladesh from November, 2014 to March, 2015. The surface soil was clay in texture, having pH 5.61, organic matter 1.58%, total N 0.10%, available P 7.03 ppm, exchangeable K 0.11 meq/100g, available S 2.57 ppm, exchangeable Mg 0.55 meq/100g, available Zn 1.30 ppm, available B 0.08 ppm. The experiment was designed with five treatments laid out in a randomized complete block design (RCBD) with three replications. The treatments were T1: NPK (control), T2: NPK + S, T3: NPK + S + Mg, T4: NPK + S + Mg + Zn and T5: NPK + S + Mg + Zn + B. All plots of wheat received 100 kg N/ha, 30 kg P/ha and 70 kg K/ha as basal dose. The secondary and micro nutrients doses were 15 kg S/ha, 6 kg Mg/ha, 2.5 kg Zn/ha and 1.5 kg B/ha. Results revealed that the plant height, tillers/hill, 1000-grain weight, yield of grain and straw, uptake of some specific nutrients in grain and straw were signifi-cantly influenced by all the treatments, though these treatments did not show any identical effect on spike length, content of P and Mg in wheat. Significantly highest amount of 1000-grain weight, yield of grain and straw weight of wheat were obtained in applying T2 treatment that employed the addition of S with recommended dose of NPK. Significant positive effects were also observed for the rest parameters in receiving the treatments composed of secondary and micronutrients (T3, T4, and T5). The highest concentration of nutrient uptake N, P, K and S in grain and straw of wheat were also obtained due to the application of T2 treatment. In the case of Mg, the maximum uptake was recorded in T4 where Mg was added as a component of this treatment. In contrast, the highest content of Zn and B were extracted in receiving the treatment T5 both for grain and straw. However, results suggested that T2 treatment comprising recommended dose of NPK with S might be economic and suitable as for better production of 1000-grain weight, yield of grain and straw, uptake of N, P, K and S in grain and straw of wheat cultivated in the North Eastern Barind Tract Soils of Bangladesh under winter condition. The treatment T5 would also be recommended in the context of addition of micronutrients.

Wheat Straw Burial Improves Physiological Traits, Yield and Grain Quality of Rice by Regulating Antioxidant System and Nitrogen Assimilation Enzymes under Alternate Wetting and Drying Irrigation

Wheat straw burial has great potential to sustain rice production under alternate wetting and drying(AWD)irrigation.A field experiment was conducted with three wheat straw burial treatments,including without straw burial(NSB),with light straw burial of 300 kg/hm^(2)(LSB)and dense straw burial of 800 kg/hm^(2)(DSB),as well as three AWD regimes:alternate wetting/moderate drying(AWMD),alternate wetting/severe drying(AWSD)and alternate wetting/critical drying(AWCD).The rice growth and grain quality were higher in LSB and NSB than those in NSB under the same AWD regime.The AWMD×DSB treatment resulted in the highest yield,brown rice rate,milled rice rate,amylose content and protein content.Conversely,the AWCD×NSB treatment led to the lowest yield,brown rice rate,milled rice rate,amylose content and protein content.The active absorption area and nitrate reductase activity of roots were higher in the AWMD×DSB treatment than those in the AWCD×NSB treatment,as the former increased organic carbon and nitrogen contents in the rhizosphere,whereas the latter reduced their availability.Total soluble protein content and glutamine synthetase activity were greater in the AWMD×DSB treatment than those in the AWCD×NSB treatment.The activities of superoxide dismutase and catalase were higher in the AWMD×DSB treatment compared with the AWCD×NSB treatment,leading to the amelioration of oxidative cell injury,as shown by a lower malonaldehyde level.This study suggested that farmers should implement AWMD irrigation after leaving the straw residues in the field,followed by deep tillage to improve soil quality and mitigate the drought stress cycles of AWD.This approach can improve rice growth and grain quality and alleviate the problems of disposal of straw residues and water scarcity for sustainable rice production.

