Sampling Design Optimization on Arable Lands for Integrated Soil Monitoring for Sustainable Production

Abstract

Proper experimental design that ensures effective sampling of each recorded environmental variable is essential during planning integrated soil-monitoring programs with the aim of assessing the ecological state of soils. In our study, three different regular sampling designs (standard, 50,000 m²; reduced area, 635 m²; and reduced area and sampling size, 2500 m²) were tested, and the required sampling sizes for 10%, 20%, and 40% minimum detectable change were calculated. Sampling designs were tested from the aspect of the most effective sampling, a sampling with the greatest precision and the least bias. The parameters determined in this study were the following: total microbial activity, concentration of 14 potentially toxic microelements, and basic soil physical and chemical characteristics. The results are presented by the example of total microbial activity and microelement concentration studies. Twenty to 120 soil samples were taken from each selected arable land under intensive and organic cultivation as well as from a pasture and protected grassland, considered as a control. It was concluded that both for microbial activity and microelement concentration measurements of 10% minimum detectable change requires enormous sampling effort at each site and sampling design. The required sampling size is especially high at the organic sites and the grassland, because the high standard deviation, and especially high mean total microbial activity. With a sampling using either the standard or reduced area design, 20% difference in total microbial activity can be detected using a reasonable (<25) sampling size. However, reduced area design minimizes spatial heterogeneity, thus requires smaller sampling effort, and can be an ideal compromise. In the case of microelement concentration, standard sampling design was more sufficient to detect a 20% change. Designs that proved to be most efficient in this study have been combined into a joint sampling design that will be applied in the first cycle of the new Hungarian Soil Degradation Monitoring System.

Keywords:

• Microelements
• sampling design
• soil microbial activity
• soil monitoring
• soil sampling

Acknowledgments

The research was funded by the Complex Monitoring System for Analytical Detection and Biological Evaluation of Soil Micropollutants for a Sustainable Environment project (NKFP_07_A4-MONTABIO). We thank our colleagues at RISSAC for their contribution in field sampling (József Szabó, László Pásztor, Zsófia Bakacsi, Péter László, Sándor Koós, Judit Matus, Zita Krammer, and Annamária Laborczi) and laboratory work (Ilona Villányi and József Koncz) and their valuable remarks and support.