Landscape-scale estimates of dinitrogen fixation by Pisum sativum by nitrogen-15 natural abundance and enriched isotope dilution
Landscape-scale estimates of dinitrogen fixation by Pisum sativum by nitrogen-15 natural abundance and enriched isotope dilution
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通过氮 15 自然丰度和富集同位素稀释对豌豆固氮的景观尺度估计
DOI：
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发表时间：
1995
影响因子：
6.5
通讯作者：
D. Pennock
中科院分区：
文献类型：
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作者：
G. Androsoff;C. Kessel;D. Pennock
地形和坡位影响豆科植物固氮的土壤和环境因子。本研究旨在(1)利用天然15N丰度和15N富集同位素稀释技术估算缓坡农田豌豆的固氮作用；(2)在景观尺度上确定影响固氮作用的土壤和环境因素。而土壤有效水分容量、有效NHinf4sup+、作物总产量和固氮所得N百分比（% Ndfa）受地形模式、土壤noinf3sup水平、种子产量的显著影响，而利用自然丰度估算的Ndfa百分比不受地形模式的影响。使用自然丰度的Ndfa百分比与NHinf4sup+相关，但与土壤水分、pH、电导率、NOinf3sup-或粒径无关。使用富集15N的Ndfa百分比估计在0到92.8%之间。富氮处理下的% Ndfa中值最高（68.6%）出现在发散型坡道上，最低（28.1%）出现在收敛型坡道上。使用自然丰度估算的% Ndfa的范围为13.2%至96.9%。有效氮库δ 15N在生长季节波动较小，与富15N相比，自然丰度对% Ndfa的变异性较小。尽管使用自然丰度（44.5）和富集15N（49.6）的% Ndfa平均值相似，但两者之间没有发现显著相关性。这些结果表明，尽管地形可能对N2固定产生总体控制，但在微观场地水平上，N2固定的巨大变化可能会排除个体估计与景观尺度上N2固定模式的极限检测之间的相关性。
Topography and slope position influence the soil and environmental factors that affect N2 fixation by legumes. The present study was conducted to (1) estimate N2 fixation by field peas in a gently rolling farm field using the natural 15N abundance and the 15N-enriched isotope dilution techniques and (2) identify soil and environmental factors that influence N2 fixation at the landscape scale. Whereas soil available water capacity, available NHinf4sup+, total crop yield, and percent N derived from N2 fixation (% Ndfa) estimated using enriched N were significantly affected by landform patterns, soil NOinf3sup-levels, seed yield, and the % Ndfa estimated using natural abundance did not follow landform patterns. The % Ndfa using natural abundance was correlated with NHinf4sup+but not with available soil water, pH, electrical conductivity, NOinf3sup-, or particle size. Estimates of the % Ndfa using enriched 15N ranged from 0 to 92.8%. The highest median value (68.6%) for % Ndfa using enriched N occurred on the divergent footslopes, with the lowest value (28.1%) on the convergent shoulders. Estimates of % Ndfa using natural abundance ranged from 13.2% to 96.9%. Smaller fluctuations during the growing season in the δ 15N of the available N pool may have resulted in less variability for % Ndfa using natural abundance compared to enriched 15N. Despite similar mean values for % Ndfa using natural abundance (44.5) and enriched 15N (49.6), no significant correlation between the two estimates was found. These results suggest that although topography may exert gross controls on N2 fixation, large variations in N2 fixation at the microsite level may preclude correlations between individual estimates and limit detection of landscape scale patterns of N2 fixation.