Abstract: This invention includes the improved composting of cane sugar press mud and lignocellulosic materials. The result is a low density humectant substrate (LDHS) for the application in agriculture. The process is developed in homogenized and aerated mechanically semi-static biopiles. The lignocellulose materials are added in a fed batch system, in stages and doses which depend on the type of lignocellulosic material and the quality of required final substrate. Another objective is to provide, in 8 weeks, a material without pathogenic microorganisms nor weeds, with low density (<0.4 g/ml), high porosity (110%), and high water retention (>90%), applicable as a substrate in horticulture and forestal production in nurseries and greenhouses; or as an humectant and soil-improving agent in agricultural ground and eroded soils. Said substrate has better physical, chemical and biological characteristics for vegetable nutrition than equivalent substrates, such as turf and coconut fibers.