长期定位施肥对夏玉米钾素吸收及土壤钾素动态变化的影响

以长期定位试验为平台,夏玉米品种郑单136为材料,设置CK（不施肥）,NP（施氮、 磷肥）,NPK（施氮、 磷、 钾肥）和1.5MNPK（小麦季施高量氮、 磷、 钾肥+有机肥,玉米季仅施用化肥）4个处理,研究夏玉米钾素吸收规律及生育期内土壤钾素动态变化。结果表明,生育期内施钾与不施钾处理夏玉米干物质积累量均一直增加,在成熟期达到最大值; 在施用氮、 磷肥的基础上增施钾肥不但可以提高夏玉米地上部干物质积累量,同时也可以提高叶片及茎秆中的钾素含量,进而提高夏玉米整个地上部吸钾量;而在氮、 磷、 钾肥基础上增施有机肥,对夏玉米干物质积累无显著影响,但可显著提高茎秆及叶片的钾素含量和地上部钾素吸收总量。夏玉米钾素吸收主要集中在灌浆期之前,在灌浆期达到最大值,之后钾素出现回流现象。夏玉米收获后与播种前相比,土壤水溶性钾和交换性钾含量无明显下降或者略有增加,而非交换性钾明显下降,非交换性钾是夏玉米钾素吸收的主要形式。夏玉米吸钾量与播种前土壤3种形态的钾素含量呈显著正相关。因此,增施钾肥对于改善夏玉米生产,维持土壤钾素平衡及实现农业可持续发展具有深远意义。     

西北典型区域旱地冬小麦农户施肥调查分析

为明确我国西北旱地小麦施肥现状,在西北旱地冬小麦典型种植区选取3个区/县连续4年进行农户养分投入调查。调查结果分析表明, 调查区域小麦产量低而不稳;氮肥投入农户31.7%适中、 21.0%偏高、 41.9%很高、 1.7%偏低、 3.7%很低;10.6%的农户磷肥投入量适中,偏低和很低的分别占41.7%和9.6%,偏高和很高的占28.3%和9.8%;钾肥投入量适中的农户占1.5%,偏低的2.1%,很低的88.3%,偏高的2.9%,很高的5.2%。氮、 磷、 钾肥的偏生产力（PFP）分别为21.7、 36.2和88.9 kg/kg。在肥料投入总量中有机肥分别占氮肥总量的3.1%,磷肥总量的2.3%,钾肥总量的53.8%。作基肥投入的氮肥占96.2%,磷肥占100%,钾肥占100%。显然,氮肥施用过量,磷肥偏多和不足并存,钾肥重视不足, 化肥偏多、 有机肥偏少, 基肥偏多、 追肥偏少问题是目前西北旱地小麦养分投入中存在的主要问题。     

Potassium release characteristics and mineralogical characteristics of some delaware soils

Abstract

Twenty‐eight agriculturally important Delaware soils were cropped intensively in a greenhouse experiment. There was no consistent positive correlation between K uptake and percent sand, silt, clay, clay minerals of the clay fraction, K‐feld‐spars of the sand fraction or K‐feldspar weathering of the soils from the A horizon. Only potassium feldspar from the sand fraction and K‐feldspar weathering correlated with K uptake in the soils of the B horizon. This correlation was only significant at the latter part of the experiment when nonexchangeable K was probably the source of plant available K.     

