【作者】 张贵龙；

【导师】 任天志；

【作者基本信息】 中国农业科学院 ， 作物栽培与耕作学， 2009， 博士

【摘要】 保护地蔬菜生产中,过量氮肥投入导致的环境问题日益突出。亟待开展相关的基础研究。本试验在北京市典型集约化农区保护地条件下,通过根菜类→茄果类—填闲—叶菜类蔬菜轮作试验,重点研究不同氮素施用水平下,作物氮素养分利用、土壤无机氮的累积、分布和淋溶规律、土壤—作物系统氮素表观平衡等。获得如下结果:(1)高肥力条件下,增施氮肥不能显著提高第一茬大萝卜产量和经济效益。第二茬番茄产量与施氮量呈二次函数关系,当季施氮量高于647.7kg/hm2时增产幅度、产值和效益下降。第四茬芹菜产量与当季投入量符合线性+平台模型,当施氮量高于617.7 kg/hm2时产值和效益不再显著增加。全年化肥氮投入效益和产投比均随氮肥投入量的增加而降低。大萝卜、油菜和芹菜硝酸盐含量显著高于番茄,且显著受施氮量影响。施氮对蔬菜Vc含量、可溶性糖和可溶性蛋白含量没有显著影响。(2)随蔬菜生长阶段推进,不施氮肥,0～100cm土体硝态氮贮量逐渐降低,单施有机肥没有引起硝态氮贮量显著变化。第一茬大萝卜和第二茬番茄生长期间,减量施氮、推荐施氮和增量施氮下土体硝态氮贮量呈波状变化。第四茬芹菜生长期间,当施氮量高于617.7kg/hm2时,土体硝态氮贮量在第二次追肥前连续降低,第二次追肥后呈增加趋势。大萝卜和芹菜阶段氮素吸收呈单峰曲线变化。番茄阶段氮素吸收呈双峰曲线变化。推荐施氮下,蔬菜生长中后期,土壤氮素供应与需求同步。农户习惯施氮导致蔬菜生长中后期氮素供应过量。(3)不合理氮肥投入对200cm以上土体硝态氮累积影响突出,且随种植季节的延续影响程度加深。第一茬不施氮肥根层土壤硝态氮含量下降,农户习惯施氮下根层和根层以下土壤硝态氮显著累积。连续两茬不施氮肥0～200cm土体硝态氮含量下降,农户习惯施氮导致0～200cm土体硝态氮含量增加。四茬蔬菜种植后,减量施氮、推荐施氮下0～60cm土体硝态氮含量无显著变化。施氮量低于增量施氮,0～400cm土体硝态氮贮量显著降低。农户习惯施氮下显著增加了1651.8kg/hm2。(4)蔬菜种植初期,氮肥施用对土壤硝态氮淋失没有显著影响。随种植季节延续,增量施氮和农户习惯施氮下,土壤硝态氮淋失量显著增加。氮肥用量在推荐量以下,土壤硝态氮没有显著淋失。整个轮作周期,土壤无机氮淋失总量为23.3～46.8 kg/hm2,氮肥淋失系数为0.2～0.6%。硝态氮平均淋失浓度为35.9 mg/L,超过饮用水卫生标准(10mg/L)。春夏季土壤氮素淋失量占全年总淋失量的60.0%～73.1%。(5)随氮肥投入量增加,蔬菜氮肥利用率降低,土壤残留和损失增加。大萝卜总吸氮量随施氮量升高,化肥氮吸收量没有变化。当季化肥氮利用率为7.2%～51.1%。土壤中残留40.7%～69.9%,损失率为8.2%～22.9%。氮肥投入量高于647.7kg/hm2时,番茄植株总吸氮量显著下降。化肥氮利用率为3.2%～14.3%,土壤中残留率和损失率分别为58.6%～79.1%,13.5%～30.6%。芹菜总吸氮量在氮肥投入量高于617.7 kg/hm2时不再显著增加,化肥氮的吸收量没有显著变化。当季化肥氮利用率为3.7%～30.8%,土壤中氮残留率为65.3%～72.0%。损失率为11.3%～32.7%;第一茬施用的化肥氮,对第二茬的后效显著,在第四茬已无明显作用。减量施氮下,化肥氮累加利用率为66.7%。(6)氮肥投入和播前残留Nmin是季节性土壤——蔬菜系统氮素主要输入项,土壤残留Nmin是主要输出项。第一茬农户习惯施氮下,季节性和阶段性表观平衡值均显著增加。第二、第四茬氮素表观平衡值和阶段表观平衡值均随施氮量增加显著增大。填闲季节,习惯施氮下表观平衡值显著增加。年度氮素平衡体系中,氮素投入是主要输入项。播前残留Nmin和土壤矿化氮为次要输入项。年施氮量低于2171.5kg/hm2时,作物氮素吸收是主要输出项,继续增加施氮量,土壤残留Nmin比重加大。年度表观平衡值与施氮量显著正相关(r0.01=0.917)。结合当地生产条件,在磷钾肥和有机肥配施的基础上,确定每年化肥氮适宜投入量为370～740 kg/hm2。每季化肥氮肥投入量以现阶段推荐施氮为上限,0.5倍推荐量为下限,以0～60cm土体硝态氮贮量变化为指标,重视氮肥后效作用和作物养分吸收高峰期的氮素调控。益于氮素利用率提高,获得较高产量和经济效益,保证蔬菜卫生品质安全,降低氮素淋流失风险。更多还原

【Abstract】 The environmental problems that resulted from excessive inputs of nitrogen (N) in planting vegetables in protected soils were more and more important. Rational management ways and strategy of N need to be researched and developed. However, foundation questions still need be deeper researched. This study targeted at vegetable production of protected soils in representative intensive agricultural zone in Beijing, main research on the dynamics of accumulation and distribution of N in soils, N use efficiency, distribution and apparent balance of N in soil～plant systems. The results showed as following:(1) There was not effect of N application increased on yield of radish (Raphanus stativus L.) and economic profits planting in high degree fertility soils. The conic model described the relationship between tomato yield and the rate of N application during the second vegetable growing, when the rate of N application was more than 647.7 kg/hm2, the margin of increasing production , production vale and economic profits begin reduce. The liner～plateau model described the relationship between celery yield and the rate of N application during the fourth season vegetable growing, when the rate of N application was more than 617.7 kg/hm2, the production value and economic profits were significant decreased . With the increasing of N rate, profits of inputting fertilizer N and output～input ratio were decreased in one year. The nitrate content of radish, rape and celery increased significantly due to the rate of N application increased, but the nitrate content of tomato little response on higher rate of N application. However, there was not effect significant of the rate of N application increased on the contents of Vc, soluble sugar and protein in vegetables.