Soil K and Ca availability showed the highest increase in the 2.5% SSP+2.5% FCM treatment.
Soil Mg availability had the highest increase with 5% SSP supplementation.
All treatments supplemented with SSP and/or FCM showed increases in the Mg availability in the soil compared with the control treatment.
Following the cultivation of lettuces after all three crop seasons, the total N, soil P and K availability remained high with the application of SSP/FCM.
In all three crops seasons, the pH and EC in soil level ranged from 6.9 to 7.2 and 0.94 to 1.65 dS m− 1, respectively.