硅钙钾镁肥对南方稻田土壤酸度的改良作用

为明确硅钙钾镁肥阻控土壤酸化的效果和作用,采用连续4a的硅钙钾镁肥田间定位试验,以农民习惯施肥处理为对照(CK),分析在农民习惯施肥基础上增施750、1125、1500和1875kg·hm~(-2)硅钙钾镁肥对稻田土壤剖面pH、电导率(EC)、交换性酸、交换性盐基离子、酸碱缓冲容量和碱产生量的影响。结果表明:农民习惯施肥降低了0～30 cm土壤pH,导致土壤酸化,酸化率为2.88kmol·hm~(-2)·a~(-1);与之相反,硅钙钾镁肥能显著提高土壤pH,较CK处理在0～15 cm和15～30 cm分别提高了1.22～1.58和0.35～0.64个pH单位,并产生大量碱,在0～30 cm达到了9.93～13.82 kmol·hm~(-2)·a~(-1),其中0～15 cm占80%。与CK处理相比,硅钙钾镁肥能显著增加0～30 cm土壤EC、交换性Ca~(2+)、交换性Mg~(2+)、盐基饱和度及0～15 cm交换性K+,减少0～30 cm交换性酸,特别是交换性Al3+。土壤交换性酸消耗量中硅钙钾镁肥释放的交换性盐基和相应碱贡献了104.3%,是交换性酸减少的主要途径。总之,多次大量施用硅钙钾镁肥在显著提高0～30 cm交换性Ca~(2+)、Mg~(2+)和0～15 cm交换性K+含量的同时,有效改良了表层(0～15 cm)和亚表层(15～30 cm)稻田土壤酸性,用量越大,效果越明显,释放的Ca~(2+)、Mg~(2+)盐基离子和碱是土壤酸化阻控的主要作用机制。     

棉纤维生物炭对稻田土壤及水稻Cd含量的影响

为生物炭应用于农田Cd污染的控制及治理提供相关科学依据,研究通过根箱试验,研究棉纤维生物炭对水稻根际和非根际土壤可交换态和不可交换态Cd含量及水稻植株中Cd分配的影响。研究表明:随着棉纤维生物炭的施用量增加,根际和非根际土壤可交换态Cd含量都呈下降趋势,同时不可交换态Cd含量都呈上升趋势。随着棉纤维生物炭的施用量增加,非根际土壤pH值呈逐渐上升趋势。非根际土壤pH值与可交换态Cd含量之间存在显著负相关关系,与不可交换态Cd含量之间存在显著正相关关系。可见,施用棉纤维生物炭可在一定程度上提高非根际土壤pH值,进一步降低了非根际土壤可交换态Cd含量;而根际土壤可交换态Cd含量的下降,主要受棉纤维生物炭的理化性质影响,受土壤pH值影响不大。随着棉纤维生物炭的施用量的增加,水稻各部位Cd含量及累积量都呈现下降趋势,其中籽粒Cd含量的下降幅度最大,为36.57%,根的Cd含量的下降幅度最小,为12.56%。由于茎鞘的生物量和Cd含量都较大,茎鞘中Cd累积量最高,平均为25.44μg plant^-1,是籽粒的2.85倍。因此,在进行农田土壤Cd修复的同时,除了要关注农产品Cd污染,还要考虑如何妥善处理大量的富集Cd的农业废弃物,避免产生二次污染风险。     

Citric acid extraction—An underestimated method in forest nutrition?

Since recent studies reveal citric acid to be favorable for estimating plant‐available P in soils, we investigated if it can also be used for assessing other nutrients. According to our results, it provides stronger correlations with the tree nutrition for Mg (beech, spruce), Ca+K (beech) and Fe (spruce) than the standard methods for determining exchangeable cations. Thus, when estimating plant‐available P by citric acid‐extraction, these cations should be additionally measured in ICP analysis.     

