Field balances and recycling rates of micronutrients with various fertilization treatments in Northeast China

Abstract

Due to their effects on human health, recent research in China has focused on the status of micronutrients in agro-ecosystems. In this study, we analyzed the concentrations of available micronutrients in cropping systems, their recycling rates in the feeding-composting cycle, and their field balances. Our results showed there were significant differences in the concentration of available micronutrients among treatments, with micronutrients found highest in the NPK + M (recycled pig manure) treatment. The recovery ratio of feed stuffs and bedding materials by a feeding-composting cycle was 25%, which was lower than the residual ratio of organic material that was decomposed for 1 year. The recycling rate of Zn, whose concentration was the lowest compared with that of other elements, was about 80%, while the recycling rates of Fe, Mn and Cu were between 85 and 90%. Micronutrient inputs by mineral fertilizer were lower than those of manure. Outputs were determined by crop yield and significantly differed among the treatments. The micronutrient contents from atmospheric deposition were 28–68 and 4–11 times greater than mineral fertilizers and manure, respectively. The balances of micronutrients were positive in all treatments, while excesses were lower in the NPK and CK treatments compared to other treatments. Since the pool of micronutrients is large, it may take hundreds of years to alter the concentration of micronutrients after reclamation. The recycling of nutrients had a positive effect on the balance of soil micronutrients, but we observed no significant changes in total micronutrient concentrations after reclamation.