粉煤灰改良砂姜黑土对冬小麦田生态因子的影响

采用桶栽试验,研究粉煤灰改良砂姜黑土对冬小麦田生态因子的影响。研究结果表明：粉煤灰 施入砂姜黑土,降低了土壤的容重、比重及土壤的粘粒含量,增加了土壤的总孔隙度、毛管孔隙度和土壤饱和 导水率,井得出土壤容重、比重、毛管孔隙度和饱和导水率与粉煤灰用量的模拟方程。与此同时,还对土壤温 度、土壤含水量及土壤微生物数量在整个生育期的变化动态进行了研究。     

PAA-AM-AMPS与PAA-AM高吸水性树脂的合成及保水性能

利用水溶液聚合法合成了聚丙烯酸系高吸水性高保水性树脂,其吸水倍率均在800 g/g以上,且在50 min内吸水饱和。研究了共聚单体和交联剂用量对树脂加压保水能力和恒温保水能力的影响。研究结果表明,树脂恒压放置7 d后保水率均在30%以上,保水能力随丙烯酰胺用量增加先增大后减小,随交联剂MBA用量增加先增大后减小。同时,PAA-AM-AMPS在沙土中恒温50℃时放置7 h后,保水率为75.5%,说明树脂能提高沙土的饱和含水量,有效地改良沙土的保水能力,为沙漠保水提供有效的保水剂。     

腐植酸保水肥与秸秆覆盖在旱作玉米上的试验研究

采用大田试验方法,对腐植酸保水肥与秸秆覆盖相结合在玉米上施用的水肥耦合效应进行了初步研究。试验结果表明,在进行秸秆覆盖的同时,土壤中施用腐植酸保水肥,可以提高土壤保水、保肥的作用。覆盖免耕加腐植酸保水肥的处理,增加土壤含水量达17．8％。水肥耦合使土壤中水分养分充分发挥了作用,促进了玉米丰产,增产幅度达14．80％～43．85％。     

煤炭腐植酸作为土壤改良剂对土壤物理性质和小麦产量的影响

在巴基斯坦旁遮普的波特瓦地区(33°N,74°E),集约化土壤耕作,土壤侵蚀和低量作物残体的投入是导致土壤结构退化的原因。结构不稳定的土壤很容易受到侵蚀,反过来,土壤侵蚀又会造成作物产量的下降。因此,为了改善土壤的物理性状,在巴基斯坦旁遮普的干旱地区进行了田间试验。试验地点位于大学(拉瓦尔品第PMAS干旱农业大学)研究农场的园区内。2种不同等级(实验室级和商品级)的腐植酸(HA)各分8个水平,施用2年,处理分别为HL_0(对照,不施腐植酸),HL_1 10 kg HA/hm~2,HL_2 20 kg HA/hm~2,HL_3 30 kg HA/hm~2,HL_4 60 kg HA/hm~2,HL_5 90 kg HA/hm~2,HL_6 120 kg HA/hm~2和HL_7 150 kg HA/hm~2,各处理同时配合施用N-P-K(120-90-60 kg/hm~2)。试验期间,检测土壤总有机碳、饱和导水率、团聚体稳定性、容重、土壤含水量和作物产量。试验结果表明,腐植酸能通过影响土壤总有机碳、饱和导水率、团聚体稳定性、容重和土壤含水量等指标来改善土壤的物理性状。2年试验结果均表现为,实验室级的腐植酸比商品级的腐植酸能更好地改善土壤物理性状,从而提高小麦产量。2种不同级别的腐植酸各施用水平与对照相比,差异均显著。在120 kg/hm~2和150 kg/hm~2的腐植酸施用水平下,大多数指标均显示出了相似的结果,因此,从经济角度考虑,120 k g/hm~2的腐植酸用量为最佳施用量。     

腐植酸在保护性耕作技术研究和应用中作用显著

保护性耕作是相对于传统翻耕的一种新型耕作技术,它是指对农田采取免耕、少耕、秸秆覆盖与保护性种植等技术,从而减少土壤风蚀和水蚀、提高土壤肥力和抗旱能力。同时,保护性耕作也可增加土壤有机质和养分含量,改善土壤结构,提高水、肥利用率,减少地表径流,降低农田扬沙,改善生态环境。近些年,保护性耕作技     