Soil microbial biomass and nitrogen supply in an irrigated lowland rice soil as affected by crop rotation and residue management

 Processes that govern the soil nitrogen (N) supply in irrigated lowland rice systems are poorly understood. The objectives of this paper were to investigate the effects of crop rotation and management on soil N dynamics, microbial biomass C (C_BIO) and microbial biomass N (N_BIO) in relation to rice N uptake and yield. A maize-rice (M-R) rotation was compared with a rice-rice (R-R) double-cropping system over a 2-year period with four cropping seasons. In the M-R system, maize (Zea mays L.) was grown in aerated soil during the dry season (DS) followed by rice (Oryza sativa L.) grown in flooded soil during the wet season (WS). In the R-R system, rice was grown in flooded soil in both the DS and WS. Three fertilizer N rates (0, 50 or 100 kg urea-N ha^–1 in WS) were assigned to subplots within the cropping system main plots. Early versus late crop residue incorporation following DS maize or rice were established as additional treatments in sub-subplots in the second year. In the R-R system, the time of residue incorporation had a large effect on NO₃ ^–-N accumulation during the fallow period and also on extractable NH₄ ⁺-N, rice N uptake and yield in the subsequent cropping period. In contrast, time of residue incorporation had little influence on extractable N in both the fallow and rice-cropping periods of the M-R system, and no detectable effects on rice N uptake or yield. In both cropping systems, C_BIO and N_BIO were not sensitive to residue incorporation despite differences of 2- to 3-fold increase in the amount of incorporated residue C and N, and were relatively insensitive to N fertilizer application. Extractable organic N was consistently greater after mid-tillering in M-R compared to the R-R system across N rate and residue incorporation treatments, and much of this organic N was α-amino N. We conclude that N mineralization-immobilization dynamics in lowland rice systems are sensitive to soil aeration as influenced by residue management in the fallow period and crop rotation, and that these factors have agronomically significant effects on rice N uptake and yield. Microbial biomass measurements, however, were a poor indicator of these dynamics. Received: 31 October 1997     

温度和金属离子对干扰素诱导剂 聚肌胞配对的影响

为提高聚肌胞（Polyinosinic-polycytidylic acid,polyI：C）的配对效果,本文研究了温度和金属离子对聚肌胞配对的影响。实验结果显示,在45℃条件下合成的聚肌胞减色效应最强,说明在该温度下聚肌苷酸（Polyinosinic acid,PI）和聚胞苷酸（Polycytidylic acid,PC）配对最紧密;Na^＋、Ca^2＋、Mg^2＋、Mn^2＋和Zn^2＋能够增强聚肌胞双链结构的紧密性,当Na^＋浓度增加到0．085mol／L后,聚肌胞的配对接近饱和;Ca^2＋、Mg^2＋、Mn^2＋和Zn^2＋对聚肌胞结构的保护效果基本一致,而Cu^2＋对聚肌胞结构具有明显破坏作用。建议采用45℃合成聚肌胞并添加适当浓度的Na^＋和Ca^2＋等增强其结构的紧密性,以避免机体内高活性RNA酶的降解而失去药效。     

Vergleich zwischen Perkolation und Extraktion mit 1 M NH4Cl‐Lösung zur Bestimmung der effektiven Kationenaustauschkapazität (KAKeff) von Böden

Comparison between percolation and extraction with 1 M NH₄Cl solution to determine the effective cation exchange capacity (CEC_eff) of soils A simple method is proposed for the determination of the effective cation exchange capacity (CEC_eff). The soil is extracted with 1 M NH₄Cl‐solution, manually shaken for three times, and the exchangeable cations are determined by ICP‐OES and pH‐measurement. Comparison with corresponding results of the percolation method (n = 110 samples) shows good agreement in reproducibility, exchangeable cations (except Fe and Na), base saturation and CEC_eff.     

