Synergies and trade-offs between yield, quality, resource use efficiency and environmental impact of potato production in China

Potato is the fourth most important food crop in China. However, the yield is relatively low and the production is associated with high resource inputs and serious environmental problems. Potato production should be enhanced with sustainable practices that strike the right balance between multiple sustainable development objectives (agronomic, economic and environmental). The major aim of the present study was to explore the theoretical possibilities and demonstrate pathways for sustainable intensification of potato cultivation in China that optimize yield and quality, use natural resources efficiently, and minimize environmental impacts simultaneously. Crop modelling and farm surveys were used to assess these objectives at national and regional level, while on-farm experiments were performed to evaluate sustainable practices at local level.The biophysical potential of the potato crop in China was explored and the scope for enhancing yield was estimated. There is large potential to improve potato yield across the country under both irrigated and rainfed conditions (the yield gap is 66% and 61%, respectively, for irrigated and rainfed potato crops). A great improvement in yield can be achieved under rainfed conditions with current precipitation levels, especially in Qinghai and Heilongjiang in the north, and Guizhou in the southwest. Enhancing yield from actual to the potential yield level (under irrigated conditions) is associated with improved water productivity (from 7.9–22.3 to 30.7–54 kg dry matter ha-1 mm-1). Compared to the major cereals, potatoes have a larger potential to contribute to future food self-sufficiency in China as implied by the remarkable energy production gap (i.e., the additional calories provided by potatoes by closing the yield gaps to 80% of the potential yield under irrigated conditions and water-limited potential yield under rainfed conditions are 1.1 1014 and 0.9 1014 kcal calories, respectively). Improving environmental sustainability of potato cultivation should also be economically viable, and both yield and quality are key components driving the revenues for farmers. A framework was developed to assess the interrelationships between yield, quality and the influences on revenue. The framework was applied in a case study of commercial French Fries potato production in Inner Mongolia in the north. Farmers obtained low revenue (the gap between the revenue from the best performing farmers and actual revenue was 43%) as a consequence of moderate yield gap (the gap between the maximum farmers’ yield and actual yield was 26%) and poor tuber quality (i.e., low dry matter percentage of tubers, and high percentage of weight of the small-sized tubers). It was found that enhancing yield up to the maximum yield obtained by farmers in the case study (55 ton fresh matter ha-1) was strongly associated to improvement in quality and revenue, suggesting synergies for reaching different objectives.An integrated assessment on yield, resource use efficiencies (nitrogen use efficiency and water productivity) and environmental impacts (nitrogen surplus and water surplus) was performed for large-scale commercial farms in three major potato production regions in northern China (Inner Mongolia, Gansu and Heilongjiang). Potato production was associated with moderate resource use efficiencies (nitrogen use efficiency was 47–68%, and water productivity was 23–35 kg dry matter ha-1 mm-1) and substantial environmental impacts (nitrogen surplus was 50–156 kg ha-1, water surplus was 52–570 mm) due to the application of excessive amounts of fertiliser and irrigation. We assessed that a higher nitrogen use efficiency (exceeding 90% in the short-term and up to 84% in the long-term) was achievable with more efficient nitrogen management. Water productivity can be increased to 29–44 kg dry matter ha-1 mm-1, and water surplus can be reduced with more efficient irrigation systems.The pathways towards sustainable intensification were explored experimentally on large-scale commercial farms in Inner Mongolia in two years (2017–2018). In both years, irrigation contributed significantly to a higher yield and better quality in comparison with rainfed conditions. Under irrigated conditions, reducing nitrogen fertiliser from the current rates (189–252 kg ha-1) to lower levels (109–181 kg ha-1) did not affect yield nor quality, while it largely improved nitrogen use efficiency (from 67% to 89%) and reduced N surplus (from 81 to 28 kg ha-1). Yet, further reducing nitrogen fertiliser inputs (to 9–117 kg ha-1) should be done cautiously, accounting for different growing conditions of fields. Farmers found the reduction of nitrogen fertiliser input by 10–20% acceptable, while they noted that the widespread adaptation to more efficient irrigation practice (drip irrigation) was hindered by high cost and labor demands. The present study provides crucial knowledge and contextualized suggestions to underpin sustainable intensification of potato production in China.