Application of biochar-coated urea controlled loss of fertilizer nitrogen and increased nitrogen use efficiency

Yiman Jia,Zhengyi Hu,Wenfang Qi,Yuxin Ba

doi:10.1186/s40538-020-00205-4

Abstract

BackgroundThe use of biochar-based N fertilizers have been considered among the most effective strategy for reducing nitrogen loss and improving nitrogen use efficiency (NUE). However, effect and mechanism of biochar-coated urea (BCU) controlling the loss of nitrogen from soil and NUE are rarely reported.MethodologyIn this study, a 65-d culture pot experiment of oilseed rape was used to investigate the impact of BCU on nitrogen leaching, ammonia volatilization, soil nitrogen concentrations, soil pH, nitrogen uptake, NUE and oilseed rape biomass as compared with urea and urea combined with biochar at same nitrogen level.ResultsResults showed that the application of BCU could minimize nitrogen loss mainly by reducing nitrate leaching loss; which could be attributed to the slow-release performance of BCU, followed by biochar induced adsorption/fixation of nitrogen due to the porous nature and surface functional groups of biochar. However, the application of BCU enhanced ammonia volatilization due to the increase of soil NH4+–N concentration and pH value of microenvironment around urea by BCU. The application of BCU increased NUE by about 20% when compared with urea, since BCU reduced losses of nitrogen fertilizer and increased concentration of nitrogen in the soil as well as nitrogen uptake in oilseed rape. Furthermore, the reduction of nitrogen application by 20% when BCU served as a nitrogen source not only reduced nitrogen loss but significantly improved NUE, with no negative effect on the biomass of oilseed rape.ConclusionBCU can serve as a promising control release nitrogen fertilizer for reducing loss of nitrogen and increasing NUE. However further investigations are required to validate the dosage-effect relationship of BCU on crop yield at the field scale.

Highlights

The use of biochar-based N fertilizers have been considered among the most effective strategy for reducing nitrogen loss and improving nitrogen use efficiency (NUE)
CK, no fertilizer; U1, urea at 100% N rate; U2, urea at 80% N rate; U1 + B, biochar combined with urea at 100% N rate; U2 + B, biochar combined with urea at 80% N rate; BCU1, biochar-coated urea at 100% N rate; BCU2, biochar-coated urea at 80% N rate; BCU1 + B, biochar combined with biochar-coated urea at 100% N rate
Ammonia volatilization from CK continued until the 7th day of the experiment; from soils fed with urea until the 23th–25th day of the experiment; from soils fed with biochar-coated urea (BCU1,BCU2, BCU1 + B) until at least the 26th day of the experiment (Fig. 2a)

Summary

Introduction

The use of biochar-based N fertilizers have been considered among the most effective strategy for reducing nitrogen loss and improving nitrogen use efficiency (NUE). The reduction of nitrogen loss and improvement of NUE could be attributed to the porosity, large specific surface area, surface charges, variety of surface functional groups and a small amount of active carbon present in biochar [13,14,15]. These properties of biochar could increase soil water holding capacity, adsorp inorganic nitrogen, influence nitrification and denitrification of nitrogen in soil, increase microbial biomass, and change soil structure of bacterial community [16,17,18,19]

Methods

Results

Discussion

Conclusion