Effect of Initial Microstructure Prior to Extrusion on the Microstructure and Mechanical Properties of Extruded AZ80 Alloy with a Low Temperature and a Low Ratio

Magnesium(Mg)alloys are the lightest metal structural material for engineering applications and therefore have a wide market of applications.However,compared to steel and aluminum alloys,Mg alloys have lower mechanical properties,which greatly limits their application.Extrusion is one of the most important processing methods for Mg and its alloys.However,the effect of such a heterogeneous microstructure achieved at low temperatures on the mechanical properties is lacking investigation.In this work,commercial AZ80 alloys with different initial microstructures(as-cast and as-homogenized)were selected and extruded at a low extrusion temperature of 220℃and a low extrusion ratio of 4.The microstructure and mechanical properties of the two extruded AZ80 alloys were investigated.The results show that homogenized-extruded(HE)sample exhibits higher strength than the cast-extruded(CE)sample,which is mainly attributed to the high number density of fine dynamic precipitates and the high fraction of recrystallized ultrafine grains.Compared to the coarse compounds existing in CE sample,the fine dynamical precipitates of Mg17(Al,Zn)12form in the HE sample can effectively promote the dynamical recrystallization during extrusion,while they exhibit a similar effect on the size and orientation of the recrystallized grains.These results can facilitate the designing of high-strength wrought magnesium alloys by rational microstructure construction.

我国乡村老龄化现状及其对粮食生产的影响与应对

根据2020年最新人口普查数据,我国乡村老龄化率为17.72%,先于城市步入中度老龄化社会。我国乡村老龄化整体呈现出老年抚养比增速快、低龄老人务农比例高等特征,与国际主要发达国家相比我国乡村老龄人口就业占比相对较高。分区域看,粮食主产区乡村老龄化增幅更多、老年抚养比更重、老龄就业比重更高;全国乡村老年抚养比28.13%,但粮食主产省份达31.28%。通过定性梳理乡村老龄化对农户参与粮食种植及其粮食生产行为效率等的影响,提出积极应对乡村老龄化、保障粮食安全的思路与对策建议。

氮肥运筹对晚播强筋小麦产量及品质的效应

为探索适宜的稻茬晚播小麦高产优质栽培技术,于2019-2021年在晚播条件下(较适播期推迟20 d播种),以强筋小麦扬麦29为材料,设置二因素随机区组试验,探究两种施氮量(210 kg·hm^(-2)和270 kg·hm^(-2))和3种基追比(基肥∶分蘖肥∶拔节肥分别为7∶1∶2、5∶1∶4和3∶3∶4)对晚播强筋小麦籽粒产量和品质的影响及其较优组合。结果表明,施氮量和氮肥基追比对扬麦29籽粒产量的影响均达极显著水平(P<0.01)。施氮量由210 kg·hm^(-2)增至270 kg·hm^(-2),扬麦29穗数、穗粒数及产量增加;随氮肥后移,穗粒数、千粒重、产量均呈增加趋势,其中基追比3∶3∶4处理两年平均产量分别比5∶1∶4和7∶1∶2高2.27%和7.69%。施氮量和氮肥基追比对蛋白质含量、湿面筋含量、面团形成时间、稳定时间、面包体积和面包评分等品质指标有极显著影响,而对籽粒硬度、吸水率、水SRC和蔗糖SRC影响不显著。增加施氮量或氮肥后移有利于提高蛋白质含量、湿面筋含量、面团形成时间、稳定时间、面包体积和面包评分等指标,在270 kg·hm^(-2)施氮量或210 kg·hm^(-2)施氮量、基追比3∶3∶4运筹下的面包评分均大于80分,达到优质强筋小麦标准。综上所述,晚播条件下,强筋小麦扬麦29在施氮量270 kg·hm^(-2)、基肥:壮蘖肥:拔节肥为3∶3∶4可实现产量与品质的协同提高。

