Adequate vegetative cover decreases nitrous oxide emissions from cattle urine deposited in grazed pastures under rainy season conditions

Ngonidzashe Chirinda,Claudia Faverín,Verónica Ruiz,Jean Víctor Savian,Michael Peters,Ciniro Costa,Sandra Loaiza,Miguel Arango,Carolina Álvarez ,Meryl Richards,Renaldo Belfon,Jacobo Arango,Catalina Trujillo,Karen Zuniga,Idupulapati M Rao ,Luis A Morales-Rincon ,Rolando Barahona,Deissy Martínez-Barón ,Laura Arenas,Todd S Rosenstock,L M Cardenas

doi:10.1038/s41598-018-37453-2

Abstract

A decline in pasture productivity is often associated with a reduction in vegetative cover. We hypothesize that nitrogen (N) in urine deposited by grazing cattle on degraded pastures, with low vegetative cover, is highly susceptible to losses. Here, we quantified the magnitude of urine-based nitrous oxide (N2O) lost from soil under paired degraded (low vegetative cover) and non-degraded (adequate vegetative cover) pastures across five countries of the Latin America and the Caribbean (LAC) region and estimated urine-N emission factors. Soil N2O emissions from simulated cattle urine patches were quantified with closed static chambers and gas chromatography. At the regional level, rainy season cumulative N2O emissions (3.31 versus 1.91 kg N2O-N ha−1) and emission factors (0.42 versus 0.18%) were higher for low vegetative cover compared to adequate vegetative cover pastures. Findings indicate that under rainy season conditions, adequate vegetative cover through proper pasture management could help reduce urine-induced N2O emissions from grazed pastures.

Highlights

A decline in pasture productivity is often associated with a reduction in vegetative cover
The key finding of our study is that, at the regional level of Latin America and the Caribbean (LAC), N2O emission factors from cattle urine patches in grazed pastures are lower for adequate vegetative cover (AVC) compared to low vegetative cover (LVC) pastures during rainy season, suggesting the importance of adequate pasture improvement/management in mitigating soil N2O emissions
We did not have soil moisture data for all the sites to be able to compute the effects of water-filled pore space, which has been shown to be a major driver of N2O emissions[24,25]

Summary

Introduction

A decline in pasture productivity is often associated with a reduction in vegetative cover. We hypothesize that nitrogen (N) in urine deposited by grazing cattle on degraded pastures, with low vegetative cover, is highly susceptible to losses. We quantified the magnitude of urine-based nitrous oxide (N2O) lost from soil under paired degraded (low vegetative cover) and non-degraded (adequate vegetative cover) pastures across five countries of the Latin America and the Caribbean (LAC) region and estimated urine-N emission factors. Rainy season cumulative N2O emissions (3.31 versus 1.91 kg N2O-N ha−1) and emission factors (0.42 versus 0.18%) were higher for low vegetative cover compared to adequate vegetative cover pastures. Findings indicate that under rainy season conditions, adequate vegetative cover through proper pasture management could help reduce urine-induced N2O emissions from grazed pastures. Cattle excreta deposited on grazed pastures is estimated to represent 16% of global anthropogenic nitrous oxide (N2O) emissions, a powerful greenhouse gas (GHG)[5]. Lower emission factors (EFs) (

Methods

Results

Conclusion