Nitrogen Use Efficiency of Paddy Husk Biochar-Based Organic Fertilizers Applied to Capsicum Plants Grown in an Ultisol.

Purpose: Low Nitrogen Use Efficiency (NUE) of urea (U) in vegetable cultivations leads to environmental pollution. This study aimed to develop N-enriched paddy husk biochar-based organic fertilizers (BOF) using liquid organic fertilizers such as fish tonic (FT) and cattle slurry (CS) as a potential solution for the low NUE. Research Method: Paddy husk biochar (BC) was enriched with N using FT, CS, and U and pelletized to produce BOF_FT and BOF_CS, and SRF_U respectively. A pot experiment was conducted using Capsicum annum with 100% N from four fertilizer treatments and 0% N control. Growth, N nutrition and NUE of plants were measured. Findings: Nitrogen content in BC (0.59%) was increased to 2.0% and 1.1% by incorporating FT and CS, respectively, while 23.0% in the SRFU. The BOFFT was comparable to urea (U), only treatment on growth and NUE of Capsicum plants. As unutilized N in BOF_FT is in organic forms, their losses to the environment should be low. BOF_CS could not provide the required N for the growth of Capsicum plants. Intercalation of U into BC provided the highest growth (5.1 g/plant) and NUE (16.7 kg/kg N) among all treatments, suggesting the requirement for further improvements to BOF_FT. Research Limitations: Produced fertilizers should be tested under different eco-physiological situations to obtain a solid overview of their performance. Originality / Value: This is the first attempt to produce paddy husk biochar-based organic fertilizers by enriching biochar with N using cattle slurry and fish tonic. [ABSTRACT FROM AUTHOR]