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73.
杉木林下套种不同树种对土壤改良效应初探 总被引:5,自引:0,他引:5
为探讨复层异龄林营建初期对土壤物理结构和养分状况的影响,研究了浙西地区杉木林下套种不同树种土壤理化特征的变化。结果表明林下套种树种后林地土壤物理结构均得到不同程度的改善,土壤养分状况进一步好转。并运用多因素主成分分析方法,评价了不同复层林模式土壤养分含量规律,并将土壤养分状况的综合优势作了排序。其结果显示杉木林下套植的12种植物在种植初期对土壤养分改良效果较好的为麻栎、毛红椿、南天竺、十大功劳、红豆杉、椤木石楠和蚊母,其中麻栎和毛红椿改良效果最佳。 相似文献
74.
以20年塿土小麦玉米轮作体系长期肥料定位试验为平台,探讨不同施肥模式下土壤化学肥力要素、微生物量碳氮及酶活性的响应。试验包括不施肥(CK)、单施氮肥(N)、氮磷(NP)、磷钾(PK)、氮磷钾(NPK)、NPK+秸秆(SNPK)以及不同量有机肥+NPK(M1NPK、M2NPK)等8种施肥模式。结果表明,与CK相比,长期施用NP提高土壤有机碳含量达34.0%、全氮34.0%、全磷58.5%、速效磷608.9%、微生物量碳23.3%、微生物量氮54.0%、蔗糖酶53.9%、脲酶132.6%、碱性磷酸酶29.9%以及脱氢酶40.9%。长期施用NPK与NP效果相似,钾素效果甚微。作物秸秆还田配合氮磷钾化肥与氮磷钾相比没有明显影响土壤有机碳、氮和磷水平,但是显著提高微生物量碳的含量(29.5%)、碱性磷酸酶(23.0%)和脱氢酶(26.9%)的活性。有机肥配合氮磷钾与其它施肥处理相比,显著提升土壤化学肥力要素、微生物量碳氮和酶活性,特别是引起了磷素的大量富集(速效磷含量大于150 mg/kg)。因此,塿土不施有机物情况下,氮磷配合可以提高土壤化学和生物肥力,作物秸秆还田配合氮磷钾化肥的培肥效果优于氮磷钾化肥配合,而合理的有机无机肥配合是塿土提升化学肥力和保证生物健康的最佳施肥模式。 相似文献
75.
外源氮输入对小叶章湿地土壤微生物活性的影响 总被引:1,自引:0,他引:1
选择三江平原沼泽湿地典型草甸植被小叶章(Deyeuxia angustifolia),在水分、温度等环境因素均一的前提下,分别以NH4NO3水溶液的形式均匀撒入0,6,12,24g/(m2.a)(以N元素量计),进行了室外盆栽实验。结果表明,氮输入后,土壤MBC、MBN、BR、qCO2、SIR季节变化明显;在植物不同生长阶段,土壤基础呼吸总体趋势均是随时间的推移而逐渐减弱,且与氮输入量间的关系不同,说明土壤基础呼吸与植物的生长阶段密切相关;不同施氮水平的土壤MBC浓度随氮输入量增加呈波动变化,氮输入量与土壤MBN、BR、qCO2、SIR之间均存在线性正相关关系,即他们随氮输入量增加而逐渐增大,说明氮输入促进了土壤MBN、BR、qCO2、SIR的增大。 相似文献
76.
巢湖表层沉积物重金属的分布特征及生物有效性 总被引:2,自引:0,他引:2
为分析沉积物中重金属的分布特征、相互关系及其可能来源,以安徽巢湖表层沉积物为研究对象,利用原子吸收分光光度法(AAS)测定5种重金属(铅、铜、镍、锌、镉)总量和同步浸提重金属(SEM)含量,同时测定酸可挥发性硫化物、总氮、总磷、总有机碳等多种指标,利用低影响程度(ER-L)和中影响程度(ER-M)基准值,[∑SEM]/[AVS]模型和[∑SEM]-[AVS]模型,判断预测表层沉积物中重金属的生物有效性。结果显示:重金属总量在全湖的空间分布不均匀,具有入湖口大于湖心的特征,共8个指标超过ER-L基准值,西湖区各金属总量大于东湖区,两者之间具有显著性差异(P<0.05),全湖[∑SEM]/[AVS]的值在1.097~2.076之间,但[∑SEM]-[AVS]的变化范围为0.127~0.996μmol/g;表明重金属Cu、Cd污染较严重,人为输入影响大,AVS对重金属的束缚作用有重要影响,大部分表层沉积物中的重金属生物有效性低。 相似文献
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78.
