Response of area- and yield-scaled N2 O emissions from croplands to deep fertilization: a meta-analysis of soil, climate, and management factors.

Abstract

Nitrous oxide (N2 O) is an important and persistent greenhouse gas making a significant contribution to global climate change. Deep fertilization has been demonstrated to increase crop yield and nutrient use efficiency by decreasing losses of volatilization and surface runoff. However, N2 O emissions from croplands induced by deep fertilization are variable and mitigation strategies remain uncertain. This study aimed to (i) quantify the response of area-scaled (N2 O emissions) and yield-scaled N2 O emissions (N2 O intensity) from croplands to deep fertilization, and (ii) identify the soil, climate, and management factors that mitigate N2 O emissions and N2 O intensity under deep fertilization. Compared with the control, deep fertilization increased N2 O emissions by 18.6% (P < 0.001) but decreased N2 O intensity by 20.1% (P=0.018). By adopting deep fertilization, N2 O emissions could be significantly mitigated in rice-paddies soils (-48.8%), with fertilizer depth > 10cm (-33.0%), and with fertilizer N amount > 200 kg N ha-1 (-8.2%). N2 O intensity following deep fertilization significantly decreased in soils with pH ≤6 (-22.5%), at sites with precipitation of 500-1000 mm (-25.5%), in rice-paddies soils (-53.0%), with the method of mixed fertilizer in the control (-21.2%), and with fertilizer depth > 10cm (-33.6%). This study provides a basis for assessing the effect of deep fertilization on N2 O emissions and provides potential measures to mitigate N2 O emissions associated with deep fertilization practices.