Relationship between nitrogen and phosphate surplus from agricultural production and river water quality in two types of production structure

Abstract

We examined the relationship between nitrogen (N) and phosphate (P₂O₅) surplus derived from agriculture and river water quality. We selected two river basins; one was a paddy farming area (Omoigawa) and the other was an intensive livestock husbandry area (Nakagawa). Nitrogen and P₂O₅ surpluses, defined as the difference between their input and output on regional farmland, from farmland in Omoigawa were twice those of Nakagawa; the surpluses came mainly from chemical fertilizer use. Although N and P₂O₅ surpluses in Nakagawa were lower, Nakagawa had a large amount of non-utilized livestock excreta, twice the N surplus on farmland in Nakagawa. Residual N and P₂O₅ in the river basin, caused by surplus and non-utilized livestock excreta, were approximately 20% and 40%, respectively, higher in Nakagawa than in Omoigawa. Outflows of N and P₂O₅ to river water were higher in Omoigawa than Nakagawa. By excluding domestic sewage N and P₂O₅ in river water, we calculated the loads of non-point source N and P₂O₅. Non-point source N and P₂O₅ were higher in Omoigawa than Nakagawa. This inverse result might be caused by the different source of residual N (i.e. chemical N fertilizer or livestock excreta).     

Recent trends in nitrogen and phosphate use and balance on Japanese farmland

Abstract

We estimated recent trends in nitrogen (N) and phosphate (P₂O₅) application, crop production and surpluses on Japanese farmlands, and calculated the N and P₂O₅ and balances in kind in crop types for 2002. Overall, chemical N and P₂O₅ fertilizer application peaked in 1985 and then decreased. Crop N production was reduced after 1985 and crop P₂O₅ production was reduced after 1990. This lag in crop P₂O₅ decline may have resulted from the accumulation of P₂O₅ in farmland soils before 1990. Nitrogen and P₂O₅ balances in 2002 indicated large surpluses in vegetables and industrial crops, despite the reduction in chemical fertilizer application, although chemical fertilizer and manure application levels were still higher than in other crops. The reduction in chemical fertilizer and manure application eventually reduced the N and P₂O₅ surplus. Substitution of currently non-utilized livestock excreta in place of chemical fertilizers would be worthwhile.     

1970-2030年精细农业耕作体系下全球和区域性氮素的表面平衡研究

Global nitrogen (N) budgets for intensive agricultural systems were compiled for a 0.5 by 0.5 degree resolution. These budgets include N inputs (N fertilizer, animal manure, biological N fixation and atmospheric N deposition) and outputs (N removal from the field in harvested crops and grass and grass consumption by grazing animals, ammonia volatilization, denitrification and leaching). Data for the historical years 1970 and 1995 and a projection for 2030 were used to study changes in the recovery of N and the different loss terms for intensive agricultural systems. The results indicated that the overall system N recovery and fertilizer use efficiency slowly increased in the industrialized countries between 1970 and 1995, the values for developing countries have decreased in the same period. For the coming three decades our results indicated a rapid increase in both the industrialized and developing countries. High values of > 80% for fertilizer use efficiency may be related to surface N balance deficits, implying a depletion of soil N and loss of soil fertility. The projected intensification in most developing countries would cause a gradual shift from deficits to surpluses in the coming decades. The projected fast growth of crop and livestock production, and intensification and associated increase in fertilizer inputs would cause a major increase in the surface N balance surplus in the coming three decades. This implied increasing losses of N compounds to air (ammonia, nitrous oxide and nitric oxide), and groundwater and surface water (nitrate).     

