共查询到20条相似文献，搜索用时 46 毫秒
1.
灌溉方式、灌水量及施氮量对小麦、玉米周年水分利用的影响 总被引：1，自引：0，他引：1
《水土保持研究》2020,(4)
为探明不同灌溉方式、不同灌水量与氮肥用量条件下小麦、玉米周年水分利用机制,采用田间试验,开展了喷灌与地面灌条件下灌水次数(0,1,2,3次,450 m~3/hm~2)与施氮量(小麦季:180,240,270 kg/hm~2;玉米季:210,270,330 kg/hm~2)对小麦、玉米生长及产量和灌水利用率、小麦生理特征等的影响研究。结果表明:喷灌较地面灌更利于小麦叶片SPAD值的提高。在不同灌量条件下,喷灌更利于促进小麦光合速率的提高,且以N270+3水处理的光合速率最高,其次为N180+1水处理。在中低氮水平,地面灌以灌2水产量最高,而喷灌在灌1水条件下产量最高。玉米产量在低氮和高氮水平下,随灌水量的增加而增加,而中氮(270 kg/hm~2)水平则表现为先增加而后降低的趋势,且中氮水平的玉米产量相对较高。对周年效应而言,喷灌的小麦、玉米周年产量和灌水利用率基本均高于地面灌。在两种灌溉条件下,均以小麦、玉米分别灌2水[450 m~3/(hm~2·次)],周年施氮量510 kg/hm~2的周年总产量最高。周年总灌水利用率在两种灌溉条件下均以周年总施氮量390 kg/hm~2+总灌水900 m~3/hm~2最高,其次为中氮(N240+N270)灌1水处理。周年总水分利用效率以喷灌周年总施氮量510 kg/hm~2+总灌水900 m~3/hm~2最高,以地面灌周年总施氮量510 kg/hm~2+总灌水1 800 m~3/hm~2最高。说明适当减少灌水更利于周年小麦、玉米水分利用率的提高。从增产与节水综合因素考虑,推荐小麦、玉米周年灌水施肥模式为:小麦N240+玉米N270+喷灌各2水[450 m~3/(hm~2·次)]。 相似文献
2.
基于能量平衡的喷灌作物冠层净截留损失估算 总被引：2，自引：1，他引：1
为了定量评价喷灌作物冠层截留损失,以地面灌为对照,利用热平衡茎流计对喷灌冬小麦和夏玉米冠层截留水量蒸发产生的蒸腾抑制效应进行了连续两年的田间观测,结果表明：各次灌水,喷灌冠层截留水量的蒸发明显影响田间小气候进而抑制作物蒸腾。喷灌冬小麦和夏玉米蒸腾抑制量变化范围分别为1.65～4.09 mm和0.50～2.75 mm。在此基础上,基于能量平衡原理,结合波文比能量平衡系统,计算出的冬小麦冠层净截留损失不足0.1 mm;夏玉米净截留损失变化范围在1～2 mm之间,占灌水量的4.3%～6.5%。 相似文献
3.
灌水对大麦／玉米带田土壤矿质氮影响的研究 总被引：5，自引：4，他引：5
在3个氮水平(0,150,300kg/hm2)和两个灌水量(816,1632m3/hm2)下,对3次灌水前、后甘肃河西走廊灌漠土大麦/玉米带田0～200cm土壤矿质氮含量变化进行了研究。结果表明:在灌水前土壤矿质氮含量在0～60cm土层比较高,灌水后0～60cm土层矿质氮含量明显减少,对土壤硝态氮变化影响较大的是第1次和第2次灌水。在150kg/hm2氮水平下,3次灌水大麦带土壤在低灌水量和高灌水量下矿质氮淋失量分别为136.06,142.93kg/hm2,占氮肥用量的90.70%和95.29%;玉米带为95.28kg/hm2和115.89kg/hm2,占氮肥用量的63.52%和77.26%。在300kg/hm2氮水平下,3次灌水大麦带在低灌水量和高灌水量下矿质氮淋失量分别为264.43,237.72kg/hm2,占氮肥用量的88.14%和79.24%;玉米带为163.06,257.76kg/hm2,占氮肥用量的54.35%和85.92%。3次灌水,玉米带土壤矿质氮淋失量在施氮量150kg/hm2时,以第2次灌水淋失量最大,在施氮量300kg/hm2时以第1次灌水淋失量最大;而大麦带都以第1次灌水淋失量最大。说明土壤中矿质氮的淋失首先取决于施氮量,其次才是灌水量。 相似文献
4.