超高产春玉米干物质及养分积累与转运特征

以金山27为供试品种,设超高产栽培（SHY）和普通高产栽培（CK）2个处理,通过2009年、2010年2年的田间试验,研究了超高产春玉米干物质及氮、磷、钾养分积累与转运特征。结果表明,超高产栽培下春玉米单位面积干物质积累量极显著高于普通高产栽培,尤以吐丝后为甚,吐丝后干物质积累率较普通高产栽培高4.5%（2009）和3.2%（2010）,干物质积累对产量的贡献率较普通高产栽培高8.5%（2009）和3.9%（2010）。超高产栽培春玉米营养器官干物质转运率为15.1%（2009）和14.9%（2010）,转运量对产量贡献率为16.6%（2009）和18.5%（2010）,确保了协调的源库关系。超高产栽培植株吐丝后氮、磷、钾的积累率及其对子粒贡献率均显著高于普通高产栽培,其中,氮积累对子粒贡献较普通高产栽培高30.0%（2009）和16.3%（2010）,磷积累对子粒贡献较普通高产栽培高10.8%（2009）和6.0%（2010）,钾积累对子粒贡献较普通高产栽培高7.9%（2009）和8.2%（2010）,在生育后期保持了较强的养分吸收能力。超高产栽培玉米茎鞘中氮、磷转运率均高于普通高产栽培,叶片中氮、钾转运率低于普通高产栽培。其中,超高产栽培玉米叶片氮的转运率为41.0%（2009）和42.9%（2010）,对子粒氮的贡献率小于普通高产栽培,超高产栽培使叶片在玉米生育后期维持了较高的光合能力。     

不同施钾量对砂质潮土冬小麦产量、钾效率及土壤钾素平衡的影响

在砂质潮土上通过田间试验研究了不同施钾量对冬小麦产量、钾素积累量、钾效率和土壤钾素平衡的影响,结果表明:砂质潮土施用钾肥能明显提高冬小麦产量,增产率为7.9%～27.7%;冬小麦植株钾素积累量随施钾量的增加而增加,拔节到灌浆期植株钾积累量增加较多;钾生理效率、钾素吸收效率、钾肥效率和钾肥当季回收率均随施钾量的增加而减少,钾效率和钾收获指数则呈先增后减趋势,以施K2O150kghm-2最佳;钾肥用量应达到K2O150kghm-2以上才能维持土壤钾素肥力;从钾肥增产增收效应、钾效率、土壤钾素平衡等多方面综合考虑,以施钾量150kghm-2效果最好,与不施钾处理相比可增产1462.2kghm-2,K2O每kg增产8.25kg,增收1069元hm-2,钾肥当季回收率为41.6%,并实现土壤速效钾的平衡。     

湖北丹江口水库库区小流域土壤可蚀性特征

土壤自身的可侵蚀性是土壤侵蚀发生的内在因素。由于具有明确的物理意义和方便的测定方法,土壤可蚀性K指标值成为水土流失预报模型的一个重要参数。采用EPIC中土壤可蚀性K值计算方法,对丹江口水库库区内1.94km2的五龙池小流域的K值进行了计算。结果显示,研究区内土壤可蚀性K值平均为0.0302thm2h(MJmmhm2)-1,与我国其他有黄棕壤分布地区已有的研究结果相一致。小流域土壤可蚀性存在一定的空间变异,但变异性不大(变异系数14.7%),86.56%土地面积上的K值位于0.0264～0.0330之间。从土壤可侵蚀性强弱判断,该区土壤为易侵蚀土。利用反距离权重插值(IDW)进行了K值图的制作,并简要介绍了K值图的应用。     

Soil microbial biomass and activity response to repeated drying-rewetting cycles along a soil fertility gradient modified by long-term fertilization management practices

The effects of repeated drying-rewetting (DRW) cycles on the microbial biomass and activity in soils taken from long-term field experiment plots with different fertilization (FERT) management practice histories were studied. We investigated the hypothesis that soil response to DRW cycles differs with soil fertility gradient modified by FERT management practices. The soils were incubated for 51 days, after exposure to either nine or three DRW cycles, or remaining at constant moisture content (CMC) at field capacity. We found that both DRW and FERT significantly affected soil properties including NH₄-N, NO₃-N, dissolved organic C (DOC), microbial biomass C (Cmic), basal soil respiration rate (BSR), urease activity (URE) and dehydrogenase activity (DHD). Except for NH₄-N and BSR, variation in the properties was largely explained by FERT, followed by DRW, and then their interaction. Irrespective of the soils' FERT treatment, repeated DRW cycles significantly raised the DOC and Cmic levels compared with CMC, and the DRW cycles also resulted in a significant decline in BSR and URE and increase in DHD, probably because the organisms were better-adapted to the drying and rewetting stresses. The variations in soil biological properties caused by DRW cycles showed a significantly negative relationship with the soil organic C content measured prior to the start of the DRW experiments, suggesting that soils with higher fertility are better able to maintain their original biological functions (i.e., have a higher functional stability) in response to DRW cycles.     

