## 1 Introduction
Problems related to fouling, slagging, and corrosion of combustion equipment, associated with higher amounts of inorganics, such as potassium, silica, and chlorine, can be bypassed by prior leaching of straw biomass before combustion or by reducing the furnace exit temperature to ranges below the initial deformation temperatures of biomass ashes [11; 15; 19]. In the EU, the estimations about the annual production of straw residues are about 330 Mton [20]. Also referred to in the literature is the significant interannual variability in EU regions, perhaps higher than 20% in southern countries, on the production of crop residues. This variability is due to factors associated with drivers, such as discrete extreme weather conditions, harvestable area changes linked with agricultural policies,or variations in technical and management factors [20,21]. In Alentejo, the hydrographic basin of the Alqueva dam, with an area of 250 km\({}^{2}\) and allowing for the irrigation of 120,000 ha, can provide a relevant potential contribution to the development of cereal and legume cultivations, allowing for bypassing heat and water scarcity episodes, typical of Mediterranean regions [20]. The biomass productivity per unit area of cereals and legumes, such as oat, triticale, barley, wheat, lupin, and broad bean, is a key variable for establishing mass and energy balances. Reported biomass productivities per unit area for all EU areas of cultivations of wheat, barley, oat, and triticale were 5.9, 4, 4.1, and 5.2 tonha\({}^{-1}\)[20]. [PERSON] et al. [22], for dryland crops in Australia with temperate or Mediterranean conditions, published an extensive review from a dataset with more than 3000 estimates of HI with biomass productivity data of six cereal and legume crops. For wheat, these authors average dry mass yields of 6.7 tonha\({}^{-1}\) with values up to 22.5 tonha\({}^{-1}\) and harvest indexes ranging between 0.08 and 0.56. For barley, the same study reports shoot biomass yields higher than those of wheat, with an average of about 8 tonha\({}^{-1}\) and values up to 19.3 tonha\({}^{-1}\) and harvest indexes between 0.09 and 0.59. For medium-textured soil in a Chinese site with a typical continental climate and an average annual precipitation of 650 mm, [PERSON] et al. [23] deliver wheat straw biomass productions ranging between 6 and 14 tonsha\({}^{-1}\). Under typical Mediterranean conditions in Lebanon, with an average annual rainfall of 592 mm, average maximum and minimum temperatures ranging, respectively, between 11.3 \({}^{\circ}\)C and 30.7 \({}^{\circ}\)C and \(-2.2\) \({}^{\circ}\)C and 8.7 \({}^{\circ}\)C, [PERSON] et al. [24] refer shoot straw biomass productivities in field trials of barley and wheat, ranging between 6.19 tonha\({}^{-1}\) and 13.14 tonha\({}^{-1}\) and 6 tonha\({}^{-1}\) and 11.7 tonha\({}^{-1}\), respectively. For oat, [PERSON] et al. [22] refer to the average values of shoot as 9.7 tonha\({}^{-1}\) with values up to 28.1 tonha\({}^{-1}\) and HI between 0.11 and 0.48. [PERSON] et al. [25], in field trials of seven oat genotypes in Ethiopia, found productivities ranging between 6.65 and 11.34 tonha\({}^{-1}\) and averaging 8.1 tonha\({}^{-1}\). [PERSON] et al. [26], from field trials in Ethiopia with 21 oat genotypes, obtained higher productivities ranging between 10.1 and 15.4 tonha\({}^{-1}\). [PERSON] et al. [27], from field trials with oat cultivars in Brazil with annual rainfall and temperatures averaging 572 mm and 16.6 \({}^{\circ}\)C obtained average productivities of biomass straw of 8.1 tonha\({}^{-1}\). For triticale, [PERSON] et al. [22] found that the average values for straw biomass productivity were 9.5 tonha\({}^{-1}\), with values up to 11.23 tonha\({}^{-1}\) and a harvest index ranging between 0.28 and 0.46. [PERSON] et al.