甘肃省农田氮磷钾养分平衡状况探析

对甘肃省农田N、P、K养分平衡状况分析结果表明,甘肃省农田N、P、K养分平衡状况为N、P盈余,而K素亏损。     

Effects of soybean raffinose on growth performance,digestibility,humoral immunity and intestinal morphology of growing pigs

There are appreciable does of raffinose in soybean, but the impacts of raffinose on pigs are poorly investigated. We used 2 experiments to investigate the influence of soybean raffinose on growth performance, digestibility, humoral immunity and intestinal morphology of growing pigs. In Exp. 1, a total of 30 crossbred (Duroc × Landrace × Yorkshire) barrows (21.93 ± 0.43 kg) were randomly divided into 3 groups, and were fed with the control diet, the control diets supplemented with 0.2% and 0.5% raffinose, respectively, for 21 d. Results showed that the addition of 0.2% or 0.5% raffinose reduced (P < 0.05) average daily feed intake (ADFI), average daily gain (ADG) and nutrient digestibility, and dietary 0.5% raffinose increased the ratio of feed to gain (P < 0.05). For serum indexes, dietary 0.5% raffinose decreased growth hormone and increased glucagon-like peptide-2, immunoglobulin G, tumor necrosis factor-α (TNF-α) and interleukin-6 concentration (P < 0.05). In Exp. 2, a total of 24 crossbred barrows (38.41 ± 0.45 kg) were randomly divided into 3 groups, and were fed with the control diet (ad libitum), the raffinose diet (0.5% raffinose, ad libitum), and the control diet in the same amount as the raffinose group (feed-pair group) for 14 d, respectively. Compared with the control diet, dietary 0.5% raffinose decreased ADFI (P < 0.05). Intriguingly, the raffinose group had lower ADG than the feed-pair group, lower nutrient digestibility, lower amylase activity in duodenum, lower amylase, lipase and trypsin activities in jejunum and higher TNF-α concentration in serum compared with the other 2 groups, and a higher ratio of villus height to crypt depth compared with the control group (P < 0.05). These results showed that soybean raffinose could reduce feed voluntary intake and body gain while improving intestinal morphology without a significant negative influence on immunity. Taken together, dietary raffinose could decrease growth performance by reducing both feed intake and nutrient digestibility while inducing humoral immune response of growing pigs.     

刈割和养分回添对羊草草原植物群落生物量及其构成的影响

基于2011年开始的养分回添控制试验,研究锡林郭勒盟草原羊草+克氏针茅+糙隐子草群落在不同肥料(氮、植物割取部分和有机质)对羊草割草场植物群落地上生物量的影响。结果表明:与不刈割相比,刈割+有机质回添、刈割+植物回添和刈割处理显著降低了植物群落地上生物量,但刈割+N素回添处理生物量并没有显著降低。4种处理均增加杂类草和一、二年生植物的地上生物量。与单纯刈割相比,刈割+植物回添处理可增加根茎禾草生物量;刈割+N素回添处理显著增加丛生型禾草地上生物量。与单纯刈割相比,刈割+植物回添处理增加了羊草(Leymus chinensis)种群地上生物量,刈割+N素回添处理增加克氏针茅(Stipa krylovii)种群地上生物量并显著增加糙隐子草(Cleistogenes squarrosa)生物量。这说明养分回添对植物群落地上生物量的影响,不仅与所施肥料种类和施肥量有关,还与该草原植物群落物种组成有关。     

矿区不同复垦年限土壤养分及有机碳特性研究——以抚顺矿区碳质页岩区复垦土壤为例

以抚顺矿区碳质页岩风化物区域的复垦土壤为例,对不同年限不同深度的复垦土壤进行分析,揭示了抚顺矿区复垦土壤养分的时空演变规律。结果表明,随着复垦年限的增加,矿山土壤pH值逐年降低,其变化范围在6.47~7.80;全氮、有效磷、碱解氮等呈现逐年增加的趋势,尤其以0~10 cm土层内增长幅度明显;随着深度增加,pH值、全氮、有效磷、氮等逐渐降低。矿山土壤中由于排弃物中含有含碳矿物和少量煤块的原因导致总有机碳含量较高;矿山土壤中有机碳随着复垦年限的增加及自然、人为活动影响,碳黑、颗粒状碳趋向于减少,而易氧化碳的数量增加。     