腐殖酸-聚丙烯酸表面交联吸水性树脂的合成与性能

将交联剂N,N′-亚甲基双丙烯酰胺溶于甲醇溶液制成表面处理液,通过表面交联反应将磺化腐殖酸（HA）与聚丙烯酸(PAA)结合,制得一种适合于农林领域应用的腐殖酸-聚丙烯酸高吸水性树脂（HA-PAA）.研究了表面处理液浓度、交联剂用量和腐殖酸量对HA-PAA吸水性能的影响规律和吸水机理,以及产物在沙土中的保水性能,并通过扫描电镜分析了HA-PAA的表面结构.研究结果表明,当含有10% HA时,HA-PAA耐电解质性能良好,吸水性能最佳;当沙土中添加0.2%的HA-PAA时,可明显改善沙土的贮水、保水性能.HA-PAA作为农林领域用保水剂,可发挥抗旱保墒和促进植物生长的双重作用.     

高吸水性树脂土壤保水剂的合成与性能研究

采用溶液聚合法以淀粉接枝丙烯酸钠盐制备了一种高吸水性树脂土壤保水剂。研究了淀粉用量、丙烯酸中和度、反应温度等因素对吸水倍率的影响,并对其土壤保水能力和热稳定性进行了分析。结果表明:在聚合反应温度为45℃条件下,当淀粉与丙烯酸单体的质量比为0.25、丙烯酸中和度为65%时,该保水剂具有最大的吸水倍率,同时具有良好的保水能力。     

粉煤灰-膨润土基保水剂的制备及应用初探

以膨润土为基材制备保水剂可以有效提高复合保水剂的吸液性能。当膨润土添加量为5%、粉煤灰添加量为3%、有机单体丙烯酸(AA)8.889 g和丙烯酰胺(AM)1.111 g、中和度为70%时,复合保水剂吸水效果最佳,对蒸馏水、自来水和0.9%的氯化钠注射液的吸液倍率分别为738.5 g/g、312.7 g/g和124.7 g/g,达到了比较理想的保水效果。该复合保水剂在实际土壤中的应用也发现,添加保水剂的土壤保水率较好,种子发芽时间较短,发芽率明显提高,且植株长势较好,耐旱时间增长。     

灌溉水质对土壤物理性质的影响

对灌溉水质对土壤物理性质的影响进行了研究。研究结果发现,灌溉水质对土壤物理性质有着非常明显的影响。灌溉水中钠吸附比一旦超过14就会造成土壤黏粒的膨胀性增大;另外,还会导致土壤碱化的情况增强,破坏土壤的物理性质,造成土壤导水率的下降。     

覆盖完全不渗透膜减少熏蒸剂用量

[目的]评价熏蒸剂1,3-二氯丙烯和威百亩覆盖完全不渗透膜(TIF膜)对根结线虫的防治效果以及对番茄产量的影响.[方法]在北京2个郊县相同条件下,采用1,3-二氯丙烯和威百亩对根结线虫发生严重、种植番茄的土壤进行熏蒸处理,各处理分别覆盖TIF膜和聚乙烯膜(PE膜).[结果]当1,3-二氯丙烯用量为100 kg a.i./hm2时,番茄收获后测定根结指数,覆盖TIF膜的根结指数显著低于覆盖PE膜;而当1,3-二氯丙烯在200 kg a.i./hm2时,覆盖TIF膜的根结指数和覆盖PE膜差异不显著;在2个试验点,用量相同时,覆盖TIF膜的产量均显著高于PE膜.当威百亩用量为420 kg a.i./hm2时,覆盖TIF膜和PE膜,根结线虫的减退率和根结指数差异不显著,而覆盖TIF膜的番茄产量显著高于覆盖PE膜的产量.[结论]覆盖TIF膜能显著减少熏蒸剂的散发和用量,并提高番茄产量.     