西南烟区氮素供应与烤烟氮素吸收的关系

【目的】氮是影响烤烟产量和品质的最重要元素,本研究旨在探索氮素供应与烤烟氮素吸收的关系,为提升西南烟区烤烟氮素营养管理水平奠定理论基础。 【方法】在云南、贵州设置多点施肥试验,采用田间原位培养试验、15N 同位素示踪方法,研究烤烟对土壤及肥料氮的吸收。 【结果】烤烟氮素累积量与土壤基础供氮量呈线性正相关,土壤基础供氮量分别解释了烤烟氮素累积量和烤烟土壤氮素累积量 82.6% 和 84.8% 的变异,是烤烟氮素累积量的决定性因素;土壤基础供氮量与土壤有机质含量密切相关,在土壤有机质含量 0～35 g/kg 范围内,土壤基础供氮能力随着有机质含量的增加而增加;鉴于烤烟对氮素的需求,土壤基础供氮量在 60 kg/hm2、土壤有机质含量 20 g/kg 左右较为适宜烟叶品质的形成。烤烟氮素来源主要包括土壤矿化氮、土壤起始无机氮及肥料氮,西南烟区在烤烟大田期土壤氮矿化量为 19.9～38.9 mg/kg,大田期土壤矿化氮量与烤烟氮素累积量呈非线性相关,当土壤矿化氮量增加至 30 mg/kg 以上时,烤烟氮素累积量不再增加;单位土壤有机质大田期矿化氮量与有机质含量的关系可以用对数方程来表达,通过此方程可初步预测土壤矿化氮供应量。西南烟区土壤起始无机氮 (0—30 cm) 和肥料氮输入量为 14.1～237.7 kg/hm2,两者输入量与烤烟氮素累积量呈显著正相关,当土壤起始无机氮和肥料氮输入量超过 150 kg/hm2 时,烤烟氮素的累积量趋于稳定;烤烟氮素累积量随无机氮素供应的增加而增加,烤烟生长季氮供应量超过 300 kg/hm2 时烤烟氮素累积量增加趋势变缓,此时烤烟氮素累积量达到了 100 kg/hm2。西南烟区氮肥利用率为 25.4%～37.1%,土壤有机质与肥料氮利用率的相关系数达到了 0.783 (P < 0.01),肥料利用率随土壤有机质含量以对数函数方式增长。 【结论】在西南烟区烤烟农田生态系统中,烤烟种植宜选择土壤基础供氮量在 60 kg/hm2、有机质含量 20 g/kg 左右的土壤,肥料氮和土壤起始无机氮供应量之和应在 150 kg/hm2 以内,烤烟生长季总无机氮供应量应控制在 300 kg/hm2 以内。西南烟区氮肥利用率平均为 32.6%,通过培育土壤,提高土壤肥力可提高氮肥利用率。     

优质樱桃番茄高效水氮耦合管理

【目的】水分和氮素是限制作物产量和品质的最重要因素,合理的水肥管理是农业生产高产高效的关键。结合同位素技术研究最优水氮耦合模式,为樱桃番茄生产中合理灌水和施氮,提高番茄果实品质及水分利用效率(WUE)提供科学依据。【方法】以樱桃番茄品种‘千禧’为试验材料,结合稳定同位素技术进行水肥耦合盆栽试验。试验设置3个灌溉水平(W)和3个氮素水平(N),灌溉水平包括90%土壤持水量(充分供水,WH),70%土壤持水量(中度水分胁迫,WM)和50%土壤持水量(重度水分胁迫,WL);氮素水平包括高氮(0.23 g/kg,NH),中氮(0.16 g/kg,NM)和低氮(0.08 g/kg,NL)。试验采用完全随机设计,共9个处理。在灌溉施肥处理60天后收获,分析测定了植株不同部位的生物量及碳、氮、氧同位素含量。【结果】在WH和WM条件下,增加氮素用量使番茄地上部干物质量和叶面积显著增加,增幅分别为19.8%~45.4%和29.4%~106.8%;相同氮素水平下,WH和WM的地上部干物质量和叶面积比WL分别增加24.7%~83.4%和17.6%~90.4%。WHNH处理干物质量和叶面积最高,WMNH处理次之,但后者耗水量低,具有最高的WUE。在WH和WM下,随着氮素用量的增加番茄植株的WUE和氮素含量同步增加。土壤水分水平下降提高了植株的WUE以及δ13C和δ18O,而WUE提高的主要原因是由于叶片气孔的优化调控,植株叶片的δ13C和δ18O可以用于表示灌溉施肥条件下长时间尺度上的WUE信息。WLNM处理提高番茄的糖分含量,而WHNM处理能降低番茄的有机酸含量,从而使番茄口感更好,提高番茄品质。【结论】中度水分胁迫和高氮处理(WMNH)能在促进番茄生长和提高氮素吸收和利用效率的同时减少水分用量,提高番茄的水分利用效率,为本试验的最优水氮耦合处理。     

