Hay cover

One particular subtype of polyethylene tarp is a hay tarp, also known as a hay cover. Because it is incredibly opaque, meaning that it lets very little light through, these tarps are very useful for farmers storing feed in their field. They have a pale or reflective upward-facing side (usually white or silver) to deflect heat and light from the sun and a dark downward-facing side (usually black) to block whatever light and heat is not directly reflected by the other side.
A hay cover should always be a heavy duty tarp, meaning that it is durable (able to withstand a great deal) and long-lasting (don't break down quickly). Ideally it will have UVI—ultraviolet inhibitor—included in the polyethylene resin during manufacturing. This helps it resist the way UV light from the sun breaks down plastic materials over time. This not only makes hay tarps even more valuable as an investment for agriculture, it also makes them an incredible options for all sorts of other applications. If you're in the market for a strong, long-lasting tarp, a hay cover is a very practical choice.