Biochar research from Papua New Guinea

Great to see biochar research coming from Papua New Guinea...

Effects of biochar, urea and their co-application on the nitrogen mineralization in soil and growth of Chinese cabbage crop

Ruth Baiga and Rajashekhar Rao BK*

Department of Agriculture
The Papua New Guinea University of Technology
Private Mail Bag, Lae 411
Morobe Province, Papua New Guinea
Tel: +675 4734464, Fax: +675 4734477

* Dr. Rajashekhar Rao B.K., E-mail: rsraobk@rediffmail.com

Abstract

Experiments were conducted to study the influence of biochar material on N mineralization pattern from the soil applications of kunai grass (Imperata cylindrica) biochar (at 0 and 10 t ha^-1) and laboratory grade urea (0, 200 and 500 kg N ha^-1) and their co-application to an acid soil. The results of incubation study showed that biochar only treatment and co-application with urea at 200 kg N ha^-1 could impede transformation of urea to NH₄⁺-N. Soil application of biochar together with urea 500 kg N ha^-1 produced the highest NO₃^--N and mineral N concentrations in the soil over 90 days. In a parallel study performed under greenhouse conditions, Chinese cabbage (Brassica rapa L. ssp. chinensis L.) crop showed highest marketable fresh weight, N uptake and N use efficiency in soil treated with biochar along with urea at 500 kg N ha^-1. However, soil incorporation of biochar only or combined application with urea did not offer any short-term agronomic advantages over mineral fertilizer only at 200 or 500 kg N ha^-1.