崩岗红土层土壤液塑限特性及影响因素研究

土壤液塑限可以反映土壤的入渗、抗冲、抗蚀和抗剪等情况,对崩岗的水土流失研究有重要的意义。通过对崩岗红土层土壤的液塑限研究以及颗粒分析和有机质测定,分析土壤有机质含量和土壤颗粒分布对土壤液塑限的影响。结果表明:崩岗红土层土壤为高液限黏土,土壤状态为坚硬;土壤液塑限值与粗砂粒、细砂粒和粉粒含量相关性不明显,与极细砂粒和黏粒含量呈二项式关系,其中极细砂粒含量与土壤液塑限呈负相关;黏粒含量与土壤液塑限均呈显著正相关关系,且模拟的方程可以较准确地描述土壤液塑限和各因素的相关关系。研究结果有利于丰富崩岗侵蚀机理的研究。     

鄂东南花岗岩崩岗剖面土壤液塑限特征及影响因子分析

崩岗是鄂东南花岗岩地区普遍存在的土壤侵蚀现象,给农业生态与经济发展带来了严重影响.研究崩岗剖面土壤液塑限特征不仅有利于崩岗侵蚀机理的研究,也为崩岗水土流失的防治改良提供理论依据.以通城县五里镇典型的花岗岩崩岗剖面为对象,通过室外采样结合室内液塑限联合测定实验,以及土壤理化性质测定,分析花岗岩崩岗剖面土壤液塑限规律及其影响因子,并探讨其与崩岗发育的关系.结果表明:花岗岩崩岗不同层次间的土壤液塑限差异显著,淋溶层和淀积层的液限值均大于50％,塑限值为30％左右,显著高于母质层;土壤液塑限值受黏粒质量分数、有机质质量分数、容重、游离氧化铁质量分数等影响,并随各因子的增大而增大,均呈正相关关系;其中,黏粒质量分数、游离氧化铁质量分数对土壤液塑限的影响更加显著(R2=0.860“,R2=0.908”).花岗岩崩岗土壤液塑限过渡层、母质层相对较低,在遇到降雨冲刷时,土体状态极易发生改变,易发生水土流失.利用土壤基本理化性质,可以对土壤液塑限进行预测,并为加强崩岗侵蚀机理研究及其治理提供依据.     

Effects of Soil Texture and CaCO3 on Turnover of Organic Material in Chao Soils

Decomposition experiments of ^14C-labelled sickle alfalfa in chao soils of different texture and these soils after removal of CaCO3 were carried out under field and laboratory conditions respectively.The amount of residual ^14C in,or ^14CO2 evolved from,the soils at intervals after the beginning of devomposition were measured and the distribution of native and labelled C between particle size fractions isolated from these soils was edtermined.Results showed that contents of both labelled (^14C) and non-labelled (^12C) carbon decreased with increasing particle size.The enrichment factor for ^14C was higher than that for ^12C in the clay fraction,the reverse being true for the silt enrichment factors.The effect of soil texture on the decomposition of plant material could not be observed in chao soils when the clay content was lower than 270g kg^-1,while it became obvious once CaCO3 was removed was correlated from these soils.The decomposition rate of plant material in the soil from which the native CaCO3 Was removed was correlated significantly to both the clay content of the soil and the application rate of CaCO3.A preliminary correction equation describing the effect of clay and CaCO3 on the decomposition of organic material in chao soil was derived from the results obtained.     

