摘要
选用陕西省 3个自然生态区 3种主要耕作土壤土样 ,在实验室培养条件下 ,研究温度、水分及不同氮肥品种对其硝化作用的影响 ,并用 d N/ dt=b N(B-N) / B方程描述硝化作用过程中硝态氮含量随时间的累积变化 ,获得定量描述硝化作用强弱的两个指标 (Kmax和 td)。结果表明 :不同土壤水分含量对硝化作用的影响在不同土壤间差异明显 ;但不同土壤在田间持水量 (F H C)的 60时 ,硝化作用的最大速率 (Kmax)及硝化率最高。土壤温度不仅显著影响硝化作用的最大速率 (Kmax)和硝化率 ,而且迟缓期 (td)也有明显变化。不同氮肥品种对硝化作用的影响主要表现在硝化率不同 ,3种土壤硝化率均为硫酸铵 >尿素和碳铵 >氯化铵 ,显示硫酸根离子的促进作用和氯离子的强烈抑制作用。但氮肥品种对硝化作用的最大速率 (Kmax)和迟缓期 (td)的影响不规律。
Leaching of nitrate causes several serious environment problems. It is better to understand the nitrification process in different soil types, so that it could be managed, especially in proper fertilization way to reduce nitrate leaching. Nitrification research has not been paid more attention to this area. Purpose of this paper is to study nitrification in three types of managed soils from three ecological regions of Shaanxi Province, China. They were Loess soils from north, Cumulic cinnamon soils from middle and paddy soils from south of the province, the soil pH was 8 18, 8 22 and 6 52, and the physical clay contents were 23 10 % , 40 00 %, and 55 12 %, respectively. The changes of NO 3 N accumulation with time were determined during the process of nitrification under various moisture, temperature regimes and four nitrogen fertilizers in the laboratory incubation. The equation, d N /d t = bN(B-N) , was used to express the accumulation of nitrate (NO - 3) with time. The maximal rate of nitrification ( K max ) and the delay period ( t d ) were derived from the equation and used to characterize quantitatively the nitrification process in different soil conditions. Soil moisture content obviously affected the nitrification. Particularly significant differences existed among the maximal rates of three soils at the same water content; but the delay period had no remarkable differences. While soil moisture content maintained 40 % of field holding capacity ( FHC ), K max of loess soils, cumulic cinnamon soils and paddy soils were 11 4, 4 72 and 2 61 mg/kg -1 ·d -1 , respectively. At 60 % of FHC , K max were 15 12, 14 04 and 8 55, and K max were 14 10, 10 12 and 3 77 mgkg -1 d -1 at 80% of FHC , respectively. K max of cumulic cinnamon soils and paddy soils changed significantly with soil moisture, but not loess soils. This is related to clay content of soils. Comparison 80 % to 40 % of FHC , the latter largely reduced nitrification of loess soils and cumulic cinnamon soils, but not on paddy soil. 60 % of FHC was proper for carrying on nitrification. Nitrification was fairly sensitive to soil temperature, K max and t d changed largely under low or high soil temperature. When soil temperature was 20 ℃ and 30 ℃, K max and t d were 6 98, 15 12 mgkg -1 d -1 and 2 9, 1 46 d for loess soils, 11 28, 14 04 mgkg -1 d -1 and 6 4, 1 44 d for cumulic cinnamon soils, 3 84, 8 55 mgkg -1 d -1 and 4 46, 3 45 d for paddy soils, respectively. Temperature of 20 ℃ not only decreased K max but also prolonged t d, and 40 ℃ seriously restrained nitrification in all soil samples. Nitrifying bacteria are more response to soil temperature than to soil moisture. 30℃ was suitable for conducting nitrification under experimental soil samples. It was no any certain regulation that different nitrogen fertilizers influenced on K max and t d in all soil samples. After adding ammonium sulfate, ammonium chloride, ammonium bicarbonate and urea, K max and t d were 15 12, 15 39, 16 28, 18 00 mgkg -1 d -1 and 1 46, 1 63, 1 41, 1 56 d for loess soils, 14 04, 12 58, 14 40, 9 68 mgkg -1 d -1 and 1 44, 3 05, 3 32, 2 70 d for cumulic cinnamon soils, 8 55, 4 61, 4 39, 5 36 mgkg -1 d -1 and 3 45, 3 44, 2 19, 2 54 d for paddy soils, respectively. On loess soils urea had the highest K max , ammonium bicarbonate on cumulic cinnamon soils and ammonium sulfate on paddy soils. t d had no big difference in each soil sample. However, the maximal NO - 3N accumulation rate of these fertilizers in three soil samples was in a descending order of ammonium sulfate > urea > ammonium bicarbonate > ammonium chloride. The effects on nitrification for the different N fertilizers depended on their anion containing, SO 2- 4 could be beneficial to nitrification, in contrast Cl - could seriously restrai
出处
《生态学报》
CAS
CSCD
北大核心
2002年第12期2147-2153,共7页
Acta Ecologica Sinica
基金
陕西省科委资助项目
关键词
温度
水分
氮源
土壤硝化作用
影响
最大速率
迟缓期
氮肥品种
nitrification
the maximal rate
delay period
soil moisture
soil temperature
N fertilizers
