Analysing soil and canopy factors affecting optimum nitrogen fertilization rates of oilseed rape (Brassica napus)
Analysing soil and canopy factors affecting optimum nitrogen fertilization rates of oilseed rape (Brassica napus)
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影响油菜最佳氮肥施用量的土壤和冠层因素分析
DOI：
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发表时间：
2008
影响因子：
0.6
通讯作者：
H. Kage
中科院分区：
文献类型：
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作者：
J. Henke;K. Sieling;W. Sauermann;H. Kage
欧盟硝酸盐指令在德国的实施将导致氮(N)平衡盈余被限制在60公斤/公顷平均三年，从2009年开始。在德国北部地区，冬季油菜（OSR）的氮素盈余超过100公斤N/公顷，是冬季油菜轮作中氮素平衡盈余的主要来源。因此，精确计算施氮量对于实现农田3年氮素平衡平均盈余低于60公斤/公顷的目标变得越来越重要。目前常用春初土壤矿质氮（SMN）作为计算春季施氮量的指标。然而，在OSR条件下，春季生长初期的SMN量通常较低，冠层氮只在非常有限的程度上得到考虑。这可能导致施氮量超过最适施氮量（Nopt）。研究了春季土壤氮和秋春季冠层氮对Nopt的影响。2005/06年度和2006/07年度进行了不同作物冠层的多地点田间试验，采用两个播种日期和两个秋季施氮水平，以及五个春季施氮水平（0-280 kg N/公顷）。利用春季氮肥处理的联合收获种子产量数据，利用二次响应函数估计了春季氮肥产量。回归分析显示，Nopt与春初SMN、春初冠层氮均无显著相关性。相反，秋末Nopt与冠层氮呈显著负相关。基于本研究结果，在计算春季氮肥施肥量时，考虑秋季冠层氮是合理的。如果秋季冠层氮较高（50 ~ 50 kg N/ hm2），则应减少施氮量。
SUMMARY Implementation of the EU Nitrate Directive in Germany will result in nitrogen (N) balance surpluses being restricted to 60 kg N/ha averaged over 3 years, starting in 2009. With N surpluses of more than 100 kg N/ha, winter oilseed rape (OSR) is a main contributor to N balance surpluses in OSR-based crop rotations in northern Germany. The exact calculation of N fertilization rates therefore becomes increasingly important in order to meet the target of less than 60 kg N/ha N balance average surplus over 3 years at a farm level. Currently, soil mineral nitrogen (SMN) at the beginning of spring growth is commonly used as an indicator for calculation of N fertilization rates in spring. However, amounts of SMN at the beginning of spring growth under OSR are usually low and canopy N is only taken into account to a very limited extent. This might lead to N fertilization rates exceeding the optimum N fertilization rate (Nopt). In the present study, the effects of SMN in spring and of canopy N in autumn and spring on Nopt were investigated. Multi-site field trials producing different crop canopies, as a result of two sowing dates and two autumn N fertilization levels, with five spring N fertilization levels (0–280 kg N/ha) were carried out in 2005/06 and 2006/07. Nopt in spring was estimated by quadratic response functions using the combine-harvested seed yield data from the spring N fertilization treatments. Regression analyses revealed no relationship between Nopt and SMN at the beginning of spring growth or canopy N at the beginning of spring growth. In contrast, a significant negative correlation between Nopt and canopy N at the end of autumn growth was found. Based on the results of the present study, it is sensible to take autumn canopy N into account when calculating N fertilization rates in spring. If canopy N in autumn is high (>50 kg N/ha), as a consequence, N fertilization rates should be reduced.