2种不同土地利用方式对山麓耕地土壤养分的影响

Effects of two land use types on soil nutrients of piedmont arable land in south-eastern part of Gansu province

研究不同土地利用方式对土壤养分的影响,以便了解土壤质量状况,为实现不同植被管理和可持续利用提供科学依据。以小陇山山麓区移栽至耕地(前期种植柴胡)后生长3年的油松Pinus tabulaeformis Carr.苗木土壤为对象,并以长期种植柴胡Bupleurum chinense的耕地作对照,采用对比和主成分分析方法,对2种人工植被类型下不同土层(0～10、10～20和20～30 cm)土壤养分特征进行了分析。结果表明:1)油松苗地3个土壤层的有机质、全磷和全钾含量均小于柴胡耕地,除0～10 cm土层有机质外,其余差异均达到显著水平(P <0.05);3个土壤层的全氮含量在油松地和柴胡地两者之间均无显著差异(P> 0.05)。油松苗地3个土壤层的速效钾均显著大于柴胡地(P <0.05);而有效磷含量却小于柴胡地(10～20 cm除外),且仅在20～30 cm土层两者差异达显著水平(P <0.05);同样,3个土壤层的碱解氮含量在油松地和柴胡地两者之间均无显著差异(P> 0.05)。2)2种植被类型下土壤的有机质、全氮、全磷、碱解氮、有效磷和速效钾含量表现出"表聚现象",即养分含量从表层向下层呈递减趋势;而全钾含量在2种植被类型下均表现出相反的变化趋势,即从表层向下层呈递增趋势,但差异均不显著(P> 0.05)。3)主成分分析表明:速效钾和全磷是影响油松苗地土壤质量的最主要土壤因子,而全氮和全磷是影响柴胡地土壤质量的最主要土壤因子,且土壤养分综合得分表现为油松地(1.467)<柴胡地(1.504)。可见,油松人工苗明显地降低了耕地土壤养分含量,长期栽植将会导致土壤养分处在较低水平,因此在大苗培育期间要因土施肥,提高土壤肥力,尤其需要及时补充土壤有机磷肥;而对柴胡耕地也应该补充有机氮肥和磷肥。这些结论可为小陇山山麓区域耕地进行土地合理利用和土壤科学管理提供科学参考。

By taking the land soil of P.tabulaeformis seedlings after transplanted from piedmont to arable land(the land early stage planted Bupleurum chinensis)and having been grown in for3years as the tested materials,that of B.chinensis in which B.chinensis seedlings were planted long term as the control soil,and by means of comparison and principal component analysis,the soil nutrient characteristics of different soil layers(0~10,10~20and20~30cm)under two types of artificial vegetation were analyzed in the southeastern part of Gansu province.The findings are as follows.1)The organic matter,total P and total K content in3layers soil were lower in P.tabulaeformis seedling land soil samples as compared to those of B.chinense land soil,except for0~10cm soil organic matter,the rest of the differences reached a significant level(P<0.05).The total N contents in land soils of P.tabulaeformis seedling and B.chinense were not significant differences(P>0.05)between in two types of seedlings.The available K contents in3layers soils of P.tabulaeformis seedlings were significantly greater than the available P contents in two layers(0~10cm and20~30cm)soils of B.chinensis,while the content of available phosphorus was lower than that of B.chinensis(except10~20cm),and the difference was significant only in20~30cm soil layer(P<0.05).Similarly,the contents of alkali hydrolysable nitrogen in3layers soil were not significant differences between P.tabulaeformis and B.chinensis(P>0.05).2)The organic matter,total N,total P,available nitrogen,available P and available K content in the soils of planting the two trees showed a surface gathering phenomenon,namely the soil nutrient contents all were a decreasing trend from upper to lower layer of soil,however,the total K content showed an increasing trend from upper to lower layer of soil,but their differences was not significant(P>0.05).3)The principal component analysis showed that the dominant soil factors influencing the soil quality of P.tabulaeformis respectively were available K and total P,while the dominant soil factors influencing the soil quality of B.chinense respectively were total N and total P,and the comprehensive scores of soil nutrients showed that:the score of P.tabulaeformis land(1.467)was less than that of B.chinensis land(1.504).Thus it can be senn,the seedlings of P.tabulaeformis plantation obviously reduced the soil nutrients content,long term planting artificial seedlings of P.tabulaeformis will lead to a low level of soil nutrients.Therefore,it is necessary to apply fertilizer to improve soil fertility according to soil condition during the seedling cultivation period,especially to supplement soil organic phosphorus fertilizer in time,and organic nitrogen and phosphate fertilizer should also be added to the farmland of B.chinensis.