脱盐味精尾液对Na2CO3胁迫下小白菜种子萌发和幼苗生长的影响

【目的】外源氨基酸能够缓解氯化钠对作物的胁迫,但其能否缓解毒害作用更大的碱性盐(Na_2CO_3)胁迫尚无定论。本文研究了富含多种氨基酸的脱盐味精尾液制剂(以下简称尾液)对Na_2CO_3胁迫下小白菜种子萌发、幼苗生长和生理指标的影响,旨在为该类制剂在农业生产中,特别是盐碱土地区的推广应用提供科学依据和理论指导。【方法】供试脱盐味精尾液粗蛋白含量为47.62%,游离氨基酸以谷氨酸、丙氨酸、天门冬氨酸、脯氨酸、甘氨酸、亮氨酸、色氨酸等为主,总含量为15.4%,Na+含量1.2%,pH 3.9 (固水比为1∶250)。以小白菜(Brassica chinensis L.)种子和幼苗为供试材料,分别进行萌发试验和幼苗培养试验。种子萌发采用标准发芽试验方法,种子在0、0.05、0.1、0.2、0.4、0.8 g/L尾液中浸种12 h后,分别移至含5 mL 0、10、20、30mmol/L Na_2CO_3溶液的培养皿中萌发,测定其发芽势、发芽率、胚根长和胚芽长。幼苗培养试验选取整齐一致的幼苗,缓苗后,于营养液中分别加入0、0.05、0.1、0.2、0.4、0.8 g/L的尾液和0、2.5、5、10 mmol/L Na_2CO_3进行培养。在碱害明显后,取样测定生长量、SPAD值、根长、株高以及叶片超氧化物歧化酶(SOD)活性、过氧化氢酶(CAT)活性、过氧化物酶(POD)活性、丙二醛(MDA)含量、超氧阴离子自由基■产生速率、脯氨酸(Pro)含量等生理指标。【结果】1)在同一浓度的Na_2CO_3胁迫下,随尾液浓度的增加,小白菜种子的发芽势、发芽率、胚根长和胚芽长均表现出先上升后下降的变化规律,以添加0.1 g/L尾液的缓解效果最佳。2)在同一浓度Na_2CO_3胁迫下,低浓度尾液(0.05～0.1 g/L)能够提高小白菜幼苗生长量、SPAD值,同时保持Pro含量,提高抗氧化酶活性,降低■产生速率和MDA含量;当尾液浓度增加到0.4 g/L和0.8 g/L时,叶片■产生速率和MDA含量明显上升,同时小白菜生长量、SPAD值、根长和株高均大幅下降,显著抑制了小白菜幼苗的生长。3)在2.5 mmol/L Na_2CO_3条件下,尾液浓度以0.05 g/L效果最好,而在5 mmol/L Na_2CO_3和10mmol/L Na_2CO_3条件下,尾液浓度以0.1 g/L效果最好。【结论】脱盐味精尾液可在一定浓度范围内缓解Na_2CO_3对小白菜种子萌发和幼苗生长的抑制作用。在外源Na_2CO_3浓度为10～30 mmol/L时,用0.1 g/L尾液浸种能够促进种子萌发,缓解Na_2CO_3对小白菜种子萌发的抑制作用;在Na_2CO_3 2.5～10 mmol/L条件下,在营养液中补充0.05～0.1 g/L的尾液能够提高小白菜幼苗叶片抗氧化酶活性,增强叶片光合作用,显著提高幼苗生长量,缓解Na_2CO_3对小白菜生长的抑制作用。     

Fe2（SO4）3/γ-Al2O3催化剂微波法玉米皮中提肌醇工艺研究

以玉米皮为原料制取菲丁,采用Fe2(SO4)3/γ-Al2O3固体酸催化剂,甘油做为水解促进剂,在常压微波辅助下催化水解菲丁制取肌醇,通过单因素及正交试验确定了最优工艺条件:辐射功率600w、水解时间70min、甘油配比为5、催化剂用量10g,在此条件下肌醇收率为72.69%。     

贵州烟田土壤pH、交换性钙镁和CaCO3含量分布特征及其相互关系

【目的】明确贵州烟田土壤pH、交换性钙(Ca²⁺)、交换性镁(Mg²⁺)和碳酸钙(CaCO₃)的含量分布特征及其相互关系,指导土壤酸碱调节及钙镁肥料施用。【方法】采集贵州全省烟区500个典型烟田耕层(0～20 cm)土样,采用经典方法测定土壤p H、Ca²⁺、Mg²⁺和CaCO₃含量,利用SPSS比较不同成土母质、土壤类型和区域之间pH、Ca²⁺、Mg²⁺和CaCO₃的含量差异,定量分析pH与Ca²⁺、Mg²⁺和CaCO₃之间的关系。【结果】土壤pH、Ca²⁺和Mg²⁺含量偏低的烟田分别占20.0%、18.2%和56.4%,偏高的烟田分别占37.0%、55.8%和29.6%。CaCO₃低于10 g kg^-1 烟田占88.4%。不同成土母质、...     

