Fertilizer application is a common grassland management technique and plays an important role in the maintenance of grassland productivity and the health of its ecosystems. In this study, five kinds of fertilizer treatment were applied to determine their effects on soil nitrogen forms and transformations in the Leymus chinensis grasslands of Guyuan, Hebei Province. The results showed that, during the whole forage-growing season, the soil nitrate and ammonium nitrogen contents in grassland fertilized with both nitrogen and phosphorus were lower than that in grassland fertilized only with nitrogen. The application of nitrogen fertilizer changed the process of soil nitrogen mineralization. Grasslands with nitrogen fertilization showed stronger soil nitrification than the other treatments during the period from May to August, and higher net nitrogen mineralization during the period from May to July, which accounted for 57.58%-68.97% of total net nitrogen mineralization over the whole forage-growing season. Positive correlations were observed between soil ammonium nitrogen content, soil nitrate nitrogen content, net nitrogen nitrification, net nitrogen mineralization, soil temperature and soil moisture ( r =0.491, P <0.01). High levels of nitrogen fertilizer application could increase the loss of nitrate nitrogen by leaching and thus the risk of environmental pollution.

施肥是常用的草地管理方式之一,对维持草地生产力和草地生态系统健康至关重要。本文以河北沽源羊草草原为对象,设置了5种施肥处理,研究了施肥对半干旱羊草草原土壤氮素形态及转化特征的影响。结果表明:在牧草整个生长季,氮磷配施处理土壤铵态氮和硝态氮含量低于相应的单施氮肥处理。氮肥施入改变了草地土壤氮矿化模式。在5-8月氮素添加各处理的土壤硝化作用强烈,明显高于其他处理,氮素添加处理土壤净氮矿化量在5-7月较大,其矿化量占整个生长季的57.58%~68.97%。土壤铵态氮含量与土壤硝态氮含量、净硝化量、净矿化量、土壤温度和土壤水分均存在显著正相关关系( P <0.05),土壤硝态氮含量与土壤温度有极显著正相关关系( r =0.491, P <0.01)。高氮添加处理增加了硝态氮淋溶损失和污染环境的风险。

The effects of long-term P application on the available P and Zn in rhizoshpere soil,P and Zn concentration in grain of winter wheat were studied on the 20 years long-term experiment station in Beijing.The main results were as follows: soil Olsen-P concentration significantly increased with long-term high P fertilization[P 2 O 5 135 kg/(ha· a)].DTPA-Zn concentration in rhizosphere was significant higher than that in bulk soil.P concentration in shoot of winter wheat both at shooting stage and heading stage was apparently improved with increasing P application rates.Whereas,Zn concentration in shoot of winter wheat treated with long-term P fertilization was significantly lower than that of no P supply at heading stage.The P/Zn ratio in winter wheat plant was significantly enhanced with increasing P application rate both at shooting stage and heading stage.Compared with no P treatment,P 2 O 5 67.5 and 135 kg/(ha· a) application significantly increased P concentration and decreased Zn concentration in grain of winter wheat.As the results observed,P/Zn ratio in winter wheat grain was significantly increased.A significantly negative relationship between P and Zn concentration in winter wheat grain was observed.

以中国农业大学昌平试验站长期定位试验为基础,研究了长期施用磷肥对冬小麦根际磷锌有效性及其对作物磷锌营养的影响。结果表明,长期施用磷肥[P 2 O 5 ,135.kg/(hm 2 .a)]导致土壤有效磷含量逐年提高;对根际和非根际土壤有效锌含量没有显著影响,但是根际土壤有效锌含量显著高于非根际土壤;长期施用磷肥冬小麦抽穗期植株锌含量显著低于不施磷处理;无论拔节期和抽穗期,植株含磷量和植株磷锌比(P/Zn)都随着施磷量的增加而显著增加。长期施用磷肥处理(P1和P2)在显著提高了冬小麦子粒含磷量的同时,显著降低了其含锌量;冬小麦子粒磷锌比(P/Zn)随着施磷量的增加也显著增加,子粒含磷量与含锌量呈极显著的负线性相关关系。

