Management zone-specific N mineralization rate estimation in unamended soil.

An ideal and efficient nitrogen (N) recommendation for precision fertilization (PF) should account for potential soil mineralizable N. This study aimed at estimating management zone (MZ) specific soil N mineralization rate (SNMR) of unamended soils. A total of 76 soil samples were collected from 21 MZs across 5 fields. An aerobic laboratory incubation was conducted under controlled conditions for two months with seven sub-sampling events. N mineralization was assessed as net increase in soil mineral N over time. Results indicated a considerable variation in mineralized soil N (9.12–41.93 mg kg⁻¹ soil) across fields. Highest and lowest net SNMRs were 0.50 and 0.0004 mg kg⁻¹ soil day⁻¹, respectively. SNMRs significantly differed across MZs in three fields, while in the other two fields no significant differences were observed. In turn, 3 of 34 MZ-pairs differed (marginally) significantly (p_adj = 0.02–0.09) from one another, namely in MZ pairs with high variation in soil particle sizes. MZ-specific SNMRs were mostly positively correlated to pH (0.20–1.00), total N (0.12–0.99), soil mineral N (0.11–1.00) and sand (0.34–0.99), negatively correlated with clay (− 1.00 to − 0.11) and correlations with SOC were mixed (0.41 to − 0.62). This along with the support from regression analysis corroborated the existing knowledge that TN is a better predictor of mineralization than SOC. While there were only few statistically significant differences in SNMR amongst MZ per field despite mathematical differences, still incorporating MZ-specific SNMR in management decisions will be crucial in optimizing the N use efficiency in precision farming, and along with other management actions, lead to more environmentally friendly PF schemes. [ABSTRACT FROM AUTHOR]