Using Urea Intercalated Biochar and Organic Fertilizer as Soil Management Option Part 2: Its interactive Effects with Soil Moisture and Compaction on Soil Properties and Carbon Emission

Soil response including carbon dioxide emission under the combination of compaction, fertilizer and soil moisture were investigated in a screenhouse. The factorial experiment consisted of two levels of moisture contents (50% and 70% field capacity, FC), three levels of compaction (0, 2 and 4 kg weights) and fertilizer treatments consisted of control, biochar, organic fertilizer + urea (FertC), urea intercalated biochar + organic fertilizer (FertD). Carbon dioxide (C02) evolution was determined using static chamber approach. Saturated hydraulic conductivity (Ksat), unsaturated hydraulic conductivity at 2 cm suction (K2cm), bulk density, total porosity, soil mean weight diameter, geometric weight diameter and organic carbon were determined using standard methods and the data was subjected to analysis of variance at 5% probability level. FertC in soil compacted under 2 kg and at 50% FC significantly enhanced (P<0.05) K2cm (3.87 x 10-4 m/s) in the sandy loam soil while the least was observed in the uncompacted soil amended with FertD. Biochar in uncompacted soil significantly increased (P<0.05) Ksat (2.77 x 10-3 m/s) while the two biochar-based amendments increased porosity (46.30 - 48.03%) and improved bulk density (1.32 - 1.33 g/cm3). Furthermore, FertD plus uncompacted soil kept between 50% - 70% field capacity significantly increased CO2 emission (21.68 g/m2/day) and this decreased as soil was compacted under 4 kg load. Organic carbon was highest in soil compacted at 2 kg but soil aggregates were unaffected by the combinations of the treatments. Thus, combinations of the treatments impact soil differently which can be explored further on the field depending on soil management focus.