Effects of fertilizer and biochar applications on the relationship among soil moisture, temperature, and N₂O emissions in farmland

Abstract

Background Di-nitrogen oxide (N2O) emissions from soil may lead to nonpoint-source pollution in farmland. Improving the C and N content in the soil is an excellent strategy to reduce N2O emission and mitigate soil N loss. However, this method lacks a unified mathematical index or standard to evaluate its effect. Methods To quantify the impact of soil improvement (C and N) on N2O emissions, we conducted a 2-year field experiment using biochar as carbon source and fertilizer as nitrogen source, setting three treatments (fertilization (300 kg N ha−1), fertilization + biochar (30 t ha−1), control). Results Results indicate that after biochar application, the average soil water content above 20 cm increased by ∼26% and 26.92% in 2019, and ∼10% and 12.49% in 2020. The average soil temperature above 20 cm also increased by ∼2% and 3.41% in 2019. Fertigation significantly promotes the soil N2O emissions, and biochar application indeed inhibited the cumulation by approximately 52.4% in 2019 and 33.9% in 2020, respectively. N2O emissions strongly depend on the deep soil moisture and temperature (20–80 cm), in addition to the surface soil moisture and temperature (0–20 cm). Therefore, we established an exponential model between the soil moisture and N2O emissions based on theoretical analysis. We find that the N2O emissions exponentially increase with increasing soil moisture regardless of fertilization or biochar application. Furthermore, the coefficient a < 0 means that N2O emissions initially increase and then decrease. The aRU < aCK indicates that fertilization does promote the rate of N2O emissions, and the aBRU > aRU indicates that biochar application mitigates this rate induced by fertilization. This conclusion can be verified by the sensitivity coefficient (SCB of 1.02 and 14.74; SCU of 19.18 and 20.83). Thus, we believe the model can quantify the impact of soil C and N changes on N2O emissions. We can conclude that biochar does significantly reduce N2O emissions from farmland.

Nitrogen flow in livestock waste system towards an efficient circular economy in agriculture

“…However, biochar and ash amended treatments did not impact N 2 O emissions. This confirms previous studies as biochar adsorbed inorganic N, thus decreasing the N concentration available for nitrification and denitrification, thus reducing N 2 O emissions (Wang et al, 2021). In addition, the use of N-fertilizers directly influences the amount of NH 4 + or NO 3 − available in the soil.…”

Effects of Land Preparation Method and Organic Soil Amendment on Soil Properties, Growth and Yield of Maize (Zea mays)

“…Increase in soil moisture in conservational land preparation was due to reduced soil disturbance which maintained the soil structure and soil water percolation. This is in agreement with [23,30] who found that conservational land preparation method increased soil moisture content significantly by 8%, 4.4% and 8.5%.…”

“…No-tillage and reduced tillage techniques increases the effectiveness of water usage and lower evapotranspiration in cereals [21,22]. Zero-tillage method has been found to conserve soil moisture up to 32%, which has been found to increase maize yields up to 17% [23]. In Kenya the common method of land preparation being used is conventional tillage method, minimum tillage and ridging method to enhance moisture conditions in semi-humid regions [24].…”

Effects of conservation tillage strategies on soil physicochemical indicators and N2O emission under spring wheat monocropping system conditions

“…Due to the unreasonable use of natural resources by humans, the cycle of carbon and nitrogen in the biosphere has been accelerated 2 , the stability of carbon and nitrogen in the soil has been changed, and the concentration of greenhouse gases has continued to increase, resulting in the greenhouse effect, which has become a relevant focus of general attention in the field 3 . N 2 O is a major greenhouse gas, 80% to 90% of N 2 O in the atmosphere emits from cultivated soils annually, and cultivated soils are a significant source of emissions 4 . Studies have shown that the main pathways for the production of N 2 O in agricultural soil are nitrification and denitrification processes.…”