原位模拟氮沉降对盐渍化土壤氮素矿化的影响

以喀什地区疏附县尔库萨克乡盐渍化土壤为试材,采用原位模拟方法,研究了不同氮素沉降水平对土壤氮素矿化的影响。结果表明:氮素的沉降量达到1.0g·m~(-2)·a~(-1)时,是土壤铵态氮含量的最佳阈值;氮素的氨化率达到0.5g·m~(-2)·a~(-1)时,是土壤氨化率的最佳阈值;当氮素的沉降量达到3.0g·m~(-2)·a~(-1)时为土壤硝化及矿化的最佳阈值。盐渍化土壤铵态氮含量及土壤氮素氨化率均是在20~40cm土层达到最大值,而硝态氮含量、硝化率、矿质氮含量、矿化率均是在表层(0~20cm)达到最大值,由此说明,土壤表层(0~20cm)矿化及硝化作用更快。     

土壤有机氮矿化特征和影响机理及对甜菜的启示

针对土壤有机氮组分、在作物氮素营养中的地位、矿化的模拟、影响矿化的土壤理化因素和微生物等方面的研究进展情况进行了综述,根据甜菜的氮素营养特点和甜菜有机氮的研究现状,提出了今后的研究方向。     

苜蓿和老芒麦生草对苹果园土壤氮素矿化的影响

采用PVC管原位培养法,研究了苹果园行间生草,肇东苜蓿（Medicago sativa‘Zhaodong’）和老芒麦（Elymus sibiricus）对土壤氮素净矿化作用及物候期间的变化特征,并进一步分析净硝化作用和净氨化作用特征及其与土壤因素之间的关系。结果表明：土壤氮素矿化作用主要以硝化作用为主,氨化作用比重很小。测试期间,0 ~ 15 cm土层中,自然生草土壤的氮素净硝化速率为0.30 mg · kg-1 · d-1,老芒麦土壤为0.68 mg · kg-1 · d-1,苜蓿土壤最低,为0.28 mg · kg-1 · d-1。不同草种的氮素矿化主要在开花期完成,苜蓿土壤中开花期的土壤氮素净矿化速率分别为营养期和果实期的3.4倍和1.6倍,老芒麦则分别为1.8倍和3.0倍。老芒麦土壤中C/N比影响着氮素硝化能力,15 ~ 30 cm土层土壤的氮素矿化相对较弱。种植老芒麦后土壤氮素矿化能力明显提高,而苜蓿土壤中硝化速率降低。     

覆膜蔬菜需肥特性与施肥技术

对大白菜、黄瓜、番茄、甘蓝、甜椒、绿菜花6种主要蔬菜进行的研究表明:①覆膜改善了土壤理化性状,加速土壤有机质矿化,土壤速效养分不仅得以增加(主要是氮),并能有效地保存在土     

无锡市郊菜园土壤调查

在80年代初期第二次土壤普查中,曾对无锡市近郊的菜园土壤作过较为详细的调查和研究。15年过去了,菜园土壤究竟发生了哪些变化?有哪些因素影响了蔬菜产量的进一步提高?近年来我们根据上级部门的要求,对无锡市近郊具有一定代表性及不同肥力类型的菜田,进行了一次调查和取样分析,发现菜园土壤的肥力特性有不少新的变化,在一定程度上影响了“菜篮子工程”的实施,值得引起重视,现综述如下:1　存在问题1.1　有机肥施用少,菜田肥力下降。本区菜田主要土壤是由水田黄泥土演变而来。开始种菜的10年内,土壤有机质的矿化强度大大高于水田,呈明显下降趋…     

菜地土壤氮素迁移转化研究进展

农业面源污染已成为我国环境污染的重要组成部分,对我国农业生产和生态环境安全带来了较大风险。农田氮素随地表径流流失和地下淋溶是引起日益突出的农业面源污染的主要因素之一。氮素养分是影响蔬菜产量的重要因子,为追求经济效益,菜地氮肥投入量大,过量施肥造成的氮素污染问题日趋严重。笔者综述了菜地氮素迁移转化研究现状,探讨了菜地施肥、地表径流、地下淋溶、氨挥发等菜地土壤氮素迁移和转化途径,分析了土壤中氮素矿化、硝化和反硝化过程,并对今后研究方向进行了展望。     

