Influence of Long-term Cultivation on Soil Nutrient Status and Properties of Paddy Fields in Panitan, Capiz, Philippines

Abstract

Soil fertility evaluation of long-term cultivated paddy fields is relevant for proper nutrient assessment and adequate fertility management. Thus, the study was conducted to evaluate the physicochemical and biological properties, as well as determine the nutrient status, and recommend proper nutrient management practices in selected barangays of Panitan, Capiz, Philippines. Soil samples were collected from six farms and analyzed for their morpho-physical, chemical, biological properties and fertility status. Results revealed that the soil of all farms are slightly to moderately developed having an Ap, AB, Bg, Btg, Bwg, BC, and C horizons. They have brown-colored horizons, which have clay texture, few to no rock fragments, sub-angular blocky soil structure, friable, slightly sticky and slightly plastic, and coarse to fine mottles. The highest soil microbial activity was noted seven days after incubation. Results also revealed that all soils studied are less fertile having a very strongly acidic to slightly alkaline soil pH (4.83 to 7.47), very low to a low amount of soil organic matter (0.15% to 2.81%), very low to medium total nitrogen (0.03% to 0.22%), low to moderate available phosphorus (0.1 mg kg-1 to 17.31 mg kg-1), low to moderate exchangeable potassium (0.06 cmol kg-1 to 0.7 cmol kg-1), and very low to low cation exchange capacity (0.027 cmol kg-1 to 12.68 cmol kg-1). Therefore, to enhance the fertility status of the paddy fields it is recommended to integrate the rice straw after harvest, practice green manuring, and combine organic and inorganic fertilizer applications.