# Farmed Insect Frass as a Future Organic Fertilizer  
[PERSON]  
1 Department of Agricultural and Environmental Chemistry, University of Warmia and Mazury in Olsztyn, Oczapowskieogo 8, 10-719 Olsztyn, Poland; [EMAIL_ADDRESS] (SJ.K. ); [EMAIL_ADDRESS] (PJ.Z.) [PERSON]  
2 Department of Entomology, Phytopathology and Molecular Diagnostics, University of Warmia and Mazury in Olsztyn, Prawoechskieology 17, 10-719 Olsztyn, Poland; [EMAIL_ADDRESS] (S.W.F. ); [EMAIL_ADDRESS] (A.K.) [PERSON]  
1 Department of Agricultural and Environmental Chemistry, University of Warmia and Mazury in Olsztyn, Oczapowskieogo 8, 10-719 Olsztyn, Poland; [EMAIL_ADDRESS] (SJ.K. ); [EMAIL_ADDRESS] (PJ.Z.) [PERSON]  
2 Department of Entomology, Phytopathology and Molecular Diagnostics, University of Warmia and Mazury in Olsztyn, Prawoechskieology 17, 10-719 Olsztyn, Poland; [EMAIL_ADDRESS] (S.W.F. ); [EMAIL_ADDRESS] (A.K.) [PERSON]  
3 Department of Genetics, Plant Breeding and Bioresource Engineering, University of Warmia and Mazury in Olsztyn, Plac Lodzki 3, 10-719 Olsztyn, Poland; [EMAIL_ADDRESS] (Department of Biogeochemistry and Soil Science, Bydgoszcz University of Science and Technology, Seminarylyn 5, 85-326 Bydgoszcz, Poland; [EMAIL_ADDRESS] (Correspondence: [EMAIL_ADDRESS] (Academic Editor: [PERSON] Received: 13 February 2024 Revised: 8 March 2024 Accepted: 9 March 2024 Published: 12 March 2024 Accepted: 12 March 2024 Ac  
have lower energy, water, and labor requirements per gram of produced protein, and their carbon footprint is considerably lower than that of conventional farms [1; 8; 9]. In addition, insect larvae effectively process various waste biomass into nutrients, thus contributing to a closed-loop economy and sustainable development [10; 11; 12]. Larvae biocontrol products [9], not only organic waste but also waste that is difficult to decompose [13; 14; 15; 16; 17; 18]. In some studies [19], insect meal with a high organic nitrogen (N) content was used as fertilizer to improve plant growth. Insect wastes can be effectively managed in a circular economy. Mealworms (_Tenebrio molitor_ L.) generate exuviae and frass. According to [PERSON] et al. [9], frass is a by-product of insect farming that can be used as an organic fertilizer. Insect frass contains many plant-essential nutrients, and its rapid mineralization in the soil leads to the conversion of hard-to-access nutrients into plant-available forms [20]. Frass can improve soil N availability and replace mineral NPK fertilizers [21; 22]. Nitrification, namely the microbial oxidation of ammonia from frass, affects the rate of N transformation in soil [23]. Insect diets influence frass quality. In a study by [PERSON] and [PERSON] [24], cabbage moths, _Mamestra brassica_ L., fed N-rich plants produced frass with a high concentration of N-NH\({}_{4}\). Frass not only enhanced plant growth but also increased plant resistance to abiotic stress [25]. Frass can stimulate the development of soil-dwelling microorganisms. The increased metabolic activity of microorganisms colonizing mealworm frass improved the soil properties and enhanced barley plants' growth and nutrient uptake [21]. Nutrients present in mealworm frass, in particular N and carbon [21; 22; 26], increase the activity of soil microbes responsible for ammonification, nitrification, denitrification, and N-fixation. At the microbiological level, these processes determine the form, loss, and availability of organic N in soil. Fertilizers should stimulate the development of beneficial bacteria (including antagonistic bacteria) and reduce the counts of phytopathogenic fungi. Beneficial soil microorganisms suppress pests and plant pathogens, induce systemic resistance, and increase crop yields [27; 28]. Due to the rapid development of insect farming and the conversion of leftover substrates into fertilizers, the fertilizing potential of frass should be explored to ensure that insect wastes can be safely used [9; 29]. Insect feed should be monitored to obtain safe frass for the environment.