Search

Application of biochar and nitrification inhibitors (NIs) to soil has been suggested as a strategy for mitigating climate change and promoting nitrogen use efficiency. However, few studies have focused on how N2O, NO and NH3 emissions and vegetable yield are affected by simultaneous biochar and NI application in vegetable fields. This study aims to investigate the effects of biochar and 3,4-dimethylpyrazole phosphate (DMPP, one type of NIs) amendment on reactive nitrogen gas emissions (GNrEs), vegetable yield, and reactive gaseous N intensity (GNrI) in an intensive vegetable field. There were three treatments: U: urea, UB: urea combined with biochar, UDMPP: urea combined with DMPP. The results show that biochar amendment increased NH3 volatilization by 92.8% (p < 0.05) compared to that under the U treatment. DMPP application abated significantly NO and GNrEs by 49.9% and 21.4%, respectively, compared to those of the U treatment. No significant differences were observed in GNrI among all three treatments; however, DMPP addition had more potential to reduce GNrI than biochar application, based on their results compared to those of the U treatment. Our findings suggest that DMPP application is a suitable practice to reduce GNrEs and maintain yields in intensive vegetable fields. [ABSTRACT FROM AUTHOR]

Organic material (OM) applied to cropland not only enhances soil fertility but also profoundly affects soil nitrogen cycling. However, little is known about the relative contributions of soil ammonia-oxidizing archaea (AOA) and bacteria (AOB) to nitrous oxide (N 2 O) production during ammonia oxidation in response to the additions of diverse types of OMs in the tropical soil for vegetable production. Herein, the soils were sampled from a tropical vegetable field subjected to 4-year consecutive amendments of straw or manure. All the soils were amended with ammonium sulfate ((NH 4 ) 2 SO 4 , applied at a dose of 150 mg N kg -1 ) and incubated aerobically for four weeks under 50% water holding capacity. 1-octyne or acetylene inhibition technique was used to differentiate the relative contributions of AOA and AOB to N 2 O production. Results showed that AOA dominated N 2 O production in soil managements of unfertilized control (CK), chemical fertilization (NPK), and NPK with straw (NPKS), whereas AOB contributed more in soil under NPK with manure (NPKM). Straw addition stimulated AOA-dependent N 2 O production by 94.8% despite the decreased AOA-amoA abundance. Moreover, manure incorporation triggered both AOA- and AOB-dependent N 2 O production by 147.2% and 233.7%, respectively, accompanied with increased AOA and AOB abundances. Those stimulating effects were stronger for AOB, owing to its sensitivity to the alleviated soil acidification and decreased soil C/N ratio. Our findings highlight the stimulated N 2 O emissions during ammonia oxidation by historical OM amendments in tropical vegetable soil, with the magnitude of those priming effects dependent on the types of OM, and appropriate measures need to be taken to counter this challenge in tropical agriculture ecosystems., Competing Interests: Declaration of competing interest The author declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021. Published by Elsevier B.V.)