The pros are straw helps control evaporation in shading the sun’s rays and can somewhat help in erosion control. The cons are straw bales are filled with weed seeds and quite often the next spring you can have some unwanted wheat growing within your lawn, also straw doesn’t hold up to high winds or heavy rain very well. An alternative is straw blankets which contain no weed seeds and are woven in a biodegradable nylon net which provide excellent erosion control while helping the ground stay shaded controlling evaporation. Peat Moss is another excellent option for smaller areas. Peat Moss retains water and is organic matter so when it breaks down it will be adding nutrients to the soil, however it will not provide any erosion control.