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Aims: To determine the influence of fertilizer on the growth and yield of sweet corn grown under Bukidnon, Philippines condition.

The study was conducted to assess the impacts brought by fertilizer towards the growth and yield performance of sweet corn under no tillage operation in Bukidnon, Philippines. The study took place at the research station of IPB-UPLB, Musuan, Bukidnon, Philippines. Soil samples were taken from the site for initial characterization. Six treatments were employed; T 1-No fertilizer,T 2-Recommended rate of inorganic fertilizer (RRIF) based on soil analysis of the experimental area, T 3-2 tons ha-1 Vermicompost, T 4-½ RRIF + 1 ton ha-1 Vermicompost, T 5-½ RRIF + 2 tons ha-1 Vermicompost and T 6-RRIF + 1 ton Vermicompost. Fertilizer treatments were incorporated in the soil to facilitate appropriate chemical reactions. Dibble planting method was employed all throughout the area. Harvesting was done at 70 days after sowing (DAS). The application of fertilizer materials in Bukidnon soil under no tillage operation has no significant effects towards the growth performance of sweet corn. The full recommended rate of inorganic fertilizer plus 1 ton Vermicompost ha-1 consistently gave significantly higher yield parameter values (ear diameter and ear length) than those with no fertilizer applied. Yield data was observed significantly highest in plots with full recommended rate of inorganic fertilizer and 1 ton Vermicompost ha-1 with a value of 49369 ears per hectare. On the other hand, soil pH was significantly affected by the application of inorganic fertilizer alone. Moreover, the application of ½ RRIF + 2 tons of Vermicompost ha-1 caused significant effects towards the organic matter content (%) of the soil at harvest. The use of inorganic fertilizer in combination with organic fertilizer in sweet corn production under Bukidnon soil with no tillage operation are productive means and ways to be executed. Yield response was significantly highest in those plots, thus, possible means to be implemented in Bukidnon setting following no tillage operation.

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<p>Soil C sequestration is widely regarded as the most reasonable way to mitigate global warming. Traditionally, a high amount of organic carbon (OC) input is strongly recommended to increase soil organic carbon (SOC) stocks in croplands. However, according to the whole-soil saturation theory, stable SOC (mineral-associated SOC) accumulation can be limited at a certain point, relying on silt and clay contents. Most studies based on the theory were conducted in aerobic soil condition. This relationship is still uncertain in a rice paddy that makes up 10.8% of total arable land and has an anaerobic soil environment. In this study, we investigated high OC addition can enhance soil C sequestration in a rice paddy. We added different OC levels (0.5, 2.0, 2.9, and 4.6 Mg C ha<sup>-1</sup> yr<sup>-1</sup>) in rice paddy by incorporating cover crop biomass for nine years. SOC stock and soil saturation degree were determined. Unprotected, sand-associated, silt-associated, and clay-associated SOC were separated via density and size fractionation. Respired C losses (CO<sub>2</sub>-C and CH<sub>4</sub>-C) were monitored using the static closed chamber method. SOC stock did not linearly increase with higher amount of OC input. The carbon sequestration efficiency (i.e. the increase of SOC per unit of OC input) decreases with the amount OC added. Higher OM input significantly increased unprotected labile SOC content. Unprotected SOC (<1.85 g cm<sup>-3</sup>) exponentially increased as the SOC saturation degree was higher. On the other hand, stable SOC content did not exhibit a linear relationship with the SOC saturation degree. The higher OC addition level exponentially increased respired C loss. In particular, C loss via CH<sub>4</sub> was more sensitive to high OC addition. We conclude that higher OC addition in rice paddy without consideration in terms of SOC stock saturation point can accelerate global warming by increasing labile SOC accumulation and CH<sub>4</sub> emission.</p>