Journal of Environmental Biology

Assessment of soil fertility along a gradient of Nambar forest and adjoining rice field in Golaghat district of Assam

G.G. Kandali¹*, B.K. Medhi¹, I. C. Barua² and A. Kachari¹ 

¹Department of Soil Science, Assam Agricultural University, Jorhat-785 013, India

²Department of Agronomy, Assam Agricultural University, Jorhat-785 013, India

*Corresponding Author Email : gayatrikandali@rediffmail.com

Received: 13.06.2020                                                                   Revised: 15.11.2020                                                    Accepted: 15.12.2020

Abstract

Aim: The study aimed to evaluate the variation in soil fertility along a gradient in Nambar Doigrung Reserve forest in Golaghat district of Assam and a rice field adjoining the forest. 

Methodology: Five composite samples from three depths viz., 0-20, 20-40 and 40-60 cm were collected from three locations of the forest and in a rice field adjoining the forest. Physical, chemical, biological parameters were assessed and soil organic matter fractionation was done to see its inter relationship with different parameters with the hypothesis that agricultural fields are usually enriched by the nutrients flown from forests and that phenomenon is more profuse in hilly terrains.

Results: The soils of forests recorded higher amounts of soil organic matter and their four fractions compared to cultivated soil. Humic acid to fulvic acid ratio was found to be lower than unity in all the locations. Degree of humification increased significantly from 0.66% in the surface layer of the highest elevation to 0.84% in the subsurface layer. Similar increase was also found in the other elevations. However, degree of humification increased significantly from 0.50% on the surface to 1.04% on the subsurface of adjoining cultivated soil. Negative correlation of humus carbon with pH (r= -0.327*) indicated that soil acidity retarded the process of humification.      

Interpretation: The increase in concentration of nutrients through decomposition of litter in the forest is capable of enriching the adjoining agro ecosystems to harness the silent role of forests in agriculture and food security.       

Key words: Fulvic acid, Humic acid, Rice field, Soil organic matter

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