论文部分内容阅读
【目的】了解初始酸度对石灰改良红壤钾素有效性的效应,为酸化红壤改良提供依据和支撑。【方法】利用湖南祁阳典型的第四纪红土,制备p H分别为4.0、4.5、4.8、5.2的土壤。每个酸度土壤的一半加石灰改良至p H 6.0(石灰改良处理),另一半不变(酸化对照),以该土壤进行了小麦盆栽试验。每盆内放入一个尼龙网根袋,袋内添加供试红壤150 g,其余放置袋外,共1.65 kg。小麦生长80天后收获,调查了小麦生物量和钾吸收量,测定比较了小麦根际和非根际土壤不同形态的钾含量变化。【结果】1)冬小麦生物量(地上部和根部)与供试土壤初始p H显著正相关(P<0.05),也与钾吸收量显著正相关(P<0.05)。石灰改良处理冬小麦生物量均显著高于相应的酸化对照,并随供试土壤初始p H升高而显著升高。2)不同酸化土壤冬小麦根际土壤速效钾含量均随p H升高显著降低,非根际土壤的速效钾含量显著高于相应的根际土壤(除p H 4.0外)。石灰改良处理根际土壤速效钾含量均显著低于相应的酸化对照,且非根际土壤显著高于根际土,非根际土壤速效钾含量随初始p H升高而显著下降。3)不同酸化土壤冬小麦根际土壤钾离子饱和度随p H升高而显著下降,非根际土壤钾离子饱和度则随p H升高呈增加趋势。石灰改良处理土壤各处理根际土钾离子饱和度均显著低于非根际土,非根际土钾离子饱和度与酸化对照的变化趋势一致。4)不同酸化处理红壤冬小麦生物量与根际速效钾亏缺量呈极显著正相关(P<0.01),冬小麦根际土壤速效钾亏缺率和冬小麦吸钾量、根际钾离子饱和度亏缺率均呈极显著正相关(P<0.01);而石灰改良处理根际土壤速效钾亏缺率则与初始p H呈显著负相关(P<0.05)。【结论】在本试验的p H范围内,酸化条件下,根际土壤速效钾含量随p H降低而升高,而冬小麦吸钾量及生物量均随p H升高而升高。表明酸化红壤影响冬小麦钾养分吸收的主导因素是土壤的酸度。施石灰降低了土壤的酸度,提高酸化红壤作物产量和吸钾量。红壤施用石灰校正酸化应在p H降到5.0之前进行。酸化红壤石灰改良后,还应注意适量补充钾肥。
【Objective】 The objective of this study is to understand the effect of initial acidity on the availability of potassium in lime-amended red soils, and provide the basis and support for the improvement of red soils. 【Method】 The soil samples with p H of 4.0, 4.5, 4.8 and 5.2 were prepared by using the typical Quaternary red earth in Qiyang, Hunan Province. Half of each acidity soil was amended with lime to p H 6.0 (lime treatment) and the other half unchanged (acidification control). Wheat pot experiments were conducted on this soil. A nylon mesh bag was placed in each pot, 150 g of red soil was added into the bag, and the rest of the bag was placed for a total of 1.65 kg. The wheat was harvested after 80 days of growth. The biomass and potassium uptake of wheat were investigated. The changes of potassium contents in different forms of wheat rhizosphere soil and non-rhizosphere soil were measured and compared. 【Result】 The results showed that there was a significant positive correlation between winter wheat biomass (aboveground and root) and initial soil p H (P <0.05), but also with potassium uptake (P <0.05). Lime improved treatment of winter wheat biomass were significantly higher than the corresponding acidification control, and with the initial soil test p H increased significantly higher. 2) The contents of available potassium in rhizosphere soil of different acidified soils decreased significantly with the increase of p H, and the contents of available potassium in non-rhizosphere soil were significantly higher than those in rhizosphere soils (except p H 4.0). The contents of available potassium in rhizosphere soil under lime treatment were significantly lower than those of the corresponding acidified controls, and those in non-rhizosphere soil were significantly higher than those in rhizosphere soil. The contents of available potassium in non-rhizosphere soil decreased significantly with initial p H increasing. 3) The potassium ion saturation of winter wheat rhizosphere soil in different acidified soil decreased significantly with the increase of p H, while the non-rhizosphere soil potassium ion saturation increased with the increase of p H. The potassium ion saturation in rhizosphere soil of lime improved treatment was significantly lower than that of non-rhizosphere soil, and the trend of potassium ion saturation in non-rhizosphere soil was in accordance with that of acidification control. (4) There was a significant positive correlation between winter wheat biomass and available potassium in rhizosphere soil under different acidification treatments (P <0.01), the rate of available K deficiency in winter wheat and potassium uptake in winter wheat, (P <0.01). However, the rate of soil available potassium in rhizosphere soil amended with lime treatment was negatively correlated with the initial p H (P <0.05). 【Conclusion】 Under the p H range of this experiment, the available potassium content of rhizosphere soil increased with the decrease of p H under acidified condition, while the potassium uptake and biomass of winter wheat increased with p H increasing. The results showed that acidification of red soil affect the absorption of potassium in winter wheat leading factor is the acidity of soil. Applying lime reduces soil acidity and increases crop yield and potassium uptake in acidified red soils. Red soil application of lime correction acidification should be pH down to 5.0 before. Acidified red soil lime improved, should also pay attention to the amount of potassium supplement.