Fertilizer played an important role in the reestablishment and recover of degraded grassland. The mass fractions of soil total nitrogen, total phosphorus, total potassium, available phosphorus, available potassium, plant total nitrogen, total phosphorus, total potassium, available phosphorus and available potassium were tested for analyzing the effects of different fertilizing levels on the plant and soil nutrients at alpine meadow in this paper. Results showed that the mass fractions of plant total nitrogen, total potassium and soil N/P reached the maximum values at H9 treatment which were 13.80 g·kg -1 , 11.99 g·kg -1 and 16.16, respectively. Soil available phosphorus and plant total phosphorus reached the maximums values at H5 treatment which were 0.022 g·kg -1 and 9.18 g·kg -1 , respectively. Plant total nitrogen had the maximum values (108.38 g·kg -1 ) at H4 treatment and plant total potassium had the maximum values at H1 treatment. Plant N/P and N/K ratios had the maximum values at H4 treatment, which were 17.78 and 7.06, respectively. Fertilizer was more important to plant nutrients than soil nutrients. These finds suggested that fertilizer significantly not only improved the total nitrogen, total phosphorus, total potassium, available phosphorus, available potassium contents of both plant and soil, but affected the stoichiometric relationship between plant and soil nutrients.

施肥对退化草地的重建和恢复有重要作用，以青藏高原典型嵩草（ Kobresia ）草甸为研究对象，采用正交试验设计，测定了植物全氮、全磷、全钾和土壤全氮、全磷、全钾、速效磷及速效钾，分析了植物N/P，N/K，P/K，土壤N/P,N/K,P/K等化学计量特征。结果表明：在H9施肥条件下，土壤全氮、全钾、土壤N/P为最大值，分别为13.80 g·kg -1 ，11.99 g·kg -1 和16.16；在H5处理下，土壤速效磷、植物全磷达到最大值，分别为0.022 g·kg -1 和9.18 g·kg -1 ；在H4处理下的植物全氮为最大值（108.38 g·kg -1 ）；在H1处理下，植物全钾为最大值（17.84 g·kg -1 ）；在H4处理下，植物N/P,N/K为最大值，分别为17.78和7.06，施肥对植物养分的作用要大于土壤。因此，施肥能显著提高高寒草甸植物全氮、全磷及全钾质量分数，影响植物及土壤养分化学计量关系。

采用根箱法，结合Ｗｉｎｒｈｉｚｏ２００４ａ根系扫描测定系统，以豆科牧草柱花草和禾本科牧草黑籽雀稗为试验材料，研究不同施磷水平对柱花草和黑籽雀稗根系分布的影响。结果表明，２种牧草根系分布随土壤深度的增加而减少，柱花草集中分布于０～１０ｃｍ 土层，黑籽雀稗集中分布于０～２０ｃｍ 土层；磷对２种牧草根系生长的影响存在较大的差异。低磷（Ｐ１，０．４８ｇＰ ２ Ｏ ５ ／ｋｇ土）更适合柱花草根系和地上部分的生长，高磷（Ｐ３，１．９２ｇＰ ２ Ｏ ５ ／ｋｇ土）水平对根系生长有抑制。黑籽雀稗对磷的需求量大，随着磷施入量的增加，根干重、总根长、根表面积、体积和根系平均直径均有所提高。

