A study on organic matter and nitrogen dynamics in wetland paddy soils of Bangladesh

The present study was aimed to evaluate the effects of different sources organic matter along with various level nitrogen fertilizations on nutrient dynamics and physicochemical variation of soil at different incubation periods in the research field of department of soil science, BSMRAU. RS, VC, RHB, CD and PM were used @ 2 t C ha-1 along with N rates 0, 100 and 150 kg ha-1 in a factorial randomized complete block design. Combined application of VC and RHB with N100 dose significantly reduces soil bulk density. PM-treated plot resulted the highest amount of TN at 90 DAT, while RHB treated plot at 45 DAT. N fertilized plot showed maxi-mum TN content at 75 DAT with N150 treatment. Significant interaction effects of OM and N on TN content of soil were exhibited at the incubation period 15, 30 and 45 DAT. Different organic amendment showed a dissimilar nutrient release pattern. Significantly higher phosphorus content was detected in VC treated soil while the S content was in the CD-treated soil. The RHB treated plots provide a significantly higher exchangeable K content in post-harvest soil. The available P, S and exchangeable K contents in post-harvest soil increased positively in all treatments as compared to initial soils. Organic manures and N fertilization had no significant effect on different chemical properties like soil pH, TN, available S and exchangeable K. Significant P enrichment was occurred in organic and N treated soil. Thus, organic and inorganic fertilization had a significant positive influence on the enrichment of physiochemical properties of wetland paddy soil

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