Integrated nutrient management for maize phenology and growth performance: Biochar, vermicompost, and N-P nutrients in northwestern Ethiopia

Abstract

Maize phenological and vegetative growth in the Nitisols of Burie District is hindered by issues such as high soil compaction (bulk density > 1.40 g cm⁻³), low total soil porosity (<50%), low total nitrogen (2.5 g kg⁻¹), low organic carbon (2.11%), strong acidity (pH 4.94), and very low available phosphorus (11.69 mg kg⁻¹). To address these challenges, a 2-year field experiment was conducted at Burie Campus research site in 2023–2024 and 2024–2025, Burie district, northwestern Ethiopia. The study evaluated the combined effects of inorganic N/P₂O₅ nutrients, maize cob biochar (BC), and vermicompost (VC) on the phenological and growth performance of maize. The randomized complete block design (RCBD) experiment included three replications and three factors, each with three levels: (1) N/P₂O₅ nutrients (N₀P₀ [none], N₁P₁ [120/69 kg ha⁻¹], and N₂P₂ [240/138 kg ha⁻¹]); (2) BC (BC₀ [none], BC₁ [4 t ha⁻¹], BC₂ [8 t ha⁻¹]); and (3) VC rate (VC₀ [none], VC₁ [0.5 of the recommendation], VC₂ [full recommendation]). The results showed that a combined application of N₂P₂, BC₂, and VC₂ led to earlier emergence (E) and phenological stages. Plants reached 50%E in just 8.13 days, 50% tasseling (T) in 95.28 days, and 50% silking (S) in 103.5 days. The maximum days to 50%E (10.69) were observed with N₂P₂, followed by N₁P₁ (10.24 days). However, the longest days to 50%T were recorded from the control (101.7 days). Similar to days to 50%T, the longest days to get 50%S were recorded from the control plot (112.67). The tallest plant height (PH) at 30 days after emergence (DAE) (18.49 cm) was achieved with N₁P₁, BC₀, and VC₂. At 60 DAE, the tallest PH (113.23 cm) was observed with N₂P₂, BC₀, and VC₂. At 90 DAE, the maximum PH (296.3 cm) resulted from N₁P₁, BC₀, and VC₁. In contrast, the shortest PHs of 11.10 cm, 44.05 cm, and 148.32 cm were recorded in the control plots at 30, 60, and 90 DAE, respectively. Based on 2 years data, at 30 DAE, the maximum number of leaves per plant (NLPP) (7.50) was documented from the combined application of N₂P₂, BC₂, and VC₂. While at 60 DAE, the maximum NLPP (12.80) was recorded from the combined application of N₂P₂, BC₂, and VC₀. At 90 DAE, the maximum NLPP (17.39) was obtained from the combined application of N₁P₁, BC₁, and VC₂. However, the lowest NLPP 5.35, 6.54, and 12.35 was documented from the control at 30, 60, and 90 DAE, respectively. Moreover, a strong positive correlation was observed between days to 50% tasseling and silking (r = 0.86; p < 0.01) and between PH and the NLPP at 30 DAE (r = 0.84; p < 0.01). In conclusion, the 2-year study showed that combining inorganic N/P₂O₅ nutrients, BC, and VC is beneficial for maize cultivation, especially during early growth stages. This integrated approach improved maize vegetative development and is recommended for use in the study area.