Soil sampling optimization using spatial analysis in irrigated mango fields under brazilian semi-arid conditions

• Published in: Revista Brasileira de Fruticultura 2020-01, Vol.42 (5)
• Main Authors: Silva, Kátia Araújo da, Rodrigues, Marcos Sales, Moreira, Filipe Bernard Ramos, Lira, Aíris Layanne Ferreira, Lima, Augusto Miguel Nascimento, Cavalcante, Ítalo Herbert Lucena
• Format: Article
• Language: English
• Subjects: Geostatistics; HORTICULTURE; Mangifera indica L; Semivariogram; Spatial dependence
• ISSN: 0100-2945; 1806-9967; 1806-9967
• DOI: 10.1590/0100-29452020173

Abstract Soil sampling is a fundamental procedure in the decision making regarding the management of the soil, thus, a sampling plan should represent as accurately as possible the evaluated crop field. Therefore, the objectives of this study were to suggest a soil sampling approach and soil sampling point allocation using spatial analyses and compare to the classic statistic method in irrigated mango orchards in the Brazilian semi-arid region. The experiment was carried out in three commercial mango orchards located in the region of the São Francisco Valley, Brazil. Soil samples were collected in 0-0.2 m and 0.2-0.4 m depths following regular grids where the number of samples varied from 50 to 56. Soil texture, soil bulk density, soil total porosity, microporosity, macroporosity, pH, Ca, Mg, Na, K, Al, P, potential acidity, and the sum of basis were evaluated. Classical and geostatistical statistics were used to determine the ideal number of soil samples. Fuzzy c-means clustering technique was used to separate the areas into homogeneous zones and to allocate the sampling points. The wide method of 20 individual soil samples proved to be inefficient. On the other hand, the use of geostatistics proved to be efficient and is required for each crop field. The c-means clustering was adequate to separate the areas into homogeneous zones and, thus, to assist the sampling point allocation. Resumo A amostragem do solo é um procedimento fundamental na tomada de decisão sobre o manejo do solo; portanto, um plano de amostragem deve representar o mais acuradamente possível o campo de cultivo avaliado. Os objetivos do estudo foram avaliar uma abordagem de amostragem de solo e a alocação de pontos amostrais usando análise espacial e comparar com o método da estatística clássica em pomares de manga irrigada na região do semiárido brasileiro. O experimento foi realizado em três pomares comerciais de manga, no Vale do São Francisco, Brasil. As amostras de solo foram coletadas nas camadas de 0-0,2 e 0,2-0,4 m, seguindo grades regulares, onde o número de amostras variou de 50 a 56. A textura do solo, de densidade, porosidade total, microporosidade, macroporosidade, bem como seu pH, Ca, Mg, Na, K, Al, P, acidez potencial e a soma de bases foram avaliados. Estatística clássica e geoestatística foram usadas para determinar o número ideal de amostras de solo. A técnica de agrupamento fuzzy c-means foi usada para separar as áreas em zonas homogêneas e alocar os pontos de amostrage