氨基酸部分替代硝态氮对小白菜生长、硝酸盐累积及大量元素含量的影响

A hydroponic experiment was carried out to determine the influence of replacing 20% of nitrate-N in nutrient solutions with 20 individual amino acids on growth, nitrate accumulation, and concentrations of nitrogen （N）, phosphorus （P）, and potassium （K） in pak-choi （Brassica chinensis L.） shoots. When 20% of nitrate-N was replaced with arginine （Arg） compared to the full nitrate treatment, pak-choi shoot fresh and dry weights increased significantly （P ≤ 0.05）, but when 20% of nitrate-N was replaced with alanine （Ala）, valine （Val）, leucine （Leu）, isoleucine （Ile）, proline （Pro）, phenylalanine （Phe）, methionine （Met）, aspartic acid （Asp）, glutamic acid （Glu）, lysine （Lys）, glycine （Gly）, serine （Ser）, threonine （Thr）, cysteine （Cys）, and tyrosine （Tyr）, shoot fresh and dry weights decreased significantly （P ≤ 0.05）. After replacing 20% of nitrate-N with asparagine （Asn） and glutamine （Gin）, shoot fresh and dry weights were unaffected. Compared to the full nitrate treatment, amino acid replacement treatments, except for Cys, Gly, histidine （His）, and Arg, significantly reduced （P ≤0.05） nitrate concentrations in plant shoots. Except for Cys, Leu, Pro, and Met, total N concentrations in plant tissues of the other amino acid treatments significantly increased （P ≤ 0.05）. Amino acids also affected total P and K concentrations, but the effects differed depending on individual amino acids. To improve pak-choi shoot quality, Gln and Asn, due to their insignificant effects on pak-choi growth, their significant reduction in nitrate concentrations, and their increase in macroelement content in plants, may be used to partially replace nitrate-N.     

K+通道基因MIRK在网纹甜瓜植株中的表达分析

在网纹甜瓜(Cucumis melovar.reticulatus Naud.)叶片中克隆了一个cDNA片段,片段长1 330 bp。这段cDNA序列及由此推测的氨基酸序列分析和多序列比对表明扩增的片段是编码K 通道MIRK(Melon Inward Rectifying K Channel)基因的5′端。由此cDNA片段推测的氨基酸序列包含了6个跨膜片段S1到S6,其间有一个对离子选择性有重要作用的特征序列结构GYGD(Gly-Tyr-Gly-Asp)。进化树分析显示MIRK属于KAT1亚家族,和在葡萄叶片中克隆的K 通道SIRK最相近。半定量RT-PCR试验表明,MIRK在甜瓜植株中根、茎、叶、花、果实等各器官中均有表达,主要在叶片和初期发育的果实中表达,在雌花和茎中也有表达,在根中的表达量最低。MIRK在甜瓜不同器官中的表达模式显示MIRK可能在甜瓜植株发育过程中起重要作用。     

生物有机肥对芥蓝生长及土壤中氮、磷、钾含量的影响

通过盆栽试验和土壤培养试验,研究了施用生物有机肥对芥蓝生长及土壤速效氮、磷、钾含量的影响.结果表明:施用生物有机肥能使芥蓝的产量显著提高,在肥力偏低的土壤上施用效果更好,每500 g土施用生物有机肥3 g,即达到施用常规化肥的效果.施用生物有机肥有利于促进蔬菜体内氮、磷、钾养分的积累,显著提高土壤中速效氮、磷、钾含量,改善土壤的供肥能力,在肥力偏低的土壤上可得到更好的效果.