FORAGE PRODUCTIVITY AND NUTRITIONAL VALUES OF RYE AND RHODES GRASS UNDER VARYING FERTILIZER APPLICATIONS

Abstract

The study was conducted to evaluate the effect of different NPK fertilizer levels on forage productivity and nutritional quality of rye grass (Lolium multiflorum) and Rhodes grass (Chloris gayana) under irrigated conditions at Rahim Yar Khan, Punjab, Pakistan, during the 2024–2025 growing seasons. The experiment was laid out in a randomized complete block design (RCBD) with four treatments and three replications, including a T1: control (no fertilizer), T2: N 55 + P 35 + K 35 kg ha⁻¹, T3: N 110 + P 70 + K 70 kg ha⁻¹, and T4: N 170 + P 105 + K 105 kg ha⁻¹. Growth and yield parameters such as plant height, green matter yield, and dry matter yield, along with nutritional attributes including crude protein, crude fiber, acid detergent fiber (ADF), neutral detergent fiber (NDF), ash   content, and metabolizable energy were recorded using standard analytical procedures. Results showed that fertilizer application significantly increased plant height, green fodder yield, and dry matter yield in both forage species. Maximum plant height was recorded in T4 with 104.8 cm in rye grass and 120.3 cm in Rhodes grass, compared with 62.6 cm and 74.5 cm in the control, respectively. Similarly, the highest green fodder yield were obtained in T4 with 63 t ha⁻¹ in rye grass and 66 t ha⁻¹ in Rhodes grass, while the lowest yields were observed in T1 (31 and 24 t ha⁻¹, respectively). Dry matter yield also increased markedly, reaching 17.8 t ha⁻¹ in rye grass and 21.2 t ha⁻¹ in Rhodes grass under T4. Nutritional quality improved significantly with fertilizer application. Crude protein content increased from 10.9% to 19.5% in rye grass and from 6.3% to 11.9% in Rhodes grass from T1 to T4. Ash content increased from 6.7% to 13.8% in rye grass and from 6.9% to 12.0% in Rhodes grass. Metabolizable energy improved from 8.5 to 9.9 MJ kg⁻¹ DM in rye grass and from 8.7 to 10.0 MJ kg⁻¹ DM in Rhodes grass. However, higher fertilizer levels also increased fiber fractions (ADF and NDF), indicating greater structural development of plants. Overall, moderately high fertilizer application (T3) provided the best balance between forage yield and nutritional quality under irrigated conditions.