科尔沁沙地固定沙丘土壤氮素空间分布特征研究

Spatial Distribution of Soil Nitrogen in Horqin Stable Sand Dune

为了研究固定沙丘土壤N素空间分布特征，选择以栽植小叶锦鸡儿25年后的固定沙丘为研究对象，从迎风坡、顶坡和背风坡3个位置4个层次（0-5、5-10、10-20和20-40cm）进行取样分析。研究结果表明：全N、NO3^--N和NH4^＋-N含量均随着土层加深而呈现出减少的趋势，0-5cm土层显著高于其他各层。表层土壤受凋落物的影响较大，从而相对于深层土壤来说积累了更多的N素。全N、NO3^--N和NH4^＋N含量在不同坡位间存在显著差异（p〈0．01）：全N和NO3^--N含量在迎风坡较高，而NH40N含量在背风坡较高。丛下全N、NO3^--N和NH4^＋-N的含量显著高于丛间（p〈0．01）。土壤电导率与全N、NO3^--N、NH4^＋-N含量呈显著正相关，而pH与NO3^--N、NH4^＋-N含量呈显著负相关，NO3^--N、NH4^＋N的富集降低了土壤pH值。小叶锦鸡儿的栽植对沙土改良具有重要意义。

To study the spatial distributions of soil nitrogen in stable sand dune, samples were collected at different depths （0-5, 5-10, 10.-20and 20-40 cm） from windward slope, top slope and leeward slope in the stable sand dune of Horqin Sandy land aRer the establishment of Caragana microphylla Lam for 25 years. The results showed that the contents of total N, NO3^--N and NH4^＋-N decreased with the increase of soil layers. The differences of total N, NO3^--N and NH4^＋-N from different slopes were significant （p〈0.01）, and the differences under shrub soil were higher than under shrubs （p〈0.01）. Nutrient contents at depth of 0-5 cm were higher than at other layers, which suggested more nitrogen was accumulated in surface layer as result of litter falling. The correlations between electrical conductivity and contents of total N, NO3^--N and NH4^＋-N were positive significantly （p〈0.01）, but the correlations between pH and the contents of NO3^--N and NH4^＋-N were negative significantly （p〈0.01）. Our results revealed that the enrichment of NO3^--N and NH4^＋-N can decrease pH value. The establishment of Caragana microphylla plays an important role in improving sandy land soil.