测定石膏性盐渍土水溶性盐的适宜水土比

土壤水溶性盐的含量与组成随制备浸出液的水土比例不同而异,对含石膏的盐渍土测定结果的影响尤为显著。为了正确反映田间水溶性盐的实际状况,作者进行了三种不同水土比例制备浸出液的对比试验。结果表明,适宜水土比为1:1,其测出的盐分含量与饱和泥浆法按近,且操作简便、快速,在我国一般土化分析实验室均可采用。     

高等农业院校无机化学教学中绿色创新思维的培养探讨

注重培养学生的绿色创新思维是当今国际人才教育发展的大趋势。该文针对目前农业院校无机化学教育体系中存在的一些问题，并结合高等农业院校所具有的独特优势，提出了在无机化学教学中注入绿色创新思维培养，并对培养的具体方法和途径进行了探讨，进而激发大学生们对无机化学学习的热情和兴趣。     

鱼菜共生系统中乳酸菌的筛选及其发酵矿化应用

针对鱼菜共生系统固体废弃物资源化利用效率低的问题,该研究旨在筛选出抗逆性好、矿化功能强的鱼源性乳酸菌,加强鱼粪残饵的发酵矿化性能。试验从鱼菜共生系统中的生物滤料和鱼体中分离乳酸菌,并通过抗逆性及发酵矿化性能检测,筛选出2株具有应用潜力的鱼粪残饵矿化菌株,经鉴定分别为乳酸乳球菌（Lactococcus lactis）L1和糊精乳杆菌（Lactobacillus dextrinicus）L2。耐温性、耐酸碱性和耐盐性检测结果显示,L1表现出较好的抗逆性。在 50 ℃时,L1存活率为96.60%,显著高于L2的存活率80.35%（P<0.05）;在pH值分别为5.0和9.0时,L1的存活率分别为65.43%和71.25%,高于L2的存活率31.10%和52.22%（P<0.05）;当盐浓度为60 g/L时,L1的存活率为37.33%,而L2无法存活。通过比较对照组（CK组,未添加乳酸菌）和乳酸乳球菌组（L组,添加乳酸乳球菌）发酵矿化过程中发酵液水质和矿物元素含量,结果显示 L组的有机物降解及矿化效果更好,除硫（S）元素以外,钾（K）、钙（Ca）、镁（Mg）、铁（Fe）、锰（Mn）和锌（Zn）元素的矿化率均在第3天达到最高（27.59%～94.67%）。综上所述,乳酸乳球菌（Lactococcus lactis）具有较强的抗逆性和显著的发酵矿化效果,且其最佳发酵矿化周期为3 d。该研究可为提高鱼菜共生系统固体废弃物资源化利用效率提供技术支持。     

不同含水率高易溶盐含量的伊犁黄土流变特性

流变学研究方法可以揭示黏弹性物质的流动和变形规律,常被应用于土体结构的力学稳定性及长期变形参数研究。为了深入探究伊犁黄土类土的黏弹性和结构稳定性,该研究采用流变仪对不同含水率和易溶盐(Na₂SO₄)含量的伊犁黄土类土进行了稳态和动态流变试验,引入Bingham模型对小剪切速率下的流变曲线进行了拟合,并分析解释了稳态和动态流变试验的演化过程。同时,讨论了含水率及易溶盐含量对稳态和动态流变参数的影响规律,定量分析了流变参数与各变量之间的关系。结果表明：稳态剪切过程中土体由固态向类固态转化,并最后趋于流态,具有剪切变稀行为;随着含水率及易溶盐含量增大,屈服应力和黏度均减小,且屈服应力在300～1 100 Pa之间。随着含水率和易溶盐含量增大,动剪切强度参数和黏弹性参数均线性减小,土体的结构稳定性降低。当剪切应变小于0.1%时,土体处于线性黏弹区,损耗因子变化不大;剪切应变大于0.1%时,损耗因子逐渐增大。高含水率及高易溶盐含量的土壤最先到达屈服点,说明高含水率和高易溶盐含量不利于土体结构的稳定性。随着含水率的增大,易溶盐含量对流变参数的影响程度变小...     