共存阳离子（Ca、Zn、K）对土壤镉有效性的影响

采用盆栽与吸附试验,研究了镉污染赤红壤上,施用相同摩尔浓度的钙、钾与锌对小油菜生物量、镉吸收量及土壤镉吸附的影响。结果表明,低和高镉污染赤红壤上,施用锌明显增加小油菜地上部生物量,较对照分别增产21.1%和7.82%。不同阳离子（钠、钙、钾和锌离子）共存改变土壤吸附镉能力的程度不同,与钠体系相比,钙、钾和锌体系中土壤镉吸附量分别降低65.6%、72.0%和96.9%,共存离子降低土壤镉吸附量的次序为锌离子〉钾离子和钙离子,锌离子的影响最为明显。高镉污染赤红壤上,钙和钾使小油菜吸镉量分别增加5.5%和14.4%,低于低镉污染赤红壤上钙和钾使小油菜吸镉的增加量（分别为16.6%和19.6%）;锌明显降低小油菜吸镉量,高和低镉污染赤红壤上,较对照分别减少45.8%和35.0%。3种阳离子与镉共存时,对土壤镉生物有效性的影响差异取决于竞争吸附与竞争吸收的大小,其机制有待进一步探讨。     

酸性黄壤施用磷石膏对高粱营养生长和膜保护酶的影响

采用盆栽试验, 研究了贵州强酸性(pH 4.3)黄壤施用磷石膏对高粱生长、养分平衡、细胞膜保护酶活性的影响.结果表明, 在强酸性土壤上种植耐铝能力弱的高粱, 铝毒害明显, 即使施用足量的氮磷钾肥, 作物也生长不良.施用磷石膏和石灰后高粱出苗和生长正常, 各生物学性状均极显著优于对照, 施磷石膏高粱长势优于施石灰处理;高粱干物质量与磷石膏(X1)、石灰(X2)的施用量呈二次曲线变化(回归方程分别为: Yw=6.88+11.92X1-1.65X12, R=0.983**;Yw=6.88+6.39X2-0.72X22, R=0.996**);磷石膏降低酸性黄壤铝毒、提高植物钙含量的效果略逊于石灰, 在提高植物营养3要素(特别是磷、钾元素)的作用方面优于石灰, 施磷石膏植株磷含量是石灰处理的1.17～2.43倍;施高量磷石膏的高粱植株氮/磷、氮/钾、钾/磷比值分别为6.8～7.1、1.2～1.3和5.4～5.6, 比值适中、变幅小, 氮/铝、磷/铝、钾/铝、钙/铝比值提高, 改善和调节了高粱体内氮、磷、钾、钙养分的平衡.高粱叶片细胞膜保护酶(SOD、CAT和POD)活性分析表明, 施磷石膏、石灰后SOD和CAT活性增加, POD活性和脯氨酸含量下降, 施磷石膏效果优于石灰.     

小分子有机酸和阳离子对含钾矿物钾素释放的影响

采用振荡提取的方法,研究不同浓度的小分子有机酸和阳离子对含钾矿物(黑云母、白云母和正长石)中钾素释放的影响。结果表明:不同小分子有机酸和阳离子均可显著提高黑云母、白云母、正长石中钾素的释放量。与对照处理(去离子水)相比,草酸、柠檬酸、酒石酸和NH4Ac溶液、CaCl2溶液、NaCl溶液、HCl溶液从黑云母中提取的K+量分别增加188.2%、151.6%、149.6%和24.6%、32.6%、3.5%、169.8%;不同溶液从白云母中提取的K+量与对照相比,分别增加211.0%、202.8%、199.4%和81.6%、38.3%、21.7%、169.1%;不同溶液从正长石中提取的K+量与对照相比,分别增加219.0%、206.6%、216.0%和144.1%、27.5%、60.4%、210.9%。同种浸提剂,不同矿物的释钾素量显著不同,表现为白云母>黑云母>正长石,含钾矿物释钾素量随着溶液浓度升高而增加。     

硫酸改性沸石中主要交换性阳离子动态变化研究

近年来天然沸石在农业中得到了广泛的应用.利用硫酸对天然沸石进行活化试验,通过对其1年的动态监测,分析沸石中对植物生长有重要影响的交换性K+、Ca2+、Mg2+、Na+以及阳离子交换量动态变化,以得到硫酸和沸石反应后各养分的动态变化,为改性后沸石生产农作物矿物肥提供理论依据.