大理烟田土壤有效锌、钼和硼含量的时空变异及其影响因素

Temporal and spatial variation of soil available zinc,molybdenum and boron contents in Dali tobacco-growing fields and the influencing factors

【目的】研究大理州烟田土壤有效锌、钼和硼含量时空分布及影响因素,旨在为科学的施肥策略及优质烟叶生产提供理论指导。【方法】2012和2022年,在云南大理州平原地区选取连片烟田,分别采集了1131和4512个烟田耕层(0—20 cm)土壤样品。调查采样点经纬度和海拔、地形、土壤质地和前茬作物等信息,分析土壤理化性质。结合1982第二次土壤普查数据,运用地统计学方法分析1982、2012和2022年土壤有效锌、钼和硼含量的时空分布,利用回归分析和随机森林模型量化土壤有效锌、钼和硼含量变化的主要影响因素。【结果】1982、2012和2022年土壤有效锌含量平均分别为2.35、3.50、4.35 mg/kg,呈上升趋势;有效钼含量分别为0.18、0.14、0.11 mg/kg,呈下降趋势;有效硼含量分别为0.26、0.63、0.58 mg/kg,呈先升后降趋势。空间上,1982、2012、2022年有效锌和硼块金效应分别为50.8%、45.5%、31.8%和41.3%、39.4%、33.8%,均呈中等空间自相关性,总体呈现四周高、中部低的地理分布格局,而有效钼的块金效应均小于25%,呈东南高、西北低的分布趋势。平原地貌土壤有效锌和硼含量显著高于山地;黏土中有效钼含量显著高于砂土和壤土,壤土中有效硼含量最高。土壤pH、有机质、碱解氮、有效磷、速效钾和海拔对3种元素的时空变异影响较强。土壤有效磷含量和海拔(解释率20.5%和16.8%)是有效锌含量变化的主要影响因子,海拔和碱解氮(解释率13.7%和12.8%)是有效钼含量变化的主要影响因子,碱解氮和速效钾(解释率分别为17.6%和15.6%)是有效硼含量变化的主要影响因子。【结论】大理州植烟土壤有效锌、钼和硼含量与40年前相比,均有不同程度的提高,目前分别处于丰富(Ⅴ级)、缺乏(Ⅱ级)和中等(Ⅲ级)水平。锌、钼和硼3种微量元素含量均同时受到地理环境、土壤质地和肥力的共同影响,也受到前茬作物的影响。为保证优质烟叶生产,总的原则是减锌保硼增钼,前茬作物为粮食和油菜时应注意施锌、施硼,前茬作物为豆科作物时应注意施钼。

【Objectives】The spatial and temporal distribution and the influence factors of soil nutrient contents reflects the rationality during a certain period of tobacco cultivation.The study will provide theoretical basis for scientific fertilization strategy in high-quality tobacco production of Dali Prefecture.【Methods】In 2012 and 2022,total of 1131 and 4512 top soil samples were collected in the tobacco fields of the plain area in Dali Prefecture,Yunnan Province.The location,altitude,soil texture and pre-crop information of each sample were investigated,and the physical and chemical properties were analyzed.The data of the second soil census in 1982 was used as reference.Geostatistics were used to analyze the spatial and temporal distribution of available Zn,Mo and B contents in 1982,2012 and 2022,and regression analysis and random forest model were used to quantify the main factors affecting the changes of soil available Zn,Mo and B contents.【Results】In 1982,2012 and 2022,the average available Zn content was 2.35 mg/kg,3.50 mg/kg and 4.35 mg/kg,respectively,showing an increasing trend;The available Mo content was 0.18 mg/kg,0.14 mg/kg and 0.11 mg/kg,respectively,exhibiting a downward trend.The available B content was 0.26 mg/kg,0.63 mg/kg and 0.58 mg/kg,respectively,showing a rising first and then decreasing trend.The nugget values of available Zn and B in 1982,2012 and 2022 were 50.8%,45.5%,31.8%and 41.3%,39.4%,33.8%,respectively,showing moderate spatial autocorrelation,and the available Zn and B contents were low in the middle and high in the outskirts of the test area geographically.The nugget values of available Mo were less than 25%,and showed a decrease trend from high in the southeast to low in the northwest.The available Zn and B contents were significantly higher in the plains than in the mountainous areas;the available Mo content was significantly higher in the clay than in the sand and loam soil,and the available B content was higher in the loam than in the other textures of soils.Soil pH,organic matter,available N,P and K,and the altitude strongly affected the spatial and temporal variation of the three elements.The main influencing factors were available P and altitude(interpretation rate 20.5%and 16.8%)for Zn,altitude and available N(interpretation rate 13.7%and 12.8%)for available Mo,and available N and K(interpretation rate 17.6%and 15.6%)for available B.【Conclusions】The soil available Zn,Mo and B contents in tobacco-growing fields in Dali Prefecture show a general increase,compared to 40 years ago,and are graded at V(rich),II(deficient)and III(moderate)levels at moment,respectively.All the Zn,Mo and B content were affected by topographic feature,soil texture and fertility.In general,Zn application should be appropriately controlled,B application be maintained,and Mo application be increased.However,Zn and B application should be considered when the previous crops are grain crop and rape,and Mo should be applied when following legumes crop,for the high-quality tobacco production in the test area.