Difference In Vegetable Yield And Cadmium Accumulation With Six Different Planting Patterns In Cadmium Soil

A soil remediation experiment was performed to assess soil contaminated with cadmium (Cd) and how to addresses Cd problems in agricultural crops. The study was conducted in a soil polluted with Cd in Hubei DaYe. Local popular vegetables were used in this experiment. This study further explored the influences of planting patterns on the Cd absorption, accumulation in vegetables, content of Cd in vegetables as well as in the soil. Soil physical and chemical index were screened to provide better planting patterns and classify suitable vegetables to plant in Cd polluted site. Results were as follows:1. About the planting pattern M3"white radish-tomato-green radish", economic yield and economic coefficient and economic benefit were highest in six patterns, respectively to95944kg/ha,0.58and24.73Million/ha. In the M3treatment, Cd content in edible parts of vegetables were in the minimum significant level, separately were0.083,0.099,0.079mg/kgFW. In three vegetables varieties, Cd content did not exceed the allowed standards, M3treatment had two kinds of vegetables:white radish and green radish. The Cd superscale mutiples of tomatoes was0.98. The accumulation of Cd in the inedible parts of vegetables was high in M1"white radish-cowpea, water spinach B. campestris". Accumulation of Cd in M3reached32.2g Cd/ha which was significantly lower than M1. Nitrate content of each vegetable was at low level in M5"red radishs-eggplant-spinach", while M3ranked only second to M5. According to the basic of the comprehensive indexes of food safety, high quality, high yields, high economic benefits and environmental protection, the study considered M3" white radish-tomato-green radish" as the best planting pattern in soils polluted with Cd.2. The content of Cd in edible parts of different vegetables varied in following order: leaf vegetables> solanaceous fruit vegetables> root and stem vegetables> beans. The contents of Cd in vegetables leaf were0.362-2.342mg/kgFW, with the average of1.099mg/kg FW. The contents of Cd in solanaceous fruit vegetables were0.099～0.461mg/kgFW, with the average of0.332mg/kg FW. The contents of Cd in root and stem vegetables were0.053～0.144mg/kgFW, with the average of0.096mg/kg FW. The contents of Cd in beans were0.013and0.033mg/kgFW, with the average of0.023mg/kg FW. The content of nitrate in vegetable edible parts were lower than the standards of GB 19338-2003, and the ranges were:leaf vegetables> root vegetables> cowpea, stem vegetables and solanaceous fruit vegetables. The content of nitrate in spinach was lower. In all the vegetables, the contents of Cd in tomatoes, B. campestris, cowpea, green radish were less than0.1mg/kgFW, and the last three ones did nnot exceed the allowed standards, which were suitable for planting in Cd pollution area. Leaf vegetables did not advocate planting, if necessarily, this study suggested growing water spinach in summer, because it is Cd content were0.374mg/kgFW.3. The capability of Cd accumulation in different parts of vegetables varied in following order:edible parts lower than unedible parts, except individual. The change trends of Cd content in the inedible organs was as follow:root> stem> leaf, and which in all the vegetable organs was as follow:root>leaf in leaf vegetables, except for amaranth and interplanting cabbage, root>leaf in root vegetables, root> leaf> stem in stem vegetables, root> stem, leaf> fruit in solanaceous fruit vegetables and cowpea.4. The content of Fe, Mn, Cu, Zn, Ca, Mg in vegetables of M1and M2were the highest among all the rotations. Except for Fe and Mn, The cumulate of the other four elements in M3were the average. The accumulations of Fe, Mn, Cu, Zn in M4, M5, M6treatment was minimum the same applies to Ca, Mg in M5and M6. Fe, Mn, Cu, Zn, Ca, Mg cumulative amount of edible parts were lower than inedible parts among M1, M2and M3, except for Cu, Mg of M3whereas accumulative law in M4, M5, M6was opposite from the former three patterns, except for Fe, Ca in M5.5. The content of total Cd in the soil was not significant in the short term. Soil available Cd contents were as following:In season one, the Cd content in the rhizosphere soil was significantly high than in non-rhizosphere soil, and there were no significant differences between different patterns. In the second season, content of Cd in the rhizosphere soil in different patterns had no significant differences, the Cd contents in non-rhizosphere soil in M1, M3and M4were significantly lower than those of M2treatment, the rhizosphere soil were higher than the non-rhizosphere soil in all the patterns. In the third season there was no significant difference both in rhizosphere soil and non-rhizosphere soil. In season four, the content of Cd in rhizosphere soil were lower than those of non-rhizosphere soil, at which M2, M4, M5, M6treatments reached significant level. A negative correlation was observed between soil pH and available Cd, and that was significant in the rhizosphere soil. The relation ship between total Cd in the soil and available Cd content were positively, and it reached significant level in the rhizosphere soil.6. The Cd enrichment coefficients of edible vegetable parts are in group Ⅲ, in planting patterns M3" white radish-tomato-green radish" and M1"white radish-cowpea-water spinach-B. campestris". The transfer coefficient of vegetables in M3belonged to Ⅳ kind. So contents of Cd of vegetables in M3were lower than others. The inedible vegetable parts in M3treatments had relatively small Cd enrichment coefficients, but large biomass, which had certain ability to restore soil pollution to ensure vegetables safety. The coefficients of Cd enrichment and coefficient transfer of Leafy vegetables were large than other kinds of vegetables, thus these vegetables were not suitable for planting in soils polluted with Cd.