干旱区生态环境知识资源中心(Arid): 半干旱区农田土壤无机的氮积累与迁移机理

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	半干旱区农田土壤无机的氮积累与迁移机理
其他题名	Mechanisms in the accumulation and movement of mineral N in soil profiles of farming land in a semi-arid region
	吴金水; 郭胜利; 党廷辉
来源期刊	生态学报
ISSN	1000-0933
出版年	2003
卷号	23 期号:10 页码:2040-2049
中文摘要	研究黄土旱塬区长期定位试验中10个典型处理土壤剖面(0～300cm)水分和无机氮的季节变化，探讨在半干旱区农田无机氮的积累与迁移机理。结果表明休闲处理除表层外土壤剖面的水分、硝态氮和铵态氮的含量分别稳定在17%～20%、4～7mgN/kg和6～10mgN/kg土的范围。种植作物显著地改变土壤剖面水分和硝态氮的分布状况，并使其含理发生大幅度的季节变化。作物利用限制了农田土壤硝态氮向深层的迁移。小麦连作无机肥氮处理及芷蓿连作不施肥或氮、磷加有机肥处理土壤硝态氮主要集中在0～40cm土层。小麦连作单施氮肥(120kgN/(hm~2·a)处理经17年后土壤剖面硝态氮积累总量达到施氮总量的55%, 40～60cm和140～220cm土层出现两个高峰，并表现出随季节性变化向土壤深层迁移的趋势。氮肥与磷肥或有机肥施用大幅度减少了土壤剖面硝态氮积累，并使其限制在160cm以上的土层内，200cm以下土层的硝态氮含量较低(<1mgN/kg土)，因而不具向深层迁移的条件。土壤剖面的铵态氮含量不受作物、施肥和季节性气候变化的影响。
英文摘要	Large accumulation of mineral nitrogen (N) in agricultural eco-systems is concerned to have potential risks to environment. This study was aimed toward better understanding on the mechanisms in the accumulation and movement of mineral N in cropping soils in semi-arid regions, based on a long-term field experiment established in 1984 to monitor semi-arid agro-systems in the Loess Plateau. The annual means of rainfalls at the experimental site were 580 mm (about 70% received between July and Oct. ) and 9.3 ℃, respectively. Between May, 2000 and April, 2001, the contents of water, NO_3-N, NI-L.-N in soil profiles (0～300 cm) were monthly determined in 10 selected treatments (in triplicates), including permanent fallow (F), continuous winter wheat (W) without fertilizer and with N (at annually 120 kgN/hm~2 as urea), NP (at annually 26 kgP/hm~2 as super-phosphate), farmyard manure (FYM, at annually 75 t/hm~2), N + FYM, NP + FYM, and continuous legumes (L) without fertilizer and with NP + FYM. All fertilizers were applied at the time of sowing. For each plots, 3 soil scores were taken from 0～300 cm soil profiles, cut into 20cm sections, then mixed to give a combined sample for each 20 cm of soil layers. Water content was measured by drying soil sample at 105 C to a constant weight. For measuring NO_3-N and NH4-N, two portions from a soil sample were extracted in lmol KC1, and the extractants were analyzed by a dual-channel nitrogen analyzer system (FIAstar 5000, FOSS). Data obtained showed that for the fallow treatment, water content fluctuated significantly with seasons in the top layer (0～20 cm) of the soil profile but little (17%～20%) in layers between 20 and 300 cm. For cropping treatments, water content in soil profiles decreased largely during the season when crop grew vigorously (from April to June), then recovered after crops were harvested and rainfalls increased (as determined from Aug. to Feb. ). However, the scales of the changes decreased as the depth increased. In general, water content in the same soil layers was 2%～6% smaller under cropping systems than under fallow, with the smallest values generally found under continuous legume (L, L-NP-FYM). For all the treatments investigated, NH4-N content in soil profiles was fairly small and constant (4～7 mgN/kg soil). Under the fallow treatment, NO_3-N content in the soil profile remained relatively constant (6～10 mgN/kg soil), with the exception of some fluctuations in the top layer (varying from 10 mgN/kg soil in April and June to 22 mgN/kg soil in Aug. and Feb.). However, NO_3-N content and seasonal changes