Spatial correlation between soil and leaf macronutrients in semiarid Brazilian mango (Mangifera indica L.) fields

Abstract Understanding the relationship between the levels of nutrients in the soil and those found in the plant is of fundamental importance for site-specific fertility management in mango (Mangifera indica L.) crop fields. This study aimed to evaluate the spatial distribution of macronutrient contents both in the soil and in the leaf and their correlations in commercial mango orchards under semiarid region conditions and to delimit the management zones using soil and leaf data. The experiment was carried out in three commercial areas in San Francisco Valley, Brazil, cultivated with irrigated mango. Soil samples were collected in 0-0.2 and 0.2-0.4 m depths as well as leaf samples following sample grids. Ca, Mg, K, P, and N contents from soil and leaf samples were determined. Descriptive and geostatistics analyses were performed. Co-kriging was used for the delimitation of management zones. Positive spatial correlations were obtained between soil Ca2+ and leaf Ca contents (R2 = 0.80-0.93), soil K+ and leaf K contents (R2 = 0.35-0.61), and soil Mg2+ and leaf P contents (R2 = 0.51). Negative correlations were observed for soil Mg2+ and leaf Ca contents(R2 = 0.79-0.93) and soil Mg2+ and leaf K contents (R2 = 0.98). The soil 0-0.2 m depth had the greatest influence on mango Ca and K uptake. The negative correlation between soil Mg2+ and leaf Ca shows the competition existing in the plant uptake process. It was possible to delimit specific management zones using co-kriging for the three areas using soil and leaf data.

摘要 明确土壤与植株体内养分水平的关联，对于芒果（*Mangifera indica* L.）种植田块的精准养分管理具有核心意义。本研究旨在评估半干旱区域条件下商业化芒果园中，土壤与叶片大量元素（macronutrient）含量的空间分布特征及其相关性，并基于土壤和叶片数据划定养分管理分区。本实验在巴西圣弗朗西斯科河谷（San Francisco Valley）的3个商业化灌溉芒果种植园区开展。按照采样网格法采集0~0.2 m、0.2~0.4 m土层的土壤样品以及叶片样品，测定了土壤与叶片样品中的钙（Ca）、镁（Mg）、钾（K）、磷（P）与氮（N）含量。开展了描述性统计与地统计学分析，并采用协同克里金（Co-kriging）法划定管理分区。研究发现土壤钙离子（Ca²+）与叶片钙含量、土壤钾离子（K+）与叶片钾含量、土壤镁离子（Mg²+）与叶片磷含量之间存在正向空间相关性，决定系数R²分别为0.80~0.93、0.35~0.61与0.51；而土壤镁离子（Mg²+）与叶片钙含量、土壤镁离子（Mg²+）与叶片钾含量之间则呈现负向空间相关性，对应R²分别为0.79~0.93与0.98。0~0.2 m土层的土壤养分对芒果钙与钾元素的吸收影响最为显著。土壤镁离子与叶片钙含量间的负相关关系，反映了植株吸收养分过程中存在的竞争效应。基于土壤与叶片数据，通过协同克里金法可对这3个园区划定精准的养分管理分区。