5.
滴灌量对冬小麦田间小气候及产量的影响研究 总被引：3，自引：1，他引：2
为优化北疆滴灌冬小麦灌溉定额,探究不同滴灌量与冬小麦田间小气候及产量的关系,大田试验滴灌条件下,采用单因子随机区组试验设计,研究了3 000 m~3×hm~(-2)(处理TA)、3 750 m~3×hm~(-2)(处理TB)、4 500 m~3×hm~(-2)(处理TC)3个不同灌水量对冬小麦地下15 cm处土壤温度、冠层温度、湿度、旗叶胞间CO_2浓度(Ci)、大气CO_2浓度(Ca)、棵间蒸发量及产量的影响。结果表明:随着灌水量的增大,冬小麦生育后期灌水的土壤温度降温效应增强,不同处理间地温差异分别达1.09℃(处理TA与处理TB)、1.61℃(处理TA与处理TC)、0.52℃(处理TB与处理TC)。随灌水量增大,冠层温度减小,湿度增大,处理间最高冠层温差达3.68℃,棵间蒸发、Ci均随灌水量增大先减小后增大。整个生育期内Ca则随滴灌量的增大基本呈逐渐降低趋势,产量则先升后降,在3 750 m~3×hm~(-2)灌水量时最高,达8 971.66 kg×hm~(-2),较低灌水量(处理TA)、高灌水量(处理TC)分别增产20.55%和6.86%。进一步将上述各要素分别与产量、灌水量进行相关性分析可知,地温、冠层温度均与产量、灌水量之间存在显著性负相关关系,冠层湿度与灌水量呈极显著性正相关,胞间CO_2浓度与产量呈极显著负相关性。本试验条件下,北疆冬小麦滴灌定额为3 750 m~3×hm~(-2)时,麦田冠层温、湿度适宜,棵间蒸发量小,产量最高,可供大田生产实践参考。 相似文献
6.
不同灌水处理对干旱区滴灌核桃树土壤温度的影响 总被引：1，自引：0，他引：1
为探究不同灌水处理对干旱区滴灌核桃树土壤温度的影响,通过大田小区试验,研究6年生核桃树在不同灌水处理（灌水定额为15 mm滴灌C1;灌水定额为30 mm滴灌C2;灌水定额为45 mm滴灌C3;灌水定额为30 mm涌泉灌C4）对核桃树土壤温度的影响。结果表明:灌前0-20 cm的含水率对0-20 cm的土壤温度有显著影响,灌前20-40 cm的含水率对0-40 cm的土壤温度有显著影响;灌后0-20 cm土壤含水率对0-40 cm的土壤温度的影响要显著大于20-40 cm的土壤含水率对其影响。各处理各土层日均土壤温度在各生育期都呈单峰曲线。C1,C2,C3处理各层日均土壤温度随着深度增大呈先增大而后减小的趋势,而C4处理的涌泉灌各层日均温度随着深度增大呈减小趋势,且C4处理各层灌前灌后土壤温度变化幅度最大。由于灌溉方式不同,灌后C4处理土壤温度要小于C2处理。综合考虑土壤温度、产量及品质情况,灌溉定额为435 mm（C2）处理的土壤温度最稳定,产量最高,品质最好,是最有益的处理。试验结果将对核桃土壤温度和最优灌溉制度研究,提供一定的理论依据。 相似文献
7.
