Gypsum application in slots for reclamation of saline-sodic soils
2001
Raza, Z.I. | Rafiq, M.S. | Rauf, A. (Mona Reclamation Experimental Project, Bhalwal (Pakistan))
Traditionally, gypsum is applied to the soil surface to reclaim saline sodic soils. The lower soil profile is left untreated. Therefore, the salts do not leach much to deeper depths, particularly in heavy textured soils. To address this issue, a field study in which gypsum was applied in slots tier the reclamation of abandoned saline-sodic soils was conducted. The excavated soil was mixed with gypsum and slots were refilled. The field trials were conducted with maize- wheat-cotton-wheat crop rotation. Three treatments included were: T1) Application of gypsum by broadcast method, T2) Control (no gypsum application), and T3) Application of gypsum in slots. The results showed that maximum increase in soil permeability by 220% occurred in slotted area; whereas, the infiltration rate increased by 152% with gypsum application by broadcast method. The electrical conductivity of soil (ECe) decreased by 49 and 15% at 0-30 and 30-60 cm depths, respectively with gypsum applied by broadcasting. On the other hand, application of gypsum in slots reduced ECe, of slotted area by 51% at 0-30 and 25% at 30-60 cm depths. In case of slotting method. less salts were accumulated at 60-90 cm depth than that of broadcast method. Similarly, gypsum application by broadcast method reduced sodium adsorption ratio (SAR) of soil by 59% at 0-30 cm depth and 8% at 30-60 cm depth. At lower depth of 6090 cm, SAR was increased by 24%. But gypsum application in slots decreased SAR by 72 and 46% at 0-30 and 30- 60 cm depths, respectively. But SAR increased only by 11% at 60-90 em depth. The gypsum application in slots also decreased the salinity and sodicity in inter slot area. Maximum crop yields were recorded from slotted area.
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