CAJ | 학술논문

土壤氮矿化速率常被作为生态系统中氮有效性和氮损失的指标。不同的土地利用方式可能影响土壤氮素的矿化、运输和植物的吸收与利用，因而造成土壤氮素循环过程的差异。该研究以苏北沿海地区杨树纯林、杨农复合、草地和农田等4种不同土地利用模式为研究对象，采用原位封顶法测定了土壤矿质氮含量的变化，分析了不同土地利用方式土壤氮净矿化速率的特征，以及土壤矿质氮与土壤微生物量氮（ SMBN）、土壤水溶性有机氮（ WSON）与土壤主要理化性质的相关关系。结果表明：不同土地利用方式土壤净矿化速率从大到小表现为杨树纯林＞杨农复合＞农田＞草地；土壤铵态氮（NH＋4-N）与N矿化速率、SMBN、全氮有显著的正相关（p＜0．05）；土壤硝态氮（ NO-3-N）与SMBN、WSON、有机碳有极显著的正相关（ p＜0．01）；NH4＋-N、矿质总氮（ TMN）与土壤C/N有极显著的负相关（ p＜0．01）。土壤矿质氮含量随土层的加深而显著减少；在＞10～25 cm土层，杨树纯林与杨农复合之间的土壤矿质氮含量差异显著（ p＜0．05）。研究结果表明土地利用方式的改变将影响土壤氮净矿化速率，森林转变为农田或农林复合结构后，氮在土壤中的储量和循环速率显著降低。
토양담광화속솔상피작위생태계통중담유효성화담손실적지표。불동적토지이용방식가능영향토양담소적광화、운수화식물적흡수여이용，인이조성토양담소순배과정적차이。해연구이소북연해지구양수순림、양농복합、초지화농전등4충불동토지이용모식위연구대상，채용원위봉정법측정료토양광질담함량적변화，분석료불동토지이용방식토양담정광화속솔적특정，이급토양광질담여토양미생물량담（ SMBN）、토양수용성유궤담（ WSON）여토양주요이화성질적상관관계。결과표명：불동토지이용방식토양정광화속솔종대도소표현위양수순림＞양농복합＞농전＞초지；토양안태담（NH＋4-N）여N광화속솔、SMBN、전담유현저적정상관（p＜0．05）；토양초태담（ NO-3-N）여SMBN、WSON、유궤탄유겁현저적정상관（ p＜0．01）；NH4＋-N、광질총담（ TMN）여토양C/N유겁현저적부상관（ p＜0．01）。토양광질담함량수토층적가심이현저감소；재＞10～25 cm토층，양수순림여양농복합지간적토양광질담함량차이현저（ p＜0．05）。연구결과표명토지이용방식적개변장영향토양담정광화속솔，삼림전변위농전혹농림복합결구후，담재토양중적저량화순배속솔현저강저。
In order to study the effect of different land use patterns on soil N mineralization, transportation, absorption and utilization of plant, and which lead to difference of soil nitrogen cycle, we selected four different land use patterns (i.e. poplar plantation, crop-poplar integrated system, meadow and cropland) in a coastal area of northern Jiangsu as the experimental sites. The variations of soil mineral N were determined by close-top incubation method. The soil net N mineralization rate, soil microbial biomass nitrogen ( SMBN) , water-soluble organic nitrogen ( WSON) and soil physical and chemical properties were analyzed. The results showed that the net N mineralization rate decreased in order of poplar plantation, crop-poplar integrated system, cropland and meadow. Ammonium N was significantly positive correlated with microbial biomass nitrogen and total nitrogen, the nitrate N was significantly positive correlated with microbial biomass nitrogen, WSON and organic carbon, but the soil C/N was significantly negative correlated with ammonium N and total mineral nitrogen. The soil mineral nitrogen decreased with soil depth increasing. In 25-40 cm soil layers, the soil miner-al nitrogen had significant difference with poplar plantation and crop-poplar integrated system. The results indicated that different land use patterns would affect soil net N mineralization rate, and the conversion of forest into cropland or crop-forest system could also alter the cycle rate of nitrogen significantly.