A split-plot experiment was designed to study the effect of two nitrogen application levels and interspecific interaction of faba bean, soybean and wheat intercropping with maize on crop growth and nutrition absorb. The results indicate that compared with sole, intercropping with maize have no significant effect on faba bean growth and nutrition absorb. Intercropping with maize promote the growth of soybean before florescence of maize but restrain its growth significant after that time. Intercropping with maize improved the growth and nutrition absorb significantly to wheat. Maize have more yield and nutrition absorb when intercropping with faba bean than sole, but it has been restricted when intercropping with soybean before florescence, and it has more benefit growth and nutrition absorb after that time. Intercropping with wheat, maize has been restricted during co-existed time, and it began to get back after wheat harvest. Land equivalent ratio of biomass at harvest is bigger to 1 when maize intercropping with faba bean but it below to 1 when it intercropped with soybean. Maize intercropping with wheat, the land equivalent ratio is below to 1 when wheat harvest but it increased and arrived at 1 with the growth of maize and more nitrogen applied. Aboveground and belowground interaction between crops determined interspecific reaction together. Effect of biological nitrogen fixation and acidification soil by excrete organic acid and proton from legumes to improve the availability of phosphorus could promote the growth of maize, but stronger ability of nutrition competition of wheat also restricted the growth of maize. Maize which have more bigger height could restrain the growth of soybean after its florescence. Specie has trends of come back to sole in biomass after another stronger competition companion specie harvest. The results indicate that reasonable collocation of species could improve the utilization of resources and got higher yield for intercropping species.

田间试验采用裂区设计，研究了蚕豆、大豆和小麦在两个施氮水平下与玉米间作对作物生长和养分吸收的影响。结果表明，与单作相比，间作对蚕豆生长和养分吸收无明显影响；间作促进大豆前期生长，但在玉米旺盛生长期其生长和养分吸收受到抑制；间作对小麦生长和养分吸收有明显的促进作用。与蚕豆间作，玉米能够获得更高的产量和养分吸收量；与大豆间作，对玉米前期生长有抑制作用，但玉米旺盛生长后其生长和养分吸收有明显增加；与小麦间作，在共处期玉米生长受到强烈抑制，小麦收获后玉米生长开始逐渐恢复。蚕豆/玉米间作具有产量优势，大豆/玉米间作为产量劣势；小麦/玉米间作在低氮条件下为产量劣势，提高氮肥用量会恢复以至达到单作水平。分析认为，蚕豆和大豆生物固氮和根系分泌物活化土壤磷的特点促进了玉米的生长，小麦强的根系竞争能力抑制了玉米生长；在共处期玉米的遮荫作用会抑制大豆的生长，而小麦收获后受抑制的玉米产量有向单作水平恢复的能力。表明选择合理的作物配置能够充分利用各种资源，促进种间有益作用，提高作物产量。

A rhizobox experiment was empolyed to study root biomass, phosphorus (P) accumulation of two different P efficiency and P fraction on alluvial soil (available P, 17.79mg·kg -1 ) under P levels of 0, 25, and 50mg·kg -1 ). Xiaoyan 54 (P-efficient) and Jing 411 (P-inefficient) were selected in the experiment. Application of P fertilizer could increase P accumulation of two kinds of wheat and biomass of Jing411. The highest biomass of Xiaoyan54 was obtained by P25. Under soil treatments of non-P and 25 mg P·kg -1, the biomass and P accumulation of Xiaoyan54 was higher than Jing411. The root biomass of Xiaoyan 54 has 87% and 56% higher respectively than Jing 411, and the total P accumulation were 40.2% and 39.7% higher at P0 and P25. The contents of different forms of inorganic phosphorus on alluvial soil followed the order of Ca10-P > Ca8-P > Al-P > Ca2-P > Fe-P. The two kinds of wheat mainly used Ca2-P, Fe-P and Ca8-P of rhizosphere. Organic phosphorus contents was moderate labile organic P > high stable organic P > moderately stable organic P> active organic P. No significant differences were found between Xiaoyan54 and Jing411 under the five forms of inorganic phosphorus, so does the active organic phosphorus, moderately stable organic phosphorus and high stable organic P. The uptake of moderate labile organic P of Xiaoyan54 under no P application was higher than Jing411, which was opposite to 50mg P·kg -1 soil treatment. P fertilizer applied properly was benefit to improvement of biomass and P accumulation of wheat. The two genotypes of wheat mainly used Ca2-P, Fe-P and Ca8-P. Xiaoyan54 had better ability of uptaking moderate labile organic P than Jing411 of rhizosphere. Two kinds of wheat in different P efficiency do not express significant difference in high P alluvial soil.

