钾肥对籽瓜产量与效益的影响

试验采用土壤养分状况系统研究法,根据土壤养分状况研究钾对籽瓜与瓜籽的经济性状、瓜籽产量及效益的影响。结果表明,施钾改善了籽瓜的单瓜重、单瓜瓜籽重、单瓜产籽数、产籽率、瓜籽百粒重、纵、横径及出仁率;施钾提高了籽瓜产量,与不施钾比较,施钾后,瓜籽产量增加157～230kg/hm^2,增产幅度9．2％～13．5％;施钾提高了籽瓜的产值与纯收入,与不施钾相比,施钾后,新增加产值942～1375元／hm^2,新增加纯收入818—1104元／hm^2,边际效益分析结果表明,籽瓜最高产量与最大利润的钾用量为135kg/hm^2。     

昆明市水源区典型林分对土壤抗侵蚀作用影响研究

为了阐明昆明市重要水源区不同林分类型对土壤抗侵蚀性的影响,以昆明迤者小流域3种不同林分下土壤为研究对象,通过野外模拟和室内分析相结合的方法,分析3种不同林地土壤的抗侵蚀性能.结果表明:3种典型样地的土壤抗剪强度值差异显著,土壤抗剪强度大小为:云南松林地＞针阔混交林地＞桉树林地.3种不同林地土壤抗冲系数差异不显著,土壤抗蚀指数针阔混交林地最大(39％),桉树林地次之(37％),云南松林地最小(24％).桉树x云南松混交林在大雨强和长历时降雨条件下林下土壤抵抗崩解的效果更显著.用主成分分析法来分析3种不同林地土壤的抗侵蚀特性,得到3种不同林地的土壤抗侵蚀性的综合评价模型:Y=0.763Y1+0.236Y2,进而得出不同林地的土壤抗侵蚀性强弱排序为:针阔混交林地(0.150)＞桉树林地(0.127)＞云南松林地(-0.079),混交林防治水土流失的效果明显强于纯林.     

黑穗醋栗倒催根育苗研究

以黑穗醋栗品种(大粒甜、黑金星、黑珍珠、黑早生)为材料,进行硬枝倒催根育苗研究,调查黑穗醋栗硬枝倒催插条形成愈伤组织和成活情况。结果发现:黑穗醋栗硬枝倒催根不管插条形成愈伤组织的能力还是成活率都超过了70%,黑穗醋栗枝条生根力强,适宜倒催根育苗。但是不同品种之间有差异,生根能力由强到弱的顺序是黑早生、大粒甜、黑金星、黑珍珠。黑穗醋栗硬枝倒催根扦插易生根、成本低、操作简单、成活率高,建议在生产中应用。     