Tillage and crop residue effects on the energy consumption,input–output costs and greenhouse gas emissions of maize crops

Improving energy use efficiency (EUE) is critical for increasing farmers’ incomes, developing sustainable agriculture, and mitigating greenhouse gas (GHG) emissions. However, data on EUE, net income, and GHG emissions across various tillage and crop residue (straw) treatments remains scarce. This study aimed to estimate these variables across different tillage and straw treatments used in summer maize production in a winter wheat-summer maize cropping system in China’s Loess Plateau. Tillage treatments included chisel plowing, no tillage, and moldboard plowing. These were studied both with straw returned to the soil, or removed. All activities and production processes were recorded. The results demonstrate that fertilizer especially nitrogen fertilizer, and to a lesser extent, the fuel used for tillage, sowing and harvesting, were the two major consumers of energy and producers of GHG emissions. These results indicated that the use of chisel plow or conducting no tillage with straw returned to the soil, can reduce energy consumption and GHG emissions, and improve the economic benefits of summer maize production in the region, compared with conventional moldboard plow tillage without straw (which is typically burned off). The results show that further improvements could be facilitated by improving the utilization of nitrogen fertilizer, returning straw to the soil, and reducing tillage. These practices can reduce GHG reductions, and improve EUE and farmers’ incomes.     

Nitrogen and residue management effects on agronomic productivity and nitrogen use efficiency in rice–wheat system in Indian Punjab

Development of a sustainable and environment friendly crop production system depends on identifying effective strategies for the management of tillage and postharvest crop residues. Three-year (2004–2007) field study was initiated on two soil types to evaluate the effect of straw management (burning, incorporation and surface mulch) and tillage (conventional tillage and zero tillage) before sowing wheat and four nitrogen rates (0, 90, 120 and 150 kg N ha⁻¹) on crop yields, N use efficiency, and soil fertility in the northwestern India. Effect of tillage and straw management on nitrogen transformation in soils was investigated in a laboratory incubation study. In sandy loam, grain yield of wheat with straw mulch-zero-till (ZT) was 7% higher compared to when residues were burnt-ZT but it was similar to straw burnt-conventional till (CT), averaged across 3 years. In silt loam, grain yield of wheat with straw mulch-ZT was 4.4% higher compared to straw incorporated-CT, but it was similar to straw burnt-CT. Response to N application was generally observed up to 150 kg N ha⁻¹ except in 2004–2005 on sandy loam where N response was observed up to 120 kg N ha⁻¹, irrespective of straw and tillage treatments. In sandy loam, RE was lower (49%) for straw burnt-ZT than in other treatments (54–56%). In silt loam, RE was higher in straw mulch-ZT compared with straw incorporation-CT (65 vs. 58%). In sandy loam, AE was higher in straw burnt-CT and straw mulch-ZT compared with the other treatments (19.2 vs. 16.9 kg grain kg⁻¹ N applied). In silt loam, AE was lower in straw incorporation-CT than in other treatments (16.0 vs. 17.6 kg grain kg⁻¹ N applied). Rice yield and N uptake were not influenced by straw and tillage management treatments applied to the preceding wheat. Recycling of rice residue (incorporation and surface mulch) compared with straw burning increased soil organic carbon and the availability of soil P and K. There was more carbon sequestration in rice straw mulch with zero tillage (25%) than in straw incorporation with conventional tillage (17%). Soil N mineralization at 45 days after incubation was 15–25% higher in straw retention plots compared with on straw burnt plots.     

周期性边界条件下埋地热油管道传热影响因素的分析

建立土壤多孔介质模型,采用有限容积法对地表温度周期性波动条件下埋地热油管道非稳态传热过程进行数值计算。考虑了土壤中水相、气相迁移对管道传热的影响,对比分析了有、无保温层及保温层厚度、保温层导热系数、土壤导热系数、土壤含水率、管径、埋深等因素对埋地管道非稳态传热规律的影响。研究表明：保温层厚度、导热系数、土壤导热系数对埋地热油管道非稳态传热的影响相对较大。管径、埋深对管道传热的影响相对次之,且埋深对管道的影响冬季远要大于夏季,而土壤含水率对管道传热的影响相对较小。     