(2) With the continuations of vegetables growing seasons, the N application rates impacted significantly on accumulative amounts of nitrate in 0～100cm soil profiles. The nitrate storage was decreased under the condition of no N application. Accumulative amounts of nitrate in soils were not significant changed with organic fertilizer application alone. There was a wave trend in the treatments with lower, recommendation and higher N application rate during the first and second seasons. When N rates were more than 617.7kg/hm2, the nitrate storage of soil body was reduced during the beginning of celery, was increased during the ending. The changes were a single apex curve during radish and celery planting, and double apex curve during tomato growing. The supply of N nutrition and demand of vegetables were changed in Synchronization with the recommendation rate of N application. The nitrate storages in soil body were significantly increased with farmers’traditional N application rates during the middle and ending period of vegetables growing season,it was resulted to excessive supply of N nutrition.(3) After four season vegetables planting, the nitrate storage in 0～400cm soil body were significantly decreased as the N rate was lower than the higher N application rate in every season , there was increased by 1652 kg/hm2 significantly in farmers tradition N application rate. There was a net lost of nitrate in 0～200cm soil body without N fertilizer application. The nitrate storages in 0～60cm soil body was not significant changed in lower and recommended N application rate. Input of N impacted significantly on accumulation nitrate in 0～200cm soil body, but little response to soils below 200cm. Nitrate content decreased in root zoon soil without N added in first season. However, nitrate content in 0～100cm soil body was great accumulation with farmers’tradition N application rate. After continuous two seasons, nitrate content decreased in 0～200cm soil body without N application, but increased significantly in farmers’tradition N application rate treatments. After continuous applying three times of farmers tradition N application rate, nitrate content rapid increased in 0～200cm soil profiles, accumulated in top soil layer moved down along soil profiles, and accumulated in 100～200cm soil profiles. The effect was not obvious through rape planting to decrease nitrate content in catch season.(4) Nitrate～N is the mostly forms of Inorganic nitrogen leaching, that 96.4%～99.2% accounts in total Inorganic nitrogen leached. There was not significant effect of N application on the concentration of nitrate in leaching liquid of soils in the first vegetable planted. The concentration of nitrate in leaching liquid of soils increased significantly in higher and farmers tradition N application rate from the second season. There was not significant change of the concentration of nitrate in leaching liquid in treatments that the rate of N application less than that of higher N application rate. Leaching amount of ammonium～N was low and little response to N application. The soil leaching amount of inorganic N was 23.3～46.8 kg/hm2 during whole rotation period. The coefficient of soil leaching amount of inorganic N was 0.2～0.6%, there was difference significant among treatments. The mean concentration of nitrate in leaching liquid of soils was 35.9 mg/L which great exceeded the standard of drinking water (10mg/L). The leaching amount of N in spring～summer was higher significantly than that of in autumn～winter, that 60.0%～73.1% accounts for whole year.