【作者】 吴成龙；

【导师】 徐阳春；

【作者基本信息】 南京农业大学 ， 植物营养学， 2010， 博士

【摘要】 水稻和小麦是世界上最重要的主食作物。水稻—小麦轮作(R—W)是南亚各国普遍采取的耕作措施。在中国,R—W主要分布于长江流域,面积达1300万hm2。R→W的稳定生产关系到中国乃至世界的粮食安全。R—W系统中,作物籽粒产量的可持续生产依赖于既能满足作物需求,又能减少损失并最大化其利用率的养分管理。有机无机氮肥的配合施用(IOF)就是一种有望能实现此目标的施肥模式并已在R—W系统广泛应用。然而,当前的研究主要集中在其生物效应方面,有关IOF处理有机肥氮和无机肥氮的相互作用还没有详尽的报道,而探讨有机无机肥氮的协同效应有助于更深入了解不同形态氮素的转化及其作物利用,为高效利用肥料氮提供依据。采用盆栽模拟生物试验,设置5个处理：对照无氮处理(CK),无机氮肥处理(IF),有机氮肥处理(OF)和两个有机无机肥氮配施的处理,其中一个15N标记有机肥氮(IOF1),另一个15N标记无机肥氮(IOF2)。选用质地不同的两种土壤(粘壤土和黏土),以15N标记的硫酸铵和兔子粪作为无机氮和有机氮的氮源,研究了稻—麦轮作(R—W)系统肥料氮仅施用在水稻第一季(O. sativa L. cv. Wuyujing 7)(记为R—W系统)和小麦(Triticum aestivum L.cv Yangmai 6)第一季(记为W—R系统)后的转化利用情况。考虑到肥料氮施用后,相当一部分残留于土壤当中,本研究侧重于第一季肥料氮在土壤的残留及其残留氮素对第二季轮作作物有效性方面的研究。主要结果如下：在R—-W系统水稻季：1)IF与IOF处理水稻籽粒产量没有显著差异；2)无论粘壤土还是黏土,IF处理肥料氮吸收利用率(NUE)值最大,其次为IOF1和IOF2处理,OF处理最低,IOF处理相比IF处理其NUE在粘壤土和黏土分别约低20%和25%以上。与IF或OF处理相比,IOF处理有机肥氮显著降低了水稻植株对无机肥15N的吸收量,而无机肥氮却增加了籽粒和植株对有机肥15N的吸收量；3)与IF或OF处理相比,IOF处理有机肥氮的存在增加了无机肥15N在土壤矿质氮库和微生物量氮(MBN)库的分配,促进了无机肥15N在土壤氮库的残留,降低了损失率,粘壤土和黏土降幅分别为12%和28%；4)植株体内回收的肥料15N大部分积累在水稻籽粒(53%～78%),有机肥氮是IOF处理水稻籽粒氮素相对分配增加的主要贡献者。在R—W系统小麦季：1)粘壤土和黏土上IOF处理其小麦籽粒产量均达到最大,且黏土上OF处理籽粒产量与IOF处理相当；2)与IF处理相比,IOF处理小麦分蘖期、拔节期以及穗期均保持了较高的矿质氮含量和MBN含量；3)粘壤土上IOF处理较高的矿质氮含量主要来自有机肥15N和无机肥15N,而黏土上主要来自无机肥15N。两种土壤上IOF处理较高的MBN均主要来自无机肥15N；4)IOF处理相比IF处理其肥料氮的吸收利用率显著增加,黏土上增幅达173%。IOF处理有机肥氮的存在促进了土壤和小麦植株对无机肥15N的回收残留,而无机肥氮的存在也促进了黏土上有机肥’5N的回收残留；5)小麦籽粒积累了超过80%的植株体内肥料15N的回收量,IOF处理有机肥氮促进了无机肥15N在小麦营养器官的分配。在W—-R系统小麦季：1)无论粘壤土还是黏土,IF和IOF处理小麦籽粒产量最高,且两处理间无显著差异；2)IOF处理无机肥氮的存在显著提高了小麦籽粒和植株对有机肥15N的吸收,粘壤土和黏土籽粒增幅分别为514%和133.3%,而植株增幅分别达216%和100%,同时有机肥氮的存在降低了其对无机肥15N的吸收,粘壤土和黏土籽粒、植株降幅分别约为30%和15%；3)IOF处理相比OF处理其NUE显著增加,粘壤土和黏土上增幅分别约为114%和85%。与IF或OF处理相比,IOF处理有机肥氮降低了无机肥15N,而无机肥氮增加了有机肥15N在土壤矿质氮库的残留。而在MBN库,IOF处理有机肥氮和无机肥氮协同促进了对方的残留；4)与IF或OF相比,粘壤土上IOF处理增加了无机肥15N和有机肥15N在小麦营养器官的积累,而在黏土上增加了无机肥15N在营养器官、有机肥15N在生殖器官的积累。在W—R系统水稻季：1)粘壤土和黏土上IOF处理水稻籽粒产量均高于IF处理；2)与IF处理相比,IOF处理其矿质氮含量均保持较高水平,且IOF处理显著增加了粘壤土上穗期和黏土上分蘖期、拔节期、穗期土壤矿质氮中来自于无机肥15N的比例。此外,IOF处理显著增加了黏土上分蘖期和拔节期MBN中来自于有机肥15N,粘壤土和黏土上分蘖期、拔节期、穗期以及成熟期来自于无机肥15N的比例；3)IOF处理有机肥氮促进了小麦季残留无机肥15N在水稻生殖器官籽粒的分配比例,降低了其在叶片等营养器官的分配比例。与之相反,IOF处理无机肥氮降低了小麦季残留有机肥15N在水稻生殖器官籽粒的分配比例,降幅约为20%,却增加其在叶片等营养器官的分配比例；4)IOF处理相比IF处理其NUE显著增加。与IF或OF处理相比,IOF处理无机肥氮促进了有机肥15N在土壤的残留,而无机肥氮促进了有机肥15N在植株和土壤的回收利用。同时,有机肥氮和无机肥氮的协同降低了各自向环境的损失,降幅均达15%以上。结合四季盆栽试验数据,对比发现：1)W—R系统各处理总生物量显著高于R—W系统,尤其是OF处理。W—R系统OF处理总籽粒产量显著高于R—W系统对应值,粘壤土和黏土上分别高81%和23%,其余各处理总籽粒产量在两系统间没有显著差异；2)无论粘壤土还是黏土,OF处理NUE在W—R系统相对较高；3)同一处理的NUE、肥料15N利用率(15NUE)、肥料15N损失率(15NLR)在不同系统、不同土壤上存在较大差异,表明土壤质地、施肥方法、施肥季节显著影响着稻—麦轮作系统中肥料氮的利用和损失。综上所述,IOF处理模式降低无机肥投入的同时,保持了作物籽粒的产量。肥料氮施用当季,IOF处理提高了有机肥氮的吸收利用。IOF处理有机肥氮促进了无机肥15N在土壤MBN库的固持,而在第二季又促进了其逐渐释放,提高了无机肥氮的吸收利用。IOF处理相比IF或OF处理增加了肥料15N在作物-土壤系统的回收,减少了向环境的损失。在稻—麦轮作系统,土壤质地、施肥方法、施肥季节显著影响着肥料氮的利用和损失,实践中需从系统水平综合考虑各个影响因子,进行施肥运筹。更多还原

【Abstract】 Both rice and wheat are the most important staple food crops in the world. In South Asia, most rice and wheat are grown in rice-wheat rotation system (R—W). R—W cropping has been widely practiced along the Yangtze River Basin in China with a total area of 13 million hectares. Therefore, it is critical for sustained production of R—W cropping to ensure the food security for China, and even for the whole world.The sustained grain production in R—W system depends mostly on better nutrient management satisifying crop demands both minimizing loss and maximizing the use efficiency. The integrated use of inorganic and organic N fertilizers (IOF) is a promising approach to achieve this requirement. However, previous studies were mainly concentrated on its biological effect in the R—W system; few report was on transformation and distribution of fertilizers nitrogen (N) among different soil N pools and plant parts. Moreover, little literature could be found on the interactive effects between