Now most of these farms are hydroponic or aeroponic systems, which means that instead of using soil, they use a substitute material like polyurethane sponges, biodegradable peat moss and even use inorganic materials like perlite and clay pellets.

现在这些农场大多是水培或气培系统，这意味着他们不使用土壤，而是使用聚氨酯海绵、可生物降解的泥炭藓等替代材料，甚至使用珍珠岩和粘土颗粒等无机材料。