凉山州植烟土壤养分与烟叶化学品质的相关性分析

为改善凉山烟区土壤合理施肥和提高烟叶化学品质,采用描述性统计和相关分析研究凉山州土壤养分和烟叶化学品质之间的关系。结果表明,凉山州各区县土壤养分丰缺状况不一且分布不均衡,植烟土壤pH总体适宜且比较稳定,土壤有机质适中偏低,有效磷变异范围较大,碱解氮含量过于丰富而速效钾含量偏低;烟叶总糖、还原糖含量偏高,烟碱含量、氮碱比总体适中但不稳定,烟叶钾、氯含量偏低。总体来看,在一定范围内,土壤碱解氮含量与烟叶还原糖含量呈显著负相关;土壤有效磷含量和烟叶总糖、氯含量呈显著负相关,和烟叶钾含量、钾氯比呈显著正相关;烟叶钾含量和土壤pH呈显著负相关,与土壤有机质呈显著正相关。不同梯度pH和有机质含量分段的相关性分析表明,在土壤pH适宜范围内,pH、有机质和土壤养分对烟叶化学品质的影响较大,在有机质适宜范围内,土壤养分和烟叶化学成分的相关性不明显。综上所述,凉山烟区在施肥时需控施氮肥,平衡磷肥,增施钾肥,降低烟糖含量。     

Do plant species encourage soil biota that specialise in the rapid decomposition of their litter?

Plants are often nutrient limited and soil organisms are important in mediating nutrient availability to plants. Thus, there may be a selective advantage to plants that alter the soil community in ways that enhance the decomposition of their litter and, hence, their ability to access nutrients. We incubated litter from three tree species (Fagus sylvatica, Acer pseudoplatanus and Picea sitchensis) in the presence of biota extracted from soil beneath a stand of each species to test the hypothesis that litter decomposes fastest in the presence of biota derived from soil where that species is locally abundant. We found that respiration rate, a measure of decomposer activity and carbon mineralisation, was affected by litter type and source of soil biota, whereas, mass loss was only affected by litter type. However, litter from each tree species did not decompose faster in the presence of indigenous soil biota. These findings, therefore, provide no support for the notion that woodland plants encourage the development of soil communities that rapidly decompose their litter.     

乳山湾东流区营养状况时,空变化及其评价

有机污染在时间上的变化为，7月前呈有机污染不断加剧的过程，到7月整个东流区均达到严重污染水平；7月后是污染程度逐渐减轻的过程，到9月整个东流区水质恢复到较好水平。有机污染程度在空间上的变化是从湾外向湾内逐渐加剧趋势。6、7和8月整个东流区均达到富营养化水平，但富营养化的程度有所不同，7月富营养化程度最严重，8月较7月减轻，到9月湾内基本恢复正常。与1994年8月比较，1995年8月东流区有机污染和富营养化程度有所加剧。     

氮钾配施对花菜产量、品质和养分吸收的影响

花菜氮、钾配施试验研究结果表明:氮、钾肥料配合施用不仅能够增加产量,提高果实中Vc和糖分含量,改善品质,而且能够促进花菜对氮、磷、钾等养分的吸收,提高肥料利用率.     

Fine root decomposition,nutrient mobilization and fungal communities in a pine forest ecosystem

Despite its importance to energy flow and nutrient cycling the process of fine root decomposition has received comparatively little detailed research. Disruption of the fine root-soil interface during preparation of root litterbags for decomposition studies could affect decay rates and nutrient mobilization in part by altering the community of decay organisms. We compared rates of decomposition and nutrient release from fine roots of pine between litterbags and intact cores and characterized the fungal community in the decomposing roots. Fine root decomposition was about twice as fast overall for intact cores than litterbags, and rapid mobilization of N and P was observed for roots in cores whereas nutrients were immobilized in litterbags. Fungal communities characterized using 454 pyrosequencing were considerably different between decaying roots in intact cores and litterbags. Most interesting, taxa from ectomycorrhizal fungal orders such as Boletales, Thelephorales and Cantharellales appeared to be more common in decaying roots from cores than litterbags. Moreover, the rate of N and P mobilization from decaying fine roots was highly correlated with taxa from two orders of ectomycorrhizal fungi (Thelephorales, Cantharellales). Although we caution that DNA identified from the decaying roots cannot be conclusively ascribed to active fungi, the results provide tentative support for a significant role of ectomycorrhizal fungi in decomposition and nutrient mobilization from fine roots of pine.     

营养面积和行株距配置对红香芋植株光合特性及产量品质的影响

以地方品种‘建昌红香芋’为材料,设置6个植株配置组合,研究其对植株生长、冠层特征、光合参数及球茎产量品质等指标的影响,以探讨营养面积和行株距配置对芋植株光合特性及产量品质的影响。结果表明,单株营养面积越小,芋植株株高越高,叶片开展度越低。在营养面积为0.165m2和0.220m2的条件下,宽窄行为(70+40)cm的植株冠层光合有效辐射透过率显著高于宽窄行为(80+30)cm的植株,而光合有效辐射截获率则相反。株距为30cm的芋植株叶面积指数和冠层光合有效辐射截获率最大,冠层光合有效辐射透过率最小,植株的净光合速率(Pn)最低,其单株球茎产量最低,品质最差。株距为35cm时,芋植株具有较高的Pn,形成的单位面积球茎产量最高,品质最好。说明,合理的营养面积和行株距配置可有效调控芋植株冠层形态结构和光合有效辐射(PAR),影响光合作用,并最终影响球茎产量和品质。