Compost and Mineral Fertilizer Application Affects Soil Microbial Activity and Nutrient Mineralization in an Ultisol

ABSTRACT

Organic additions help improve soil biophysical qualities, but they are insufficient to supply nutrient demand and could result in unintentional nutrient immobilization in soils, particularly soils with low fertility status. A 16-week laboratory incubation study was conducted to determine how the method of application of compost and inorganic fertilizers influence microbial respiration, nitrogen (N), and phosphorus (P) mineralization. Topsoil (500 g, 0–15 cm) was amended with compost (0, 5, and 10 g kg⁻¹) and either inorganic N (50 kg N ha⁻¹) or P (30 kg P ha⁻¹). Two soil amendment strategies, applying compost and inorganic fertilizer separately to opposite sides of the soil using a divider and mixing them evenly throughout the soil, were compared for their effects on microbial activity and nutrient mineralization. The cumulative amounts of carbon dioxide (CO₂) evolved were measured fortnightly using the static CO₂ absorption method and inorganic N and P mineralization. N mineralization was unaffected by the method of compost and inorganic fertilizer application (p > .05), while at the end of day 42, available P in separate applications of compost and mineral N fertilizers was 33% greater than combined applications. Compost and inorganic P fertilizer had favorable N priming effects, but compost and inorganic N had negative effects. The different N priming effects of compost and inorganic N and P fertilizers may be attributable to microbial nutrient demand. The data suggest that composting with conventional fertilizers may change microbial nutrient demand and crop nutrient availability.

KEYWORDS:

• Conventional fertilizers
• nutrient demand
• nutrient mineralization
• organic fertilizers
• Ultisol

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplemental data

Supplemental data for this article can be accessed online at https://doi.org/10.1080/00103624.2024.2372415.

Data availability statement

The data generated by the research are available from the corresponding author upon request.