Abstract

This study was undertaken to determine the spatial variability of pH, organic matter, soil salinity and spear yield of asparagus (Asparagus officinalis L.) in an area of plastic-greenhouse cultivation on Chongming Island, an alluvial island in the Yangtze River Delta and forming part of Shanghai City. Classical statistic and geostatistic analysis were applied. Results showed that, different soil properties were found to have different spatial heterogeneities as a result of agricultural practices and fertilization. Spatial dependences of the electrical conductivities of 1:5 soil: water extracts (EC), organic matter (OM), exchangeable sodium percentage (ESP) and total soluble salt (TSS) were moderate, while pH was high. Soil EC varied from 0.27 to 2.10 mS cm^-1, pH from 6.59 to 8.28, OM from 0.3 to 3.4%, ESP from 2.4 to 16.7 and TSS from 0.07 to 1.11%. In this study, Ca²⁺, Mg²⁺ and K⁺ were the predominant soil cations, while the anions were Cl^-, NO₃^-, SO₄^2- and HCO₃^-. In addition, the in situ electrical conductivity of greenhouse soil had a significantly positive correlation (R2 = 0.97) with soil EC. Meanwhile, different fertilization management practices had significant effects on asparagus spear yield (P < 0.05).

Key words: Greenhouse cultivation, soil quality, asparagus, spatial variability, geostatistic.