基于区域和亚类水平的中国水稻土氮储量空间分异格局研究

SPATIAL PATTERNS OF NITROGEN STORAGE IN PADDY SOILS AT REGIONAL AND SUBGROUPS LEVELS IN CHINA

农田氮循环是陆地生态系统氮循环的一个重要环节,因此对中国水稻土氮储量及其空间变异特征的研究有利于了解农田土壤氮循环。本研究基于中国1∶100万土壤数据库和1490个水稻土剖面数据,在水稻土亚类和土壤大区水平上对中国水稻土氮密度和氮储量的空间变异特征进行研究。结果表明:中国水稻土平均氮密度为12.4Mghm-2;中国水稻土氮储量为569Tg。不同亚类水稻土平均氮密度以潜育型水稻土最高(19.7Mghm-2),漂洗型水稻土最低(8.71Mghm-2)。不同土壤分区氮密度最高的是西南区(17.4Mghm-2),最低则是南方区(11.5Mghm-2)。各亚类和区域间水稻土氮密度均有显著差异,但水稻土氮密度在各亚类间的变异大于各区域的差异,这表明水稻土地表水分状况对水稻土氮空间变异的影响程度较气候的影响大。

Nitrogen （N） recycling in agricultural soils plays a key role in the terrestrial N cycle. A thorough understanding of N storage and its spatial distribution in Chinese paddy soils would be helpful to research on N cycle. Total soil N density and total soil N storage of paddy soils in China was evaluated based on the data of 1 490 paddy soil profiles and the 1 ： 1 000 000 soil database of China. Results showed that the mean nitrogen density of paddy soils at a depth of 0 - 100 cm was 12.4 Mg hm^-2, and the N storage was 569 Tg. Nitrogen density varied substantially with the soil subgroups and regions. Submergenic paddy soils were the highest in mean N density （19.7 Mg hm^-2） among all paddy soil subgroups, whereas Bleached paddy soils the lowest （8.71 Mg hm^-2 ） , and Southwest China was the highest （ 17.4 Mg hm^-2 ） , while South China had the lowest （11.5 Mg hm^-2） The variation of N density in both paddy soil subgroups and soil regions are quite significant, but it was higher between soils subgroups than between regions. This indicates that spatial variation of soil N in paddy soils was sensitive to surface water regime rather than climate.