organic and inorganic N fertilizers. It is helpful in investigating transformation mechanisms and interaction effects of different fertilizer N types for high utilization efficiency.Pot experiments were employed in present study with five treatments, namely, inorganic fertilizer N (IF), organic fertilizer N (OF), integrated inorganic fertilizer and organic fertilizer (IOF) with different 15N labelling at organic fertilizer N (IOF1) and inorganic fertilizer N (IOF2) and no fertilizer N as control (CK). Two soils with contrast textures (clay loam and clay) were selected, and 15N-labelled ammonium sulphate and rabbit feces were used as IF and OF sources, respectively. To investigate the availability of the soil residual N for subsequent crop, fertilizer N was applied only to rice (O. sativa L. cv. Wuyujing 7) season or only to winter wheat (Triticum aestivum L.cv Yangmai 6) season in R—W rotations and recorded as R—W system or W—R system accordingly.In the case that N was applied to only rice season in the R—W system, results for the current rice season showed that 1) grain yields were similar among IF and IOF treatments, 2) In two soils, clay loam and clay, NUE was lower in the IOF treament than in the IF treatment by more than 20% and 25%, respectively. In comparison with the treatment IF or OF alone, organic fertilizer N decreased the plant uptake of inorganic fertilizer 15N while inorganic fertilizer N increased the uptake of organic fertilizer 15N in grain and plants in the IOF treatments,3) for the treatment IOF, organic fertilizer N increased soil residual N and MBN pools of inorganic fertilizer 15N and thus reduced its loss by 12% in the clay loam and 28% in the clay, while inorganic fertilizer N increased N accumulation of organic fertilizer 15N fertilizer in rice grains in both clay loam and clay, and 4) fertilizer 15N recovered by plant was mainly (53% to 78%) allocated to rice grain and organic fertilizer N was the main contributor to grain N increase for the IOF treatment.Results for the subsequent winter wheat season in the R—W system showed that 1) treatment IOF produced the highest grain yields and treatment OF also gave similarly high grain yield in the clay,2) in comparison with the treatment IF, IOF treatment resulted in higher soil mineral N and MBN at tillering, jointing and heading stages of winter wheat,3) the increased soil mineral N in the IOF treatment was mainly derived from organic and inorganic fertilizer 15N for the clay loam, while for the clay, inorganic fertilizer 15N was the main contributor. The increased MBN in the IOF treatment was mainly derived from inorganic fertilizer 15N,4) IOF treament increased NUE compared with IF with 173% increase in the clay. In the IOF treatmet, organic fertilizer N increased the recovery of inorganic fertilizer 15N in soil and plant, while inorgaic fertilizer N increased the recovery of organic fertilizer 15N in the clay only, and 5) more than 80% of fertilizer 15N recovered by plant was accumulated in grain part and for the IOF treatment, organic fertilizer N increased the distribution rate of inorganic fertilizer 15N in vegetative organs of winter wheat.In the case that N was applied to only winter wheat season in the W—R system, results showed that 1) treatments IF and IOF produced the highest grain yields without significant difference,2) for the IOF treatment, inorganic fertilizer N enhanced N uptake of organic fertilizer 15N by grain and plant parts in the clay loam and clay to 514% and 133.3% for grain and 216% and 100% for plant, respectively whereas decreased uptake of inorganic fertilizer 15N by 30% for grain and 15% for plant, respectively,3) for the IOF treatment, inorganic fertilizer