采用根箱土培试验,研究在速效磷较高的河北潮土(17.79mg·kg -1 )施磷(P)量为0、25、50 mg P·kg -1 土 对小麦的生物量、含磷量和土壤有机、无机磷形态的影响,供试品种为典型磷高效型小麦小偃54和磷低效型小麦京411。本文用小麦的生物量与含磷量表现对磷的吸收,结果表明:增加磷肥投入可以提高两种小麦的含磷量以及京411的生物量,小偃54的生物量在P25水平下最高。P0和P25水平下小偃54的各部分生物量和含磷量显著高于京411。两种处理下小偃54的根系生物量分别比京411高出87%和56%,总含磷量分别比京411高出40.2%、39.7%。种植小麦后潮土中无机磷形态按含量大小排序为:Ca10-P>Ca8-P>Al-P>Ca2-P>Fe-P,Ca2-P、Fe-P、Ca8-P的有效性较高;有机磷形态按含量大小排序为:中等活性有机磷>高稳性有机磷>中稳性有机磷>活性有机磷。小偃54与京411对5种无机形态磷的吸收无显著性差异。不施磷肥,种植过小偃54的内室土中等活性有机磷的质量分数比京411低24%,P50处理时小偃54比京411高18%,差异均达到显著性水平。适量施用磷肥有利于小麦干物质量积累和含磷量的提高。小偃54对中等活性有机磷的活化能力高于京411,高磷条件削弱了两种磷效率小麦生长指标的差异。

As a prosperous fertilizer in crop production, release-controlled urea (CU) promotes the yield of maize ( Zea mays L.) and nitrogen use efficiency with less environmental pollution than normal fertilizers. However, the interaction effects of CU and soil water content on the growth and development of maize have been rarely reported. In this study, the maize cultivar Zhengdan 958 was used to compare the differences of root activity, root and shoot growth, and yield between treatments with normal urea and CU under two water soil moisture conditions. The experiments were carried out in pools (10 m in length, 60 cm in width, and 1.2 m in depth) under a mobile water-proof shelter in 2006–2007. The normal urea was applied with basal (100% applied before sowing, NU) and split (40% applied before sowing and 60% applied at pre tasselling stage, NS ) dressing methods, whereas, the CU was totally applied before sowing. No urea applied was taken as the control. The results showed that the shoot dry weight and leaf area index of CU treatments were higher after anthesis and lower before anthesis than those of NU and NS treatments. As a result, the grain yield of CU treatment was significantly higher than those of NU and NS treatments, and the biomass of CU treatment was significantly higher ( P he grain yield of CU treatment was higher than those of NU and NS treatments by 27.3% and 12.1%, respectively. Under the condition of soil moisture at 75% of field capacity (W2), t he grain yield of CU treatment was higher than those of NU and NS treatments by 17.4% and 8.1%, respectively. In the same urea treatment, the average values of grain yield and biomass were higher by 20.6% and 17.0% under W2 than those under W1, respectively. Root weight, root activity, and root/shoot ratio were lower before anthesis in CU treatment than in NU and NS treatments , but higher after anthesis in CU treatment than in NU treatment. The results suggest that the CU could have a remarkable early-decrease-and-late-increase effect on maize growth, and its coupling effect with soil moisture was higher than that of normal urea. The positive coupling effect of CU might be caused by the higher root activity and root/shoot ratio after anthesis, which could increase the accumulation and transportation of dry matters in the aboveground organs.

