导　　师： 同延安;Ray Weil

学科专业： 090302

授予学位： 博士

作　　者： ;

机构地区： 西北农林科技大学

摘　　要： 合理进行土壤培肥不仅是提高土壤肥力质量的关键，也是保证土壤资源可持续利用的核心手段，对于从区域或国家尺度上提升农田生产力和保障粮食安全意义重大。国内外研究表明，进行土壤有机培肥是众多培肥措施中最有效和最可靠的途径，其中，添加有机物料和种植覆盖作物的措施受到人们广泛关注。然而，如何因地制宜确定具体措施并筛选关键性指标来评价土壤培肥效果，从而确立合理高效培肥模式，仍需在不同地域结合当地农业生产实际开展深入研究。鉴于此，本研究特选取气候类型、土壤性质和耕作管理措施等差异较大的中国典型旱区土壤（陕西渭北旱塬）和美国东北部湿润区土壤（马里兰州）为研究对象，进行了土壤添加有机物料培肥模式的筛选、评价和种植覆盖作物培肥效应等关键科学问题的试验研究，旨在通过有机物料施用和耕作制度优化等措施，为旱区和湿润区农田土壤生产力提升、养分资源高效利用和生态环境保护提供科学依据。主要结果如下：具体的试验研究内容及获得的相应结果和结论如下： （1）与单施化肥相比，有机培肥的土壤容重呈缓慢下降趋势，其中厩肥下降6.56/%，达显著性水平。化肥配施有机物料减少了>10mm和<0.25mm不良结构体含量，增加了5–3mm和1–0.5mm理想团聚体数量。同时也从不同程度增加了>5mm、5–2mm和2–0.25mm水稳性团聚体含量，其中秸秆堆肥使>5mm团聚体含量显著增加了6.5/%，高量秸秆使5–2mm团聚体含量增加了78.0/%。秸秆堆肥使土壤湿筛团聚体平均质量直径（MWD）和几何平均直径（GMD）分别显著增加了33.3/%和24.7/%。 （2）化肥配施有机物料显著增加了耕层土壤（0-20cm）高锰酸盐易氧化碳（POXC）含量（P<0.05），其中厩肥处理增加幅度最大，达108.6/%。与单施化肥相比，有机培肥各级团聚体土壤有机碳含量普遍增加，其中厩肥使0.5–0.25mm团聚体有机碳含量明显增加12.8/%。同时，各级团聚体POXC含量也大幅度提高，其中秸秆堆肥使1–0.5mm团聚体POXC含量明显增加98.5/%。有机培肥耕层土壤POXC含量与粒径>0.25mm水稳性团聚体含量呈显著正相关（R2=0.625，P<0.05）。与单施化肥和对照相比，有机培肥耕层土壤碳库管理指数明显增加，其中厩肥处理指数高达231.8。 （3）与单施化肥相比，化肥配施有机物料使部分土壤养分状况（全氮、速效磷、速效钾、阳离子交换量）以及土壤微生物学特性［微生物量碳（MBC）、微生物量氮（MBN）、脲酶、碱性磷酸酶］均得到进一步改善。化肥配施秸秆堆肥处理效果最明显，其中MBC、MBN、脲酶和碱性磷酸酶活性分别增加了42.0/%，54.6/%，19.7/%和7.4/%。同时，土壤微生物量碳氮、脲酶与土壤速效磷、速效钾密切相关（P＜0.01），与土壤全氮、阳离子交换量、作物产量显著相关（P＜0.05）。 （4）选取有机质等12个能够反映该区土壤肥力质量特性的关键性定量因子作为评价指标，采用因子分析法对土壤肥力质量进行综合评分，然后用欧氏距离最短距离法对其进行聚类，最后利用作物产量结果进行验证。结果表明：通过土壤有机培肥，土壤肥力水平和作物产量均有显著提高。与单施化肥相比，施加秸秆堆肥和厩肥处理的小麦产量分别提高13.31/%和16.17/%；对土壤肥力综合评价，秸秆堆肥配施化肥的土壤肥力质量最高，综合得分达58.94，厩肥配施化肥次之。 （5）覆盖处理下秋季饲料萝卜地上和地下部平均生物量分别为2763和2326kg ha-1，含碳量分别为1011和883kg ha-1。土壤有机碳含量在不同季节均随着土层深度增加而不断减少，但并未受到覆盖处理显著影响。然而无论施氮与否，覆盖处理均使土壤表层和深层POXC含量显著增加。同时土壤POXC与TOC呈显著正相关（P<0.01）。施氮56、112和168kg ha-1（8月），覆盖处理使0-30cm土层POXC分别明显增加23/%，20/%和26/%。 （6）饲料萝卜秋冬季具有捕获土壤剖面大量氮素的能力，而春季残茬腐解后释放出储存的养分，可供后续作物循环利用。秋季饲料萝卜地上部捕获氮素的数量几乎是未覆盖处理的4倍。饲料萝卜生长后期（12月）表层土壤NO3-N含量明显下降，施氮100kg Nha-1和0kg N ha-1条件下，分别下降18.31/%和9.56/%；而萝卜残茬腐解后（5月），表层土壤NO3-N含量分别显著增加165.16/%和119.56/%，且深层土壤无明显NO3-N累积。覆盖处理对土壤全氮和NH4-N含量无显著性影响。 （7）种植饲料萝卜促进了后续作物青贮玉米生长，提高了玉米秸秆和籽粒干物质量。施氮0、56、112和168kg ha-1条件下，覆盖处理明显提高了玉米氮素吸收总量，分别增加了23.88/%，6.61/%，18.20/%和1.75/%。由于不施氮时（无肥对照），覆盖处理全株玉米吸氮量显著高于未覆盖处理，因此，同一施氮水平下覆盖处理青贮玉米氮肥回收利用率和氮肥农学利用效率明显降低，且随着施氮量的增加而不断降低。 通过上述研究，本文得出两条重要结论：第一，在秸秆资源丰富的中国旱区土壤，施用有机物料（秸秆）并配施化肥，可以调节土壤容重及土壤团聚体的分布和稳定性，并有效提高土壤团聚体结合态碳含量，从而显著改善旱地土壤结构和提高土壤肥力；另外，采用因子分子综合评价法能够准确反映土壤肥力水平和预测土壤生产力状况。第二，在实行土地休闲的美国东北部湿润区土壤，种植覆盖作物具有提升碳库容量和增加碳库活性的潜力，同时能有效提高氮素利用效率，从而减少施肥对环境的潜在污染威胁。因此，种植覆盖作物并减少后续作物氮肥施用量是湿润区提高土壤肥力和提高肥料利用率的有效途径。 The improvement and management of soil fertility is not only the key to improve soilquality but also the core means of ensuring sustainable use of soil resources. It is alsosignificant to improve farm land productivity and ensure food security on regional or nationalscale. Both the domestic and foreign research showed that the most effective and meaningfulway for improving soil fertility is organic amendments among many soil fertilizationmeasures. Adding organic materials and planting cover /(catch/) crops have caused widespreadconcern. However, how to evaluate the effects of organic amendments through identifyingspecific measures and filtering key indexes of soil fertility according to local conditions thusestablishing highly-efficient fertilization mode still needs further research on regionalagriculture production. Because of this, two soils /(typical dryland soil /(Weibei arid loessplateau of China, Shaanxi/) and humid region of northeast U.S./(State of Maryland/)/) ofdifferent climate types, soil properties and tillage managements, were selected