Climate-smart planting for potato to balance economic return and environmental impact across China.

Potato production plays an important role in safeguarding food security in China since the central government implemented the 'Potato-as-Staple-Food' policy in 2015. However, a key challenge facing China's potato production is to realize a tradeoff between economic return and environmental impact. Effective strategies for reducing carbon emission without compromising potato yield remain to be developed. This study conducted a comprehensive assessment by integrating climate, soil, crop, and agricultural input data, crop model and life cycle impact assessment model to quantify potato yields, GHG emission amounts and intensities (GHGI), and economic benefits under the conventional planting pattern (CPP), the lowest GHG emission pattern (LEP), and the highest yield pattern (HYP) across China's potato planting regions including four sub-regions, i.e., North Single planting region (NS), Central Double planting region (CD), South Winter planting region (SW), and Southwest Mixed planting region (SWM). Averaged fresh potato yield, GHG emission amount, and GHGI under the CPP were 21.7 t ha-1, 2815.1 kg CO2eq ha-1, and 137.3 kg CO2eq t-1, respectively, in China's potato planting region. Compared with the CPP, averaged GHG emission amount and GHGI under the LEP could be decreased by 48.2 % and 51.5 % respectively while the fresh potato yield and economic benefit could be enhanced by 8.1 % and 18.5 %, respectively. For the HYP, averaged GHG emission amount and GHGI could be decreased by 24.2 % and 39.8 % respectively while the fresh potato yield and economic benefit could be enhanced by 18.7 % and 39.6 %, respectively, compared with the CPP. Across the four potato planting regions, SW had the largest potential in reducing GHG emissions owing to a high reduction amount of nitrogen application rate. Our study demonstrates that optimizing agronomic management could reduce environmental impact without compromising economic benefit and provides a scientific method for assessing crop potential to realize the climate-smart planting.

N2O emission characteristics and its affecting factors in rain-fed potato fields in Wuchuan County, China.

Representing an important greenhouse gas, nitrous oxide (N2O) emission from cultivated land is a hot topic in current climate change research. This study examined the influences of nitrogen fertilisation, temperature and soil moisture on the ammonia monooxygenase subunit A (amoA) gene copy numbers and N2O emission characteristics. The experimental observation of N2O fluxes was based on the static chamber-gas chromatographic method. The ammonia-oxidising bacteria (AOB) and ammonia-oxidising archaea (AOA) gene copy numbers in different periods were measured by real-time polymerase chain reaction (PCR). The results indicated that rain-fed potato field was a N2O source, and the average annual N2O emission was approximately 0.46 ± 0.06 kgN2O-N/ha/year. N2O emissions increased significantly with increase in fertilisation, temperatures below 19.6 °C and soil volumetric water content under 15%. Crop rotation appreciably decreases N2O emissions by 34.4 to 52.4% compared to continuous cropping in rain-fed potato fields. The significant correlation between N2O fluxes and AOB copy numbers implied that N2O emissions were primarily controlled by AOB in rain-fed potato fields. The research has important theoretical and practical value for understanding N2O emissions from rain-fed dry farmland fields.