在微垄膜下滴灌种植方式下设置不同施肥比例与灌水定额试验组合,对蒜苗生长、产量和品质指标进行定量监测。结果表明,施N 300 kg/hm2、P2O5 225 kg/hm2、K2O 225 kg/hm2+灌水量1 350 m3/hm2处理的假茎粗12.36 mm,单株鲜重41.43 g;折合产量最高,为46 094.40 kg/hm2。施N 300 kg/hm2、P2O5 225 kg/hm2、K2O 225 kg/hm2+灌水量900 m3/ hm2处理的WUE最大,达46.05 kg/m3。综合产量、品质等评价指标,推荐应用施N 300 kg/hm2、P2O5 225 kg/hm2、K2O 225 kg/hm2+灌水量1 350 m3/hm2的灌溉施肥制度。 相似文献
8.
水氮耦合供应对日光温室番茄产量和品质的影响 总被引：7，自引：0，他引：7
以番茄为试材,采用2水平灌水量(W1:4541.0 m3/hm2、W2:2270.6 m3/hm2)×3水平氮肥追施量(N1:747.4 kg/hm2、N2:373.7 kg/hm2、N3:0 kg/hm2),研究了不同水分和氮素供应水平对日光温室越冬栽培番茄产量和品质的影响。结果表明,氮肥追施量较多(N1)时可显著提高番茄产量,减少灌水量并未导致产量的显著下降。高量施氮或不施氮,番茄果实Vc含量均相应下降。高量施氮可显著提高果实中游离氨基酸及可溶性蛋白质含量。增加施氮量和灌水量可显著提高果实中有机酸含量,但对可溶性糖含量无显著影响。加大氮肥追施量和减少灌水量可显著增加果实中硝酸盐含量。采用灰关联理论对不同水分和氮素供应条件综合评价,结果以灌水量2270.6 m3/hm2和施氮量373.7 kg/hm2为最佳处理组合。 相似文献
9.
水分调控对冬小麦同化物分配与水分利用效率的影响研究 总被引：15，自引：0，他引：15
试验研究 12个灌溉组合方式对冬小麦干物质积累与分配、产量和水分利用效率的影响结果表明 ,地面灌水条件下不同处理的地上部干物质积累量由高至低依次为田间持水量 65%的处理 >50 %的处理 >80 %的处理 ;地下 3 0cm、50cm和 10 0cm灌水条件下田间持水量 80 %的处理 >65%的处理 >50 %的处理。产量以地下 3 0cm灌水× 80 %田间持水量处理最高 ,为 6512 .4kg/hm2 ,地下 50cm灌水× 50 %田间持水量处理产量最低 ,为3 568.1kg/hm2 。保持相同田间持水量的灌水处理 ,随灌溉深度的增加其作物水分利用效率呈增大趋势。地下3 0cm灌水× 80 %田间持水量处理和地下 3 0cm灌水× 65%田间持水量处理是较合理的节水灌溉组合方式 相似文献
10.
不同施磷水平下灌水量对小麦水分利用特征及产量的影响 总被引：2，自引：2，他引：2
采用大田试验,设灌水和施磷2个因素,其中灌水设W0(不灌水)、W1(拔节水60mm)、W2(拔节水+开花水,每次灌水60mm)、W3(拔节水+开花水+灌浆水,每次灌水60mm)共4个水平;磷肥设P1(90kg/hm2)和P2(180kg/hm2)2个水平,研究不同施磷水平下灌水量对小麦耗水特征、旗叶水分生理特性及产量的影响。结果表明:同一施磷水平下,随灌水量的增加,灌水量占总耗水量的比例增大,而降水量和土壤供水量所占总耗水量的比例下降,且土壤供水量占总耗水量的比例降低幅度增大。与P1相比,P2处理的0-100cm土壤贮水消耗量显著大于P1处理,并且P2处理提高土壤供水量占总耗水量的比例,说明增施磷肥可提高小麦对土壤水的利用。W2和W3处理灌浆中后期旗叶相对含水量和水势高于W0和W1处理;灌浆后期旗叶相对含水量和水势为P2W0和P2W1处理显著分别高于P1W0和P1W1处理,说明增加灌水和磷肥能显著提高旗叶水势和相对含水量。在本试验条件下,施磷90kg/hm2、拔节水和开花水分别灌60mm的W2处理籽粒产量、水分和磷素利用效率高,农田耗水量较低;增加灌水量后籽粒产量无显著变化,农田耗水量增高,土壤贮水消耗量、水分利用效率、灌溉水利用效率均降低。 相似文献
11.
