## 1 Introduction
For example, the corn cob represent about 20% by weight of standing residue and are buried or left in the field. In limited cases, they are collected during the harvesting and used as a biomass source for energy purposes, an alternative use having very limited economic value. Concerns associated with crop residue enhancement include an increase in nutrient removal from the field, and the potential for soil compaction due to additional field activities, an increase in the potential for wind and water erosion, and a potential reduction in soil organic matter [18]. As residue in the field, the cob could play a role in soil and water conservation and in soil nutrient dynamics since they provide surface cover and contain carbon and nutrients. However, Ref. [19] demonstrated that cob removal does not affect erosion or runoff and nutrient loss by rainfalls. Ref. [20] evaluated dry matter loss of buried cobs compared to the case of cobs placed on the soil surface, in three tillage systems, founding that the loss of dry matter was greater in the case of buried cobs. Nevertheless, effects on the nutrient dynamics, during the decomposition processes, are not sufficiently investigated, in the scientific literature. In [19], carbon and nutrient dynamics have been monitored, during the year after harvest, in the cases of cobs buried and laid on the surface. The decline in cob carbon content was due to the respiration losses, as soil microorganisms break down the residues [21]. In fact, while carbon content decreases as carbon compounds--used as energy sources by soil microorganisms--the nitrogen, phosphorous, and sulfur contents do not change, suggesting that little content of these elements is available for the crops during the first year of cob decomposition. In synthesis, harvesting cob results in a low nutrient removal rates. Then, corn cob can be considered an abundant and inexpensive biomass that can be removed from the field without deleterious effects, if a proper management is used. Considering the fact that corn cobs are a lignocellulosic material composed of cellulose, hemicellulose, and lignin, they can be turned into valuable raw materials to feed circular processes aimed at producingenergy and bio-based products to be used in agricultural buildings and structures and more in general in the construction sector [22; 23]. Moreover, potentially the cobs could be collected during the grain harvesting operations [24; 25; 26]. Further considerations should be made on the harvesting procedures and on the advancements needed to valorize the cob as a co-product. For example, Ref. [26] tested a single-pass combine equipped with an ear-snapper head able to collect 30% of the stover, where the higher percentage of mass is represented by cobs. In general, since the cob is more dense and less bulky than corn stalks and leaves, few additional operations should be required for harvesting, transporting, and storing. Finally, the decision to collect cob during harvesting would leave the more bulky material as stalks and leaves [27] on the soil for protection and improvement, preserving the current role of the residues on the field. The possible solutions, to use the cobs as co-product, are multiple and mainly related to energy production, organic biomass supply for farms or biogas production, feed preparation, and biotechnological production. In this case, the corn cobs are considered as raw material for the production of pellets, for energy purposes, and of inert grits, usable as blasting or finishing media, in the metalworking sector. To compare the different possibilities and select the most appropriate choice from the environmental sustainability point of view, the results of an analysis of the environmental impact assessment of the different alternatives can be used as selection criterion. Considering this aspect, Life Cycle Assessment (LCA) is one of the methodologies that can be applied to compare the benefits of different production processes with respect to others.