N increased plant uptake of organic fertilizer 15N while organic fertilizer N increased the soil residual N and MBN pools of inorganic fertilizer 15N, and 4) compared with OF, IOF treatment increased NUE by about 114% and 85% in the clay loam and clay, respectively. Compared with the IF or OF treatment, IOF treatment increased the accumulation of both inorganic and organic fertilizer 15N in vegetative organs in the clay loam, while for the clay, increased only inorganic fertilizer 15N in vegetative organs and organic fertilizer 15N in reproductive organs.For the subsequent rice season in the W—R system, results showed that 1) IOF treatment gave higher grain yields than IF treatment for both soils,2) compared with the IF, IOF maintained higher soil mineral N content. IOF treatment increased inorganic fertilizer 15N derived soil mineral N at heading stage in the clay loam and at tillering, jointing and heading stages in the clay. In addition, IOF treatment increased organic fertilizer 15N derived MBN at tillering and jointing stages in the clay, and inorganic fertilizer 15N at tillering, jointing and heading stages in both soils,3) organic fertilizer N increased the distribution rate of soil residual inorganic fertilizer 15N in reproductive organs, whereas inorganic fertilizer N decreased the distribution rate of soil residual organic fertilizer 15N in reproductive organs by about 20% but increased in vegetative organs, and 4) IOF treatment increased NUE of inorganic fertilizer N relative to IF treatment. In comparison with the IF or OF, organic fertilizer N increased plant uptake and soil residual of inorganic fertilizer 15N. Similarly, inorganic fertilizer N increased soil retention rate of organic fertilizer 15N. As a result, the losses of inorganic and organic fertilizer 15N were decreased by more than 15%.N utilization efficiency in the two consecutive crops was compared between the R—W and W—R systems. Results demonstrated that 1) W—R system yielded higher plant biomass than R—W system, without significant difference in grain yields except that W—R gave higher grain yield than R—W for OF treatment by 81% in the clay loam and 23% in the clay, than R—W system, without significant difference in grain yields except that W—R gave higher grain yield than R—W for OF treatment by 81% in the clay loam and 23% in the clay,2) W—R system had higher fertilizer N use efficiency (NUE) for OF treatment than R—W system both in clay loam and clay, and 3) NUE, fertilizer 15N use efficiency (15NUE), and fertilizer 15N loss rate (15NLR) under the same treatment within the two soils differed between R—W and W—R, suggesting that soil textures, fertilization methods and its application season have a significant effect on the transformation and fate of fertilizer N in the rice—wheat system.In summary, IOF approch produced similarly high grain yield for rice and winter wheat at reduced cost of inorganic fertilizer. During fertilizer application season IOF treatment increased the NUE of organic fertilizer N, while in the succeeding season increased the NUE of inorganic fertilizer N. In the IOF treament organic fertilizer N increased the immobilization of inorganic fertilizer 15N in soil MBN pool for the first crop season which will gradually release during the succeeding crop season. Moreover, IOF increased the recovery of fertilizer N in plant-soil system and thus decreased N loss to the environment. In the rice—wheat system, soil textures, fertilization methods and its application season have a significant effect on the transformation and fate of fertilizer N, thus all factors should be considered synthetically in the fertilization managements above a system level.更多还原