【作者】 谢岷；

【导师】 魏占民；

【作者基本信息】 内蒙古农业大学 ， 农业水土工程， 2011， 博士

【摘要】 气象、土壤和田间管理因素对作物生长和农田氮素吸收与淋洗损失有着重要地影响。一直以来,农学、土壤学、农业气象学和农业水土工程学等各学科的研究者们都积极关注此研究领域。气象因素(主要是气温和降雨)是影响和制约作物生长和发育,氮素吸收和淋洗损失的主要外部因素。此外,土壤和田间管理因素对作物的氮素利用有着直接影响。因此,研究气象、土壤和管理因素对玉米氮素利用的影响,深入了解玉米氮素利用关键时期的各因素的效用,以及各因素之间的交互作用对玉米氮素利用的影响,对于提高玉米氮素管理水平和减少氮素淋洗损失造成的水土污染有着极其重要的实际意义。Meta-Analysis是一种可以对同一主题下不同研究成果进行整理和综合,得出一个定量且严谨结果的综述性统计方法。在本研究中利用Meta-Analysis这一当前最具权威地综述性统计方法,选择两个不同的玉米氮素数据库为研究对象,结合相应地气象参数(玉米热量单元指数,累积降雨量和降雨均匀度)与不同的土壤和管理因素,系统地探讨了气象、土壤和田间管理因素对玉米氮素利用影响的一般规律,为更好地进行玉米农田氮素管理、评价与调控提供有力的科学理论依据。本文完成的主要工作和取得的主要结论如下:⑴基于Meta-Analysis的玉米氮素利用的研究结果与其它试验方法的研究结果基本相似,表明Meta-Analysis在玉米氮素管理的研究中具有较高地可信度,能够较好地反映出不同的气象、土壤和管理等因素对玉米氮素利用的影响。⑵热量单元指数、累积降雨量和降雨均匀度对玉米氮素利用率的研究结果表明,高氮素利用率年份的气象特征为具有较高地追肥前期和追肥后期的累积降雨量,适中的降雨均匀度,和在生长季后期和整个生长季中具有较低的温度,且玉米高氮素利用率年份并不意味着玉米高产年份。⑶土壤和田间管理因素对玉米氮素利用率的研究表明,粘粒百分含量为(28~40%)区间内,可以显著地增加氮素利用率;适中的土壤pH值(6~7)和种植密度(6~7万株/每公顷)也可以增加氮素利用率,但前季作物类型基本对氮素利用率没有影响。“基肥+追肥”的施氮方式可以显著地提高玉米氮素利用率,建议“基肥+追肥”的施氮方式应被广泛地推广和应用。⑷比较各气象、土壤和管理因素对玉米氮素利用率的影响后发现,就整个生长季来讲,降雨因素(包括降雨量和降雨均匀度)对氮素利用率的影响要大于玉米热量单元指数的影响;施氮量和施氮方式因素的影响要大于其它土壤和田间管理因素的影响。气象、土壤和管理等多因素的协同和交互效应明显。⑸比较追肥前期与追肥后期的气象因素对玉米氮素利用率的影响后发现,玉米生长季追肥前的各气象因素对氮素利用率的影响要大于追肥后的各气象因素对氮素利用率的影响。⑹在基肥和追肥共同施用的情况下,结果表明:中、高施氮水平的玉米氮素利用率响应比在不同气象因素水平下分别显著高于低施氮水平的氮素利用率响应比18.8%和28.2%。但在中、高氮水平两者之间并无显著性差异。而在只施用基肥的情况下,中、高施氮水平的玉米氮素利用率响应比在不同气象因素水平下分别显著高于低施氮水平的氮素利用率响应比11.2%和24.8%。显著性测试表明,中氮和高氮之间也无显著差异。为了有效地提高玉米氮素利用率,减少氮素损失和维持玉米高产,建议中等施氮水平(总氮量“100~150 kg N ha-1”和基肥氮“0~50 kg N ha-1”)的施氮量应该作为最佳施氮量而被生产实践所采用。更多还原

【Abstract】 Weather has a strong impact on crop growth and nitrogen uptake and loss in soil-crop systems, also soil and field managements are especially important for crop and nitrogen. Increasing nitrogen fertilizer response and improving nitrogen management have long been recognized as a most challenge of agricultural development, because worldwide nitrogen use efficiency (NUE) for cereal production is only estimated at 33%. As a consequence, current agricultural and environmental concerns demand improved NUE and reduced N losses to protect environment, while maintaining an optimal yield.Meta-analysis is a methodology used to intergrate a set of statistical techniques developed to provide an objective comparison of research results from independent studies. A meta-analysis combines the results of several studies that address a set of related research hypotheses. In this study, a meta-analysis was performed on the relationship between the application rates of nitrogen fertilizer and the corn yield response in order to understand the effects of weather (air temperature, rain) and other factors (including soil pH, soil surface textures, plant density, previous crop, nitrogen rates and application methods). The database is constituted by two parts: a database of nitrogen response trials covering the years 1997 to 2008 in 60 locations in the grain corn growing area of Quebec, and a database is built up by collecting publications from Africa, Europe and America published between 2000 and 2009, inclusively. Those data are submitted to meta-analyses procedures in conjunction with a corresponding weather database. The response ratio (RR) used to measure effect size indicates significantly positive response of corn yield.A better understanding of the effects of weather, soil and managements would allow for adjustments of the nitrogen rate targeted for optimal N supply. In this dissertation, meta-analysis is used to determine: (1) Which weather variables are the most determinant for corn response to nitrogen rates; (2) Which soil and managerial factors are the most predominant in term of corn response to nitrogen rates; (3) The relationship between corn response to N rates and specific ranges of weather variables and other factors. Also, the main results obtained are as follow: (1) Traditional statistics are not appropriate when the data come from numerous studies, while meta-analysis, which uses effect size and weighted statistical models, should therefore be applied in the analysis of a large collection of results originating from different studies. It can be used to reflect the magnitude of the treatment effect or the strength of a relationship between two variables. (2) High-yield years do not necessarily mean high-RR years, and high-RR years are characterized by cooler and wetter growth season, together with the appropriate rainfall evenness. (3) The results indicate that RRs are not influened by previous crop, and the highest RRs were found by the percent of clay (28~40%), soil pH (6~7) and plant density (60, 000~70, 000 plants/ha-1). The starter N and top-dressing N should be recommended for high RR. (4) A major result of this analysis is that rainfall was more important than corn heat units for RR, and the amount and application method of nitrogen are more important than other soil and factors relating to field management. (5) The results indicate that weather condition before side-dressing is more important than after side-dressing for RR. (6) The meta-analysis shows that response ratios to weather factors tend to be higher in High-N and Med-N than in Low-N, but there is no significant difference between High-N and Med-N. Therefore total nitrogen range (100~150 kg ha-1) and starter N range (0~50 kg ha-1) rate application under the different weather conditions can be considered the optimal selection to maintain cron productivity and limit environmental losses. RRs have no significant differences from one another within three starter N rates.更多还原