Abstract:
Phosphogypsum (PG) is one of the largest industrial solid wastes, which stacked on the open yard could pose many environmental risks. Meanwhile, PG contains phosphorus (P), sulphur (S) and the other plant-essential nutrient elements, so that the application feasibility of PG in agriculture is very important for sustainable development of phosphate fertilizer and complex fertilizer industry. PG also contains harmful substances for human body such as arsenic (As). Mycorrhizal fungi may play an important role in protecting plants against As uptake under As and other heavy metals stress. Therefore, the introduction of mycorrhizal technology may become an effective and new way of application PG to the soil with P deficiency and low S. A pot experiment was conducted to study the plant growth and P, S and As uptake by shallot (Allium schoenoprasum L.) under 3 different PG addition levels (0, 20, 40 g/kg) (PG0, PG20, PG40) and inoculating 3 different arbuscular mycorrhizal fungies (AMF) (Glomus mosseae (GM), Glomus aggregatum (GA), Diversispora spurcum (DS)). This objective of this research was to explore the potential utilization value of PG compound with mycorrhizal technology to agricultural soil for Southern China. Furthermore, the experiment was carried out in the plastic greenhouse located at Yunnan Agricultural University in November 2010. The samples were harvested after plant growth for 14 weeks. Mycorrhizal colonization rate, dry weight, P, S and As concentrations in shallots were determined. SPSS11.5 statistical software was used for analyzing the interactions for PG addition and AMF inoculation treatments. The results showed that a low root colonization rate (<30%) was detected. The biomass of shallot was increased with the increasing PG additive levels. Concentration of P, S and As in shallots also increased with the increasing PG additive levels. For PG20 and PG40 treatment, GM, GA and DS colonization respectively can improve plant biomass and P uptake by shallot at different degrees. Comparing with corresponding control treatments, the treatment of PG40 addition together with GM inoculation had a significant effect in improving shallot biomass and P, S uptake. This treatment had the best growth-promoting effect in soil with P deficiency and low S. Meanwhile, the uptake ratio of P to As in shallot was the highest for GM inoculation with PG40. As concentrations in shallot were decreased significantly in the treatments of GM and GA inoculation with PG20, which were lower than the national arsenic limit standard for food. However, As concentration in shallot with PG40 combined with DS inoculation was in food arsenic limited standard, which showed the most obvious anti-arsenic effect. Therefore, the PG40-DS combined treatment and PG20 with AMF inoculation appeared the perspective for promoting PG use and ensuring food security. When PG application rate of advantage anti-arsenic treatment is 20 and 40 g/kg soil, respectively, the application amount of 2700 and 5400 kg per acre will be expected to be used to solve some problems from PG stacking on the field.