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Maize (Zea mays L.) production in Northeast China is vulnerable to climate change. Thus, exploring future adaptation measures for maize is crucial to developing sustainable agriculture to ensure food security. The current study was undertaken to evaluate the impacts of climate change on maize yield and partial factor productivity of nitrogen (PFPN) and explore potential adaptation strategies in Northeast China. The Decision Support System for Agrotechnology Transfer (DSSAT) model was calibrated and validated using the measurements from nine maize experiments. DSSAT performed well in simulating maize yield, biomass and N uptake for both calibration and validation periods (normalized root mean square error (nRMSE) < 10%, −5% < normalized average relative error (nARE) < 5% and index of agreement (d) > 0.8). Compared to the baseline (1980–2010), the average maize yields and PFPN would decrease by 7.6–32.1% and 3.6–14.0 kg N kg−1 respectively under future climate scenarios (2041–2070 and 2071–2100) without adaptation. Optimizing N application rate and timing, establishing rotation system with legumes, adjusting planting dates and breeding long-season cultivars could be effective adaptation strategies to climate change. This study demonstrated that optimizing agronomic crop management practices would assist to make policy development on mitigating the negative impacts of future climate change on maize production. [ABSTRACT FROM AUTHOR]

Great changes have been happened over the past 30 years in chemical fertilizer input in China, and thus a gross potassium (K) budget model established to evaluate the variation of farmland K balance for China in 1980 and 2010 at the national scale is important. Results indicated that total K input in 1980 was 6.8 million tonnes, in which chemical fertilizer, organic manure and other sources accounted for 5.6, 77.5 and 16.9% respectively. Total K input in 2010 was 21.6 million tonnes, in which chemical fertilizer, organic manure and other sources accounted for 43.5, 50.4 and 6.1% respectively. Total K output in 1980 was 8.1 million tonnes, in which crops removal and loss accounted for 98.2 and 1.8% respectively. Total K output in 2010 was 19.1 million tonnes, in which crops removal and loss accounted for 99.2 and 0.8%, respectively. Similar to K input, the spatial distribution of K output differed greatly. Total K deficit was 1.3 million tonnes, and the range of K balance in each province was −86.7 to 53.6 kg KO ha in 1980. Compared with that, total K surplus was 2.5 million tonnes and the range of K balance in each province was −43.0 to 256.6 kg KO ha in 2010. Chemical fertilizer K application over the past 30 years makes the great changes in average K balance from deficit to surplus in general; however, the great spatial variation in K balance drives urgent need for site-specific K nutrient management. [ABSTRACT FROM AUTHOR]

Sensitivity analysis of DSSAT outputs to inputs parameters was conducted in two Canadian locations: one for spring wheat ( Triticum aestivum L.) in the semi-arid Prairies in Swift Current, Saskatchewan and the second for maize ( Zea mays L.) under humid conditions in Woodslee, Ontario. The nominal range sensitivity method, regression, and graphical analysis were used to assess the sensitivity of crop yields, biomass, soil inorganic N, nitrate leaching and soil water contents to soil hydraulic properties, management practices and precipitation. Wheat and maize yields were highly sensitive to soil water drainage upper limit, fertilizer nitrogen rate and precipitation at both locations. At Swift Current, very high soil nitrate leaching (25-140 kg N ha) was found in 1994, 1996, 1997 and 2003 as affected by high precipitation in the previous years (i.e., 1993, 1995, 1996 and 2002). Soil N leaching was greater in 2011, a wet year at Woodslee, Ontario, with 20-85 kg N ha than in the normal rainfall years of 2010 and 2012. Based on the fitted N response curves, the maximum yields were obtained at 112 kg N ha for spring wheat at Swift Current and 150-210 kg N ha for maize at Woodslee. The optimum planting date for maize at Woodslee was predicted to be from late May to early June. Sensitivity analysis was found to be useful in assessing the influence of crop management practices, soil parameters and precipitation on crop production and potential environment risks. [ABSTRACT FROM AUTHOR]