气量法测定土壤CaCO3结果计算问题的商榷

用气量法测定土壤中的CaCO₃含量,其准确度虽不如重量法高,但由于气量法简单迅速,因而使用仍较广泛。     

黄土丘陵区典型沟道侵蚀诱发的CO2通量估算

以黄土丘陵区典型侵蚀沟道为对象,基于沟道剖面有机碳和¹³⁷Cs数据,采用碳库重分布模型估算了典型沟道侵蚀诱发的CO₂通量,并通过检验模型预测效率、解析影响因子,提出了模型校正的思路。结果表明:(1)在长期侵蚀作用下,沟道侵蚀区和沉积区均表现为剧烈的侵蚀效应,侵蚀区侵蚀速率介于30.99~46.44 mm/a,沉积区侵蚀速率介于34.20~37.88 mm/a,沉积区土壤流失速率略小于侵蚀区;(2)碳库重分布模型估算显示,侵蚀区与沉积区均表现为较强烈的碳源效应,侵蚀区CO₂通量介于18.41~28.44 g/(m²·a),沉积区CO₂通量介于22.19~29.25 g/(m²·a);(3)侵蚀部位、土壤容重、有机碳含量、侵蚀量、沟道平均坡度、植被地上部与地下部生物量共同解释了碳库重分布模型预测效率的变异特征(R²=0.68),其中侵蚀部位、侵蚀量、有机碳含量、土壤容重、植被地下部对预测效率有强驱动效应;(4)引入被忽略的植被新输入有机碳库参数,有望校正碳库重分布模型,提升模型预测效率。该研究结果明确了碳库重分布模型在沟道侵蚀区相比沉积区有更高的CO₂通量预测效率,为进一步提高模型的预测精度,可以考虑引入植被输入有机碳库作为校正参数。     

重塑Q3黄土K0三轴蠕变特性的试验研究

[目的]研究陕西省延安地区重塑Q_3黄土高填方工程的后期沉降变形特性,为高填方工程的设计、施工提供一定的技术和理论支撑。[方法]通过改进K0三轴蠕变仪,对所取黄土进行了不同压实度、不同含水量、不同竖向应力下的室内土的静止侧压力系数K_0三轴固结排水蠕变试验。[结果]重塑Q_3黄土具有明显的蠕变特性,在低应力条件下,呈现出典型的衰减蠕变;在K_0条件下,随着含水量增大、竖向应力的增大,压实度的减小,蠕变呈增强趋势,蠕变变形量增大;在低水平应力的条件下,土体所受侧向应力与竖向应力成线性关系。[结论]建立了重塑Q_3黄土关于竖向应力的自定义蠕变模型,通过试验数据拟合获得了模型参数,所建模型能很好地描述延安地区重塑Q_3黄土的蠕变特性。     

西部黄土丘陵区降雨特征及其对坡地土壤侵蚀的影响

以甘肃省定西市安家沟流域的大型径流观测场为依托,以2009—2011年天然降雨在不同土地利用条件下产流产沙特征数据为依据,研究了黄土高原西部黄土丘陵区降雨特征及其对坡地土壤侵蚀的影响。结果表明,在次降雨条件下不同处理径流过程分别经历了产流、峰值、稳定、消减4个表征时刻,土壤侵蚀过程分别经历了发生、峰值、消减3个表征时刻。次降雨条件下,不同处理其径流总量、侵蚀总量排序均为:15°春小麦10°春小麦10°油松林15°荒地15°沙棘林10°荒地15°油松林10°沙棘林。通过层次聚类分析得出,在10°,15°的坡度下,灌木林沙棘、乔木林油松分别具有明显的水土保持效应。所以结合试验地的气候和环境特点,10°坡面适宜种植沙棘林,15°坡面适宜退耕还林。     

