The deep nitrogen (N) fertilization coupled with mechanical pot‐seedling transplanting rice (DNF‐MPT) is an effective alternative to traditional transplanted rice (Oryza sativa L.) with broadcasting fertilizer; however, little is known about its effects on grain yield, nutrient accumulation, and economic profitability. In present study, a 2‐yr field experiment was conducted in early seasons (Mar.–July) of 2019 and 2020. All seedlings were transplanted by DNF‐MPT, whereas four treatments were designed as mechanized deep placement of all fertilizers as basal fertilizer (MD); mechanized deep placement of 70% basal fertilizer and 30% broadcasting fertilizers at panicle initiation (MDB); manual broadcasting of 40, 30, and 30% fertilizers at the transplanting, tillering, and panicle initiation stages, respectively (MB); and no fertilizer (CK). The results indicated that the MD treatment substantially improved the grain yield by 33.48–36.35%, total N accumulation by 26.38–44.15%, total phosphorus (P) accumulation by 28.72–30.23%, and total potassium (K) accumulation by 25.61–37.33% compared with MB. Deep placement of N fertilization treatments, that is, MD and MDB, remarkably promoted root morphological indexes including total root volume, total root length, and root superficial area. Furthermore, nitrate reductase, glutamine synthetase activities, and total chlorophyll content of leaves were also enhanced under deep placement of N fertilizer. Overall, the MD treatment had the highest benefit/cost ratio due to high gross returns and low input costs. Therefore, deep placement of N fertilizer coupled with mechanical pot‐seedling transplanting rice could be better alternative to conventional rice production system with more economic benefits.

中文翻译：

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华南地区机械播种水稻机械化深施氮肥的生产力与收益

深氮施肥与机械盆栽移栽水稻（DNF-MPT）结合使用是传统移栽水稻（Oryza sativa）的有效替代品L.）播撒肥料；然而，对其对谷物产量，养分积累和经济效益的影响知之甚少。在本研究中，在2019年和2020年的早期（3月至7月）进行了为期2年的田间试验。所有幼苗均通过DNF-MPT进行了移植，而四种处理方式则设计为将所有肥料机械化深施为基础肥料（MD）; 在穗开始时机械化深施70％的基肥和30％的播撒肥（MDB）; 在移植，分er和穗萌动阶段分别手动播种40％，30％和30％的肥料（MB）；而且没有肥料（CK）。结果表明，MD处理显着提高了谷物产量，提高了33.48-36.35％，总氮累积提高了26.38-44.15％，总磷（P）累积提高了28.72-30。与MB相比，总钾（K）累积量为23％，降低了25.61–37.33％。深施氮肥（即MD和MDB）显着提高了根系形态指标，包括总根系体积，总根系长度和根系表层面积。此外，深施氮肥还增强了叶片的硝酸还原酶，谷氨酰胺合成酶活性和总叶绿素含量。总体而言，由于高总回报率和低投入成本，MD处理具有最高的收益/成本比。因此，与传统的水稻生产系统相比，深施氮肥和机械盆栽移栽水稻可以更好地替代传统水稻生产系统，并具有更大的经济效益。MD和MDB显着提高了根的形态学指标，包括总根体积，总根长和根表皮面积。此外，深施氮肥还增强了叶片的硝酸还原酶，谷氨酰胺合成酶活性和总叶绿素含量。总体而言，由于高总回报率和低投入成本，MD处理具有最高的收益/成本比。因此，与传统的水稻生产系统相比，深施氮肥和机械盆栽移栽水稻可以更好地替代传统水稻生产系统，并具有更大的经济效益。MD和MDB显着提高了根的形态学指标，包括总根体积，总根长和根表皮面积。此外，深施氮肥还增强了叶片的硝酸还原酶，谷氨酰胺合成酶活性和总叶绿素含量。总体而言，由于高总回报率和低投入成本，MD处理具有最高的收益/成本比。因此，与传统的水稻生产系统相比，深施氮肥和机械盆栽移栽水稻可以更好地替代传统水稻生产系统，并具有更大的经济效益。氮肥深度施用后，叶片的总叶绿素含量也增加。总体而言，由于高总回报率和低投入成本，MD处理具有最高的收益/成本比。因此，与传统的水稻生产系统相比，深施氮肥和机械盆栽移栽水稻可以更好地替代传统水稻生产系统，并具有更大的经济效益。氮肥深度施用后，叶片的总叶绿素含量也增加。总体而言，由于高总回报率和低投入成本，MD处理具有最高的收益/成本比。因此，与传统的水稻生产系统相比，深施氮肥和机械盆栽移栽水稻可以更好地替代传统水稻生产系统，并具有更大的经济效益。