Combined Application of Organic and Inorganic Amendments Improved the Yield and Nutritional Quality of Forage Sorghum

The use of organic amendments is seen to be a promising method for enhancing crop productivity and soil health. Therefore, this study was performed for two consecutive years (2019 and 2020) to determine the effects of organic biochar (BC), sugar industry press mud (MUD), and poultry manure (PM) combined with inorganic amendments on the yield and nutritional quality of forage sorghum at the College of Agriculture, Bahauddin Zakariya University, Bahadur sub-campus, Layyah, Pakistan. The treatments were comprised of the following: control (no inorganic or organic amendments added); recommended dose of NPK (59:72:30 kg ha−1); half dose of NPK (29.5:36:15 kg ha−1); recommended dose of poultry manure (PM) at 5 t ha−1; recommended dose of press mud (MUD) at 40 t ha−1; recommended dose of biochar (BC) at 11 t ha−1; BC + half NPK; MUD + half NPK; PM + half NPK; PM + BC + half NPK; PM + MUD + half NPK; BC + MUD + half NPK; PM + BC + MUD + half NPK. The treatments were carried out in a triplicate randomized complete block design. Results revealed that combined application of PM + BC + MUD + 1/2 NPK significantly enhanced the plant height (201 cm), number of leaves (17), stem diameter (18 mm), stem dry weight (201.7 g), leaf dry weight (30.4 g), leaf area (184.3 cm2), green forage yield (31.8 Mg ha−1), and dry biomass yield (12.7 Mg ha−1) compared with the control treatment. Forage quality traits, including crude protein (CP), brix percentage, acid detergent fiber (ADF), and acid detergent lignin (ADL), showed maximum value with the combined application of PM + BC + MUD + 1/2 NPK. ADF and ADL are linked with lower digestibility; therefore, it was concluded that the combined application of PM + BC + MUD + 1/2 NPK can improve the productivity, dry biomass yield, and CP of sorghum, but reduces the digestibility under semi-arid conditions, such as those in Central Pakistan.