Microbial activities and nitrogen (N) availability in soil directly affect root morphology and consequently crop yield. These relationships are even more critical at the filling stage of wheat due to the grain formation. The objective of this study was to compare effects of blended controlled-release N fertilizer (CRFS) and conventional urea (BBFS) on soil microflora, soil N content, and root growth of wheat at the filling stage in a field with straw return for seven years. The method of 16 s rRNA and ITS high-throughput sequencing was used to probe soil microbial status, and the in-situ root scanner was used for in-situ observation and monitoring of wheat root morphology during two growing seasons. The results showed that CRFS increased the relative abundance of Penicillium and Aspergillus fungal genera and reduced the operational taxonomic unit of nitrifying bacteria of the genus Nitrospira compared to BBFS treatment. Nitrate, ammonium, total N, and organic matter in soils treated CRFS were 15.8 %, 10 %, 7.5 %, and 11.6 % higher than these in soils treated with BBFS, respectively, while the total root length, root surface area, and root volume from CRFS treatment were 57.6%, 48.8 %, and 54.1 % higher than these from BBFS, respectively. Above-ground growth of wheat showed that CRFS increased plant height by 5.8–12.6 %, net photosynthetic rate by 13.5–22.2 %, N content of stems and spikes by 10.0 % and 64.1 %, respectively compared to BBFS. Wheat yield and economic efficiency were increased by 9.9–46.8 %, 11.6–41.7 %, respectively with CRFS treatments than these with BBFS treatments. Wheat received reduced application rate (2/3) of CRFS had similar availability of N and plant growth as the full rate of BBFS. Therefore, using blended controlled-release N fertilizer is a practically and environmentally feasible approach for wheat production in the straw retuning wheat-corn rotation system.

土壤中的微生物活动和氮（N）的利用率直接影响根系形态，从而影响作物产量。由于谷物的形成，这些关系在小麦的灌浆阶段甚至更为关键。这项研究的目的是比较七种秸秆还田田在灌浆期混合控释氮肥（CRFS）和常规尿素（BBFS）对土壤微生物区系，土壤氮含量和小麦根系生长的影响。年。采用16 s rRNA和ITS高通量测序方法探测土壤微生物状况，用原位根扫描仪进行两个生长季小麦根形态的原位观察和监测。结果表明，CRFS增加了青霉菌和曲霉菌的相对丰度。真菌属，减少了硝化螺旋藻属硝化细菌的操作分类单位与BBFS治疗相比。处理过的CRFS土壤中的硝酸盐，铵盐，总氮和有机质分别比使用BBFS处理过的土壤分别高15.8％，10％，7.5％和11.6％，而总根长，根表面积和根CRFS处理的血容量分别比BBFS的血容量高57.6％，48.8％和54.1％。小麦的地上生长表明，与BBFS相比，CRFS的株高增加了5.8-12.6％，净光合速率增加了13.5-22.2％，茎和穗的氮含量增加了10.0％和64.1％。CRFS处理的小麦单产和经济效率分别比BBFS处理提高9.9-46.8％，11.6-41.7％。小麦CRFS施用量减少（2/3）时，氮素和植物的生长与BBFS的全量相似。所以，