PJB-2006-29
GROWTH RESPONSE OF RICE AND WHEAT CROPS DURING RECLAMATION OF SALINE-SODIC SOILS
M. H. ZIA, A. GHAFOOR, G. MURTAZA, SAIFULLAH AND S.M.A. BASRA*
Abstract
Productivity and internal drainage of saline-sodic soils can be restored by better management practices like combination of physical and chemical treatments. A field experiment was carried out for 3 years at two saline-sodic sites, in Punjab-Pakistan to improve soil physical/chemical properties and increase wheat and rice yields. The site 1 was highly deteriorated (bulk density 1.77-1.86 Mg m-3) followed by site 2 (bulk density 1.6-1.7 Mg m-3). Due to a very low infiltration rate at both sites, vertical drainage through auger holes that extend down to a permeable soil layer was suggested to flush down excess saline water thus minimizing temporary waterlogging and associated hypoxia. Gypsum as a source of calcium was applied @ 3.8-7.2 t ha-1 at site 1 and 3.6-11.4 t ha-1 at site 2, to all vertical drainage treatments to replace excess sodium on soil exchanger and decrease dispersion. Saline-sodic tube well water, used to irrigate rice and wheat crops, also helped attain a significant decrease in soil salinity and sodicity within a reasonable time period. After harvesting the final wheat crop (6th in sequence), non-significant differences were observed between the vertical drainage/gypsum treatments and the control treatments regarding the final electrical conductivity, sodium adsorption ratio, and yields of crops. Detailed economic analysis indicated that at site 1, combination of gypsum and vertical drainage technique was the best, with benefit cost ratio of 8.0 while at site 2, the vertical drainage + gypsum treatments did not work. As the study was carried out with farmers' participation approach, there seems a need to educate and train the farmers, as well as supply them with quality inputs, in time and space, to maximize the benefits from the projects dealing with the management of saline-sodic groundwater resources and saline-sodic soils.
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