In a PQNK system, the layer of organic mulch should be thick enough to cover the soil surface and prevent sunlight from reaching the soil. This inhibits weed germination, resulting in a non-chemical strategy for weed management. Maintaining permanent biomass cover on the soil surface also protects the land from overheating in direct sunlight, which adversely affects the soil biota. In fact, temperatures higher than 40℃ kill almost all life in the soil. Organic Mulch also buffers the force of winds and storms that erode the topsoil. Further, organic mulch applied as soil cover adds carbon and minerals to the soil system and supports the proliferation of soil microorganisms and mesofauna. The evaporative losses of moisture are also reduced by biomass cover, ultimately improving the water-use efficiency. In addition to this, the retention of non-harvested crop biomass, rootstocks, and stubble in the field after harvesting conserves the stock of carbon in the soil. These materials, when they decompose, support the soil biota and improve soil structure. PQNK makes crop residues a valuable source of biomass as well as a tool for integrated weed and nutrient management, giving farmers incentive not to burn them and thus also improving air quality
