Effect of Nitrogen Fertilizer and Biochar on Organic Matter Mineralization and Carbon Accretion in Soil

Soil carbon (C) mineralization was studied in an incubation experiment comprised of two factors having six organic materials and three nitrogen (N) rates. Cow dung (CD), rice straw (RS), wood ash (WA), cow dung biochar (CB), rice straw biochar (RB) and wood biochar (WB) considering 2.5 g C kg(-1) soil along with three levels of N, i.e., 0, 0.05 and 0.10 g N kg(-1) soil were mixed with 400 g of soil used in each pot. The pots were placed for 0, 30, 60, 90, 120, 150 and 180 days of incubation, and soils were collected after each incubation and analyzed for C and N. Irrespective of treatment factors, C decreased in an irregular fashion until 180 days of incubation. From the initial level of 1.91%, C contents decreased to 1.08, 1.10, 1.06, 1.23, 1.17 and 1.12% in soil mixed with CD, RS, WA, CB, RB and WB, respectively, and to 1.28, 1.11 and 0.99% in 0, 0.05 and 0.10 g N kg(-1) soil, respectively, at 180 days of incubation. The mineralization followed the order of WA > CD > RS > WB > RB > CB. Biochars could supply stable C in soil, while N enhances mineralization; optimization of N is therefore essential to ensure soil C accretion.

Automated summary

This study investigates soil carbon mineralization in an incubation experiment, finding that biochar can provide stable carbon in soil and nitrogen enhances mineralization, therefore optimizing nitrogen levels is crucial for soil carbon accumulation.