【作者】 许红卫；

【导师】 王人潮；

【作者基本信息】 浙江大学 ， 土壤学， 2004， 博士

【摘要】 田间土壤养分和作物产量不仅具有明显的空间变异，而且这种变异在时间上也表现出一定的变化。而长期以来，农业生产一直以田块为基础，在同一地区所有的农田上、或者一片较大的农场，单位面积基本上都使用了等量的种子和肥料、除草剂、生长剂等。这样做，除了由于用量盲目、往往供过于求而造成浪费外，还导致了土壤和地下水的污染。实际上，在同一块农田里，有许多因素影响着作物的生长和产量，存在着明显的时空差异性，更不用说不同地块之间存在巨大的差异。这样的结果一方面造成生产成本加大，另一方面造成环境的负面效应，是造成农业生产效益低下与环境恶化的重要原因。目前受到广泛关注的精确农业就是针对田间不同的局部地块的土壤、地理等条件，通过适当的方法在适当的位置投入适量的物质(如种子、农药、化肥等)而实施的一种田间管理方式，其中，变量施肥是精确农业的一项重要技术。而了解田间土壤养分和作物产量的时空变异，是实施田间变量施肥，进行精确施肥管理的基础。因此，对土壤特性及作物产量的时空变异研究，是近期国内外学者共同关注的热点。 尽管目前国内外对土壤养分的变异已有了比较深入的研究，但大多集中在对土壤养分的空间变异上，对其时间变异的研究甚少，而且目前的研究主要集中在旱地的土壤养分变异上，对水稻田的土壤养分的变异研究较少。对作物产量变异的研究大都局限于了解、分析产量变异的状况，而对其产生原因研究甚少；对土壤、作物营养、作物产量变异的一体化研究，未见报道。实际上，作物的产量是由多种变异因素综合作用的结果，土壤肥力的变异是作物产量变异的主要原因，通过对各种与产量有关的因素进行分析往往可以预测产量的变化，反过来，通过中文摘要对产量变异的分析也可以了解土壤养分等因素的变异程度，有助于精确田间管理方案的制定。本研究以英国北爱尔兰牧草地和我国南方典型农田(水稻田)为研究区，研究十壤养分和作物产量的时空变异，并进行牧草地土壤养分、牧草养分、牧草产量的相关性、一体化研究;在此基础上，提出研究区实施精确养分分区管理和田间施肥的初步方案;同时探索适合我国农业分散经营管理的国情的土壤养分采样方式和养分管理模式。 对牧草地土壤养分、牧草N素吸收量(又称牧草N素产量或移走量)、牧草产量的相关性、一体化研究结果表明，牧草地土壤养分存在一定的空间变异与时间变异，且各养分的变异程度不尽相同。十壤全N、全C等全量元素的空间变异比较小，时间稳定性好，而有效K、有效P这些有效养分的空间与时间的变异都较大:同时，土壤有效养分与牧草产量有较好的相关性，其时空变异更能影响牧草的产量，因此，田间土壤养分的精确管理应以土壤有效养分为主。牧草干物质产量、牧草氮素吸收量在田块间存在较大的空间变异，而且这种变异在不同的生长季各不相同，因此，不同生长季需要采用不同的管理方式，有必要进行变量施肥。其中，第一季的空间变异最小且在时间上基本稳定，因此，可以根据结合产量空间趋势和时间稳定性的分级管理图对该牧草地进行精确管理。对土壤养分、牧草产量、牧草N素吸收量的一体化研究还表明，牧草干物质量、牧草氮素吸收量与十壤养分的时空变异互为影响，可以说，土壤、作物管理等条件的差异导致了作物产量的不同，而这种不同反过来又加剧了十壤原有养分的变异程度。试验田牧草干物质量、牧草氮素吸收量以及各土壤养分的时空变异，都与试验区地形有很人的关系，地势较高区域与较低区域的变异情况有较大的差别。因此，本研究根据地形将试验区分成3个小区，拟采用不同的管理方案进行精确管理，具体的施肥等管理方案还需进一步研究，但在上述研究的基础上，提出了试验田施肥建议:特别是对试验田N肥的施用，根据牧草产量的时空变异性及土壤一牧草N素平衡，提出了分区管理的建议方案。 水稻田土壤的特性与牧草地(早地)土壤有很大的不同，其土壤养分的空间变异特点也不同。本文对水稻田试验区土壤养分的空间变异的研究表明:水稻田土壤养分在田间尺度内也存在一定的空间变异，各主要养分的空间格局与自然田中文摘要块的方向基本一致，并明显受到农户耕种习惯、施肥习惯的影响。但这种变异是否对水稻的生长及其产量造成影响，还需要进行土壤、产量等空间变异的一体化研究。通过对试验区各土壤养分的合理采样数研究，以及不同农户耕种、管理下各田块土壤养分的差异显著性研究，可以肯定，农户不同的经营方式与施肥习惯等人为因素对水稻田田间土壤养分的变异起主导作用。因此，对试验区这样的我国南方平原水网地区的小规模分散经营体制下的精确田间管理，提出以农户经营地块为单位，并采用以农户为单元的混合样采样方式，既能了解田块土壤养分的基本状况，又有可能大大减少土壤采样量和分析成本。 土壤采样的方式、采样密度，影响到对土壤养分空间变异程度的了解，从而直接影响变量施肥的实施效果。目前最常用的格网采样法，可以获取传统的整个田块混合采样所不能发现的变异信息，对于指导变量施肥意义重大，但这种方法?更多还原

