土壤交换性酸测定方法优化的研究

土壤永久负电荷引起的酸度通过淋洗与K+交换进入溶液,因此,淋洗时间和淋洗效率对土壤中交换性酸准确测定至关重要。本项目拟在林业分析方法的基础上改进,将过滤淋洗改进为抽滤淋洗,降低土壤黏性对测试过程的影响,达到控制淋洗速率的目的,提高工作效率,为第三次全国土壤普查和农用地合理开发利用提供科学依据。

多年施用有机肥对植烟土壤酸化的缓解作用

【目的】探明多年有机肥还田对植烟土壤酸化的影响,为植烟土壤的酸度调控提供科学依据。【方法】以我国北方典型的植烟棕壤为研究对象,采用连续8年田间定位试验设置CK,不施肥;T_(1),单施化肥(N、P2O5、K2O分别为82.20 kg/hm^(2)、83.25 kg/hm^(2)、249.75 kg/hm^(2));T_(2),在化肥基础上配施有机肥(N、P2O5、K2O分别为82.20 kg/hm^(2)、83.25 kg/hm^(2)、249.75 kg/hm^(2),有机肥15.00 t/hm^(2));T_(3),单施有机肥(有机肥22.50 t/hm^(2))共4个处理,通过测定土壤的活性有机碳、pH、土壤交换性酸和土壤交换性盐基含量,分析其对土壤酸化的影响。【结果】与CK相比,单施化肥处理显著降低土壤pH;施有机肥处理增加土壤pH,其中,单施有机肥处理T_(3)效果最显著;施有机肥处理可显著降低交换性酸含量,其中,主要降低土壤交换性铝含量,对交换性氢含量的影响不显著,T_(3)降低效果最显著;施有机肥处理可显著增加交换性盐基总量,但分别对土壤交换性钾钠钙镁影响不显著;随着施肥和耕作年限的增加,施肥处理土壤的总有机碳和活性有机碳含量较CK均有所增加,其中,土壤活性有机碳含量显著增加,以无机肥配施有机肥处理T2效果最优,较CK显著增加143.14%。【结论】植烟土壤经多年有机肥还田后,土壤质量显著提升,有效防治土壤酸化。在实际生产中,合理配施有机肥,既能防治土壤酸化,又能全面提升土壤质量。

石灰石粉提高酸性土壤紫云英产量及养分截获

南方耕作土壤酸化问题普遍,探明酸性土壤施用石灰石粉对紫云英产量与养分截获的影响,为紫云英轻简化高产高效栽培提供依据。盆栽试验条件下,在强酸性水稻土和酸性红壤上分别设7个水平的石灰石粉改良剂施用量。每盆装土2 kg,石灰石粉用量分别为0(CK)、0.267 g/盆(T_(1))、0.534 g/盆(T_(2))、0.801 g/盆(T_(3))、1.068 g/盆(T_(4))、1.335 g/盆(T_(5))、1.602 g/盆(T_(6))(折算为0、600、1200、1800、2400、3000、3600 kg/hm2)。盛花期测定紫云英产量、养分截获、土壤pH值及交换性酸。结果表明,与CK相比,水稻土施用石灰石粉的紫云英鲜草产量增幅为41.5%~122.8%,产量随施用量的增加呈先增加后降低的趋势,红壤增幅为175.2%~989.1%,增产效果随施用量的提高呈递增趋势,两种土壤分别以T_(4)与T_(6)处理鲜草产量最高,与CK差异显著;水稻土施用石灰石粉氮素截获量增幅为147.5%~614.7%,红壤氮素截获量增幅为285.7%~1316.8%。水稻土施用石灰石粉后土壤pH值较CK增长1.5%~5.1%,交换性铝含量降幅为7.3%~55.9%,红壤施用石灰石粉pH值比CK增长3.4%~18.8%,交换性铝含量降幅为32.3%~95.4%;红壤施用石灰石粉后鲜草及干草产量与土壤pH值呈极显著正相关关系。酸化土壤是限制紫云英产量与养分截获提升的重要的因素。在红壤和水稻土上施用石灰石粉能提高紫云英的产量、养分截获、土壤pH值,降低土壤交换性铝含量。相同用量下,在酸性红壤上的改良效果优于强酸性水稻土。强酸性水稻土与酸性红壤施用石灰石粉后土壤pH值分别为4.66和7.05时,紫云英鲜草和干草产量最高。

施用不同土壤改良剂对砖红壤酸度的影响

对砖红壤施用不同的改良剂,经一年的大田试验,测定土壤的活性酸与交换酸研究不同土壤改良剂对酸性土壤酸度的影响。试验结果表明:滤泥单施与石灰单施处理能有效降低土壤的活性酸以及交换性酸的含量,有较好的降低土壤酸度的效果,而施用绿肥、甘蔗渣、羊粪以及羊粪与膨润土混施均不能有效降低土壤的酸度。

Soil Acidification of Alfisols as Influenced by Tea Cultivation in Eastern China

Soil acidification is an important process in land degradation around the world as well as in China.Acidification of Alfisols was investigated in the tea gardens with various years of tea cultivation in the eastern China.Cultivation of tea plants caused soil acidification and soil acidity increased with the increase of tea cultivation period.Soil pH of composite samples from cultivated layers decreased by 1.37,1.62 and 1.85,respectively,after 13,34 and 54 years of tea plantation,as compared to the surface soil obtained from the unused land.Soil acidification rates at early stages of tea cultivation were found to be higher than those at the later stages.The acidification rate for the period of 0-13 years was as high as 4.40 kmol H + ha ?1 year ?1 for the cultivated layer samples.Soil acidification induced the decrease of soil exchangeable base cations and base cation saturation and thus increased the soil exchangeable acidity.Soil acidification also caused the decrease of soil cation exchange capacity,especially for the 54-year-old tea garden.Soil acidification induced by tea plantation also led to the increase of soil exchangeable Al and soluble Al,which was responsible for the Al toxicity to plants.

Potential of Industrial Byproducts in Ameliorating Acidity and Aluminum Toxicity of Soils Under Tea Plantation

It is imperative to choose some low cost, available and effective ameliorants to correct soil acidity in southern China for sustainable agriculture. The present investigation dealt with the possible role of industrial byproducts, i.e., coal fly ash （CFA）, alkaline slag （AS）, red mud （RM） and phosphogypsum （PG） in correcting acidity and aluminum （Al） toxicity of soils under tea plantation using an indoor incubation experiment. Results indicated that CFA, AS and RM increased soil pH, while PG decreased the pHs of an Ultisol and an Alfisol. The increment of soil pH followed the order of RM 〉 AS 〉 CFA. All the industrial byproducts invariably decreased exchangeable Al and hence increased exchangeable Ca, Mg, K and Na and effective cation exchange capacity. RM, AS and lime decreased total soluble Al, exchangeable Al and organically bound Al. Formation and retention of hydroxyl-Al polymers were the principal mechanism through which Al phytotoxicity was alleviated by application of these amendments. In addition, the heavy metal contents in the four industrial byproducts constituted a limited environmental hazard in a short time at the rates normally used in agriculture. Therefore, the short-term use of the byproducts, especially AS and RM, as amendments for soil acidity and AI toxicity in acid soils may be a potential alternative to the traditional use of mined gypsum and lime.