新疆典型膜下滴灌棉花种植模式的用水效率与效益

膜下滴灌技术因具有显著的节水、保温、抑盐、增产效果,在新疆自治区棉田中已获得大面积推广应用。在目前的大田棉花生产条件下,结合当地的光热、土壤、机械等条件,因地制宜选择合理的膜下滴灌种植模式,对合理调控棉田土壤水盐分布、促进棉花生长与增产、提高劳动生产率和增加棉农收入等具有十分重要的意义。迄今为止,在新疆自治区主要存在3种典型的膜下滴灌棉花种植模式,分别为传统模式、机采模式和超宽膜模式。该文通过开展实地调查取样,基于种植密度、灌溉定额、根区土壤水盐分布、覆膜宽度以及其它影响棉花生产收益的因素,对3种典型膜下滴灌棉花种植模式的水分利用效率与经济效益进行了对比分析。结果表明,由于各种种植模式下不同的种植密度、灌溉定额、根区土壤水盐分布、覆膜宽度等对棉花的耗水与产量产生了较大影响,导致棉花的水分利用效率存在明显差异：超宽膜模式棉花的水分利用效率为1.04 kg/m3,明显高于传统模式的0.98 kg/m3与机采模式的0.89 kg/m3。另外,经济效益受种植模式（影响前期投入与棉花产量）与采棉方式（影响采棉支出与籽棉收购单价）的影响较大：超宽膜模式具有最高的经济效益,其单位面积纯收入达18582元/hm2,稍高于机采模式下的18298元/hm2,传统模式下纯收入最低,仅11725元/hm2。因此,为高效利用农业水资源并增加种棉收益,建议在新疆自治区大力推广超宽膜模式,并对现有采棉机进行适当改进以在超宽膜模式下实现采棉机械化;或适当调整现有机采模式下的滴灌带布置形式（如将其布置在窄行的中央）,但相关的效应仍有待更进一步研究。     

添加尿素和无机盐土对秸秆厌氧消化的影响

向厌氧消化体系加入外源添加剂是一种有效且简单的用于提高产气效率的方法。为了解决秸秆厌氧消化原料转化率低、易酸化、厌氧消化时间长等问题,该文选取尿素和无机盐土作为秸秆厌氧消化的添加剂,研究比较不同添加量对玉米秸秆厌氧消化过程产气特性、发酵环境、微生物活性以及物能转化效率的影响。结果表明,对于出现酸化问题且甲烷菌活性较低的厌氧消化系统,添加尿素和无机盐土有利于缓解酸化并促进微生物生长繁殖,三磷酸腺苷（ATP）峰值时的微生物数量可增加2.76×1011-5.31×1011个/L。添加一定量的尿素和无机盐土可使产气高峰提前,添加10%的无机盐土处理组与纯秸秆处理相比,产气高峰可提前4d;但酸化也会削弱尿素和无机盐土对产甲烷过程的促进作用,添加量越大,削弱效果越显著。研究结果可为秸秆厌氧消化的工程应用提供参考。     

Population size and specific potential of P-mineralizing and -solubilizing bacteria under long-term P-deficiency fertilization in a sandy loam soil

The effects of organic manure, mineral fertilizer (NPK), and P-deficiency fertilization (NK) on the individual biomass of young wheat plants, arbuscular mycorrhizal (AM) colonization in wheat root systems, population sizes of soil organic phosphorus mineralizing bacteria (OPMB) and inorganic phosphate solubilizing bacteria (IPSB) as well as soil P-mineralization and -solubilization potential were investigated in a long-term (18-year) fertilizer experiment. The experiment included five treatments: organic manure, an equal mixture of organic manure and mineral fertilizer, fertilizer NPK, fertilizer NK, and the control (without fertilization). Plant biomass, population sizes of soil OPMB and IPSB were greatly increased (P<0.05) by the application of organic manure and slightly increased by the balanced application of mineral fertilizer, while undiminished AM colonization in wheat root system was only observed in the case of the NK treatment. Compared to balanced fertilization, P-deficiency fertilization resulted in a significant increase (P<0.05) of OPMB-specific mineralization potential (soil P-mineralization potential per OPMB cell) and highest IPSB-specific solubilization potential (soil P-solubilization potential per IPSB cell), suggesting that OPMB and IPSB are likely more metabolically active in P-deficiency fertilized soils after long-term fertilizer management, and mycorrhizal plants are more dependent on AM in P-poor soils than in P-fertilized soils. Our results also showed the different effects of mineral fertilizer versus organic manure on soil P-mineralization and -solubilization potentials, as well as specific potentials of OPMB and IPSB in arable soils.     

