Sabina Yeasmin
Department of Agronomy, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh
Eshara Jahan
Department of Agronomy, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh
Md. Ashik Molla
Department of Agronomy, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh
A. K. M. Mominul Islam
Department of Agronomy, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh
Md. Parvez Anwar
Department of Agronomy, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh
Md. Harun Or Rashid
Department of Agronomy, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh
Sirinapa Chungopast
Department of Soil Science, Faculty of Agriculture, Kasetsart University Kamphaeng-Saen Campus, Nakorn Pathom 73140, ,Thailand
Organic Carbon Storage, Potential of Soils, Native Organic Matter Content
Sonatola Upazila, Bogra, for AEZ-3, Pirganj Upazila, Rangpur, for AEZ-9, Bangladesh Agricultural University, Mymensingh, and for AEZ-5, A damdig high Upazila, Bogra,
Crop-Soil-Water Management
Carbon sequestration
2.1.Sampling Sites. Soil sample were collected from farmers field in agroecological zones (AEZ)–7 (active Brahmaputra-Jamuna floodplain), 3 (Tista Meander floodplain), 9 (Old Brahmaputra floodplain), and 5 (lower Atrai basin) to represent soils with very low (<1%), low (1–1.7%), medium (1.7–3.5%), and high (>3.5%) OM content. For rep-resenting AEZ-7, Sonatola Upazila, Bogra, for AEZ-3, Pirganj Upazila, Rangpur, for AEZ-9, Bangladesh Agricultural University, Mymensingh, and for AEZ-5, A damdig high Upazila, Bogra, Bangladesh locations were selected. & e climate is characterized as the subtropical monsoon with moderately high temperature and heavy rainfall during summer and low rainfall with moderately low temperature during the winter season. A base survey was conducted in the selected Upazilas to find out the most prevalent soil type, topography, and existing land use systems so that the selected samples can represent the majority of the AEZ scenario. Based on the survey, four land-use types, i.e., cropland, orchard, grass land, and fallow were nominated, and for each land use, 12 sites were selected per AEZ. &us, 48 sites (12 per land use×4 land uses) per AEZ,i.e., total 192 sites for four AEZs were selected which were similar in climatic condition, topography, and soil type. Medium high land was selected from all AEZs. Cropped lands had been covered with rice, and mixed fruits (Litchi chinensis and Mangifera indica) trees were grown in orchards for about 15 years. Grassland had been covered with naturally grown deep-rooted native grass for>10 years, and the fallow land remained uncultivated for>5 years and covered with naturally regenerated grasses in all AEZs. Flood irrigation, conventional tillage, and typical fertilization were practiced in croplands whereas the orchard was managed by only preparatory tillage, very rare irrigation, and a yearly application of fertilizers+manure. & grassland and fallow lands remained undisturbed. 2.3. Physical Fractionation of Soils. Bulk soil samples from four land-use types of each AEZs were fractionated into particulate OM (POM) and mineral-associated particulate soil OM (MOM) by using the method adopted from a 100mL sample bottle, and 60mL of 5gL−1 sodium hexametaphosphate was added. Soil suspension was shaken in a horizontal shaker overnight and then passed through a 53μm sieve. &e soil samples retained on the sieve were considered as POM while those that pass through the sieve were MOM fraction. Both the fractions were rinsed with water,driedinanovenat40°C, hand-ground to fine powder, weighed and stored in plastic vials for further analyses.2.4. Soil Sample Analysis2.4.1. Bulk Soil Properties. Bulk soils from four AEZs were analyzed for pH, carbonate, electrical conductivity (EC), and texture. Soil pH and EC were measured by a glass electrode pH meter and conductivity meter, respectively, using a soil-to-water ratio of 1:5. Bulk density was determined by the core method. Carbonate and bicarbonate were analyzed through the titration method. Particle size analysis was conducted by the hydrometer method. All laboratory analytical measurements of individual bulk soil samples were performed in triplicate. 2.4.2. Organic Carbon and Nitrogen Determination in Bulk Soils and Soil Fractions. Soil OC and total nitrogen (N) content of bulk soils and two soil fractions were measured for all four AEZs’ samples. Statistical Analysis. Analysis of variance was performed to find out the effects of land use on bulk soil and fractionated OC pools for both AEZs. Variation in soil OC and N due to native OM content was also determined. All the statistical analyses were performed using the software package IBM SPSS 21.0.
International Journal of AgronomyVolume 2020, Article ID 8042961, 9 pages
Journal