Effects of nitrogen application rate, nitrogen synergist and biochar on nitrous oxide emissions from vegetable field in south China

Abstract

Globally, vegetable fields are the primary source of greenhouse gas emissions. A closed-chamber method together with gas chromatography was used to measure the fluxes of nitrous oxide (N2O) emissions in typical vegetable fields planted with four vegetables sequentially over time in the same field: endive, lettuce, cabbage and sweet corn. Results showed that N2O fluxes occurred in pulses with the N2O emission peak varying greatly among the crops. In addition, N2O emissions were linearly associated with the nitrogen (N) application rate (r = 0.8878, n = 16). Excessive fertilizer N application resulted in N loss through nitrous oxide gas emitted from the vegetable fields. Compared with a conventional fertilization (N2) treatment, the cumulative N2O emissions decreased significantly in the growing seasons of four plant species from an nitrogen synergist (a nitrification inhibitor, dicyandiamide and biochar treatments by 34.6% and 40.8%, respectively. However, the effects of biochar on reducing N2O emissions became more obvious than that of dicyandiamide over time. The yield-scaled N2O emissions in consecutive growing seasons for four species increased with an increase in the N fertilizer application rate, and with continuous application of N fertilizer. This was especially true for the high N fertilizer treatment that resulted in a risk of yield-scaled N2O emissions. Generally, the additions of dicyandiamide and biochar significantly decreased yield-scaled N2O-N emissions by an average of 45.9% and 45.7%, respectively, compared with N2 treatment from the consecutive four vegetable seasons. The results demonstrated that the addition of dicyandiamide or biochar in combination with application of a rational amount of N could provide the best strategy for the reduction of greenhouse gas emissions in vegetable field in south China.

Biochar Mitigated Yield-Scaled N2O and NO Emissions and Ensured Vegetable Quality and Soil Fertility: A 3-Year Greenhouse Field Observation

“…As generally accepted, biochar soil implementation could significantly lower N 2 O emission in agroecosystems [40,41], but the size effect for vegetable soils differed across the field studies [4,11,[42][43][44]. During the vegetable growing season in 2018 and 2019, biochar interacted with N and significantly mitigated N 2 O emissions by 23.6-40.0% and 17.7-36.4%, respectively (Figure 2a).…”

Biochar Is Comparable to Dicyandiamide in the Mitigation of Nitrous Oxide Emissions from Camellia oleifera Abel. Fields

“…No significant differences were observed between DCD and biochar treatments in their effects on N 2 O emission rates ( Figures 3C and 4), indicating biochar application could be considered as a potential mitigation strategy of soil N 2 O. Similarly, both DCD and biochar reduced the yield-scaled N 2 O following N fertilization, while biochar showed stronger effects than DCD in N 2 O mitigation in a sweet corn field [55].…”

Reduction of nitrous oxide emission by using stearic acid combined zinc coated urea in silty clay and sandy loam soils under bare and planted conditions

“…The application rate of N in this study was much higher than the crop requirement (250 kg N ha −1 ) which could be one of the main reasons behind the higher emissions. It was reported in the literature that N 2 O emissions increased linearly with the increase in fertilizer rate [ [61] , [62] , [63] ].…”