(5) With the increasing of N rate, recovery efficiency of N fertilizer reduced, residual rate of inorganic N fertilizer in soil and losses increased. The total N uptake of radish (Raphanus stativus L.) increased significantly with rate of N application increased, but the amounts of fertilizer N uptake was not significant changed. The 7.2%～51.1%, 40.7%～69.9% and 8.2%～22.9% of total inorganic N application was taken up by plants, left in soil and lose, respectively. When rate of N application was higher than 647.7kg/hm2, the total N uptake of tomato plant was decreased significantly. The 3.2～14.3%, 58.6～79.1% and 13.5～30.6% of total seasonal fertilizer N application was taken up by plants, left in soils and lose, respectively. The total N uptake of celery will not increased significantly when the N rate was more than 617.7 kg/hm2. The 3.7～30.8%, 65.3～72.0% and 11.3～32.7% of total seasonal inorganic N application was taken up by plants, left in soils and lose, respectively. Residual N of the first season has significant after～effect on the growth of tomato in second season, but there was not significant residual effect on celery yield in fourth season. The total recovery efficiency of fertilizer N was 66.7% with lower N application rate. (6) The main N was from the input of N fertilizer and residual Nmin in the beginning stage in the seasonal N balance of soil～vegetable. The total N input increased significantly with the increases of N fertilizer application. The main N output was residual Nmin in soils in this system. The apparent balance of seasonal N was not change significantly in soils with organic fertilizer alone and lower N application during the first season. The apparent balance values decreased in soils with recommendation and higher N application rate. The apparent balance values increased significantly in the treatments with traditional N application rates was not change significantly in the other treatments in the phase system. The apparent balance of season N and of phase increased significantly with the increases of N application rate during the second and fourth seasons. In spare season, the N apparent balance still increased significantly in soils with traditional N application rate in last season. The annual input of N was the second main resources in the N balance system of soil～vegetable. The residual Nmin before seeding and mineralization N from initial soils self were the second N resources. When annual N application rate was less than 2171.5kg/hm2, the radio of crop N uptake to total N output was relative high; When annual N application rate was more than 2171.5kg/hm2, the radio of residual Nmin in soils to total N output was high. There was a positive relationship between apparent balance of system N and annual N application rate (r0.01 = 0.917).According to the native conditions, on the base of mixing organic fertilizer and phosphor (P) fertilizer and potassium (K) fertilizer together, the annual rate of N fertilizer should control in 370-740 kg/hm2. The upper limit of N rate in every season should be at the recommendation N application rate in current stage., the lower limit be at 0.5 times of the recommendation N application rate. The nitrate storage in 0～60cm soil layer should be looked as a index, and focusing on aftereffect of N fertilizer and regulation of N during the fastigium of crop take up nutrients. Benefit to increase N use efficiency, gain high crop yields and economic benefit, ensure vegetables sanitation and quality safety, decrease the risk of N leaching and losing.更多还原