氮素供应对露地胡萝卜生长及其氮素利用的影响

研究在氮素供应水平对露地胡萝卜的产量、养分吸收和氮素利用的影响。结果表明,胡萝卜肉质根的产量、氮素吸收及可溶性固形物含量随施氮量的增加而明显增加,但在氮素投入量超过120 kg·hm-2时肉质根的产量和可溶性固形物含量没有明显地增加。在本试验条件下,保证胡萝卜肉质根产量的最低氮供应水平(0-60 cm土壤初始无机氮+肥料氮)为227kg·hm-2,根据土壤氮素的分析,作物生长期间根层土壤的氮素净矿化量为58kg·hm-2,因此满足作物生长所需要的氮素临界供应目标值(0～60 cm土壤初始无机氮+肥料氮+根层土壤的氮素净矿化量)为285kg·hm-2,即从合理施肥的角度来看,京郊露地胡萝卜生产中氮肥的最大投入量不应超过该值。     

京郊保护地秋季番茄的氮素供应及利用

研究了氮素供应水平对保护地番茄产量、养分吸收和氮素利用的影响。结果表明,氮素供应量(N)为225kg·hm~(-2)时番茄的产量最高,但随着施氮量的增加,番茄产量反而有所下降。增施氮肥对番茄地上部N、P、K的吸收没有明显的影响。在京郊传统生产条件下,保护地番茄生产相对合适的氮素供应水平(播前根层起始土壤无机氮含量+化学氮素用量)为510 kg·hm~(-2),但如果考虑番茄生长期间土壤氮素的矿化作用,番茄生产的氮素供应水平应为584kg·hm~(-2)。     

地膜覆盖栽培番茄干物质积累与养分吸收分配规律的初步研究

地膜覆盖栽培是蔬菜生产中一项有效的增产措施,覆盖后的番茄一般增产20-40%。据国内外资料,地膜覆盖栽培改变了土壤理化性状和农田小气候效应,提高了土壤有机质矿化速度和养分的释放强度。土壤养分状况的改变,必将影响到番茄植株的代谢过程和体内物质的再分配。本项研究旨在探明地膜覆盖栽培番茄同化产物积累与养分吸收分配的规律,为其科学施肥提供理论依据。 试验材料与方法 本项研究于1982年以池栽培形式进行,供试品种为有限生长类型的青岛早红。试验地为潮棕壤,耕层土壤容重1.34克/厘米3,有机质0.8053%,全氮0.0689%,水解氮78.6ppm,速效磷…     

森林经营对土壤动物影响研究进展

森林经营是实现森林可持续发展的根本途径,土壤动物是森林生态系统的重要组成部分,可对森林经营及其带来的变化及时做出反应。为了探讨土壤动物对森林经营措施的响应,归纳总结了森林经营理念的发展以及森林经营对土壤动物影响的文献资料。结果表明森林经营主要通过对地上结构和微环境的改变对地下土壤动物的群落组成、分解功能及生物指示功能等方面产生影响。在今后研究中应加强森林经营对土壤动物连续长期的动态影响研究,同时利用现代研究技术与方法深入探讨森林经营对土壤动物影响的机制研究。     

Applying spent coffee grounds directly to urban agriculture soils greatly reduces plant growth

There are frequent anecdotal recommendations for the use of locally produced spent coffee grounds in urban agriculture and gardens, either through direct soil application or after composting with other urban organic wastes. This study investigates the scientific basis for direct application of spent coffee grounds (SCG) and the influence of different: (i) plant pH and nitrogen preferences, (ii) soil types, and (iii) application rates. We specifically consider impacts upon plant growth, soil hydrology and nitrogen transformation processes.We grew five horticultural plants (broccoli, leek, radish, viola and sunflower) in sandy, sandy clay loam and loam soils, with and without SCG and fertilizer amendments. The same horticultural plants were grown in the field with 0, 2.5, 5, 10 and 25% SCG amendment rates. Plant biomass growth was related to soil pH, soil moisture, nitrogen concentration and net mineralization, as was weed growth after harvesting.All horticultural plants grew poorly in response to SCG, regardless of soil type and fertiliser addition. Increasing SCG amendment significantly increased soil water holding capacity, but also decreased horticultural plant growth and subsequent weed growth. There was evidence of nitrate immobilization with SCG amendment. Growth suppression was not explained by soil pH change, or nitrogen availability, so is more likely due to phytotoxic effects.Fresh SCG should not be used as a soil amendment in ‘closed loop’ urban food production systems without consideration of potential growth suppression. Further research is required to determine the optimal composting conditions for SCG and blends with other organic wastes.     