to conductresearch on filtering and evaluating modes of adding organic materials and on effects ofplanting cover crops and so on. Through organic materials and optimized cropping system,theoretical basis concerning soil productivity improvement, efficient use of nutrient resourcesand eco-environment protection in dryland and humid regions can be provided. The resultsare as follows: /(1/) Compared to T1treatment, soil bulk desity under other organic fertilization treatmentsdeclined slightly, and it obtained the highest decrease /(by6.56/%/) in T6treament. Organicamendments /(low-, medium-, and high-level maize stalks, stalk composts, and cattle manure/)combined with inorganic fertilization decreased the air-dried aggregate /(>10mm and <0.25mm/) content and increased53mm and1-0.5mm aggregate content. Meanwhile, organicamendments also increased>5mm,5–2mm and2–0.25mm water-stable aggregate content.The proportion of water-stable aggregates>5mm was the highest in T5treatment,6.5/%,significantly higher than that in T1treatment, while those of52-mm increased remarkablywith organic amendments, with78.0/%significant increase in T4treatment compared to T1treatment. Compared to T1treatment, T5treatment resulted in a greatest increase in meanweight diameter /(MWD/) and geometric mean diameter /(GMD/) of wet-aggregates by33.3/%and24.7/%respectively. /(2/) In the020cm soil layer, the POXC content was significantly higher in theorganically amended treatments than in T1treatment /(P<0.05/). Among the organicamendments, T6treatment showed a greatest increase by108.6/%. Compared to NPKfertilization, the organically amended treatments increased the SOC content in most aggregatesize classes. The SOC content in0.50.25mm aggregates increased by12.8/%significantly inT6treatment. Meanwhile, the POXC content in most aggregate size classes was alsosignificantly higher in the organically amended treatments. Among them, T5treatment showeda greatest increase by98.5/%in1-0.5mm aggregates. There were significant positive relationsbetween the proportions of>0.25mm water-stable aggregates and POXC content /(R2=0.625,P<0.05/). In addition, the carbon management index of surface soil was higher in organicallyamended treatments than that of NPK fertilization and Control. T6treatment received ahighest value with231.83. /(3/) Compared with T1treatment, the organic treatments /(T2-T6/) improved some nutrientsituation of soil /(total nitrogen, available phosphorus, available potassium and CEC/) and soilmicrobiological properties /[soil microbial biomass C /(MBC/&N /(MBN/), urease activity,alkaline phosphatase activity/], especially in T5treatment. As follows, MBC, MBN, ureaseactivity and alkaline phosphatase activity increased by42.0/%,54.6/%,19.7/%and7.4/%respectively. Meanwhile MBC, MBN and urease activity are positively and significantlycorrelated with available phosphorus and available potassium /(P＜0.01/), the same to soil totalnitrogen, CEC, and crop yield as well /(P＜0.05/). /(4/) A total of twelve important quantitative indices were selected, and factor analysis andminimum Euclidean distance method were employed to evaluate the overall soil fertility. Cropyield was used to verify the evaluation results. Applying organic materials promoted soilfertility and crop yield significantly. Compared with applying chemical fertilizer alone, itscombination with straw compost and with organic manure increased the wheat yield by13.31/%and16.17/%, respectively. The soil quality under the combined