Economic use of degraded land and brackish water by growing salt tolerant trees

Abstract

The agricultural based economy of Pakistan is confronted with waterlogging and salinity problem and more than 25% of irrigated area (16.47 mha) is affected by this menace. This area needs to be reclaimed/utilized to feed the increasing population of the country by scientific use of land and water resources especially the degraded land and brackish water. The good quality water is scarce. To augment the inadequate fresh water supplies the poor quality groundwater needs to be utilized. This study was carried out in Fordwah Eastern Sadiqia South (FESS) Project, Bahawalnagar during 1998–99 with the broad objective to test salt tolerant tree species under actual production conditions and to evaluate the impact of brackish water on soil and plant growth. For this purpose an area of about 29 ha (72 acres) having initial EC_e and SAR between 48.7–94.5 dS m ⁻¹ and 64.3–129.1 (mmol L⁻¹)1/2 respectively was selected. The groundwater was shallow having EC and SAR between 16.5–74.0 dS m⁻¹ and 28.987.9(mmol_c L⁻¹)^1/2. The water table varied between 0.74–2.84 m during this period. The quality of water applied to irrigate these plants varied between 2.5–4.8 (dS m⁻¹). The canal water was used for 2–3 times at transplanting and early stages for the establishment of the seedlings. Different planting times tested were September-October 1998 and February, March, April & August 1999. The planting densities/ha tried were 2500, 1975, 1600 and 1322. During this period the survival rate and impact on soil salinity/sodicity was evaluated. The survival rate during the months of September, October, February, March and April was 68, 47, 31, 38 and 63 percent respectively. hi August planting, presently, the survival rate is above 90 percent. The number of irrigation applied to September, October (1998) and February, March, April and August 1999 were 20, 18, 14, 12, 11 and 5 respectively. The data revealed that the salt tolerant eucalyptus tree species was fairly successful in salt-affected degraded soil and irrigation with drainage water. The extremely hot and dry weather coupled with shortage of irrigation water, during summer, affected the plants very badly. The impact of different treatments on EC and SAR of soil indicates a considerable improvement. The data about plant height, plant growth and groundwater quality are also discussed in the paper. The surrounding environment with the vegetation of this area will also improve. The financial rate of return from Ecualyptus and Acacia was found 32 and 27% respectively. Similarly due to low inputs for trees and their tolerance to Salinity, drought and flooding, the production of trees on farms could challenge traditional agricultural production as the main income earned for farmers.