夏季种植甜玉米减少果类菜田土壤氮素损失的效果

研究冬、春茬番茄收获后种植夏季填闲甜玉米对土壤剖面无机氮含量及氮素损失的影响,以解决我国北方设施果类蔬菜生产中夏季休闲期较长,夏季土壤氮素矿化强烈,无机氮积累严重,下茬定植前后大水漫灌容易导致淋洗损失等问题。结果表明:在夏季期间没有任何肥料投入和灌溉,甜玉米生长状况良好,其生物量鲜重达66.7 t/hm2,干物质累积为5.9 t/hm2,玉米穗净鲜重达7.5 t/hm2,农民净收入达8 000元/hm2;甜玉米地上部可带走土壤氮素128.1 kg/hm2,减少土壤无机氮累积数量403.1 kg/hm2,从而减少氮素损失风险。夏季种植玉米不仅可以减少氮素损失,而且其根茬还田作为一个很好的碳源补充,改善菜田土壤环境,提高菜田土壤生物肥力。     

Die Eignung unterschiedlicher Komposte im Vergleich zu Stallmist für die organische Düngung in der Baumschule

For three years the influence of biowastecompost, greencompost and farmyard manure (horse) on several soil properties and on the growth of Ligustrum vulgare L. were investigated on a sandy soil with about 3% organic matter. The following treatments were carried out: 200, 400 and 800 dt/ha farmyard manure and corresponding amounts of biowastecompost and greencompost to result in equal amounts of applied organic carbon as well as no addition of organic fertilizer. Frequency of application was also investigated: only once within three years and twice within three years, i.e. the organic fertilizers were given again before the second culture of Ligustrum vulgare L. after two years.There were no significant differences in soil organic matter between the treatments and the untreated plots.Already for the 200 dt/ha-treatments the amount of N given with the organic fertilizer was much higher than the uptake of most of the tree nursery plants. The mineralization of N from the biowastecompost and the farmyard manure increased the mineral N-Content of the soil compared to the untreated plots. The mineralization was biggest for the 400 dt/ha treatment. The mineralized N was not taken up by the plants. For the greencompost the mineralization was smaller compared to the untreated plots. Immobilization took place, which was for the 200 and 400 dt/ha treatments in part compensated by the mineralization of N from the organic matter of the soil.Plant growth was slightly increased for the greencompost. This was attributed to lower water tensions during times of high water tensions. The greencompost used in this experiment can be recommended as a good substitute for farmyard manure.     

施氮量对花椰菜生长和产量的影响

研究了不同施氮水平对花椰菜生长和产量的影响,以期为江苏沿江高沙土地区花椰菜高产的适宜施氮量提供依据.结果表明:不同的施氮量处理间花椰菜产量存在显著差异,施氮能显著提高花椰菜产量,但施氮量达到一定值后,继续增施氮肥产量下降,说明花椰菜施氮量存在阈值.在该试验条件下,花椰菜氮肥的施用量应控制在38 kg/667m2,试验推荐施氮量是在江苏省泰州市高港区的土壤及生态条件下的试验结果,对当地及江苏沿江高沙土地区花椰菜氮肥施用具有一定的参考价值.     

