Spatial heterogeneity of soil fertility in coastal zones: a case study of the Yellow River Delta, China

Abstract

At the intersection of land and sea, coastal zones are unstable areas that can suffer intensive coastal erosion or sedimentation. The Yellow River Delta, which has experienced rapid land growth, is of great significance in soil fertility research. To qualitatively and quantitatively analyse the basic soil fertility characteristics of coastal zones, we sampled six soil chemical indicators obtained from the Yellow River Delta in July 2019. Principal component analysis (PCA) and the Nemoro quality index (NQI) were integrated for the geostatistical analysis of soil fertility by using the ArcGIS and SPSS software. The NQI, modified NQI (mNQI) and PCA results significantly represented soil fertility, and the mNQI performed better than the NQI. The soil fertility met the classification of ‘III, generally fertile’. The main factors affecting soil fertility were total potassium, total nitrogen and organic matter. The soil fertility indexes declined consistently from west to east. Increasing distance from the sea significantly negatively affected soil fertility, while soil fertility positively impacted land productivity. Therefore, future agricultural planning should focus on soil total nitrogen, total potassium and organic matter and control salinization to improve land productivity. The eastern coastal zone, especially the south-eastern region, should be the first area of focus.