Effects of phosphate fertilization and sulfadiazine on plant growth, root morphology, nitrogen and phosphorus uptake of soybean and maize

Low soil phosphorus (P) availability is a limiting factor for crop production. Application of livestock manure as organic fertilizer can increase soil P availability, but may cause soil contamination with antibiotics such as sulfadiazine (SD), thus adversely affecting plant growth and nutrient uptake. The effects of P (0 and 50 mg kg−1) and SD (0, 1, 10, and 100 mg kg−1) levels on plant growth, root development, and nitrogen (N) and P uptake of maize and soybean were examined in a pot experiment using a loess soil as the test soil. High levels of SD considerably inhibited plant growth of both crops. Both P fertilization and SD negatively affected root development of both crops, especially at higher SD levels. For both crops, the average root diameter and the proportion of thick roots increased with increasing soil SD level. When soil SD level was ≤10 mg kg−1, the effects of P fertilization and SD on plant N and P concentrations, and N:P, N- and P-utilization efficiency were not significant in most cases. The effects of SD on plant N and P nutrition could not be of a great concern when soil SD level was ≤10 mg kg−1. Overall, soil SD pollution could reduce plant biomass and inhibit root development of soybean and maize, with a stronger effect on root development than on plant biomass at a high soil SD level (≥10 mg kg−1). In agricultural production, attention should be paid to soil SD pollution via manure application.