植物富集环境污染物的我国研究进展

综述了植物富集环境污染物的研究现状,从植物富集无机污染物,植物富集有机污染物以及植物富集放射性污染物方面进行了探讨,旨在展望植物富集环境污染物的研究趋势。     

不同含水量天然硫酸盐盐渍土中二氧化碳和氧化亚氮的排放

Soil salinization may negatively affect microbial processes related to carbon dioxide(CO_2) and nitrous oxide(N_2O) emissions. A short-term laboratory incubation experiment was conducted to investigate the effects of soil electrical conductivity(EC) and moisture content on CO_2 and N_2O emissions from sulfate-based natural saline soils. Three separate 100-m long transects were established along the salinity gradient on a salt-affected agricultural field at Mooreton, North Dakota, USA. Surface soils were collected from four equally spaced sampling positions within each transect, at the depths of 0–15 and 15–30 cm. In the laboratory, artificial soil cores were formed combining soils from both the depths in each transect, and incubated at 60% and 90% water-filled pore space(WFPS) at 25?C. The measured depth-weighted EC of the saturated paste extract(EC_e) across the sampling positions ranged from 0.43 to 4.65 dS m~(-1). Potential nitrogen(N) mineralization rate and CO_2 emissions decreased with increasing soil EC_e, but the relative decline in soil CO_2 emissions with increasing ECe was smaller at 60% WFPS than at 90% WFPS. At 60% WFPS, soil N_2O emissions decreased from 133 μg N_2O-N kg~(-1) soil at EC_e 0.50 dS m~(-1) to 72 μg N_2O-N kg~(-1) soil at EC_e = 4.65 dS m~(-1). In contrast, at 90% WFPS,soil N_2O emissions increased from 262 μg N_2O-N kg~(-1) soil at EC_e = 0.81 dS m~(-1) to 849 μg N_2O-N kg~(-1) soil at EC_e = 4.65 dS m~(-1), suggesting that N_2O emissions were linked to both soil ECe and moisture content. Therefore, spatial variability in soil EC_e and pattern of rainfall over the season need to be considered when up-scaling N_2O and CO_2 emissions from field to landscape scales.     

Tillage, cover crops, and nitrogen fertilization effects on soil nitrogen and cotton and sorghum yields

Sustainable soil and crop management practices that reduce soil erosion and nitrogen (N) leaching, conserve soil organic matter, and optimize cotton and sorghum yields still remain a challenge. We examined the influence of three tillage practices (no-till, strip till and chisel till), four cover crops {legume [hairy vetch (Vicia villosa Roth)], nonlegume [rye (Secaele cereale L.)], vetch/rye biculture and winter weeds or no cover crop}, and three N fertilization rates (0, 60–65 and 120–130 kg N ha⁻¹) on soil inorganic N content at the 0–30 cm depth and yields and N uptake of cotton (Gossypium hirsutum L.) and sorghum [Sorghum bicolor (L.) Moench]. A field experiment was conducted on Dothan sandy loam (fine-loamy, siliceous, thermic, Plinthic Paleudults) from 1999 to 2002 in Georgia, USA. Nitrogen supplied by cover crops was greater with vetch and vetch/rye biculture than with rye and weeds. Soil inorganic N at the 0–10 and 10–30 cm depths increased with increasing N rate and were greater with vetch than with rye and weeds in April 2000 and 2002. Inorganic N at 0–10 cm was also greater with vetch than with rye in no-till, greater with vetch/rye than with rye and weeds in strip till, and greater with vetch than with rye and weeds in chisel till. In 2000, cotton lint yield and N uptake were greater in no-till with rye or 60 kg N ha⁻¹ than in other treatments, but biomass (stems + leaves) yield and N uptake were greater with vetch and vetch/rye than with rye or weeds, and greater with 60 and 120 than with 0 kg N ha⁻¹. In 2001, sorghum grain yield, biomass yield, and N uptake were greater in strip till and chisel till than in no-till, and greater in vetch and vetch/rye with or without N than in rye and weeds with 0 or 65 kg N ha⁻¹. In 2002, cotton lint yield and N uptake were greater in chisel till, rye and weeds with 0 or 60 kg N ha⁻¹ than in other treatments, but biomass N uptake was greater in vetch/rye with 60 kg N ha⁻¹ than in rye and weeds with 0 or 60 kg N ha⁻¹. Increased N supplied by hairy vetch or 120–130 kg N ha⁻¹ increased soil N availability, sorghum grain yield, cotton and sorghum biomass yields, and N uptake but decreased cotton lint yield and lint N uptake compared with rye, weeds or 0 kg N ha⁻¹. Cotton and sorghum yields and N uptake can be optimized and potentials for soil erosion and N leaching can be reduced by using conservation tillage, such as no-till or strip till, with vetch/rye biculture cover crop and 60–65 kg N ha⁻¹. The results can be applied in regions where cover crops can be grown in the winter to reduce soil erosion and N leaching and where tillage intensity and N fertilization rates can be minimized to reduce the costs of energy requirement for tillage and N fertilization while optimizing crop production.