不同耕作模式下旱作玉米氮磷肥产量效应及水分利用效率

为了探讨不同耕作模式下氮磷肥施用量对旱作玉米产量及水分利用效率的影响,于2003－2008年在山西寿阳旱农试验站进行了免耕、少耕和传统耕作下氮磷肥用量（105、179和210 kg/hm2 N;N∶P2O5=1∶1）试验。6 a结果显示,该区推荐氮磷用量为105 kg/hm2,传统耕作模式下玉米平均产量和水分利用效率分别为5 234 kg/hm2和12.4 kg/(hm2·mm);少耕模式下玉米平均产量和水分利用效率分别达到5 751 kg/hm2和13.6 kg/(hm2·mm),较传统耕作提高9.9%和9.7%。而免耕模式下氮磷用量为179 kg/hm2时玉米平均产量和水分利用效率最高,分别为5 336 kg/hm2和13.2 kg/(hm2·mm),较传统耕作提高6.1%和9.7%。免耕模式下土壤保水效果最佳,干旱年增产作用尤为明显。3种耕作模式下玉米平均产量和水分利用效率以少耕为最高,免耕次之,传统耕作最低。     

不同磷、钾肥对保水剂吸水、保肥性能的影响

通过对保水剂在磷肥、钾肥溶液中的吸水倍率和对肥料养分吸持量的测定,研究了不同磷、钾肥对保水剂吸水、保肥性能的影响。结果表明,保水剂在各种肥料溶液中吸水倍率显著下降,并随肥料浓度的增加下降幅度增加;磷、钾肥对聚丙烯酸钠盐型保水剂的影响大于聚丙烯酰胺-丙烯酸盐型保水剂;不同磷、钾肥对保水剂吸水倍率的影响按磷酸一铵、氯化钾、硫酸钾、过磷酸钙顺序递增。保水剂在大量吸水的同时,也对溶液中的肥料分子或者离子有吸持作用,吸持量均随肥料浓度的增加而增加;保水剂和肥料品种不同,吸持量也不同;保水剂对肥料的吸持率随肥料浓度的增加而降低,最高浓度下,吸持率按过磷酸钙、硫酸钾、氯化钾、磷酸一铵次序依次增大。     

化肥有机肥配合施用下双季稻田氮素形态变化

为揭示有机无机肥配合施用下稻田氮素的动态及迁移特征,在湘南双季水稻农作区第四纪红土发育的红黄泥稻田上进行了连续6年田间试验。通过比较不施氮肥（PK）、施用有机肥猪粪（M）、化肥（NPK）及有机肥化肥配合（NPKM）,研究稻田表层全氮、无机氮动态变化,不同层次（25—30、55—60、85—90 cm）土壤溶液无机氮动态,耕层土壤无机氮动态等。结果表明,NH4+-N是红壤双季稻田无机氮素存在的主要形态,施用化学肥料处理（NPK）施肥后1～3 d表面水NH4+-N浓度占全氮比例可达0.5～0.9,有机肥处理（M）为0.3左右。不同层次土壤溶液及其土壤氮素浓度呈现一致的特征,即施肥后短期内出现浓度峰值随后迅速下降,且随着往下推移,氮素峰值出现时间延长,表层水全氮及无机氮在施肥后1～2 d出现浓度高峰,耕层土壤及25—30 cm土壤溶液无机氮浓度高峰约在施肥后3～5 d。化肥有机肥配施有利于水稻稳产高产,年产量达12.2 t/hm2,比不施氮肥的对照产量（7.3 t/hm2）增加68%;土壤有机质6年提升18.5%,显著高于化肥。施用有机肥（M）及有机无机肥配合（NPKM）显著降低了稻田表层水全氮及不同层次土壤溶液和耕层土壤NH4+-N峰值浓度,提高水稻产量和培肥土壤,有利于减少当前氮肥过量施用带来的环境负荷。     

