Soil Fertility Status in Relation to Fallow Cycle in Shifting Cultivated Areas of DIMA HASAO

Aim: To understand the effect of fallow cycle on soil fertility status under shifting cultivation.

Study Design: Latin square design (LSD).

Place and Duration of Study: Dima Hasao District, Assam. Between September 2019- August 2021.

Methodology: The present investigation was carried to study the effect of jhum fallow cycle on soil properties in the DIMA HASAO district of Assam. Total of 120 geo-referenced soil samples were collected from short jhum (1-3yrs.) fallow cycle, medium jhum (4-6yrs.) fallow cycle, long jhum (7-9 yrs.) fallow cycle and undisturbed soil. The collected soil samples were analyzed for parameters like pH, OC, N, P, K, S, Ca, Mg, CEC and soil texture.

Results: The studied soil samples showed wide variations in texture varying from sandy loam to clay loam. Coarse texture sand was found to be dominant in short jhum and medium jhum while finer particles (silt and clay) were dominant in the long jhum and the undisturbed soil. The Soil pH was found lowest (mean value 4.55) in short jhum and highest (mean value 5.00) in the undisturbed soil. The OC content was minimum at initial short jhum fallow cycle and maximum was observed in the Undisturbed soil. The CEC of the study area was found highest in undisturbed soil (mean value 8.64 cmol (p+) kg-1) followed by long jhum, medium jhum and short jhum. The Avl. N content of the study area was found low to medium. Among the jhum fallow cycle Avl. N of short jhum was lowest (mean value 269.30kgha-1) followed by medium jhum, long jhum and highest in undisturbed soil (mean value 350.11 kgha-1). The Avl. P content of the study area was found low to medium, highest mean value 12.61 kg ha-1 was observed in long jhum fallow cycle and lowest in short jhum (mean value 9.33 kgha-1). The highest content of Avl. S was observed in long jhum fallow cycle and lowest in the short jhum. The highest of Ex. Ca, Mg was found in the undisturbed followed by long jhum, short jhum and lowest in the medium jhum. All the soil fertility parameters i.e., N, P, K, S, Ca and Mg exhibited significant positive correlation with pH, OC, CEC, and percent Clay.

Conclusion: From the study it was observed that minimum of 7 to 10 years jhum fallow cycle is required in Dima Hasao are for the soil to restore its fertility and sustainable jhum cultivation.