水热耦合对冻土区埋地管道土壤温度场的影响

冻土区埋地热油管道最常见的安全问题是冻害破坏。当环境温度降至冰点以下,土壤中水分的冻结将伴随着水分向冻结前锋迁移,产生不均匀冻胀,加之周期性不可逆的冻融循环,极易造成管道失稳甚至破裂。研究管道冻害成因,应先预测埋地管道周围土壤冻融过程中温度场的变化,以及温度场与水分场的变化关系。采用有限体积法,建立土壤多孔介质水热耦合相变模型,利用SIMPLER算法进行数值求解,为了研究水分对土壤温度场的影响,这里对无水土壤和饱和含水土壤两种极限情况进行对比分析,结果表明：在输油管道运行初期,两种情况土壤温度场接近,随着运行时间的延长,饱和含水土壤温度场偏高,水分迁移和冰水相变对土壤温度场具有一定影响。     

新型秸秆洗涤装置试验研究

目前农作物秸秆主要通过水利碎浆机进行洗涤,具有功耗大、洗涤效果不好等缺点。本试验中设计了一种新型秸秆洗涤装置,并以小麦秸秆为原料对新型秸秆洗涤装置进行试验研究,主要考察了单因素搅拌转速、进水量以及进料速度对小麦秸秆含水量、洗涤机除杂率和洗涤装置单位产量功耗的影响。根据单因素的试验结果,对洗涤装置进行响应面优化,得到洗涤装置单位产量功耗最小的操作条件为：搅拌转速9.5r/min,进水量1.35倍于饱和进水量,进料速度1400kg/h。在此条件下对小麦秸秆进行洗涤,既能满足小麦秸秆含水量和洗涤机除杂率要求,又能使单位产量功耗最小,洗涤装置的综合效率最高。     

Compared imbibitions of ordinary and high performance concrete with null or positive water pressure head

A method to simultaneously measure the moisture diffusion coefficient, D_θ, of unsaturated concrete, and the saturated concrete hydraulic conductivity, K_l, was developed for cylindrical specimens placed on a container filled with water that could be maintained at a given hydraulic pressure. Ordinary Portland cement Concrete (OPC) with a moderate and High Performance Concrete (HPC) with a low water to cement ratio were tested. The time dependent distribution of water content in the specimens was measured using a non-intrusive method based on gamma-ray attenuation. The measurements were conducted with varying hydraulic head (positive or null). Boltzmann's transformation was used to analyze the experimental results obtained at different hydraulic pressures and the difference between the null (or atmospheric) and positive pressure results is used to accurately determine K_l and also D_θ . This paper will present the results obtained using this original method, possible interpretations and future research.     

Tillage and residue management effects on soil carbon and CO<Subscript>2</Subscript> emission in a wheat–corn double-cropping system

The mitigation of CO₂ emission into the atmosphere is important and any information on how to implement adjustments to agricultural practices and improve soil organic matter (SOM) stock would be helpful. We studied the effect of tillage and residue management on soil carbon sequestration and CO₂ emissions in loam soil cropped in a winter wheat–corn rotation in northern China. There were five treatments: mouldboard ploughing, rotary tillage and no-tillage with chopped residues (MC, RC and NC), additional no-tillage with whole residue (NW) and mouldboard ploughing without residue (CK). After 5 years of each tillage system, MC and RC had higher annual CO₂ efflux from soil. The CO₂ effluxes were correlated with the ratio of dissolved organic carbon to soil microbial biomass (DOC/MBC) among treatments. This effect may be due to less immobilization of soil carbon by microorganisms under long-time intensive tillage. Although both MBC and DOC showed seasonal variability, when averaged across the sampling period only MBC discriminated between treatments. After 5 years of tillage, all treatments except CK increased SOM (0.16–0.99 Mg C ha⁻¹ year⁻¹) at 0–30 cm depth and NC was the greatest, resulting from historical SOM depletion and large C return from recent residues. Despite the lowest CO₂ flux being from the NW treatment, lower input residue from decreased biomass may have lowered C sequestration. To improve soil C sequestration in rotations, the input of residue and the CO₂ emission should be balanced by adopting appropriate tillage and residue management.     

秸秆还田的效果与方法

综述了国内秸秆还田技术的研究成果和进展。肯定了秸秆还田在有效提高土壤肥力、保持土壤水分、减少环境污染等方面的作用 ,并从秸秆还田的方式、适用对象以及注意事项三方面探讨了秸秆还田的科学方法。