有机肥氮替代部分化肥氮对棉花养分吸收、氮素利用和产量的影响

为探讨有机肥氮替代化肥氮在新疆棉花生产中的增产增效作用,在滴灌条件下,采用连续2年定位试验,研究了不施氮(CK)、牛粪堆肥(OM)、农民常规施肥(CF)和不同有机肥氮替代10%(OF1)、20%(OF2)和30%(OF3)的化肥氮时,对棉花氮磷钾养分吸收、氮素利用率及产量的影响。与单施化肥相比,有机肥氮替代部分化肥氮均有利于棉花氮磷钾养分吸收,可提高棉花氮素表观利用率、偏生产力、肥料氮贡献率和农学效率。在有机肥氮替代10%化肥氮的情况下,氮素利用率最高并能提高氮素表观利用率10.5个百分点,棉花产量增加6.8%(P<0.05),而且棉花经济效益与单施化肥相当。有机肥氮替代20%的化肥氮时,棉花产量增加7.9%(P<0.05)。有机肥氮替代30%化肥氮,获得与单施化肥相当的产量,氮素表观利用率仅提高3.4个百分点。综合养分吸收、氮素利用效率、产量及经济效益等方面考虑,有机肥氮替代10%化肥氮是该地区中等肥力棉田增产稳产、氮肥增效的合理施肥方式。     

Nitrogen flow associated with food production and consumption and its effect on water quality in Japan from 1961 to 2005

Using statistical data, we evaluated food supply and consumption in terms of nitrogen flow to clarify its effects on water quality from 1961 to 2005 in Japan. We revised a nitrogen flow model to incorporate food production, trade and consumption as well as nitrogen mineralization of crop residues and livestock manure and denitrification. Food consumption increased steadily from 1961 to the mid 1980s and has been almost stable since then. There was a notable increase in the consumption of livestock products. By 1996, consumption had risen to fivefold the 1961 level of consumption, but it has been stable since then. We concluded that the demand for food reached a maximum in the 1990s. The increasing demand for animal feed was filled by an increase in the imports of coarse cereals until the 1980s and of oil cakes until now. As the consumption of food and animal feed increased until the mid 1980s, the nitrogen load to the environment also gradually increased during this period, after which it tended to decrease. We estimated the nitrogen concentration in river water for 8 km × 8 km grid cells from 1961 to 2005 and compared these estimated values with measurements taken at more than 4000 points from public bodies of water in 1998. The spatial distribution and prefectural average of the estimated nitrogen concentration roughly corresponded with the measured values, and both indicate that food supply and consumption have had considerable effects on water quality in Japan.     