秸秆还田及不同比例控失尿素对华北平原小麦产量及潮土性质影响

为探讨不同控失尿素比例和秸秆还田对华北平原小麦产量及潮土化学性质的影响,本研究以华北潮土区小麦-玉米轮作体系为研究对象,采用裂区试验设计,以秸秆还田为主区,控失尿素比例为副区。秸秆还田模式设秸秆全量还田(S1)、秸秆不还田(S0)2种;控失尿素比例设不施肥(CK)以及控失尿素占总施氮量比例为0、40%、70%和100%(LCU0、LCU40、LCU70、LCU100)5个处理。在作物收割后进行产量测定,并采集0~20 cm耕层土壤进行常规土壤养分含量测定。结果表明:与S0处理相比,S1处理显著提高土壤有机质和速效钾含量。控失尿素显著提高土壤硝态氮含量,其他土壤养分含量无显著变化。秸秆不还田条件下,施用化肥显著降低了土壤pH值。控失尿素比例为70%时土壤养分含量最高。秸秆还田对小麦产量及吸氮量无显著影响,控失尿素对小麦产量及吸氮量增加具有极显著影响。在所有处理中,S1-LCU40处理的籽粒和秸秆产量最高,籽粒产量达7009.26 kg·hm^(-2),秸秆产量达11361.38 kg·hm^(-2)。秸秆还田对土壤氮素依存率具有显著影响,不同比例控失尿素对氮素收获指数具有显著影响,对氮肥表观利用率、土壤氮素依存率具有极显著影响。控失尿素比例为40%或70%时氮素吸收利用指标较优。综上,在华北平原潮土区,秸秆还田与40%控失尿素比例配施可以显著提升土壤供氮能力,提高小麦产量和氮素吸收与利用指标,是较为适宜的管理措施,但其机理及长期效应还需进一步研究。

不同季秸秆还田对冬小麦不同穗粒位结实粒数和粒重的影响

为探讨安徽淮北平原砂姜黑土区长期秸秆连续全量还田对冬小麦穗部结实特性的影响,2021-2022年基于农业农村部华东地区作物栽培科学观测站13年的长期定位试验,比较分析了小麦单季秸秆全量粉碎覆盖还田(T1)、小麦玉米秸秆全量粉碎还田(T2)、玉米秸秆全量粉碎翻埋还田(T3)、小麦玉米秸秆全年不还田(CK)4个不同还田模式下小麦不同小穗位结实粒数及粒重的差异。结果表明,T1、T2、T3处理的主茎穗小穗结实总粒数较CK分别提高了21.21%、7.50%和12.55%;第2粒位(G2)结实粒数分别提高了7.71%、7.71%和5.79%;上部小穗结实粒数分别提高了51.41%、22.79%和31.36%,其G2结实粒数分别提高了30.95%、30.95%和23.09%,其中T1处理对小麦粒数的提升效果最好。不同季秸秆还田处理下小麦主茎穗及其G2粒重、分蘖穗及其第三粒位(G3)粒重均高于CK,T1、T2和T3处理的主茎穗粒重增幅分别为16.06%、4.14%和16.06%,分蘖穗增幅分别为9.86%、0.71%和8.87%;T1、T2和T3处理下主茎穗G2粒重增幅分别为20.69%、10.34%和17.24%,分蘖穗G3粒重4.55%、2.27%和6.82%,其中T1处理对粒重提升效果最好,其次是T3。综合来看,在安徽淮北平原砂姜黑土区长期秸秆还田能够提高小麦穗粒数和粒重,进而促进产量提升,其中T1处理对小麦结实粒数和粒重的提升效果最好,是适宜在该地区推广的秸秆还田模式。

不同秸秆还田技术模式对冬小麦强弱势粒灌浆特性的影响

为揭示砂姜黑土区不同秸秆还田技术模式对冬小麦籽粒灌浆进程的影响,该研究基于农业农村部华东地区作物栽培科学观测站15a的长期定位试验,设置单季小麦秸秆全量粉碎覆盖还田(T1)、小麦秸秆全量粉碎覆盖还田+玉米秸秆全量粉碎翻埋还田(T2)、单季玉米秸秆全量粉碎翻埋还田(T3)和小麦玉米秸秆全年不还田(CK)4种不同秸秆还田技术模式,采用Richards方程模拟冬小麦籽粒灌浆过程,研究不同秸秆还田技术模式对冬小麦强弱势粒灌浆特征参数的调控效应。结果表明:1)相较于秸秆不还田,秸秆还田处理能提升冬小麦强、弱势粒的籽粒体积、千粒质量和产量,T1、T2、T3处理下强势粒千粒质量和籽粒产量较CK分别显著提升11.02%、10.63%、13.75%和16.28%、14.29%、13.94%,弱势粒千粒质量和籽粒产量较CK分别显著提升9.73%、6.64%、7.57%和19.24%、23.25%、11.50%。Richards方程能极显著模拟不同秸秆还田技术模式下冬小麦籽粒灌浆过程,拟合方程决定系数(R^(2))均在0.997以上。2)对冬小麦强势粒,秸秆还田可延长小麦强势粒灌浆时间,主要通过缩短灌浆渐增期持续时间和提高其灌浆速率,延长灌浆缓增期的持续时间来提升强势粒千粒质量。其中T1、T3处理下冬小麦强势粒灌浆持续时间较CK分别延长2.137 d和4.443 d,T1、T2处理下强势粒单粒最大灌浆速率较CK分别显著提高了7.81%和12.26%。3)对冬小麦弱势粒,T1处理下弱势粒灌浆持续时间较CK延长1.477 d,T1、T2、T3弱势粒单粒最大灌浆速率较CK分别显著提升16.46%、22.69%和17.13%。该研究表明秸秆全量还田可提升砂姜黑土区冬小麦籽粒库容和籽粒灌浆速率,最终增加粒质量。研究可为砂姜黑土区秸秆资源的高效利用提供理论指导和技术支撑。

