Soil Nutrient and Rice (Oryza sativa L.) Growth Characteristics under Different Arsenic Contamination Levels

Abstract

Arsenic (As) contamination in agricultural soils causes adverse influences on crop growth and yield, and serious human health issues. The objectives of this study were to (a) verify the change of chemical properties under different As contaminated soils, (b) compare the growth and yield of rice grown in different concentrations of As-contaminated soil, and (c) investigate the relationship between total As and phytoavailable As concentrations in the soil and As concentrations accumulated in the polished rice. Rice plants were cultivated in a greenhouse under six As concentrations: 6 (control), 25, 34, 42, 50, and 59 mg kg-1. Soil As concentration showed significant positive correlations with NH4-N, available P2O5, and exchangeable K. A significant negative correlation was indicated between soil As concentration and NO3-N, whereas no significant correlation was found between soil As concentration and total N. Increased soil arsenic decreased plant heights and number of tillers; caused yield reduction depending on the increasing As concentrations in soils. The yield of As-exposed rice plants was 38 - 90% less than that of untreated plants. This was mainly due to the reduced number of panicles per plant and spikelets per panicle. We also found that total and phytoavailable As concentrations in the soil for the edible limit of As in polished rice (0.2 mg kg-1) were 21.85 and 1.04 mg kg-1, respectively. Relationship between As concentrations and available P2O5 (A) and exchangeable K (B) concentrations in the soil at the harvesting stage of rice plants.