Brazil is the second largest soybean production and export country in the world, which is also the most important soybean import country to China. The yield changes and the supply of Brazil' soybean have great impacts both on the international soybean market and Chinese soybean import and export, which also become one of the important factors affecting the safety of food supply in China .Using Normalized Difference Vegetation Index (NDVI), which is the most widely used in crop growth remote sensing monitoring at present, this paper monitored and analyzed the soybean growth condition in Brazil in 2017 using a difference crop model by comparing the growth condition average values of this year with those of the same period of last year. The study can obtain the changing trend of soybean yield in 2017, and provide the data support for China's soybean import policy. The results showed that the soybean growth condition in Brazil showed "better in the early period in 2017, slightly worse in the middle period, and better again in the late "tendency. The soybean growing conditions were overall better than last year. In spatial distribution, the soybean growth condition was better than the same period of last year in Midwest, Northeast and Southeast of Brazil, while in Southern states, the soybean growth condition showed a normal state compared with the same period of last year. From the autumn of 2016 to March of 2017 year, the overall weather were fine are the main agricultural regions of Brazil, soil moisture was all favorable to the soybean growth, which are the main reasons that the soybean growth was better than last year in Brazil.%巴西是我国重要的大豆进口国.研究巴西大豆的产量变化和供给状况对中国大豆进出口贸易乃至国际大豆市场的发展具有重要意义.利用目前作物长势遥感监测中应用最广泛的归一化植被指数NDVI,对巴西2017年大豆长势进行监测,并采用差值模型,与2016年同期大豆长势的平均状况进行对比研究,以期获得巴西大豆2017年产量变化趋势,为我国大豆进口政策提供数据支撑.研究结果表明:巴西大豆长势在2017年期间呈现"前期较好,中期略变差,后期变好"的趋势,大豆长势总体好于2016年同期.在空间分布上,巴西中西部、东北部和东南部大豆全年长势好于2016年同期,而在南部的一些州,大豆长势基本与2016年同期持平.大豆主要生育期内良好的天气因素是2017年巴西大豆长势较好的主要原因.
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