Impact of bio-digestate and fertilization on the soil chemical properties, growth and yield of maize (Zea mays L.)

Recognizing the significance of maize cultivation, it is imperative to determine the appropriate levels of NPK fertilizer along with the supplementary inclusion of bio-digestate (an organic fertilizer), to achieve optimal soil chemical properties and crop yields. Hence, a field study was conducted in 2022 at the Teaching and Research Farm of Bowen University, Iwo, Osun State, Nigeria. The study evaluated the effects of bio-digestate fertilizer (D), applied alone and integrated with urea (N), single superphosphate (P) and muriate of potash fertilizers (K) at low (N₁K₁P₁) and high (N₂P₂K₂) rates on soil chemical properties, growth, and yield of maize (Zea mays (L.). The treatments consisted of application of: D at 2500 L/ha alone, D + N₁ P₁ K₁, D + N₁ P₁ K₂, D + N₁ P₂ K₁, D + N₁ P₂ K₂, D + N₂ P₁ K₁, D + N₂P₁ K₂, D + N₂ P₂ K₁, D + N₂ P₂ K₂, Control. N₁ = 60 kg N/ha, N₂ = 120 kg N/ha, P₁ = 30 kg P₂O₅/ha, P₂ = 60 kg P₂O₅/ha, K₁ = 30 kg K/ha, K₂ = 60 kg K/ha. The 10 treatments were arranged in a randomized complete block design and replicated three times. Results showed that bio-digestate (D) fertilizer applied alone or integrated with NPK fertilizers improved soil chemical properties, growth, and yield of maize compared with the control. High rate of fertilizer DN₂P₂K₂ increased soil chemical properties and growth parameters of maize relative to low rates DN₁P₁K₁ whereas a higher yield was recorded at a low rate DN₁P₁K₁ relative to a high rate of fertilizer DN₂P₂K₂. Overall, the treatment DN₁P₁K₁ demonstrated the highest grain yield. D alone increased shelled maize yield by 187.9 % relative to no application of any amendment (control), also integrating D with N₁P₁K₁ (DN₁P₁K₁) increased maize yield by 97.2% relative to D alone. Bio-digestate can be used for maize cultivation in lonely soil especially when integrated with NPK fertilizer. Therefore, to avoid waste of fertilizer due to cost and negative environmental effects of excessive fertilization, the lower rate of NPK fertilizer: N (60 kg N/ha), P (30 kg P₂O₅/ha), and K (30 kg K/ha) with 2500 L/ha of bio-digestate (DN₁P₁K₁) is recommended for sustainable maize production.