Zn and Pb release of sphalerite (ZnS)-bearing mine waste tailings

Background, aim, and scope  Contaminated mine drainage water has become a major hydrogeological and geochemical problem. Release of soluble metal contaminants and acidity from mining sites can pose serious chemical risks to surface and groundwater in the surrounding environment, and it is an important socio-economic factor addressed by working groups like SUITMA Morel and Heinrich (J Soils Sediments 8:206–207, 2008). The release of Zn and Pb from sulfide-bearing flotation residues of a small scale mine in Western Germany is investigated with focus on metal transfer to soil solution. Total contents of the soil material as well as soil water sampled with suction cups were analyzed. The influence of pH on leaching behavior was investigated with pH_stat tests. Isotopic analyses helped assessing seepage water velocity. The aim of this study was the assessment of the environmental behavior of zinc and lead caused by the weathering of sulfide-bearing mine tailings. Especially, we address in this paper the dissolution of sphalerite (ZnS) in contrast to the well-known dissolution processes of pyrite (FeS₂). Materials and methods  Total metal contents of the soil samples were analyzed by energy-dispersive X-ray fluorescence spectroscopy, total C concentration was measured using a CHNS elemental analyzer. X-ray diffraction (XRD) spectra were recorded from powdered soil samples. Soil water was sampled in nylon suction cups. Electrical conductivity (EC), pH, and temperature of the soil water samples were measured in the field immediately after sampling. Major anions (F, Cl, NO₂, NO₃, SO₄) were analyzed by ion chromatography, major cations (Ca, Na, K, Li) were analyzed by flame photometry, heavy metals (Zn, Pb, Fe, Mn, and Mg) by flame atomic absorption spectrometry. Tritium was analyzed by liquid scintillation counting (LSC), ¹⁸O and ²H were analyzed by isotope ratio mass spectrometry (IRMS). pH_stat tests were performed at four different pH values between 2 and 5. Results  Total Zn contents of the soil samples averaged 10 g kg⁻¹, Pb contents averaged 2.5 g kg⁻¹, Fe 22 g kg⁻¹, S 8.0 g kg⁻¹, and total carbon 4.0 g kg⁻¹. Below 2-m depth, soil samples had neutral pH values. Toward the surface, pH decreased down to pH 5.4 in P1 and P3, and to pH 5.9 in core P2, respectively. Dissolved contents of major ions (Mg, Ca, K, SO₄, and HCO₃) in the soil solution increased with depth. Metal concentrations (Fe, Mn, Zn) decreased with depth. The solution pH was neutral to slightly alkaline in samples below 2 m and slightly acidic (pH 6) at 1 m depth. Tritium values are around 7 TU and correspond to modern rain, i.e., after 1975. Stable isotope values plot on the global meteoric water line. The pH_stat tests provide two kinds of information, the acid neutralization capacity after 24 h (ANC24) and the release of metals depending on pH. The ANC24 increases linearly with decreasing pH from about 60 mmol(eq) kg⁻¹ at pH 5 to about 460 mmol(eq) kg⁻¹ at pH 2. Zn and Fe release show a strong increase with decreasing pH to 126 and 142 mmol(eq) kg⁻¹, respectively. Pb release increases at pH <4 and Mn release at pH <5, both to about 10 mmol(eq) kg⁻¹. Discussion  With an average of 10 g kg⁻¹, this field site is highly enriched in Zn. In the oxidized topsoil, Zn concentrations are significantly lower than in the anoxic subsoil. The distribution pattern of total Zn contents and soil pH values indicate that the topsoil, which is prone to oxidation and acidification, is already depleted in Zn. Only in soil core P2, Zn (and Fe) contents in the topsoil were higher than in the subsoil. Oxidation of the sulfidic material leads to redistribution into mobilizable species. High soil water concentrations (10 to 15 mg L⁻¹) can be found at acidic pH. The dominant Zn species in the soil solution is Zn²⁺. At neutral pH, Zn concentrations are below 0.001 mg L⁻¹. During the soil passage, the contaminated seepage water enters the anoxic subsoil with pH buffering carbonates. Results indicate that Zn is immobilized there. However, when the acid neutralization capacity is exhausted, a breakthrough of dissolved Zn to the groundwater has to be expected. Lead averages 2.5 g kg⁻¹ inside the flotation dump. In contrast to Zn, the first centimeters of the oxidized topsoil with high TOC contents show higher Pb contents than the anoxic subsoil. About 80% of the cation exchange capacity in the topsoil is occupied by Pb. In contrast to Zn, Pb is not abundant as aqueous species at slightly acidic pH. Values lower than pH 4 are necessary to mobilize Pb in higher amounts, as pH_stat experiments confirm. Hence, Pb is not expected to be leached out until the buffer capacity of the soil is exhausted. Conclusions  The environmental fate and behavior of Zn and Pb in the flotation dump is strongly depending on pH and redox conditions. Oxidation of sphalerite leads to a transfer of Zn from immobile to easily mobilizable species. Sulfide oxidation leads to an acidification of the topsoil where the buffer capacity is already exhausted due to the leaching of carbonates. At acidic pH, Zn is transferred to the aqueous phase and leached to the subsoil where soil pH is neutral. Electron supply and the buffer capacity of the material are found to be the main factors controlling the mobility of Zn. In contrast, the transfer of comparable amounts of Pb to the aqueous phase requires pH values <4. Since Pb is enriched in the topsoil, not leaching to the groundwater, but direct uptake (e.g., children, animals) and uptake by plants is the highest environmental risk. If the acidification of the soil proceeds with the same rate as in the last 40 years, it will reach the bottom of the tailing in about 200 years and a breakthrough of metals to the groundwater has to be expected. Recommendations and perspectives  The behavior of the different metals and their environmental impact depends on the different metal properties as well as on external conditions, e.g. pH, redox conditions, buffer capacity, and groundwater recharge. To assess the future release of metals from a flotation dump it is crucial to determine the main processes leading to acidification, the buffer capacity, and heavy metal binding forms. The release of heavy metals to the groundwater could be prevented by liming or other buffering techniques de Andrade et al. (J Soils Sediments 8:123–129, 2008). Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

不同造林模式对渭北黄土高原林地土壤及土壤微生物化学计量的影响

本研究以农田为对照,通过对陕西永寿县农田、人工纯林(刺槐、侧柏和油松)和混交林(刺槐+油松、刺槐+侧柏及侧柏+油松)两种造林模式下土壤和土壤微生物碳、氮、磷及化学计量的分析,探究造林模式对土壤养分循环的影响。结果表明造林显著改变了土壤和土壤微生物碳、氮、磷含量及化学计量特征,其影响程度不仅受到造林模式的影响,同样受树种组成和树种特性的影响。     

棉田土壤温度与气温的关系及膜地增温效应对有效气积温的补偿作用的研究

通过田间试验和数据分析,本研究确定了地膜棉和露地棉田土壤温度与气温的线性和幂函数统计回归数学模型,并根据有效积温原理推出了地膜棉有效气积温补偿值和各生育期天数的试算方程。可将其用于ＧＯＳＳＹＭ模型,使ＧＯＳＳＹＭ模型推广应用于地膜棉栽培