Effects of Three Types of Organic Fertilizers on Greenhouse Gas Emissions in a Grassland on Andosol in Southern Hokkaido, Japan

Abstract

Reduction of chemical fertilizers and effective use of livestock excrement are required for the realization of sustainable agriculture and reduction of greenhouse gas (GHG) emissions. The purpose of this study was to estimate the reduction rate of GHG emissions represented by comparing global warming potential (GWP) using organic fertilizers instead of chemical fertilizers. The study was conducted in a managed grassland on Andosol in southern Hokkaido for 3 years from May 2017 to April 2020. There were five treatment plots: no fertilizer, chemical fertilizer, manure, slurry, and digestive fluid. Organic fertilizers were applied such that the amount of NPK did not exceed the recommended application rate, and the shortage was supplemented with chemical fertilizers. Fluxes in CO2 caused by heterotrophic respiration (RH), CH4, and N2O were measured using the closed chamber method. Net ecosystem carbon balance (NECB) was obtained as net primary production + organic fertilizer application—RH—harvest. The GWP was estimated by CO2 equivalent NECB and CH4 and N2O emissions in each treatment. Chemical fertilizer nitrogen application rates in the organic fertilizer treatments were reduced by 10% for manure, 19.7% for slurry and 29.7% for digestive fluid compared to chemical fertilizer only, but the grass yields were not significantly different among the fertilizer treatments. The 3-year NECB showed significantly smallest carbon loss in manure treatment, and smaller carbon loss in the organic fertilizer treatments than in the chemical fertilizer only. The reduction rate in the GWP with use of organic fertilizers relative to that of chemical fertilizer was 16.5% for slurry, 27.0% for digestive fluid, and 36.2% for manure. The NECB accounted for more than 90% of the GWP in all treatments. CH4 emissions were < 0.1% of the GWP. On the other hand, N2O emissions accounted for more than 5% of the GWP, and was larger in the order of slurry > chemical fertilizer only > digestive fluid > manure. As a conclusion, these organic fertilizers can be used without no reduction of crop yield instead of chemical fertilizer, however, manure is the best way to increase soil carbon and to decrease GWP, followed by digestive fluid.

Dairy Slurry Application to Stubble-Covered Soil: A Study on Sustainable Alternatives to Minimize Gaseous Emissions

“…No significant differences were observed with respect to cumulative CO 2 emissions among the studied slurry application strategies and injected slurry or mineral fertilizers (Table 3). Unexpectedly, the CO 2 emissions from mineral fertilizers (MS and MB) were similar to those of slurry-based treatments, despite being in line with the results reported in [54], possibly influenced by the high organic carbon content in the soil, the low rate of initial fertilization and the short duration of the experiment. Carbon dioxide emissions from raw manure are markedly greater than emissions from mineral fertilizers in long-term experiments with high manure application rates [55][56][57].…”

Applications of nanotechnology to combat the problems associated with modern food

“…46 Plants only absorb 10-20% of total fertilizer added to the soil, while the remainder is wasted and pollutes the environment. 47 It is then converted to another compound and remains unavailable to plants, polluting water bodies and groundwater, 48 which directly causes harm to the human population and becomes another source of LSD. Moreover, these fertilizers result in the rapid growth of plants, resulting in crops having less nutritional value.…”

“…Nitrogen also adds to the greenhouse effect and contributes to global warming 46 . Plants only absorb 10–20% of total fertilizer added to the soil, while the remainder is wasted and pollutes the environment 47 . It is then converted to another compound and remains unavailable to plants, polluting water bodies and groundwater, 48 which directly causes harm to the human population and becomes another source of LSD.…”

Short-Term Assessment of Nitrous Oxide and Methane Emissions on a Crop Yield Basis in Response to Different Organic Amendment Types in Sichuan Basin

“…Our study focused on the influence of the application of organic amendments on N 2 O and CH 4 fluxes and their impact on crop yields in a Sichuan basin wheat-maize system. The application of organic amendments could significantly impact SOC pools in agricultural soils and could, therefore, influence their CO 2 emissions [73][74][75][76][77]. However, we did not integrate soil organic carbon changes and associated CO 2 emissions in our estimates of GWP.…”