橡胶园酸性、中性土壤交换性钙、镁测定方法研究

为了获得简单、易操作、准确度高的橡胶园酸性、中性土壤交换性钙、镁测定方法,本试验通过响应面优化试验,建立称样量、提取液体积、提取方式与交换性钙测定结果之间的数学模型。结果表明：在25℃条件下,以1 mol/L的乙酸铵为土壤浸提液,称样量为2 g、提取液体积175 mL、振荡36 min,为橡胶园酸性、中性土壤的最佳提取条件。将上述条件下得到的结果与标准方法条件下得到的结果相对比,两结果的相对误差在1.25~3.04之间,均属合理范围。利用标准样品对优化方法进行试验验证,结果与推荐值相符。改进后的方法分析成本低、操作简便、测定结果准确、稳定性好,可用于橡胶园酸性、中性土壤交换性钙、镁的测定。     

Ionic Ratios and Crop Performance: II. Effects of Interactions amongst Vanadium, Phosphorus, Magnesium and Calcium on Soybean Yield

Because vanadium (V) is easily reduced to a cationic form within plant cells, data from resin-extraction of soil were analysed for evidence of interactions between V and the resin-extractable concentrations of magnesium (Mg) and calcium (Ca) on soybean seed yield. Three varieties, 9091, 9061 and 704, were grown over a 3-year period in a corn–soybean–wheat rotation. Surface soil samples (0–15 cm) were extracted with ion-exchange resins, extracts were analysed by inductively coupled plasma methods (ICP), and the results were regressed against seed yield using SAS PROC STEPWISE analysis using forward selection, backward elimination and maximum R² routines. The seed yield of each variety showed a correlation with a unique set of resin-extractable concentrations of V, phosphorus (P), Mg and Ca, and the V:(V + P), Mg:(Mg + Ca), Mg:(Mg + 1000 V) and Ca:(Ca + 1000 V) ratios. Variety 9091 was most sensitive to the Mg:(Mg + Ca) ratio. Variety 9061 was most sensitive to extractable V and to the V:(V + P) ratio. Variety 704 was sensitive to extractable P, V and Ca and the Mg:(Mg + 1000 V) ratio. For variety 9091, Mg fertilization (not currently practised) may be an economical practice, whereas P fertilization of 704 may not be economical. Each regression technique varied slightly in identification of important factors in seed yield. Concentrations and ratios of resin-extractable elements in soil provide insights into optimal genotype selection and possible management alternatives for a given soil.     

晋中市左权县作物土壤有效镁营养状况分析

以长治市左权县东隘口村土壤为研究对象,将48个分别来自玉米地、蓖麻地、谷子地、药材地内的不同土壤类型样品,用原子吸收分光光度计进行有效镁含量的检测。结果表明,试验区内,土壤有效镁含量处于中等水平,且有效镁含量与电导率呈现正相关关系。不同作物下的土壤有效镁含量无显著性差异,而在不同土壤类型间差异性显著。土壤缺镁时,可以施用硫酸钾镁。     

硒肥与钝化材料组配对土壤Cd钝化及稻米Cd消减效果

为了探讨不同硒肥施用方式联合钝化材料对土壤镉钝化和稻米镉消减的效果,采用盆栽试验的方式,选用亚硒酸钠作为硒肥,钙镁磷肥和硅藻土作为钝化材料,设置基施硒肥+钙镁磷肥+硅藻土和叶面喷施硒肥+钙镁磷肥+硅藻土2种方式,研究其不同用量对镉污染酸性稻田土壤修复与安全利用的影响。结果表明：随着施用量的增加,稻米产量增加,基施硒肥产量略高于叶面喷施硒肥,产量差为 2.115 g/pot,与对照(CK)相比,基施0.28%钙镁磷肥+0.12%硅藻土+0.004‰硒(T3)能够提高1.68倍的稻米产量;随着施用量的增加,pH升高,有效Cd降低,有机质与CEC变化不大;基施硒肥与叶面喷施硒肥处理对土壤pH、有机质与CEC差异不显著,但基施硒肥处理有效Cd含量略低于叶面喷施硒肥处理,T3对土壤Cd的钝化效果最佳;随着基施硒肥用量的增加,稻米Cd含量降低,随着叶面喷施硒肥用量的增加,稻米Cd含量先降低后升高,基施硒肥处理对稻米Cd的消减程度强于叶面喷施硒肥处理,相差 0.021 mg/kg,与对照(CK)相比,T3处理稻米Cd降低0.063 mg/kg。可见,硒对调控稻米镉累积具有重要作用,且基施硒肥强于叶面喷施。综上所述,基施0.28%钙镁磷肥+0.12%硅藻土+0.004‰硒对土壤Cd钝化与稻米Cd消减的效果最佳,值得在镉污染稻田推广应用。     

Mineral absorption in the black rhinoceros (Diceros bicornis) as compared with the domestic horse

