The study Key Insect Pests and Weeds in Irrigated Rice fields at Varying Fertilization Regimes was conducted during July to December 2020 cropping season. It aimed to describe the occurrence of pests and weeds along with the soil characteristics and fertilizer regimes in different rice fields in RTRomualdez, Agusan del Norte. Relative to the objectives, findings were obtained. Pests and weeds are rising at the sampling sites which are contributory factors to the poor production of rice. Pests and weeds are significantly linked to fertilizer applications such as potassium (K) and nitrogen (N). The soil characteristics such as soil PH and soil phosphorus (P) of the farm sites in RTRomualdez Agusan del Norte are in the normal range. Organic matter (OM) content is low. However, soil potassium (K) is higher which is above the normal range when farmers applied more potassium fertilizers it may cause fixation rather than availability which aggravated further the occurrence of insect pests. Rice crops have a very low nitrogen (N) concentration and marginal potassium (K) levels. Regarding pest occurrence, Rottboellia cochinchinensis (Aguingay) grows more with increasing N concentration. The occurrence of pests is positively correlated to organic matter and phosphorus (P). Further, Nitrogen (N) is positively correlated to the occurrence of weeds. These implied that soil characteristics are significant factors in the occurrence of pests and weeds. The optimal use of potassium (K) and nitrogen (N) can be studied in the occurrence of pests and weeds. The growth of plant hopper and green leaf hopper can be further investigated at varying concentrations of organic matter and phosphorous content. A deeper study on the influence of Nitrogen uptake on the growth of Rottboellia cochinchinensis (Aguingay) is also suggested. Wide sampling sites may also be considered to understand the variability of pests and weeds.

Keywords : Fertilization, Nitrogen, Pests, Potassium, Weeds