液态有机肥对酚酸胁迫下马铃薯生长发育和土壤酶活性影响

为明确液态有机肥对土壤酚酸导致马铃薯的连作障碍的缓解效应,采用盆栽试验,将阿魏酸与香草酸等量混合后按不同浓度(0,50,100,150 mg/kg)施加于马铃薯基质土壤中,模拟马铃薯连作分泌的有机酸自毒物质,并施加不同浓度梯度液态有机肥(0,225,450,675 kg/hm^2),探讨酚酸胁迫下液态有机肥对马铃薯生长发育以及土壤酶活性的影响。结果表明:单一施加外源酚酸对马铃薯株高、茎粗、叶面积以及干物质量皆有不同程度的抑制作用,随酚酸浓度增加,土壤中脲酶、酸性磷酸酶、蔗糖酶活性相对对照分别降低2.74%~10.95%,11.11%~20.55%,5.29%~12.96%,过氧化氢酶、多酚氧化酶活性升高,FDA水解酶活性表现为低促进高抑制。施加液态有机肥后提高了马铃薯株高、茎粗、叶面积以及干物质量,土壤酶活性均有提高,脲酶、酸性磷酸酶、蔗糖酶、过氧化氢酶、多酚氧化酶、FDA水解酶活性相对对照处理最高分别提高了10.80%,21.40%,18.20%,29.60%,37.69%,12.31%,但是液态有机肥浓度过高降低了其对磷酸酶、脲酶、过氧化氢酶的提升效果,抑制了FDA水解酶活性。因此合理施加液态有机肥可以促进马铃薯生长发育,提高土壤酶活性,增强马铃薯的抗逆性,从而缓解酚酸对马铃薯的胁迫作用。     

水蚀条件下硝酸铵施用对黄绵土氮素流失的影响

研究结果表明不同坡度谷子地,高N处理小区径流中铵态氮、硝态氮和有效氮浓度平均为1.06、0.76和1.82mg/kg,低N分别为0.64、1.29和1.93mg/kg;高氮处理土壤铵态氮、硝态氮和有效氮平均流失量分别达到17.90、12.93和30.84kg/(km²·a),低N流失量为11.90、23.86和35.77kg/(km²·a)。高氮处理小区泥沙中有机质和全氮浓度平均为5.21和0.536g/kg,而低氮处理分别为4.94和0.481g/kg;高氮和低氮处理土壤有机质流失量分别为5702和5743kg/(km²·a),土壤全氮流失量为498和559kg/(km²·a)     

Influence of Salicylic Acid and Jasmonic Acid on Wheat Under Drought Stress

Salicylic acid and jasmonic acid play an important role in plants coping with abiotic stresses. An experiment was conducted to examine the effect of salicylic acid and jasmonic acid on wheat under drought. Seeds were primed with jasmonic acid (100µM) and salicylic acid (10 Mm). Water stress was applied by withholding water and each treatment was replicated three times with a factorial block design. Application of Salicylic acid and Jasmonic acid mitigated drought effects in wheat. Results revealed that 100µM Jasmonic acid was more effective than 10 mM SA. Drought decreased germination by 26%, whereas application of Jasmonic acid and Salicylic acid ameliorated stress with the increase of germination by 27% and 21%, respectively. An increase in the shoot length of 23% and 20% was observed with Jasmonic acid and Salicylic acid, under drought conditions. The increase in water potential was 60% and 47% with JA and SA while the increase in proline and soluble sugar was 14% and 25% respectively. The application of Jasmonic acid and Salicylic acid has a potential to enhance the growth of wheat plants under drought.     

Long-term impact of conservation tillage on stratification ratio of soil organic carbon and loss of total and active CaCO3

Under semi-arid conditions, the properties of many soils are influenced by the presence of organic matter and calcium carbonate (CaCO₃). However, the influence of different tillage systems on the development of these properties has scarcely been studied under semi-arid Mediterranean conditions. We studied the effect of long-term conservation tillage (CT) and traditional tillage (TT) on the stratification ratio of soil organic carbon and on CaCO₃ content. The study was conducted in a wheat (Triticum aestivum L.)–sunflower (Helianthus annuus L.) crop rotation established in 1991 under rainfed conditions in Southwestern Spain. As is traditional in this area, wheat was fertilised, but sunflower was not. Conservation tillage was characterised by reduced number of tillage operations and leaving crop residues on the soil surface, while TT was with mouldboard ploughing. Stratification ratio of soil organic C was calculated from C contents in the 0–5 and 5–10 cm soil layers divided by that in the 25–40 cm. Stratification ratio of soil organic C under the CT (>2) was significantly greater than under TT (<2); values >2 indicating better soil quality. Our results show a loss of CaCO₃ under both tillage systems. However, the loss of CaCO₃ was significantly higher under TT than under CT. Also, P and K accumulated in the soil surface and stratification ratio for both nutrients was greater in CT than in TT.     