通过田间小区对比试验,研究生物黑炭作为改良剂与堆肥等其他生物质改良剂相比对新疆低产土壤——灰漠土的改良和玉米增产的效果。结果表明,施入20t·hm^-2和40t·hm^-2的生物黑炭,能显著提高土壤有机质含量,与基础土壤相比,提高了22.77%和49.80%,明显高于秸秆还田、羊粪和腐植酸有机肥等对土壤有机质的提升效果。施用生物黑炭提高了玉米单穗重、千粒重、产量以及生物量,降低了玉米的根冠比,促进玉米根系生长,而追施氮肥对玉米产量的影响差异不显著。因此,施用生物黑炭能够大幅度提高土壤有机质含量,对灰漠土土壤质量和作物产量以及农艺性状的提高具有重要作用。 相似文献
79.
The use of chlorate as a nitrate analogue to screen soft red winter wheat (Triticum aestivum L.) cultivars for differences in nitrate reductase activity (NRA) was studied by adding potassium chlorate to a hydroponic nutrient solution in which wheat seedlings were growing. After 14 days, leaf symptoms indicating chlorate‐induced toxicity were rated. It was hypothesized that wheat plants which were susceptible to chlorate‐induced toxicity reduced chlorate and nitrate more rapidly than did resistant plants. In experiments testing the potential of this assay, wheat and barley (Hordeum vulgare L.) cultivars previously reported to have low NRA were less susceptible to chlorate‐induced toxicity than were cultivars reported to have high NRA. The assay was used to screen 15 soft red winter wheat cultivars for differences in sensitivity to chlorate‐induced toxicity. Variable toxic reactions were observed both among and within the cultivars. To determine whether the within‐cultivar variation was environmental or genetic, single plant selections for contrasting chlorate response were made, and bulked progeny were rescreened. In eight of 15 cultivars, the contrasting selections were different for chlorate‐induced toxic response, indicating heterogeneity for this trait within these eight cultivars. These chlorate‐selected lines may also be near‐isogenic lines for NRA. Seedling screening of wheat for chlorate response may be useful for identification of high NRA breeding lines. 相似文献
80.
Shannon L. Taylor William R. Raun John B. Solie Gordon V. Johnson Marvin L. Stone Richard W. Whitney 《Journal of plant nutrition》2013,36(11):2287-2302
The use of variable rate technology has become increasingly popular for applying plant nutrient elements. The most widely used method for determining variable fertilizer rates is presently based on soil testing and yield mapping. Three field studies (Bumeyville 1995, Burneyville 1996, and Ardmore 1996) were initiated in established Midland bermudagrass [Cynodon dacrylon (L) Pers.] pastures to determine the relationship between spectral radiance at specific wavelengths with forage nitrogen (N) removal and biomass, and to determine field variability of soil test parameters. Variable N (applied to 1.5 × 2.4 m subplots within 2.4 × 45.7 m main plots), fixed N and check treatments were evaluated at each location. Spectral radiance readings were taken in the red (671±6 nm), green (570±6 nm), and near infrared (NIR) (780±6 nm) wavelengths. The normalized difference vegetation index (NDVI) was calculated as NIR‐red/NIR+red. Variable N rates were applied based on NDVI. The highest fixed variable N rate was set at 224, 336, and 672 kg N ha‐1 for Burneyville, 1995, 1996, and Ardmore, 1996, respectively. At Bumeyville, soil samples were collected in all variable rate plots (1.5 × 2.4 m) and analyzed for various soil test characteristics. NDVI, red, green, and NIR spectral radiance readings were correlated with bermudagrass forage N removal and yield. Correlation of forage yield and N removal with red, NIR, and NDVI were best with maximum forage production, however, when forage production levels were low correlation decreased dramatically for the red wavelength compared with NIR and NDVI. Forage yield and forage N removal in variable rate treatments increased when compared to the check while being equal to the half‐fixed and fixed rates where higher N rates were applied. Also, variability about the mean in variable rate plots was significantly lower than half‐fixed and fixed rates which supports adjusting N rates based on indirect NDVI measurements. Variable N rate plots reduced fertilizer inputs by 60% and produced the same yield as fixed rate plots, while fixed and half‐fixed rates did not increase N content in the forage over that of the variable rate treatment. Soil sample data collected from small consecutive plots (<4 m2) was extremely variable indicating that intense sampling would be needed if variable fertilizer application were to be based on soil test results. 相似文献