New compositions of multipurpose soil additives were developed and evaluated. The compositions comprise three main components including a polyanionic component like sulfonated urea-melamine-formaldehyde (SUMF), a bridging agent like sodium chloride, and an aggregating and bonding agent like urea-formaldehyde (UF). The water-soluble compositions were tested on four types of soil including dune sand, Marl, and Gatch-type sandy soils with varying degrees of chemical composition. The compressive strengths of the various soils improved by a factor of 2-50 after they have been treated with the new compositions. The addition of 1.0% of SUMF improved the compressive strength of dune sand from 0.16 to 5.8 kg/cm(2), Marl-A sand from 15.4 to 28.0 kg/cm(2), Marl-B sand from 7.1 to 11.3 kg/cm(2), and Gatch sand from 4.74 to 13.38 kg/cm(2). The addition of 0.5% each of SUMF and UF with 0.25% Of sodium chloride improved the compressive strength of dune sand from 0.16 to 9.1 kg/cm(2). The erosion resistance of dune sands to water and wind improved significantly by the addition of small doses of the new compositions. When dune sands were treated with 30 g/m(2), they resisted erosion by water for 6 h under a water flow rate of 6 L/min. And they resisted 60 km/h wind speed when they were treated with 20 g/m(2) of the present compositions. The new compositions are water-soluble, and they are environment friendly chemicals. They are relatively cheaper than commercially available products, and they are more effective soil additives. They can be utilized for many applications including stabilizing sand dunes, and strengthening road beds and foundations and they can be used as good soil conditioners. A postulated mode of action of these compositions and their interaction and synergism with each other and with other organic and inorganic additives are also presented and discussed.