【目的】以富士（Fuji）、 秦冠（Qinguan）嫁接在平邑甜茶（Malus hupehensis Rehd.）上的当年生盆栽苗为试验材料,采用砂培方法,研究了缺氮胁迫和干旱对富士和秦冠生长情况、 光合参数、 植株各部位氮磷钾含量及氮素利用效率的影响,分析比较了低氮干旱条件下富士和秦冠生长及氮素利用的差异,以期为果树生产高效肥水利用提供理论指导。【方法】试验共设四个处理: 正常氮正常水（ZZ）、 低氮正常水（DZ）、 正常氮干旱（ZG）、 低氮干旱（DG）。氮素和水分均设置两个水平,分别为正常氮（6 mmol/L NO-3-N）、 低氮（0.3 mmol/LNO-3-N）、 正常供水（保持盆中砂子相对含水量为饱和含水量的80%~85%）、 干旱处理（保持盆中砂子相对含水量为饱和含水量的60%~65%）。【结果】富士和秦冠的生物量（茎和叶）、 株高茎粗等生长指标以及光合速率、 气孔导度、 蒸腾速率均为正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）,并且相对应处理下秦冠的以上指标均高于富士;正常供水下,缺氮处理使富士、 秦冠的根冠比比正常氮处理均有所增加,富士提高了2.05%,秦冠提高了22.40%。富士和秦冠的氮、 磷、 钾含量均表现出正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）; 氮、 钾元素含量在植株各部位的分布顺序依次是叶＞根＞茎,磷元素则是根＞叶＞茎;光合氮素利用效率（PNUE）和氮素利用效率表现为秦冠处理之间差异极显著,富士处理之间差异不显著;秦冠的PNUE和NUE明显高于富士,在低氮正常水（DZ）处理下,秦冠氮肥利用率比富士高42.07%,在低氮干旱（DG）处理下高64.14%;低氮胁迫下富士和秦冠的NUE显著提高,并且秦冠提高的幅度高于富士。【结论】施用氮肥能够显著提高富士与秦冠的干物质量,同等水肥条件下,秦冠生长优于富士;水分亏缺会减少叶片对氮的吸收,干旱条件下适度增施氮肥,可提高果树的抗旱能力;低氮干旱胁迫下秦冠的生长指标、 光合指标及氮素利用效率指标均优于富士,表现出较强的抗低氮干旱胁迫的能力。 相似文献
12.
Kyle Devey Michael Mucalo Gordon Rajendram Joseph Lane 《Communications in Soil Science and Plant Analysis》2015,46(4):72-80
Laser-induced breakdown spectroscopy (LIBS) is a new technique for the analysis of plant material. This study investigates the application of LIBS to pasture-based plant samples. The LIBS measurements were obtained from pelletized pasture samples (100 samples) that had been also analyzed by inductively coupled plasma–optical emission spectroscopy (ICP-OES) following microwave digestion for calibration and comparison purposes. Comparisons for elements sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), boron (B), phosphorus (P), and sulfur (S) showed that LIBS could be used for almost all the standard profile total elements with concentrations down to low mg/kg levels (observed error of Na: 0.024 percent, K: 0.18 percent, Mg: 0.016 percent, Ca: 0.073 percent, P: 0.017 percent, Mn: 31 mg/kg, Fe: 150 mg/kg, Zn: 6.6 mg/kg, and B: 1.1 mg/kg). Elemental analysis at less than mg/kg levels was not possible using LIBS. The elements S and Cu were particularly difficult to analyze with reliability using LIBS at the concentration levels found in the plant samples. Replacing microwave digestion and subsequent ICP analysis with a direct analysis of dried plant samples using LIBS has the potential to improve the productivity and reduce the cost of testing. 相似文献
13.
《中国生态农业学报》2014,(8)
正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology, 相似文献
14.
