宁南山区不同年限撂荒梯田土壤碳氮磷化学计量特征

Stoichiometry of Soil C, N and P in Abandoned Terrace Lands with Different Years in Hilly Region of Southern Ningxia

为了探究不同年限撂荒梯田对土壤碳氮磷含量及其化学计量特征的影响,为宁南山区撂荒梯田的管理利用和植被恢复提供科学依据。选择宁南山区彭阳中庄示范区不同年限撂荒梯田(2,5,15,17,20 a)为研究对象,通过野外采样与室内测定相结合的方法,对研究区5个不同年限撂荒梯田0—60 cm土壤样品中的C,N,P元素含量及其化学计量比特征进行了分析。结果表明:在0—60 cm土层,不同年限撂荒梯田的土壤C,N分布规律一致,均随土层深度的增加而减小,表层0—10 cm出现了富集现象,且随着撂荒年限增加呈先降低后升高的趋势,其他4层呈波动式下降趋势,土壤全磷含量分布比较均匀。土壤C∶N随着不同撂荒年限的增加呈波动式升高趋势,撂荒20年0—40 cm土层土壤C∶N最高,并与其他各年呈显著性变化(p<0.05)。土壤C∶P和N∶P均表现为在表层0—10 cm随着撂荒年限的增加,总体呈现出先降低后升高的趋势,其他各层总体呈现下降的趋势。土壤C∶P和N∶P随土层增加呈减小趋势。土壤C∶N与全N和土壤C含量相关性不显著。土壤C∶P与土壤C含量呈极显著的正相关,与全磷含量呈显著的正相关。土壤N∶P与土壤全N含量呈极显著的正相关,与全磷含量呈显著的正相关。通过上述分析,总体反映出撂荒梯田土壤碳氮磷及其化学计量比受到不同年限和土层深度的双重影响,农地弃耕撂荒演替对土壤肥力有一定程度的改善。

We investigated effects of years of abandoned terrace lands on the stoichiometry of soil C,N and P,and provided scientific support for management and vegetation recovery of abandoned terrace lands in southern Ningxia.Abandoned terrace lands with different years(2 years,5 years,15 years,17 years,20 years)were selected as subjective to research the contents of soil C,N and P in 0—60 cm layers by combining the means of field sampling and laboratory analysis.The results showed that:in 0—60 cm layer,the contents of soil C and N decreased as depth increased,there was a enrichment of C and N in 0—10 cm layer,which declined first and increased as abandon years increased;the contents of C and N in 4 layers of subsurface profile declined with fluctuation,the total P evenly distributed in soil layers;the ratio of C∶N increased with fluctuation as abandon years increased,the C∶N was the highest in the 0—40 cm layer in abandoned land with 20 years of abandonment,and demonstrated a significant variation with other abandoned years(p<0.05);the ratios of C∶P and N∶P in 0—10 cm layer increased first and then declined with the abandonment years,but totally decreased in other layers,the ratio of C∶P and N∶P decreased as soil depth increased,the ratio of C∶N was not related to total N and C significantly,the ratio of C∶P was extremely significant related to soil C and significant related to total P,the ratio of N∶P was extremely significant related to soil N and significant related to total P.The contents and stoichiometry of C,N and P were affected by both abandonment age and soil depth.Abandonment of terrace land can improve soil fertility to a certain extent.