To test whether mineral recommendations for horses are likely to guarantee adequate mineral provision for black rhinoceroses (Diceros bicornis), we investigated the apparent absorption (aA) of macro- and microminerals in eight black rhinoceroses from three zoological institutions in a total of 32 feeding trials with total faecal collection, with additional data from three unpublished studies (18 feeding trials). Feeds and faeces were analysed for Ca, P, Mg, Na, K, Fe, Mn, Cu, Zn and Co. The resulting aA coefficients, and the linear relationships of apparently absorbable dietary mineral content to total dietary mineral content [per 100 g dry matter (DM)], were compared with data for domestic horses. Rhinoceroses had significantly higher aA coefficients for Ca and Mg (because of a higher calculated 'true' absorption), and lower ones for Na and K (because of calculated higher endogenous faecal losses). High absorption efficiency for divalent cations is hypothesized to be an adaptation to a natural diet of particularly high Ca:P ratio (approximately 14:1); an effective removal of Ca from the ingesta guarantees sufficient P availability at the fermentation site in the hindgut. Higher faecal losses of Na and K are hypothesized to be linked to a higher faecal bulk per DM intake in black rhinoceroses as compared with horses because of a generally lower digestive efficiency. There were no relevant differences in the absorption patterns of microminerals. In particular, there were no discernable differences in Fe absorption within the rhinoceroses for diets with and without tannin supplementation. Several of the zoo diets assessed in this study were deficient in Cu, Mn or Zn, and most contained excessive levels of Fe when compared with horse requirements. The findings of this study indicate that differences in mineral absorption between occur even between species of similar digestive anatomy; that in particular, Ca absorption might vary between hindgut fermenters with Ca:P ratio in their natural diet; that Na might be a particularly limiting factor in the ecology of free-ranging rhinoceroses; that moderate doses of tannins do not seem to markedly influence mineral absorption; and that diets for captive animals should contain adequate, but not excessive mineral levels.     

石灰性土壤交换性钙和镁测定方法的研究

石灰性土壤交换性盐基组成的测定,通行的方法是采用70%乙醇溶液反复洗盐,再经pH 8.50.1 mol L-1氯化铵-70%乙醇(CH3CH2OH)溶液进行多次交换处理,测定交换液中的K+、Na+、Ca2+、Mg2+浓度。但此方法常常受操作步骤繁琐,以及土壤中碳酸盐的溶解量因多次浸提而增加的困扰,最终导致测定结果偏高。基于上述原因,选择不同浓度、不同pH的NH4OAc和NH4Cl 10种交换剂,对比分析10种交换剂中的碳酸盐溶解度和土壤交换性钙镁含量。结果表明,pH=8.5 1 mol L-1氯化铵-70%乙醇(CH3CH2OH)溶液较适合石灰性土壤交换性盐基的测定。此新方法是先经70%乙醇(CH3CH2OH)溶液洗盐,再用pH8.5 1 mol L-1氯化铵(NH4Cl)-70%乙醇(CH3CH2OH)溶液进行一次性交换处理,然后测定交换液的K+、Na+、Ca2+、Mg2+浓度,简化了操作程序的同时有效抑制了土壤碳酸盐的溶解,降低了测定结果的偏差。     

两种不同镁盐在牛粪堆肥高温期的保氮效果研究

利用恒温培养箱模拟堆肥高温期,添加硫酸镁、磷酸二氢钾和含镁废渣,研究磷酸铵镁(MAP)反应中各成分的保氮效果以及含镁废渣作为堆肥过程中氮素固定剂的可行性。结果表明:添加镁盐固定剂显著降低了堆体中的pH值,减少了氮素损失。同时添加硫酸镁和磷酸二氢钾的保氮效果最佳,添加相同比例的含镁废渣和硫酸镁的保氮效果无显著差别。含镁废渣添加量的保氮效果与其添加量成正相关,添加质量比为2%、4%、8%的含镁废渣的保氮率分别为6.15%、10.13%、19.51%。添加镁盐会提高堆体中的EC值,降低GI值,各处理均可达到腐熟。说明可以利用镁盐作为堆肥保氮固定剂,而含镁废渣因其价格低廉,更具应用前景。     

正交试验处理下配施锌、镁、钼肥对烤烟钾、氯含量影响

为协调烟株营养平衡,优化烟草专用肥配方,将硫酸锌0、6、12 kg/hm2和硫酸镁0、30、60 kg/hm2及钼酸铵0、90、180 g/hm2按L9(34)方式,运用SPSS 17.0 正交试验设计生成施肥处理表,通过田间试验,研究配施锌、镁、钼肥对烤烟钾、氯含量影响的主次因素,肥料施用量对烤烟钾、氯含量的影响及主体间的效应。结果表明：硫酸锌的施用对烤烟钾含量的影响高于硫酸镁、钼酸铵,就烤烟钾含量而言最佳的配施方案为硫酸锌6 kg/hm2、钼酸铵0 g/hm2、硫酸镁60 kg/hm2;烤烟氯含量受钼酸铵施用的影响高于硫酸锌、硫酸镁。     

缺镁胁迫对龙眼苗期氮代谢的影响

采用溶液培养方法研究了缺镁胁迫对龙眼苗期氮代谢的影响。结果表明 ,缺镁胁迫下 ,龙眼叶片硝酸还原酶 (NR)活性下降 ,游离氨基酸总量增加 ,水解氨基酸总量减少 ,蛋白质合成受阻而分解加剧 ;核酸酶 (RNase)活性提高 ,核糖核酸 (RNA)、脱氧核糖核酸 (DNA)含量降低 ,缺镁对RNA的影响比DNA大 ;活性氧 (O2-)净产生速率增加。统计分析表明 ,缺镁胁迫下 ,龙眼核酸和蛋白质含量下降是其合成受阻、分解加剧以及活性氧毒害综合作用的结果