Wu Meng, Li Guilong, Li Weitao, Liu Jia, Liu Ming, Jiang Chunyu, Li Zhongpei
State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of SciencesNanjing, China.
Graduate University of Chinese Academy of SciencesBeijing, China.
Front Plant Sci. 2017 Jul 11;8:1227. doi: 10.3389/fpls.2017.01227. eCollection 2017.
Field plot experiments were conducted over 3 years (from April 2014 to November 2016) in a double-rice () cropping system in subtropical China to evaluate the effects of N fertilizer placement on grain yield and N recovery efficiency (NRE). Different N application methods included: no N application (CK); N broadcast application (NBP); N and NPK deep placement (NDP and NPKDP, respectively). Results showed that grain yield and apparent NRE significantly increased for NDP and NPKDP as compared to NBP. The main reason was that N deep placement (NDP) increased the number of productive panicle per m. To further evaluate the increase, a pot experiment was conducted to understand the N supply in different soil layers in NDP during the whole rice growing stage and a N tracing technique was used in a field experiment to investigate the fate of urea-N in the rice-soil system during rice growth and at maturity. The pot experiment indicated that NDP could maintain a higher N supply in deep soil layers than N broadcast for 52 days during rice growth. The N tracing study showed that NDP could maintain much higher fertilizer N in the 5-20 cm soil layer during rice growth and could induce plant to absorb more N from fertilizer and soil than NBP, which led to higher NRE. One important finding was that NDP and NPKDP significantly increased fertilizer NRE but did not lead to N declined in soil compared to NBP. Compared to NPK, NPKDP induced rice plants to absorb more fertilizer N rather than soil N.
在中国亚热带地区的双季稻种植系统中进行了为期3年（2014年4月至2016年11月）的田间小区试验，以评估氮肥施用位置对水稻产量和氮素回收效率（NRE）的影响。不同的施氮方法包括：不施氮（CK）；氮肥撒施（NBP）；氮和氮磷钾深施（分别为NDP和NPKDP）。结果表明，与NBP相比，NDP和NPKDP处理的水稻产量和表观氮素回收效率显著提高。主要原因是氮肥深施（NDP）增加了每平方米有效穗数。为进一步评估这种增加效果，进行了盆栽试验以了解水稻全生育期氮肥深施时不同土层的供氮情况，并在田间试验中采用氮素示踪技术研究水稻生长和成熟期水稻-土壤系统中尿素氮的去向。盆栽试验表明，在水稻生长期间，氮肥深施比氮肥撒施能在深层土壤中保持52天更高的供氮量。氮素示踪研究表明，氮肥深施在水稻生长期间能在5-20厘米土层中保持更高的肥料氮含量，且能诱导植株比氮肥撒施吸收更多的肥料氮和土壤氮，从而导致更高的氮素回收效率。一个重要发现是，与氮肥撒施相比，氮肥深施和氮磷钾深施显著提高了肥料氮素回收效率，但并未导致土壤中氮素含量下降。与氮磷钾处理相比，氮磷钾深施诱导水稻植株吸收更多的肥料氮而非土壤氮。