氮磷与硅钙肥配施对辣椒产量和品质的影响

【目的】长期高纯度化肥施用导致作物其他养分供应的不平衡,中微量元素已成为越来越多作物产量和品质限制因子。本文旨在通过开展硅钙肥、氮肥和磷肥配施对辣椒产量和品质的影响研究,确定硅钙肥、氮肥和磷肥在干辣椒中最佳配施方案。【方法】借助于DPS软件,采用三因素二次饱和D-最优设计方法分析研究了氮磷与硅钙肥配施对辣椒产量和品质的影响,整个研究过程分为回归建模、模型解析和模型决策三个步骤,首先,根据2013年获得的辣椒产量和品质数据,进行优化多项式回归分析,得出辣椒产量、品质分别与硅钙肥、氮肥、磷肥之间的回归方程。其次,对两个方程进行F检验,对回归系数进行t检验,确定模型可行性,模型分析包括因子主效应分析、单因子效应分析和因子互作效应分析。最后进行模型决策,通过计算机模拟运算,提出辣椒高产与优质的施肥方案。【结果】通过对模型进行检验分析得出:硅钙肥、氮肥、磷肥对辣椒的产量和品质均有显著的影响,并且因素间存在显著的互作效应。以硅钙肥、氮肥交互效应为例,在编码范围内,辣椒的产量较好的互作空间是中等的硅钙肥配较高氮肥水平;辣椒的品质较好的互作空间是较高的硅钙肥水平配中等的氮肥施用水平。三因素对产量的影响顺序为:氮肥磷肥硅钙肥,而对品质影响则相反。在本研究区地力水平下,辣椒的产量和品质会随着硅钙肥、氮肥、磷肥的用量增加而升高;当用量过高,产量和品质反而会下降。通过计算机模拟运算,产量在4500~6000 kg/hm2之间,品质综合得分95分以上时,施肥方案为硅钙肥304.76~398.24 kg/hm2,氮肥220.05~263.26 kg/hm2,磷肥44.80~64.50 kg/hm2。经边际效应分析,在经济效益和产量达到最大,即分别为80548.64元/hm2和5916.23kg/hm2时,硅钙肥、氮肥、磷肥最佳施用量组合为332.66、250.58、57.75 kg/hm2,配施比例为1:0.75:0.17。【结论】硅钙肥、氮肥、磷肥具有提高辣椒产量和品质,调节辣椒营养元素吸收等功能,但应适量施用,过多施用反而会造成产量降低、品质下降等现象的产生。本文构建的模型可以详细地解释三种肥料对辣椒产量和品质的影响,通过模型模拟可以得到三种肥料之间的联系。     

Nitrogen flow associated with food production and consumption and its effect on water quality in Japan from 1961 to 2005

Abstract

Using statistical data, we evaluated food supply and consumption in terms of nitrogen flow to clarify its effects on water quality from 1961 to 2005 in Japan. We revised a nitrogen flow model to incorporate food production, trade and consumption as well as nitrogen mineralization of crop residues and livestock manure and denitrification. Food consumption increased steadily from 1961 to the mid 1980s and has been almost stable since then. There was a notable increase in the consumption of livestock products. By 1996, consumption had risen to fivefold the 1961 level of consumption, but it has been stable since then. We concluded that the demand for food reached a maximum in the 1990s. The increasing demand for animal feed was filled by an increase in the imports of coarse cereals until the 1980s and of oil cakes until now. As the consumption of food and animal feed increased until the mid 1980s, the nitrogen load to the environment also gradually increased during this period, after which it tended to decrease. We estimated the nitrogen concentration in river water for 8 km × 8 km grid cells from 1961 to 2005 and compared these estimated values with measurements taken at more than 4000 points from public bodies of water in 1998. The spatial distribution and prefectural average of the estimated nitrogen concentration roughly corresponded with the measured values, and both indicate that food supply and consumption have had considerable effects on water quality in Japan.     

灌溉模式和供氮水平对水稻氮素利用效率的影响

以Ⅱ优838为材料,湖北潮土为供试土壤,通过2年稻麦轮作柱栽试验研究了2种灌溉模式（FW: 土表淹水3 cm; CW: 保持土壤湿润但土表不积水）和4个供氮水平(N 0、126.0、157.5、 210.0 kg/hm2）对水稻地上部干物重、 氮素积累量、 氮素利用效率的影响。结果表明,灌溉模式和供氮水平对水稻产量、 地上部氮素积累量和氮素利用效率均有显著（P0.05）或极显著影响（P0.01）。其中,淹水处理下水稻产量、 地上部氮素积累量、 水稻氮素农学利用率、 氮肥吸收利用率、 氮肥偏生产力和氮素生理利用率显著高于控水处理;地上部生物量及氮素积累量随供氮水平的提高而增加趋势明显; 氮肥农学利用率、 氮肥偏生产力和氮素生理学利用率均表现为随施氮量提高而下降的趋势,但减氮25%处理（N 157.5 kg/hm2）与常规施氮量处理（N 210.0 kg/hm2）间的差异并不显著。综合分析水稻产量与氮素吸收利用效率的各项指标,在8个供试处理中,淹水灌溉模式并减氮25%的处理为值得推荐的稳产高效水氮运筹模式。     

