Long-term application of organic amendments enhances soil microbiota and chemical properties in maize rhizosphere

Soil degradation and declining fertility are pressing concerns in modern agriculture, compromising soil health and ecosystem services. This five-year field study aimed to investigate the long-term impact of soil amendments on soil microbiota and functions in the rhizosphere of maize plants, addressing the need for sustainable agricultural practices that promote soil health and ecosystem services. A 5-year field trial was setup in the monomodal rainforest agro-ecology in Littoral region of Cameroon, using a split plot design. Four soil fertility management options were evaluated with four replications, including chemical inputs (urea+triple superphosphate+muriate of potash), organic inputs (poultry droppings+Mucuna green manure), combined chemical and organic inputs (urea+triple superphosphate+muriate of potash+poultry droppings + cow dung), and a virgin forest as a control. Results showed that organic inputs significantly (P < 0.001) enhanced soil microbial biomass and enzyme activities, with poultry droppings+Mucuna green manure exhibiting the highest microbial biomass (1293 mg−1kg− 1 soil) and enzyme activities, including acid phosphatase (43.98 mU−1g− 1 soil), alkaline phosphatase 16.23 mU−1g− 1 soil), urease (57.17 mU−1g− 1 soil), β-glucosidase (6.54 mU−1g− 1 soil), and arylamidase (2.49 mU−1g− 1 soil), compared to chemical inputs (742 mg−1kg− 1 soil, 21.66 mU−1g− 1 soil, 3.81 mU−1g− 1 soil, 28.16 mU−1g− 1 soil, 2.61 mU−1g− 1 soil, and 0.86 mU−1g− 1 soil, respectively) with the lowest. The combination of poultry droppings and Mucuna green manure also modulated soil pH (6.23), increased organic matter content (7.53%), and improved N, P, and K nutrient availability, while, chemical inputs recorded the lowest pH (5.08) and organic matter content (4.00%). The combined chemical and organic input treatments showed intermediate effects, with average values of 994 mg−1kg− 1 soil (microbial biomass), 35.52 mU−1g− 1 soil (acid phosphatase), 6.61 mU−1g− 1 soil (alkaline phosphatase), 46.79 mU−1g− 1 soil (urease), 4.35 mU−1g− 1 soil (β-glucosidase), 1.71 mU−1g− 1 soil (arylamidase), 5.95 (pH), and 6.88% (organic matter). The study highlights the benefits of integrating organic amendments into agricultural practices to promote soil biological and chemical properties, and ecosystem services. These findings have significant implications for developing eco-friendly and sustainable agricultural practices that prioritize soil microbiology and ecosystem functioning.