膜下滴灌对土壤CO2与CH4浓度的影响

在温室进行了马铃薯盆栽试验,采用静态暗箱气相色谱法比较了滴灌(D)和漫灌(F)两种不同灌溉制度对土壤CO2与CH4浓度的影响。在每种灌溉制度下再分设覆膜(M)与不覆膜两种农艺措施处理。覆膜滴灌(MD)下按土壤湿润比(P)不同,再设3个处理,分别为P1(P=25%)、P2(P=33%)、P3(P=50%),共6个处理,即DP1、MDP1、MDP2、MDP3、FC(不覆膜漫灌)和MF(覆膜漫灌),裸土(BS)和覆膜裸土(MBS)为对照。研究结果表明:覆膜的增温保湿作用及薄膜对土壤与大气间气体传输的自然阻隔作用使土壤CO2浓度升高10.4%~94.5%,CH4浓度降低5.1%~47.4%。滴灌的干湿交替现象以及漫灌对土壤通气性的降低使漫灌处理土壤中CO2浓度高于滴灌7.4%~49.7%,CH4浓度降低6.6%~68.2%。而土壤湿度通过影响土壤通气性和土壤溶解性有机质两方面来影响土壤温室气体排放,覆膜滴灌下湿润比越高,土壤中CO2浓度越低,其对CH4浓度的影响不确定。土壤温度是土壤呼吸的主要驱动因子,也会影响CH4的氧化过程。观察DP1处理灌水后土壤中温室气体浓度发现,CO2浓度与温度呈显著正相关关系,CH4浓度与温度呈显著负相关关系,土壤中CO2浓度与CH4浓度呈显著负相关关系。     

土壤的石灰反应强度估测CaCO_3含量和pH研究——以山西省黄土性母质土壤为例

pH和CaCO_3含量是土壤常规分析的两个测定指标,但其室内测定均需借助相应的仪器设备完成,耗时费力。以山西省土系调查采集的110个典型土壤剖面的426个发生层土样的野外测定的石灰反应强度和实验室测定的土壤pH、CaCO_3含量、交换性钠饱和度(Exchangeable Sodium Percentage,ESP)数据为基础,尝试建立石灰反应强度与pH、CaCO_3含量之间的定量关系模型。结果表明:北方黄土性母质土壤,当pH9.0时,CaCO_3含量是影响土壤pH的重要因素,二者的回归拟合最优关系符合幂函数曲线;当pH9.0时,CaCO_3与pH之间无明显关系。石灰反应强度在一定程度上可以半定量地反映pH或CaCO_3含量,但其确定的pH或CaCO_3含量尚是一个范围,并非精确值。同时,从发生学意义角度,土壤中CaCO_3含量高低对形态学研究具有重要意义,在这种情况下,如果需要用pH或CaCO_3含量来确定准确的土壤系统分类类型(如确定土体是否为酸性、具有钙积层/钙积现象等),为慎重起见建议还是以实验室的准确测定数据为准;对于非碱化(pH9.0)、野外有泡沫反应的北方黄土性母质土壤,无论泡沫反应强弱和CaCO_3含量高低,土壤pH基本稳定在8.51±0.49,这一pH范围对作物生长基本没有制约,如果仅从pH或CaCO_3含量是否影响作物生长角度考虑,无需实验室测定pH或CaCO_3含量。     

碳酸钙与石膏对土壤磷及溶解有机碳淋溶的影响

研究碳酸钙与石膏对南澳大利亚典型土壤P和溶解有机碳淋溶的影响结果表明,碳酸钙可同时降低土壤P和溶解有机碳的淋溶,而石膏可降低土壤P淋溶和增加溶解有机碳的淋溶。