【Abstract】 Soil nutrients and crop yields have spatial within-field variability, changing with the time. However, agricultural production has been taking based on field unit for a long time past and same quantities of agricultural materials are applied to the whole field or all the fields in the area from year to year, so the spatial and temporal variability within fields is ignored, which wastes the natural resource and exerts a harmful impact on the environment. The aim of Precision Agriculture (PA) is to change this status, matching resource application and agronomic practices with soil and crop requirements as they vary in space and time within individual field units. An understanding of both the temporal and the spatial components of variability is essential, therefore, before decisions can be made about the feasibility of site-specific management. Thus, the research on spatial and temporal variability of soil properties and crop yields is the key topic which has being attracted the attention of scholars in the world.In present, much of the research done has concentrated on quantifying and understanding the spatial components of soil nutrients and crop yields variability; less attention has been given to the effects of time and season on the spatial patterns. Relatively little is known about the nature, extent or temporal stability of ’within-field’ variability of soilnutrients in paddy field, and whether or not it would be feasible to manage it in a site-specific way. Actually, the crop yield is an integrate effect of a lot of factors, and soil nutrient variability is the main cause of the crop yield variability. In this present study, the spatial and the temporal components of variability of certain key soil properties and sward yields in a grassland field and their correlations, the spatial components of variability of certain key soil properties in three paddy fields were evaluated to assess the likely feasibility of adopting a site-specific approach to fertilization management. A 7.9 ha grassland field managed by the Agricultural Research Institute at Hillsborough, Co. Down, Northern Ireland and three paddy fields in Jiashan and Huzhou were selected for the study. Then a scheme of classed management and fertilization for the sward field was put forwarded, and soil sampling strategy and nutrient management mode adapt to the fields under the family responsibility system in southern China were explored. The main results obtained in this paper are as follows: Soil available nutrients, such as available P and available K, had the greatest within-field variability and the highest degree of temporal instability, whereas, soil total N and total C had the least within-field variability and were much more stable over time in the sward field. Soil available nutrients had good correlation with sward yields, their variability could influenced the sward yields more, therefore, available soil nutrients ought to be managed in a site-specific way. At cut 1, the spatial patterns of sward dry matter (DM) and N yield (N offtake) proved to be well defined and temporally stable. In contrast, at cut 2 and cut 3, the patterns of DM production were temporally unstable. Itwas concluded that site-specific management approach to fertilization according to the classified management map, in spring, ought to be feasible. It was also concluded that the spatial and temporal within-field variability of soil nutrients, sward DM and N yield (offtake) were influenced each other. In other words, the difference of soil, management way etc. can cause the crop yield variability, which enhances the soil variability again. The variability in the sward field was related with the topography, so three zones which ought to be managed in different site-specific ways were divided by elevation. Further work should be done to make fertilizer management scheme later. However, some fertilizer suggestion for the field was put forward especially for fertilizer N.Characteristics of soil properties of paddy field are different with those of sward fiel更多还原