Nitrogen is a key nutrient for soybean cropping and can be fully supplied by the biological nitrogen fixation (BNF) process. Inoculation with elite Bradyrhizobium strains greatly improves the supply of N to soybean; however, inoculation of large areas in short‐sowing windows delays the sowing process, demanding the development of technologies for pre‐inoculation. Here we report the evaluation of a liquid formulation containing cell protectors that proved, in four field experiments located in different edaphoclimatic conditions of Brazil, symbiotic performance comparable to the peat‐based inoculant, traditionally considered as the best carrier. The liquid inoculant was also effective when applied to seeds not treated with pesticides 15 days before sowing, providing efficient BNF and time‐flexibility to the farmers. Benefits of the liquid inoculant in improving grain yield were confirmed in two areas cropped for the first time and devoid of Bradyrhizobium, with an average increase of 89%, and also in two areas traditionally cropped with inoculated soybean, with an average increase of 6.8%, both in comparison to the non‐inoculated control without N‐fertilizers (NI). It is worth mentioning that, also in comparison to the NI control, the addition of 200 kg N ha⁻¹ impacted grain yield in +54% and −1,8%, in new and traditional areas, respectively, indicating that BNF was more effective than the application of N‐fertilizer. Large increases in total N content in grains were observed as well in response to the liquid inoculant, on average 47% and 27%, when compared to the NI and NI + N controls, respectively.

中文翻译：

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根瘤菌对种子的预接种是大型大豆种植系统的时间优化选择

氮是大豆种植的关键营养素，可以通过生物固氮（BNF）过程充分供应。接种精英根瘤菌菌株大大提高了大豆的氮素供应。但是，在短播窗口内大面积接种会延缓播种过程，这需要开发预接种技术。在这里，我们报告了一种含有细胞保护剂的液体制剂的评估，该评估在位于巴西不同水生气候条件下的四个野外实验中证明了与基于泥炭的孕育剂（传统上被认为是最佳载体）相当的共生性能。液体接种剂在播种前15天施用于未经农药处理的种子时也很有效，为农民提供了有效的BNF和时间灵活性。在两个初次种植且没有缓生根瘤菌的地区，证实了液体孕育剂提高谷物产量的好处，平均增幅为89％，在传统上种植了大豆的两个地区，平均增幅为6.8％，两者均与未接种非氮肥的对照相比。值得一提的是，与NI对照相比，在新区和传统区添加200 kg N ha ^-1的谷物单产分别提高了+ 54％和-1.8％，表明BNF更高。比施用氮肥有效。相比于NI和NI + N对照，响应液体接种剂，谷物中的总N含量也显着增加，平均分别为47％和27％。