为了进一步探讨控释尿素在玉米上的应用效果 , 于 2006 — 2007 年在防雨棚中 , 应用郑单 958 进行了池栽试验。在不同水分条件下 , 比较了施用常规尿素和控释尿素后 , 玉米各生育阶段的根系活力、植株生长及籽粒产量。与常规尿素 ( 全部基施和基施 + 小喇叭口期追施 ) 相比 , 地上部干重、叶面积指数开花前较低 , 开花后较高；成熟期籽粒产量显著高于不施氮对照和两个常规尿素处理 , 生物产量显著高于不施氮对照和常规尿素全部基施处理。从籽粒产量看 , 维持土壤田间最大持水量的 50% 时 , 控释尿素处理分别比常规尿素全部基施处理和分次施处理高 27.3% 和 12.1% ；维持土壤田间最大持水量的 75% 时 , 分别比常规尿素全部基施处理和分次施处理高 17.4% 和 8.1% 。相同氮肥处理 , 土壤田间最大持水量维持 75% 处理 比维持 50% 处理 籽粒产量和生物产量平均分别高 20.6% 和 17.0%, 差异均达极显著水平。与常规尿素处理相比 , 控释尿素处理花前根系数量、活性和根冠比均较低 , 但花后三者能维持较高水平。可见 , 控释尿素对玉米生长具有明显的 “ 前控后保 ” 效果；控释尿素与水分对玉米产量的耦合效应高于常规尿素 , 其原因是生育后期能维持较高的根系数量及活性 , 促进地上部干物质积累和转移。

Aims Rising soil temperature under the warming process stimulates microbial activity in soils on the Qinghai-Xizang Plateau. Moreover, the eastern edge of Qinghai-Xizang Plateau has been experiencing distinct atmospheric nitrogen deposition with an increasing trend. All of these have led to an increase in the available nutrients in soils. This study was aimed to determine the responses of carbon fixation in the alpine meadow to nitrogen and phosphorus additions on the Qinghai-Xizang Plateau. Methods The study was conducted in an alpine meadow ecosystem at the Haibei National Field Research Station of Alpine Grassland Ecosystem, Northwest Institute of Plateau Biology, Chinese Academy of Sciences. Four treatments were set up in 2009, including control, nitrogen addition only (N), phosphorus addition only (P), and combined nitrogen and phosphorus additions (NP). Nutrients were added in June or July each year. The aboveground biomass of functional groups and the above- and belowground biomass of plant communities were measured by harvesting in 2012. Important findings (1) N and P additions increased the aboveground biomass of grass, and the proportion of grass biomass in the community, but decreased the proportion of forb biomass in the community. Only P addition decreased the aboveground biomass of sedge, and the proportion of sedge biomass in the community. (2) N and P additions increased the aboveground biomass by 24% and 52%, respectively, compared with the control. (3) N addition had no effect on the belowground biomass, whereas P addition slightly increased the belowground biomass. (4) N addition had no effect on the total biomass, whereas P addition significantly increased the total biomass. Therefore, N and P additions could relieve the nutrient limitation and stimulate plant growth. Furthermore, the results suggest that the Qinghai-Xizang Plateau could be more limited by P than N on plant growth.

青藏高原正经历着明显的温暖化过程, 由此引起的土壤温度的升高促进了土壤中微生物的活性, 同时青藏高原东缘地区大气氮沉降十分明显, 并呈逐年增加的趋势, 这些环境变化均促使土壤中可利用营养元素增加, 因此深入了解青藏高原高寒草甸植物生物量对可利用营养元素增加的响应, 是准确预测未来全球变化背景下青藏高原高寒草甸碳循环过程的重要基础。该研究基于在青藏高原高寒草甸连续4年(2009–2012年)氮、磷添加后对不同功能群植物地上生物量、群落地上和地下生物量的测定, 探讨高寒草甸生态系统碳输入对氮、磷添加的响应。结果表明: (1)氮、磷添加均极显著增加了禾草的地上绝对生物量及其在群落总生物量中所占的比例, 同时均显著降低了杂类草在群落总生物量中的比例, 此外磷添加极显著降低了莎草地上绝对生物量及其在群落总生物量中所占的比例。(2)氮、磷添加均显著促进了青藏高原高寒草甸的地上生物量增加, 分别增加了24%和52%。(3)氮添加对高寒草甸地下生物量无显著影响, 而磷添加后地下生物量有增加的趋势。(4)氮添加对高寒草甸植物总生物量无显著影响, 而磷添加后植物总生物量显著增加。研究表明, 氮、磷添加可缓解青藏高原高寒草甸植物生长的营养限制, 促进植物地上部分的生长, 然而高寒草甸植物的生长极有可能更受土壤中可利用磷含量的限制。