Agriculture faces great challenges to ensure global food security by increasing yields while reducing environmental costs. Here we address this challenge by conducting a total of 153 site-year field experiments covering the main agro-ecological areas for rice, wheat and maize production in China. A set of integrated soil-crop system management practices based on a modern understanding of crop ecophysiology and soil biogeochemistry increases average yields for rice, wheat and maize from 7.2 million grams per hectare (Mg ha(-1)), 7.2 Mg ha(-1) and 10.5 Mg ha(-1) to 8.5 Mg ha(-1), 8.9 Mg ha(-1) and 14.2 Mg ha(-1), respectively, without any increase in nitrogen fertilizer. Model simulation and life-cycle assessment show that reactive nitrogen losses and greenhouse gas emissions are reduced substantially by integrated soil-crop system management. If farmers in China could achieve average grain yields equivalent to 80% of this treatment by 2030, over the same planting area as in 2012, total production of rice, wheat and maize in China would be more than enough to meet the demand for direct human consumption and a substantially increased demand for animal feed, while decreasing the environmental costs of intensive agriculture.

Sustainably feeding a growing population is a grand challenge, and one that is particularly difficult in regions that are dominated by smallholder farming. Despite local successes, mobilizing vast smallholder communities with science- and evidence-based management practices to simultaneously address production and pollution problems has been infeasible. Here we report the outcome of concerted efforts in engaging millions of Chinese smallholder farmers to adopt enhanced management practices for greater yield and environmental performance. First, we conducted field trials across China's major agroecological zones to develop locally applicable recommendations using a comprehensive decision-support program. Engaging farmers to adopt those recommendations involved the collaboration of a core network of 1,152 researchers with numerous extension agents and agribusiness personnel. From 2005 to 2015, about 20.9 million farmers in 452 counties adopted enhanced management practices in fields with a total of 37.7 million cumulative hectares over the years. Average yields (maize, rice and wheat) increased by 10.8-11.5%, generating a net grain output of 33 million tonnes (Mt). At the same time, application of nitrogen decreased by 14.7-18.1%, saving 1.2 Mt of nitrogen fertilizers. The increased grain output and decreased nitrogen fertilizer use were equivalent to US$12.2 billion. Estimated reactive nitrogen losses averaged 4.5-4.7 kg nitrogen per Megagram (Mg) with the intervention compared to 6.0-6.4 kg nitrogen per Mg without. Greenhouse gas emissions were 328 kg, 812 kg and 434 kg CO equivalent per Mg of maize, rice and wheat produced, respectively, compared to 422 kg, 941 kg and 549 kg CO equivalent per Mg without the intervention. On the basis of a large-scale survey (8.6 million farmer participants) and scenario analyses, we further demonstrate the potential impacts of implementing the enhanced management practices on China's food security and sustainability outlook.

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In a series of eld studies, di ering rainfall patterns within the rst month a er N fertilizer application to a coarse-textured soil signi cantly a ected yields and N-use e ciency of irrigated corn (Zea mays L.), and responses varied with N source. A laboratory study was conducted to evaluate e ects of N source with precipitation following N application to a coarse-textured soil. Nitrogen sources included urea-ammonium nitrate solution (UAN), UAN with additives of either nitrapyrin (2-chloro-6-[trichloromethyl] pyridine) as a nitri cation inhibitor or maleic-itaconic acid copolymer as a urease and nitri cation inhibitor, or polymer-coated dry urea (PCU). ese products were applied to soil in chambers from which ammonia (NH 3 ) volatilization and nitrate (NO 3 -) leaching were measured over 31 d following fertilization. Precipitation events simulated rainfall frequencies and amounts that occurred in eld studies in dry and wet conditions. Ammonia volatilization was lower in wet than dry conditions. Total NH 3 loss for the dry precipitation regime ranged from 11 to 18% of applied N fertilizer for all treatments except PCU (<1%). In contrast, all treatments in wet conditions had low NH 3 loss (<1% of applied N). However, substantial NO 3 leaching occurred with wet conditions, comprising 48 to 66% of applied N for most treatments. Leaching loss was the greatest for UAN, followed by UAN with additives. For either dry or wet environments, losses of N from PCU to either NH 3 volatilization or NO 3 leaching were negligible.

Poor management is the main reason for high N losses and reduced yield in rice production. Improved crop management in northeastern China is becoming increasingly important due to economic pressures in southern and central China along with rising temperatures in the Northeast, which have led to a major shift in rice (Oryza sativa L.) production to this region. Here, we examine the opportunities for improving the yield and nitrogen use efficiency (NUE) of irrigated rice in northeastern China by optimizing nutrients and increasing the transplanting density. In 2009 to 2011, field experiments were conducted to compare optimized nutrient management (ONM) and optimized crop management treatments (OCM) with the farmers’ crop management (FCM) and no N treatment (control). Compared with the FCM, the ONM and OCM treatments significantly increased average grain yield by respective averages of 9 and 17%. These yield gains resulted from a combination of increases in grains per panicle and panicles per unit area. Compared with the FCM treatment, agronomic efficiency (AEN), recovery efficiency of applied nitrogen (REN) and partial factor productivity of applied nitrogen (PFPN) were enhanced by an average of 120, 116, and 67% across the ONM and OCM treatments in the 3‐yr study period, respectively. It is clear that high yields combined with high N use efficiency are possible in northeastern China by appropriately increasing rice transplanting density and optimizing nutrient management.