影响土壤有机碳动态变化的因素研究进展

土壤作为地球上最大的碳库,对全球碳循环贡献巨大。土壤有机氮循环已经成为近年来国内外研究的热点;而土壤有机碳对于土壤理化性质和土壤肥力有着不可忽视的影响,国内外关于土壤有机碳的输入、输出和转化等方面已经做了大量研究。该文主要归纳总结土壤有机碳动态的影响因素如微生物、温度和水分等。     

Soil nitrogen and carbon dynamics in a fragmented landscape experiencing forest succession

Forest fragmentation is an increasingly common feature across the globe, but few studies examine its influence on biogeochemical fluxes. We assessed the influence of differences in successional trajectory and stem density with forest patch size on biomass quantity and quality and N transformations in the soil at an experimentally fragmented landscape in Kansas, USA. We measured N-related fluxes in the laboratory, not the field, to separate effects of microclimate and fragment edges from the effects of inherent biomass differences with patch size. We measured net N mineralization and N₂O fluxes in soil incubations, gross rates of ammonification and nitrification, and microbial biomass in soils. We also measured root and litterfall biomass, C:N ratios, and δ¹³C and δ¹⁵N signatures; litterfall [cellulose] and [lignin]; and [C], [N], and δ¹³C and δ¹⁵N of soil organic matter. Rates of net N mineralization and N₂O fluxes were greater (by 113% and 156%, respectively) in small patches than in large, as were gross rates of nitrification. These differences were associated with greater quantities of root biomass in small patch soil profiles (664.2 ± 233.3 vs 192.4 ± 66.2 g m⁻² for the top 15 cm). These roots had greater N concentration than in large patches, likely generating greater root derived organic N pools in small patches. These data suggest greater rates of N cycling in small forested patches compared to large patches, and that gaseous N loss from the ecosystem may be related to forest patch size. The study indicates that the differences in successional trajectory with forest patch size can impart significant influence on soil N transformations in fragmented, aggrading woodlands.     

丛枝菌根真菌与土壤养分交互作用的生态效应研究

土壤养分影响AM真菌种属组成、AM真菌的丰度、孢子数量、孢子密度以及频度;AM真菌反过来影响宿主植物和土壤微生物及其群落多样性。在总结国内外相关研究成果基础上,分析了土壤养分N、P、K以及土壤有机质等因子对AMF生长发育及群落多样性的影响,不同AMF在不同土壤养分环境中对宿主植物的生长及N、P、K营养元素的吸收的影响,以及AMF对土壤微生物及其群落的影响。最后提出了AM真菌与土壤交互作用的几个重要方向,为今后开展菌根多样性及生物多样性研究提供依据。     

富士苹果果实膨大期肥料氮去向及土壤氮素平衡的研究

采用~(15)N同位素示踪技术,研究了不同施氮水平(0、50、100、150、200、250 kg·hm~(-2))对富士苹果膨大期肥料氮吸收利用、土壤残留和土壤氮素总平衡的影响。结果表明,当施氮水平低于100kg·hm~(-2)时,随施氮水平的提高果实单果质量及产量均显著提高,但当施氮水平高于100 kg·hm~(-2)时,各处理间差异不显著。随施氮水平的提高,肥料氮利用率逐渐下降,且树体吸收的氮来自土壤氮的比例逐渐降低,来自肥料氮的比例逐渐升高;果实膨大期结束时(施氮2个月后),肥料氮的5.98%~13.78%被树体吸收,27.26%~37.38%残留在0~60 cm土体中,48.84%~66.76%通过其他途径损失。随施氮水平的提高,树体吸收的肥料氮量和土壤残留氮量逐渐增加,但肥料氮利用率和土壤残留率却不断降低,同时损失量和损失率不断增加。随施氮水平的提高,0~60 cm土体无机氮(硝态氮+铵态氮)含量显著提高,且残留在土壤剖面中的无机氮主要分布在表土层(0~20 cm)。不施氮和低氮水平(施氮50 kg·hm~(-2))土壤无机氮积累量为负积累,当施氮水平高于100 kg·hm~(-2)时,土壤无机氮积累量均呈正积累。随施氮水平的提高,土壤氮素总平衡由亏缺转为盈余,表明供氮不足会造成土壤氮肥力的下降,过量施氮则会加剧土壤氮素累积,增加氮素污染风险。拟合分析发现,在试验施肥水平土壤氮素总平衡与施氮水平呈线性极显著正相关关系,其回归方程为y=0.2912x–22.481(R~2=0.986),当施氮水平为77.20 kg·hm~(-2)时,土壤氮素达到平衡。