中国农业科学 ›› 2007, Vol. 40 ›› Issue (7): 1422-1431 .

• 土壤肥料·节水灌溉 • 上一篇    下一篇

石灰性土壤供氮能力几种生物测定方法的评价研究

金发会,李世清,卢红玲,李生秀   

  1. 西北农林科技大学/中国科学院水利部水土保持研究所,黄土高原土壤侵蚀与旱地农业国家重点实验室
  • 收稿日期:2006-10-31 修回日期:1900-01-01 出版日期:2007-07-10 发布日期:2007-07-10
  • 通讯作者: 李世清

Comparing the biological Methods of Assessing Soil N-Supplying Capacity in Calcareous Soil

  

  1. 西北农林科技大学/中国科学院水利部水土保持研究所,黄土高原土壤侵蚀与旱地农业国家重点实验室
  • Received:2006-10-31 Revised:1900-01-01 Online:2007-07-10 Published:2007-07-10

摘要: 【目的】目前测定土壤供氮能力的生物方法较多,但基于土壤氮素形态的复杂性、土壤和微生物的高度变异以及生态条件的差异,不同土壤及不同测定方法结果之间仍然存在一定差异,对石灰性土壤采用哪些生物培养方法较好,目前仍无明确结论。【方法】以采自于黄土高原差异较大的25个农田耕层石灰性土壤为供试土样,以淋洗和未淋洗土壤起始NO3--N小麦和玉米两季盆栽试验作物吸氮量为参比,对可反映土壤供氮能力的淹水培养法、通气培养2周法、通气培养4周法、干湿交替通气培养2周法、间歇淋洗长期通气培养法、短期淋洗通气培养法、微生物量碳和微生物量氮等8种生物方法进行了比较研究,其中干湿交替通气培养法和通气培养4周法,是我们对通气培养2周的修订方法。【结果】在不包含起始矿质氮条件下,以上8种生物培养方法与淋洗土壤起始NO3--N盆栽试验作物吸氮量的相关系数依次为0.530,0.700,0.777,0.768,0.764,0.650,0.555和0.465(r0.05=0.369,r0.01=0.505),其中间歇淋洗长期通气培养法确定的氮素矿化势与作物吸氮量的相关系数为0.790;在包括起始矿质氮后(起始矿质氮+矿化氮),以上8种生物方法与未淋洗土壤起始NO3--N盆栽试验作物吸氮量相关系数依次为0.351,0.963,0.962,0.959,0.825, 0.963,0.289和0.095(r0.05=0.369,r0.01=0.505),其中氮素矿化势与作物吸氮量的相关系数为0.812。【结论】在排除起始矿质氮,特别是硝态氮的影响后,在反映旱地石灰性土壤可矿化氮量上,以氮素矿化势最佳;其次为通气培养4周、干湿交替通气培养2周和间歇淋洗长期通气培养法。包括起始矿质氮后,即在反映土壤供氮能力方面,各种通气培养法与未淋洗土壤起始NO3--N作物吸氮量相关性均大幅度提高,其中通气培养2周、通气培养4周、干湿交替通气培养2周和短期淋洗通气培养法相关系数均在0.950以上。而淹水培养法和微生物量碳、氮在表征石灰性土壤供氮能力上均比其它通气培养法逊色。综合考虑各方法在反映土壤可矿化氮和土壤供氮能力上的优劣,以及考虑到间歇淋洗长期通气培养法和以此获得氮素矿化势需培养时间较长,不适于作为实验室常规分析和快速测定土壤供氮能力的方法。根据本研究结果,可将干湿交替通气培养2周作为旱地石灰性土壤供氮指标,该方法不仅更加符合旱地土壤实际水分变化特征,而且既可反映土壤可矿化氮,也可用于评价土壤供氮能力。

关键词: 土壤供氮指标, 生物培养方法, 可矿化氮

Abstract: Based on pot experiments which including leaching soil initial nitrate and without leaching, we studied the correlations between the 9 biological methods which reflecting soil nitrogen supplying capacity and nitrogen uptake by wheat and maize. Test soils were taken from 25 different calcareous surface soil on Loess Plateau. Dry-wet alternation aerobic incubation method was a modification of the aerobic incubation (for 2 weeks) method according to the actual farmland moisture. The results showed that the nitrogen mineralization potential (N0) was significantly correlated with crop uptake nitrogen with leaching soil initial nitrate (r=0.790, p<0.01). The mineralized nitrogen obtained by aerobic incubation for 4weeks, dry-wet alternation aerobic incubation method and long-term alternate leaching aerobic incubation method had remarkably positive correlations with crop uptake nitrogen with leaching soil initial nitrate (Correlation coefficient were 0.777, 0.768 and 0.764, respectively, p<0.01). The correlation coefficient was low between the water logged incubation method and crop uptake nitrogen with leaching soil initial nitrate (r=0.530, p<0.01). If mineralized nitrogen obtained by any methods included the soil initial nitrate, the correlation between the obtained nitrogen and crop uptake nitrogen without leaching soil initial nitrate was significantly increased. The correlation coefficient were highest for short-term leaching aerobic incubation method and the aerobic incubation (for 2 weeks) method with crop uptake nitrogen (r=0.963,p<0.01). The nitrogen obtained by aerobic incubation for 4weeks, dry-wet alternation aerobic incubation (for 2 weeks) method, long-term alternate leaching aerobic incubation method and N0 had remarkably positive correlations with crop uptake nitrogen without leaching soil initial nitrate (Correlation coefficient were 0.962, 0.959, 0.825 and 0.812, respectively, p<0.01). It could be seen that high contents of soil initial mineral nitrogen, especially nitrate affected the correlations between the biological methods and crop uptake nitrogen. The correlation coefficient between the microbial biomass carbon (BC), microbial biomass nitrogen (BN) with crop uptake nitrogen with leaching initial nitrate were respectively 0.555 (p<0.01) and 0.465 (p<0.05). The correlation between BC, BN with crop uptake nitrogen without leaching initial nitrate were not significantly. Thus, due to long-term alternate leaching aerobic incubation method and N0 needed long term incubating, they were not suitable for general analysis in laboratory. So, we choose the dry-wet alternation aerobic incubation method as the best index for reflecting calcareous soil nitrogen supplying capacity, which were accord with the actual farmland character.

Key words: soil nitrogen supplying index, biological methods, mineralized N