水稻秸秆拆解工艺参数优化及纤维自交织结构

大尺寸高长径比纤维是影响非织造秸秆纤维生态毯质量的关键。机械揉搓是获得高长径比纤维的最佳处理技术工艺。该研究探究了揉丝机主轴转速和锤齿间隙对不同含水率秸秆纤维拆解揉丝的影响,其工艺参数为主轴转速、锤齿间隙及物料含水率,指标输出为秸秆丝化率与标定单位生产率,并对纤维自交织结构特性进行评价。结果表明,采用Box-Behnken响应面法(response surface method,RSM)开发了一个可确定输入和输出参数间的函数,2种评价指标模型均具有较高的可信度,决定系数分别为R^(2)>0.95,R^(2)>0.84。优化数学模型工艺参数:含水率41.2%,主轴转速2498 r/min,锤齿间隙12.84 mm组合下秸秆丝化率达96.93%,标定单位功率生产率为29.33 kg/(kW?h)。大尺寸高长径比秸秆纤维长度>70 mm和长宽比>80比例增幅分别达120.55%和16.01%,有效改善纤维自交织能力,所开发的RSM模型秸秆的实际揉搓拆解丝化率达96.27%,加工成本降低27.50元/t,可广泛应用于生产大尺寸纤维秸秆基高值农用制品。该研究为生物质秸秆的有效循环利用和高值化材料产业的绿色可持续发展提供重要依据和技术支撑。

中小型青贮玉米收获机械研究现状及发展趋势

随着牛、羊等草食性牲畜的快速发展,畜牧业对青贮玉米饲料的需求持续增长,我国青贮玉米的种植规模也在不断扩大。由于我国耕地类型和地块面积差异较大,青贮玉米的收获需要多种类型的作业机械。为促进玉米青贮收获机械的研发和应用,从畜牧产业适度规模发展的需要和当前我国分段收获与直接收获并存的现实情况出发,采用分作业环节的方式,针对青贮玉米收获机械的共性关键技术:秸秆切割、秸秆切碎揉丝、玉米籽粒破碎、青贮打捆包膜等,分析青贮玉米收获机械生产中的常用结构和最新研究现状。介绍青贮玉米收获机械的研发应用情况,从青贮作业环节中分析总结出存在秸秆切割与粉碎理论研究较少、各装置作业质量研究不足、整机适应性不强等共性问题。提出加强刀具与秸秆互作机理的研究、作业质量的研究、整机适应性的研究,使中小型青贮玉米收获机械在不同规模和作业需求下具有更好的作业性能、作业质量和综合生产效率。

不同原料配比对芦笋秸秆堆肥发酵效果的影响

为促进芦笋秸秆资源化利用,通过加入不同比例的鸭粪和稻壳于芦笋秸秆中,进行资源化堆肥效果的试验研究。以发酵温度、pH、发芽指数、有机质、氮、磷、钾等为评价指标,研究鸭粪和稻壳添加对堆肥发酵过程的影响。结果表明:单一芦笋秸秆堆肥发酵过程,无高温阶段,未能达到发酵堆肥要求。添加不同比例的鸭粪和稻壳均能促进芦笋秸秆堆肥发酵,高温维持时间12~13 d,高温阶段平均温度为56.3~60.4℃,发酵周期21~29 d,发酵30 d结束时,发芽指数达到了92%~118%,pH>8.0,有机质含量50.70%~57.02%,氮磷钾总养分含量4.64%~5.20%。综合各项指标,在本试验条件下,70%芦笋秸秆+10%鸭粪+20%稻壳粉的配比发酵效果优于其他配比,更适合芦笋秸秆发酵。