The dynamics of soil-soluble nitrogen and soil-retained nitrogen in greenhouse soil

Field experiments were conducted to determine the effects of nitrogen (N) fertilization and manure addition on the soil-soluble nitrogen (SSN) (soil mineral N (SMN); soil-soluble organic N (SSON)) and soil-retained N (SRN) (soil fixed ammonium; soil microbial biomass N). The combined application of manure and inorganic N (different N fertilizer rates: M3N0, M3N1, M3N2, and M3N3; different manure rates: M0N2, M1N2, M2N2, and M3N2) was used in a greenhouse fertilization experiment. SSN and SRN increased with increasing N rate up to M3N2. SSON decreased with increasing manure rate and was the highest in the M1N2, whereas SMN and SRN were the highest in the M3N2, and increased with increasing manure rate on all sampling dates. Both SSN and SRN declined significantly with increasing soil depth in the different application rates of manure (p < .05). Moreover, the SSN and SRN significantly varied with plant growth and followed a different pattern during the growing season. SSN and FA peaked in the first ear fruit period, but SMBN was at its highest level in the second ear fruit period. There was a significant positive relationship (p < .05) between SSN and SRN throughout the plant growing season, and the annual apparent loss of N in the M3N3 was the highest. The combined application of inorganic N fertilizer and manure at an appropriate rate may be an effective strategy for maintaining the long-term health of greenhouses.     

Increased total nitrogen content of poultry manure by decreasing water content through composting processes

Microbial mineralization of urea and uric acid in poultry litter can lead to loss of nitrogen (N) content and its value as a fertilizer. To minimize the loss of N in the composting processes, controlling the water content in litters is a key to reduce the mineralization processes of N compounds. The N content of litter may be influenced by diets, hen age and the type of poultry houses used. The objectives of the present study were i) to determine the relationship between the water content and the decomposition rate of uric acid in poultry litter and ii) to investigate the effect of hen age and crude protein (CP) percentages in diets on the N content of poultry litter. A layer feeding trial was conducted in two poultry farms with windowless and open-floor houses. An incubation study of poultry litter was performed under different levels of water content. Our study found that the diet CP percentage (16.5–18%) and the growth stage of laying hens did not have a significant effect on the amount of total N (52–56?g?kg^?1) and uric acid-N (26–31g?kg^?1) in fresh litters. At the 7^th day of litter incubation study, the concentration of uric acid-N was 22 g kg^?1 in litters with a water content of 35%, whereas it further decreased to less than 1.3 g kg^?1 in litters with a water content of 55% and higher levels. The decomposition rate of uric acid-N in litter was 0.3–3.1g?kg^?1?day^?1 in the windowless house and 3.1–7.1g?kg^?1?day^?1 in the open-floor house. Decomposition of uric acid in litters was positively correlated to the litter moisture content that is controlled to be lower in windowless houses (40–50%) than in open-floor houses (55–80%) during the composting period. Our study suggests that the use of windowless houses for layer chicken production is effective for producing poultry manure with a high N content.     

局部供应水氮条件下玉米不同根区的耗水特点

利用分根装置,采用传统均匀灌水、根系分区交替灌水2种方式和作物根区均匀施氮、固定部分根区施氮和根系分区交替施氮3种方式,对零、低、中、高4个施氮水平下玉米根系不同区域的耗水特点进行了研究。结果表明：交替灌水与均匀灌水均表现为,在均匀施氮时玉米两个根区的耗水量随施氮水平的增大一致减小;固定施氮时,随施氮水平的增大,施氮区的耗水量呈明显的减小趋势,从而使两个根区耗水量间的差距增大;交替施氮时的耗水量变化与之相同。而且,两种局部施氮方式下,低氮水平时,玉米两根区间耗水量无显著差异;高氮水平时,未(后)施氮区的耗水量较之先施氮区显著增大,其中尤以固定施氮的增幅更大。与均匀灌水所不同的是,交替灌水缩小了局部施氮条件下不同根区耗水量间的差距。     

