电超滤浸提土壤养分的研究 Ⅲ.电超滤-吸光量与培养矿化氮的相关性

STUDIES ON THE EXTRACTION OF SOIL NUTRIENTS BY ELECTRO-ULTRAFILTRATION(EUF)Ⅲ.CORRELATIONS BETWEEN THE SOIL ELECTROULTRAFILTRATION-ABSORBILITY(EUF-Q)AND THE INCUBATION MINERALIZED NITROGEN

研究证明我国各类土壤(包括酸性、碱性、石灰性或旱地、水田土壤)好气培养法(测定培养后的 NO_3-N 和 NH_4-N)与厌气培养法(测定培养后的 NH_4-N 和初始 NO_3-N)结果之间都有很高的相关性;冬小麦盆栽试验的相关研究表明这二种培养法都可作为测定土壤有效氮的参比方法。另一方面,我国各地不同土类的三项电超滤-吸光量(EUF-Q_T,-Q_(OM)和-Q_(NO_3)能对应地表征土壤的 EUF-N_T,-N_(OM)和-N_(SO_3)。通过以培养矿化氮为参比的相关研究,证明我国各土类旱地土壤的这三项 EUF-Q 值可以很好地分别反映有效氮容量因子、土壤易水解的有机氮和土壤硝态氮;但 EUF-Q 法不能适用于水田土壤。

The EUF-Q_T,-Q_(OM),and-Q_(NO_3) of 12 upland and waterloggcd soils were determined by the method described in the previous paper^([a]) with the mixed EUF-cathode and -anode filtrate or wiLh Lhe anode filLrate alone.We have found that Lhe values of these EUF-Q fractions of the EUF-anode filtrate may be used instead of the EUF-Q values of Lhe mixed EUF filtrate.We have also proved experimentally that the values of Lhese EUF-Q fractions can reflect the soil EUF-N_T,-N_(OM),and -N_(NO_s) respectively and the EUF-NO_3 value of Lhe EUF-anode filtrate is almosL as Lhe same of the soil NO_3-N value. The aerobic and anaerobic incubation minetalized N of 51 upland soil samples collected from North China and 37 soil samples of various soil types including acidic,all aline,and calcareous upland and paddy soils collected from all over China were determined.It was found that the aerobic incubation mineralized N (incubated NO_3-N and NH,-N) and the anaerobic incubation mineralized N (incu- bated NH_4-N and soil initial NO,-N) were very closely correlated with each other.There is also a close correlation present between the mineralized N from two incubation methods respectively and the N uptake by winter wheat in pot experiments (n=51) .Both the N mineralization methods can be suitably used as reference method for assessing soil available N. Both results of correlation studies with winter wheat in pot experiments (n=51) and with incubation methods (n=37) indicated that the EUF-Q method, whether the applied voltage is depressed or not,was a promising method for upland soil available N evaluation,but was not suitable for waterlogged soils. The values of soil EUF-Q_T,-Q_(OM),and -Q_(NO_a) can reliably characterize the capaci- ty of available N pool,labile hydrolizable organic N,and nitrate N respective- ly for upland soils.