Exponential population growth and soaring fertilizer prices are among the main challenges threating food security worldwide. Probably, substituting chemical inputs (partially or completely) with organic and/or bio-alternatives are the keys for sustainable development. Thus, a field experiment was conducted for two successive seasons in a randomized block design to achieve this goal, comprising the following treatments: (1) 100% mineral P and K fertilizers (T1, control), 10 g potassium humate (KH) kg-1 (T2), 10 g humic acid (HA) kg-1 (T3) and 10 g kg-1 fulvic acid (FA) (T4). For treatments from T2 to T4, supplementary doses of chemical fertilizers were added to satisfy wheat needs for P and K. Also, a combined treatment of 50% biogas (added on nitrogen bases) plus supplementary PK doses as either (i) rock phosphate and feldspars + biofertilizers (Bacillus megatherium and Bacillus circulans) (T5) or (ii) supplementary chemical P and K fertilizers were included (T6). All plots were planted with wheat and received 20% of the recommended N requirements via N2-fixation with Bacillus polymyxa while the other 80% was accomplished as ammonium nitrate (after considering the added N in organic additives). Key findings indicate that application of biogas+ supplementary chemical PK fertilizers (T6) recorded the highest increases in P and K available contents in soil. This in turn significantly raised their concentrations within different plant parts and boosted straw and grain yields during the two seasons of study. Application of 100% mineral PK (T1) recorded significantly lower values in all abovementioned parameters versus T6. Nevertheless, these two treatments (T1 and T6) recorded comparable increases in 1000-grain weight, plant height, spike lengths and number of grains per spike. Application of KH, HA and FA as partial substitutes for chemical fertilizers (T2-T4) lessened significantly nutrient bioavailability and their distribution within wheat parts; as a result, plant growth and yield components declined significantly. The least values were recorded for the treatment that received biogas+ rock phosphate and feldspar + biofertilizers (T5). Overall, straw and grain yields of wheat plants were correlated significantly with P and K contents in both shoots and grains. In conclusion, the combination between biogas and chemical fertilizers seemed to be the optimum selection to satisfy wheat needs for nutrients; hence increase their productivity under arid conditions.