Evaluating Soil Variability in District Mirpurkhas, Sindh, Pakistan through Digital Mapping
Evaluating Soil Variability in District Mirpurkhas, Sindh, Pakistan through Digital Mapping
Rashid Saraz1, Saiqa Amur1, Zia-ul-Hassan1*, Naheed Akhter Talpur1, Inayatullah Rajpar1, Muhammad Sohail Memon2, Muhammad Nawaz Kandhro3, Khalid Hussain Talpur1 and Nizamuddin Depar4
ABSTRACT
Understanding soil variability is highly indispensable to achieve the goals of agricultural sustainability and environmental health. Soil variability mapping of district Mirpurkhas, Sindh, Pakistan – globally known as the city of high-quality mangoes – was done for the first time. Surface (20 cm depth) soil samples were collected from 127 locations of six sub-divisions of district Mirpurkhas (locally known as talukas) i.e. Digri, Hussain Bux Mari, Jhuddo, Kot Ghulam Muhammad, Mirpurkhas and Sindhri. The coordinates of each sampling point were recorded with Magellan® Triton™ 200 GPS device. Efforts were made to include all agriculturally important union councils of six talukas, involving a variety of soil use and crop scenarios, viz. wheat, sugarcane, mango, brassica. Soil texture (Bouyoucos Hydrometer method), electrical conductivity and pH (1:2 soil-water extract), organic matter (Walkley-Black method), and ABDTPA (Ammonium bicarbonate diethylene triamine penta acetic acid) extractable phosphorus (P) and potassium (K) were determined using standard protocols, with no further alterations. Soil variability mapping was done using ArcGIS ver. 10.7. through IDW interpolation. The results reveled that majority (40%) of soils were clayey in texture, followed by clay loam and silty clay loam (16% each). Slightly to moderately medium-textured soils were dominant, followed by heavy clays. Majority of soils had high to excessively high salinity (56%) followed by the soils having medium salinity (38%), slightly (46%) to medium alkaline (38%) pH, high (44%) to medium (39%) organic matter content, while soils with low organic matter content was comparatively lower (only 17%). Nonetheless, spatial variability map predicted medium organic matter content in the district. Moreover, majority of soils had low (75%) to medium (16%) ABDTPA-P while only small portion (9%) of soils had adequate ABDTPA-P. Contrarily, soils having adequate ABDTPA-K were higher (62%) followed by those having marginal (36%) ABDTPA-K. The results of present study clearly highlighted that the soils of study area vary spatially. Elevated surface salinity, low P status and decreasing soil K reserves appeared to be the major constraints for sustainable agriculture in the district and must be kept in mind while taking soil fertility and fertilizer management decisions, by referring to the recently developed maps.
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