Effect of Saline Aquaculture Effluent on Salt-Tolerant Jerusalem Artichoke (Helianthus tuberosus L.) in a Semi-Arid Coastal Area of China

An experiment with six treatments: CK1 (rainfed), CK2 (irrigated with freshwater), and 4 treatments of saline aquaculture effluent blended with brackish groundwater at different ratios of 1:1, 1:2, 1:3, and 1:4 (v/v) was carried out during 2004 to assess the effect of saline aquaculture effluent on plant growth and soil properties in the Laizhou region, Shandong Province, China and to determine an optimal salinity threshold for aquaculture effluent. Cumulative evapotranspiration for the saline aquaculture effluent irrigation and non-irrigation treatments was lower than that for the freshwater irrigation treatment. Soil electrical conductivity was higher with respect to saline aquaculture effluent irrigation treatment compared to that with respect to non-irrigation or freshwater irrigation treatment. For Jerusalem artichoke (Helianthus tuberosus L.), in comparison to the freshwater treatment, plant height and aboveground biomass for the 1:3 and 1:4 treatments were constrained, whereas stem width and root biomass were enhanced. Concomitantly, higher tuber yield was obtained for the 1:3 and 1:4 treatments compared to that for CK1 and 1:1 treatments. Nitrogen and phosphorus were higher in tubers of the 1:4 treatment. This study demonstrated that saline aquaculture effluent could be used successfully to irrigate Jerusalem artichoke with higher tuber yield and nutrient removal.

Modeling Cadmium Transport in Neutral and Alkaline Soil Columns at Various Depths

Human health has been potentially threatened by cadmium (Cd) contained in sewage irrigation water.Previous studies of Cd transport in soils were mainly conducted using small soil cores with pH values less than 6.The objectives of this study were to determine the parameters of the convection-dispersion equation (CDE) for Cd transport in relatively larger columns with neutral and alkaline soils,and to investigate the parameters' variability with depth.The soil columns were 50 cm in length and 12.5 cm in diameter.Ceramic suction lysimeters were buried at depths of 2.5,7.5,17.5,27.5,and 37.5 cm to abstract soil solution.Cd concentration in the soil solution samples were subsequently analyzed to obtain breakthrough curves (BTCs).Equilibrium and nonequilibrium models in CXTFIT program were used to estimate parameters of the CDE.The results suggested that both equilibrium and non-equilibrium models performed well in modeling Cd transport.The hydrodynamic dispersion coefficient (D) ranged from 0.18 to 10.70 cm 2 h 1,showing large differences among different depths.The retardation factor (R d) ranged from 25.4 to 54.7 and the standard deviation of R d value was lower than 30% of the mean value.Precipitation coefficient (R p) decreased consistently with increasing depth,varying from 1.000 × 10 10 to 0.661 h 1.Sensitivity tests showed that D was less sensitive than R d.These results would be helpful in understanding the transport and retention of Cd in non-acidic soils.