Background Research
Ice
A phase change is when a substance changes from one state of matter to another. Ice is a phase change of water. When water, the liquid form of H2O, reaches a cold enough temperature (usually 0°C) it freezes and goes from liquid state into solid state. This phase can be reversed. When a solid turns to a liquid, it goes through a phase change called melting. The normal freezing point of water is 0 degrees Celsius, so if the temperature is above that then ice will melt.
Salt
If you live in an area where there is ice or snow on the roads, you have probably seen salt spread on the roads to melt the ice. This is because salt is used to melt ice/snow and keep it from freezing. Salt is also used in making home-made ice cream. In both of these cases, salt is used to lower the melting or freezing point of water. Ice forms when the water reaches 0°C, but when you add salt that temperature drops. (E.g. A 10% solution freezes at -6°C and a 20% solution freezes at -16°C). Salt dissolves into the water of the ice and lowers the freezing point so you can melt it. The term for this effect is "freezing point depression".
Sand
Sand can melt ice if heated y the sun or by a warm temperature. Like any other substance that is warmer than ice, the substance may heat the ice, causing it to melt. The actual texture of sand does not cause ice to melt. However, sand can cause the ice to melt faster if it was placed in direct sunlight as sand heats up very quickly, acting as a warm blanket on the ice. The direct sunlight on ice does not have as good an effect, as ice reflects light off its surface and doesn't absorb it very well.
Sugar
Sugar and anything else capable of being dissolved in water will melt ice. Sugar melts ice by lowering water's melting and freezing points, just like salt. Sugar dissolved on ice and interferes with the water molecules. The water molecules are needed to bind the ice crystals in order for it to freeze. The presence of sugar requires a much lower temperature before the water molecules come into contact with the ice crystals. With that said, sugar will melt ice but is not as effective as salt because salt breaks down into sodium and chloride ions so when one molecule of salt dissolves into the ice, it will add two components to the solution which provide more interference in preventing the water molecules from freezing.
Coffee
"Anything that is capable of dissolving in water will melt ice." Like salt and sugar, instant coffee granules are also capable of dissolving water, so therefore it is capable of melting ice. The freezing point of a solution is always lower than the freezing point of the pure solvent so the freezing point of a solution, where you have solute masses (e.g. sugar, instant coffee granules) in a pure solvent (e.g. water), is less than 0°C.
Soil
Soil does not dissolve in water so it will not melt ice. It has no properties that will affect how ice melts and will not speed up or slow down the process of melting ice.
Cotton
Cotton has air pockets as cotton molecules are made up of long, twisted chains of cellulose twisted together and leaves spaces that hold air. When these fibres of long molecules are twisted further to be woven into cloth, more air is held. The pockets of air capture heat from the body and slow down its radiation into the environment, but can also do the opposite where it can insulate the skin against hot environments whilst absorbing moisture. This goes the same for cotton on ice. When cotton is places on ice, it's air pockets are used and can insulate the ice, keeping it cooler for longer (also absorbing the water) and it will trap the warmer temperature away from the ice, acting as a barrier between the air and the ice.
Conclusion
Salt and sugar both causes freezing point depression, therefore making the ice melt faster, however salt is more effective as salt dissolves into two components and creates more interference in preventing water from freezing. Sand melts ice by absorbing heat which will bring it to a higher temperature than ice, causing it to melt. Soil has no effect on ice whatsoever and cotton will serve as an insulator, acting as a barrier between the ice and the warmer temperature for the ice will stay cooler for longer.