Aleš Lebeda Ivana Doležalová Eva Křístková Barbora Mieslerová 《Genetic Resources and Crop Evolution》2001,48(2):153-164
Staff members of the Department of Botany of Palacký University in Olomouc and Gene Bank Department – Workplace Olomouc, Research Institute of Crop Production in Prague, Czech Republic, conducted an expedition in seven European countries (Austria, Czech Republic, France, Germany, Italy, the Netherlands, Switzerland) in August/September 1999 to collect wild Lactuca spp. germplasm and study its geographic distribution, ecology and biodiversity. During the mission, more than 600 locations were visited resulting in the collection of 602 seed samples (accessions) of wild Lactuca species and 13 seed samples of related genera (Chondrilla and Mycelis). Lactuca serriola f. serriola, L. serriola f. integrifolia, L. saligna and L. viminea subsp. chondrilliflora were prevalent in southern Europe (Italy, France), however, only L. serriola was common in central and western Europe (Austria, Czech Republic, Germany, Netherlands, Switzerland). The greatest diversity of Lactuca species was found in France, where also the most seed samples (165) were collected. The most characteristic habitats with a high density of Lactuca spp. populations were observed along roads and highways, grassy ditches, ruderal communities, and dust-heaps. Natural infections by powdery mildew (Erysiphe cichoracearum) and downy mildew (Bremia lactucae) on some wild Lactuca spp. were observed. Recent observations concerning the geographic distribution, population structure, habitats, and natural occurrence of diseases of Lactuca spp. are discussed. This assemblage of genetic resources of Lactuca spp. can serve as the basis of future studies of species diversification, spatial population structure, plant microevolution, domestication processes, and genetic variability of host-parasite interactions. 相似文献
15.
M.A. Callaham Jr. J.M. BlairT.C. Todd D.J. KitchenM.R. Whiles 《Soil biology & biochemistry》2003,35(8):1079-1093
The responses of tallgrass prairie plant communities and ecosystem processes to fire and grazing are well characterized. However, responses of invertebrate consumer groups, and particularly soil-dwelling organisms, to these disturbances are not well known. At Konza Prairie Biological Station, we sampled soil macroinvertebrates in 1994 and 1999 as part of a long-term experiment designed to examine the effects and interactions of annual fire, mowing, and fertilization (N and P) on prairie soil communities and processes. For nearly all taxa, in both years, responses were characterized by significant treatment interactions, but some general patterns were evident. Introduced European earthworms (Aporrectodea spp. and Octolasion spp.) were most abundant in plots where fire was excluded, and the proportion of the total earthworm community consisting of introduced earthworms was greater in unburned, unmowed, and fertilized plots. Nymphs of two Cicada genera were collected (Cicadetta spp. and Tibicen spp.). Cicadetta nymphs were more abundant in burned plots, but mowing reduced their abundance. Tibicen nymphs were collected almost exclusively from unburned plots. Treatment effects on herbivorous beetle larvae (Scarabaeidae, Elateridae, and Curculionidae) were variable, but nutrient additions (N or P) usually resulted in greater densities, whereas mowing usually resulted in lower densities. Our results suggest that departures from historical disturbance regimes (i.e. frequent fire and grazing) may render soils more susceptible to increased numbers of European earthworms, and that interactions between fire, aboveground biomass removal, and vegetation responses affect the structure and composition of invertebrate communities in tallgrass prairie soils. 相似文献
16.
Thomas Larsen Jesper Luxhøi Jakob Magid Lars Stoumann Jensen Paul Henning Krogh 《Biology and Fertility of Soils》2007,44(1):59-68
We have studied the effect of anaerobically digested (ADMSW) and composted municipal solid waste (CMSW) on mineralization
and foodweb dynamics to verify the hypothesis that ADMSW would immobilize N right after addition to soil in contrast to addition
with CMSW. Another hypothesis was that the mesofauna (enchytraeids and microarthropods) would stimulate N release from the
decomposer community. We measured excretion of -N and urea-N from the mesofauna and hypothesized that enchytraeids would release urea. ADMSW and CMSW were amended to pots
with sandy loam and barley. The pots were divided into treatments with or without mesofauna. Mesofauna, plant N and biomass,
soil N and ergosterol (fungal biomass) were measured over a 113-day period of four equidistant samplings. Soil respiration,
N mineralization and N release by the mesofauna were modelled from concurrent studies. ADMSW- and CMSW-treated soils initially
(<20 days) immobilized N. The amendments did not increase plant growth substantially, and this was probably due to N-limitation
in the early stages of plant growth. Enchytraeid abundance was about three times higher in ADMSW- than CMSW-treated soils,
indicating that ADMSW contained more labile compounds, bacteria, and microfauna. The mesofauna did not affect N-content, but
the cumulated -N excreted by the mesofauna was estimated to be substantial and about one-fifth of total plant N in ADMSW. An explanation
for this discrepancy might be that in the absence of the mesofauna, other members of the detrivore and microbivore community
performed the mesofauna’s function. Neither enchytraeids nor microarthropods excreted urea. 相似文献
17.