application ofchemical fertilizer with straw compost was the highest, with an integrated score up to58.94,followed by the combined application of chemical fertilizer with organic manure. /(5/) Forage radish produced quantities of shoots and roots biomass /(2763and2326kg ha-1respectively/) in the fall, which was obviously higher in amount than that of no-cover crop.The carbon intake for radish shoots and roots were1011and883kg ha-1seperately. The TOCin soil dropped with the deepening of soil, but was not significantly affected by the covertreatment. However, under any nitrogen rates, forage radish’s significant impacts on POXCwere observed in both surface soils and deep soils. Additionally, a strong positive relationshipbetween POXC and SOC has also been displayed in this study /(P<0.01/). At0-30cm soil layer, compared with the no-cover treatment, POXC in cover treatment soils has increased23/%,20/%and26/%respectively under N56, N112and N168kg ha-1/(August/). /(6/) Forage radish takes up N from both the top and deep soil layers, storing the N intissues near the soil surface for use by the next crop. Nitrogen captured in the radish shoots atthe experimental sites was nearly4times greater than in weeds under both N levels. Duringthe later period of fodder carrots growth /(December/), the NO3-N in the top soil hassignificantly decreased, about18.31/%and9.56/%under the N fertilization rate of100and0kg N ha-1, respectively. However, after the decomposition of the residues /(May/), the NO3-Nin the top soil has increased about165.16/%and119.56/%, and no significant accumulation inthe deep soil. Forage radish had no significant effect on total N and NH4-N in soil. /(7/) Planting forage radish promoted the growth of following silage corn, and improvedthe production of dry matters of stalks and corn kernels. The nitrogen intake for corn wasobviously increased under N0, N56, N112, and N168kg ha-1,23.88/%,6.61/%,18.20/%and1.75/%respectively. When applying no nitrogen, the N intake of corn under cover treatmentwere dramatically higher than those of no-cover treatment, thus lowering the recovery andagronomic efficiency of applied N significantly under the same N fertilization rate.Meanwhile, the recovery and agronomic efficiency of applied N decreased steadily withfertilizer rates increased. Based on the above research, two important conclusions have been drawn in this paper.First, the combined application of organic materials /(straw/) and chemical fertilizer to soil inarid areas in China, where straw resources are very rich, can regulate the soil bulk density andthe distribution and stability of soil aggregates, and effectively increase the soil aggregateassociated carbon content to significantly improve the soil structure and fertility in the aridareas; meanwhile, a comprehensive evaluation of the factor analysis is employed to accuratelyreflect the soil fertility level and predict the soil productivity. Second, in the soil of U.S.Anortheastern humid areas where the farmland is kept fallow, planting cover crops caneffectively improve the potential of carbon storage capacity, the carbon sink activity potentialand the nitrogen use efficiency to reduce the potential environmental pollution caused byfertilizer. Therefore, the effective way of improving the soil fertility and the fertilizer useefficiency is to plant cover crops and reduce follow-up crop nitrogen fertilizer application inhumid areas.

关 键 词： 旱区 湿润区 有机培肥 作物覆盖 土壤肥力

分 类 号： [S158.3]

领　　域： [农业科学] [农业科学]