The deterioration of tall wheatgrass pastures on saline sodic soils.

Abstract

The deterioration of sown tall wheatgrass (Elytrigia elongata) growing on 3 sodic saline soils was investigated in the Laprida basin, in the center of the Buenos Aires province of Argentina. These soils are known to have poor drainage and high saline levels and support different species associations. On each soil type the native grassland was compared to sown wheatgrass, in terms of plant density and cover and soil physical and chemical characteristics. The 3 soil types reacted differently to tillage. Tillage had little impact on soil type A (typic Natraquoll), a poorly drained soil with a loamy A horizon (14 cm) overlying a silty clay loam. Soil type B (typic Natraquaf), a wet texture contrast soil with bleached horizons has characteristics that are likely to severely limit plant growth. The sowing of wheatgrass increased ground cover by live vegetation on this soil type. This contrasted with soil type C (typic Natralboll), a saline soil with an organic matter-rich but thin (8 cm) A horizon. In this soil, the plant density declined and other components such as pasture cover also declined with time. This pasture deterioration was attributed to several soil factors including decreased organic matter content and increased soil bulk density. It was concluded that the varied performance of wheatgrass sown pastures was a function of the different inherent characteristics of the soils.