《中国生态农业学报》2014,(7)
正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology, 相似文献
18.
《中国生态农业学报》2014,(6)
正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology, 相似文献
19.
Grete Skrede Berit Karoline Martinsen Anne-Berit Wold Stein-Erik Birkeland Kjersti Aaby 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2013,63(3):193-208
Abstract A 3-year study was carried out to investigate quality parameters in 14 tree fruit and berry species grown in southern Norway. The species were blueberry, apple, aronia, sour cherry, sweet cherry, red raspberry, strawberry, blackcurrant, gooseberry, red currant and elderberry, harvested along with wild bilberry, cloudberry and lingonberry. Significant differences between species were identified for all quality parameters. The coefficient of variation between species was lowest for pH (12.5%), dry matter (18.9%) and soluble solids (25.3%), followed by titratable acids (59.3%), total phenolics (83.8%), antioxidant capacity FRAP (85.7%) and antiradical power by the DPPH-assay (97.8%), total monomeric anthocyanins (132%) and ascorbic acid (137%). Average coefficient of variation within species were lower and ranged from 4 (pH) to 62% (ascorbic acid). Only the FRAP values were significantly affected by harvesting year with lower levels in 2004 than in 2005 and 2006. There were significant interactions between species and harvesting year for dry matter, soluble solids, pH, ascorbic acid and FRAP. The results indicate generic ranges in composition within species independent upon growing location and climate, and the composition of the tree fruits and berries is not likely to deviate from these ranges. It is concluded that desirable composition of tree fruits and berries and their products should primarily be achieved by selection among species rather than searching fors broadened variation within individual species. 相似文献
20.
《Communications in Soil Science and Plant Analysis》2012,43(7):865-877
Potassium (K) fixation and release in soil are important factors in the long-term sustainability of a cropping system. Changes in K concentration and characteristics of K fixation and release in rhizosphere and nonrhizosphere soils in the rapeseed (Brassica napus L.)–rice (Oryza sativa L.) rotation were investigated using a rhizobox system. The concentrations of different forms of K in both rhizosphere and nonrhizosphere soils decreased with plants compared to without plants, regardless of K fertilizer application. Potassium uptake by crops mainly came from the rhizosphere soil. In the treatment without K fertilizer (–K), the main form of K supplied by the soil to the crops was 1.0 mol L?1 nitric acid (HNO3) nonextractable K, followed by nonexchangeable K, and then exchangeable K. In the treatment with K fertilizer (+K), the main K forms supplied by the soil to the crops were exchangeable K and nonexchangeable K. The amount and rate of K fixation after one cycle of the rapeseed–rice rotation was greater in rhizosphere soil than in nonrhizosphere soil. The amount and rate of K fixation of soil in the +K treatment were significantly less than in the –K treatment. The cumulative amounts of K released with 1.0 mol L?1 ammonium acetate (NH4OAc) and 1.0 mol L?1 HNO3 extraction increased with the increasing numbers of extractions, but the K-releasing power of soil by successive extraction decreased gradually and finally became almost constant. The release of K was less in rhizosphere soil than in nonrhizosphere soil. The release of K in the +K treatment was similar to that in the –K treatment in rhizosphere soil, but the K release in nonrhizosphere soil was greater with the +K than the –K treatment. Overall, the information obtained in this study will be helpful in formulating more precise K fertilizer recommendations for certain soils. 相似文献