Method for passivating heavy metal in rice field and increasing nitrogen immobilization amount

Abstract

The invention relates to a method for passivating heavy metal in the rice field and increasing nitrogen immobilization amount. The method comprises steps as follows: a rice planting area is selected,after base fertilizer is applied, rotary tillage and irrigation are performed, and water depth keeps 3-4 cm; rice seedlings are transplanted in the rice planting area, and the water depth of field surface keeps 3-4 cm; after the seedlings revive, microalgae bio-fertilizer water is sprayed, periphytons in the planting area are observed periodically, the microalgae bio-fertilizer water is added according to the growth vigour condition, and the water depth of field surface keeps 1-2 cm; and after rice harvesting is finished, lower straw is retained, and the periphytons and the straw in the rice field are turned into the ground by rotary tillage. According to the method for passivating heavy metal in the rice field and increasing the nitrogen immobilization amount, periphyton community is constructed by application of microalgae bio-fertilizer, soil pH is changed through photosynthesis and growth and metabolism activity of algae, furthermore, a large quantity of extracellular polymeric substances are secreted, and heavy metal adsorption, passivation capacity and biological nitrogen fixation ability of the periphytons are improved. The method has the characteristics of being low in cost, flexible and easy to operate and is one green eco-technological approach.

Description

technical field [0001] The invention belongs to the field of agriculture and environmental protection, relates to the fields of passivation of heavy metals in paddy fields and improvement of fertility, and in particular relates to a method for passivating heavy metals and increasing the nitrogen fixation capacity of paddy soil. Background technique [0002] Heavy metal pollution is one of the main types of soil pollution. In my country and even the world, due to the discharge of industrial and mining wastes and excessive use of pesticides, heavy metals accumulate in the soil around industrial and mining areas and farmland, and soil health quality declines. Therefore, soil heavy metal pollution remediation technology has attracted much attention. Cadmium (Cd) is a heavy metal element with strong biological toxicity. It has strong chemical activity and long-lasting toxicity in the environment. It is easy to endanger human health through the enrichment of the food chain and ind...

AI Technical Summary

Problems solved by technology

However, the composition of the restoration agent in this method is complex, and the water content of the soil needs to be maintained at 25-40% to ensure the restoration effect

CN106591277A discloses a preparation and application method of bacillus with both passivation of heavy metals and phosphorus-solubilizing functions, mainly by expanding the cultivation of bacillus cereus, and then adding biochar to its fermentation liquid and continuing to cultivate to obtain immobilized bacillus, Thereby while reducing the bioavailability of cadmium, increase available phosphorus content in soil, guarantee the growth of crops, yet, the bacterium used in this invention is single strain (Bacillus cereus), its passivation when microhabitat changes in field environment The effect of heavy metals and phosphorus solubilization will be greatly reduced

However, monitoring shows that the current season utilization rate of nitrogen fertilizer in rice planting in my country is lower than 30%, and the high loss rate is the main reason for the low nitrogen utilization rate. Among the lost nitrogen, the nitrogen lost through runoff and other liquid forms About 10% of the amount of fertilization