Effects of Manure and Chemical Fertilizer on Nitrogen Transformations and Functional Bacteria in a Black Soil of the Song-nen Plain

Intensities of ammonification, nitrification, denitrification, and the numbers of functional bacteria were measured in a black soil of the Song-nen Plain under different fertilizer managements over a period of 3 years. The six fertilizer managements were as follows: no fertilizer applied, manure at low and high rates, chemical fertilizer at low and high rates, and manure and chemical fertilizers in equal ratio. Manure increased the numbers of ammonifying and nitrifying bacteria and the intensities of ammonification and nitrification, whereas chemical fertilizer increased numbers of denitrifying bacteria and intensity of denitrification. Average denitrifying intensities ranged from 52.5% to 61.1%. There might be some coupling relation between nitration and denitrification in black soil.     

白洋淀流域种植结构及氮盈余的时空变化特征

针对种植业氮素过量投入造成的流域农业面源污染问题,该研究以白洋淀流域核心区域粮食作物和经济作物为研究对象,以粮经比为种植结构评价指标,从氮素平衡角度考虑,探究白洋淀流域种植结构变化对区域水环境的影响。研究结果显示：1）白洋淀流域种植结构时空变化明显,时间上,研究期内白洋淀流域粮经比总体呈小幅度上升趋势（4.47～5.72）;空间上,距白洋淀淀区距离越大,区域内粮经比越小,临白洋淀区粮经比（15.11～19.23）明显高于白洋淀上游粮经比（2.44～2.64）;2）白洋淀流域种植业氮盈余量时空分异特征明显,时间上,研究期内白洋淀流域种植业氮盈余量总体呈下降趋势（26.29×104～18.49×104 t）;空间上,各区域种植业氮盈余量表现为：白洋淀中游（10.39×104 ～14.48×104 t）>白洋淀下游（4.35×104～7.09×104 t）>临白洋淀（2.24×104～2.64×104 t）>白洋淀上游（1.51×104～2.58×104 t）;3）白洋淀流域种植业氮盈余强度与粮经比呈显著负相关关系（P<0.05）,其中,研究期内某一区域粮经比基础值越小,其上升幅度越大,种植业氮盈余强度下降幅度越大;4）通过调控粮经比可明显改变区域内种植业氮盈余强度,如将白洋淀中游粮经比调整到12.13～17.79,其区域内种植业氮盈余强度可由Ⅳ级水平（>220～260 kg/hm2）降低到Ⅱ级水平（≥140～180 kg/hm2）。因此,基于区域种植结构与氮盈余强度的关系,可通过调整种植结构来调控氮盈余强度,从而控制氮盈余量以降低种植业氮素投入的环境风险。研究结果可为白洋淀流域和其他流域种植业氮素污染控制提供科学依据。     

Relationship between nitrogen accumulation and nitrogen use efficiency of rice under different urea types and management methods

We aimed to clarify the effectiveness of polyaspartic acid (PASP)-urea on nitrogen (N) accumulation and N use efficiency in rice. We compared PASP-urea with conventional urea with two N management methods (farmer’s fertilizer practice and optimized N management) in Wenjiang, Sichuan Province, China, in 2014 and 2015. N recovery efficiency (NRE), N agronomic efficiency (NAE), and N partial factor productivity (PFP) decreased with increasing N uptake by the shoot and the stem plus sheath at 14 days after transplanting (DAT), while they were positively related to N uptake of the shoot, leaf lamina, and stem plus sheath at the middle and later stages. N use efficiency and N uptake differed according to urea type and N management. PASP-urea increased N accumulation of the shoot by improving N uptake of the leaf lamina and stem plus sheath from DAT 27, contributing to the significant improvement in NRE, NAE, and PFP. PASP-urea with optimized N management markedly improved the N uptake of each organ at the middle and latter stages, leading to increased final N uptake of the shoot, NRE, NAE, and PFP. Using PASP-urea with ONM method is a suitable way for improving both N accumulation and N use efficiency.