in soil profiles varied widely with different cropping and fertilizer practices. In general, seasonal changes in NO_3-N content in the soil profiles under cropping treatments occurred in similar patterns as to water content (decreased significantly from April to June, recovered by Aug.). Under cropping treatments without fertilizer (W and L), NO_3-N content in the top layer (2-12 mgN/kg soil, dependent on the time determined) was remarkably smaller than that under the fallow treatment, and decreased further to a minimal level (< 2 mgN/kg soil) in soil layers below 100 cm. For continuous wheat with FYM or P + FYM fertilizers (but no chemical N), N03-N content varied largely with the time determined (large increases in Aug.) in 0～40 cm layers, then decreased to a minimal level (also < 2 mgN/kg soil) by 60- 100 cm deep in the soil profiles. A large amount of N03-N (1065 kgN/hm2, accounted to 55% of total N applied during 14 years since the experiment was established) has accumulated in the soil profile under continuous wheat with N fertilizer alone. In difference from all of the other treatments where the highest NO_3-N content was present in the upper layers (20～140 cm, dependent on the types of crops and fertilizers used), the soil profile under continuous wheat with N fertilizer (W-N) had two NO3-N peaks, the first present in the layers between 40 and 60 cm and the second between 140 and 220 cm. Both peaks increased significantly between June and Aug. (after the harvest of wheat), and shifted into 20 - 40 cm deeper layers in Feb. and April. It was also marked that the second peak was much wider and greater than the first one. When N fertilizer was applied with P fertilizer (W-N+NP) or farmyard manure (W-N 4-FYM, W-NP+FYM), the second peak as formed under W-N completely disappeared, and for a instead, NO3-N content in the lower layers (below 160 cm) was minimal (< 2 mgN/kg soil). With continuous legume, NO3-N content in the soil layers decreased sharply in the layers below 40 cm. In conclusion, results presented suggest that cropping and fertilizer practices are the prime factor determining seasonal changes and differences in the contents of water and NO_3-N but have little effect on NH_4-N content in soil profiles under agro-systems in semi-arid regions. Continuous wheat with N fertilizer alone can result in a large accumulation of NO_-N in the soil profile, particularly in the lower layers. In this case, NO_3-N accumulated moves into deeper layers during the wet season. The application of P fertilizer and farmyard manure companied with N not only decreases in a large extent the accumulation of NO_3-N but also effectively protects it from movement into deeper soil layers. Compared to continuous wheat systems, continuous legume consumes more soil water but can largely decrease NO_3-N content in the soil profiles.
中文关键词	无机氮 ; 积累 ; 迁移 ; 半干旱型农业区
英文关键词	mineral N accumulation movement emi-arid region
语种	中文
国家	中国
收录类别	CSCD
WOS类目	AGRICULTURE MULTIDISCIPLINARY
WOS研究方向	Agriculture
CSCD记录号	CSCD:1269893
资源类型	期刊论文
条目标识符	http://119.78.100.177/qdio/handle/2XILL650/204300
作者单位	中国科学院水利部水土保护研究所, 黄土高原土壤侵蚀与旱地农业国家重点实验室, 杨凌, 陕西 712100, 中国
推荐引用方式 GB/T 7714	吴金水,郭胜利,党廷辉. 半干旱区农田土壤无机的氮积累与迁移机理[J],2003,23(10):2040-2049.
APA	吴金水,郭胜利,&党廷辉.(2003).半干旱区农田土壤无机的氮积累与迁移机理.生态学报,23(10),2040-2049.
MLA	吴金水,et al."半干旱区农田土壤无机的氮积累与迁移机理".生态学报 23.10(2003):2040-2049.