Activity of Soil Microorganisms During the Second Growing Season of Sweet Corn (Zea Mays Saccharata Sturt) Applied with Organonitrophos and Biochar

Efforts to increase the production of sweet corn can be done, among others, by the application of fertilizers, either inorganic, organic or its combination. In addition, the application of soil amendments such as biochar is expected to improve soil fertility that will further increase the production of sweet corn. Organonitrophos fertilizer is an organic fertilizer developed by lecturers of Faculty of Agriculture, University of Lampung. The research was aimed to study the effect of the combination of organonitrophos and inorganic fertilizers, biochar and the interaction between fertilizer combination and biochar on soil respiration and soil microbial biomass.The research was conducted at the Agriculture Experimental Field of University of Lampung using a Randomized Block Design with 6×2 factorials and 3 replications. The first factor was six levels of combination of organonitrophos and inorganic fertilizers (P0, P1, P2, P3, P4, and P5). The second factor was two levels of biochar dosage (B0 and B1). The data were analyzed using Analysis of Variance and further tested using the Least Significant Difference (LSD) Test at 5% significance level. The variables measured were soil respiration and soil microbial biomass carbon (SMBC). The results showed that the highest soil respiration was observed in the plots with P3B1 treatment (300 kg Urea ha-1, 125 kg SP-36 ha-1, 100 kg KCl ha-1 + 2500 kg organonitrophos ha-1) at 60 days after planting (DAP). Among other treatments, the highest SMBC was observed in the plots with P5 treatment (5,000 kg Organonitrophos ha-1) at 60 and 90 DAP. Soil respiration and SMBC were higher in the plots with B1 treatment (5,000 kg biochar ha-1) compared to that in the plots with B0 treatment (0 kg biochar ha-1). There was an interaction effect between combination of organonitrophos and inorganic fertilizers, and biochar on soil respiration at 90 DAP. However, there was no interaction effect between fertilizer combination and biochar on SMBC.