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。     

磷酸盐、石灰和膨润土降低冶炼厂污染石灰性土壤重金属活性的研究

通过土壤培养试验探讨了磷酸盐配合石灰或膨润土对铅冶炼污染石灰性土壤(全铅和全镉含量分别为497和5.22 mg kg-1)中铅、镉等重金属的稳定效果。石灰和膨润土均可使土壤pH明显上升,而磷酸盐使土壤pH下降。各处理措施均使土壤EC上升。膨润土、石灰有利于土壤磷有效性下降。稳定剂施用后30 d时,与对照相比,磷酸盐单独施用、石灰单独施用、膨润土单独施用、磷酸盐配合膨润土施用处理土壤DTPA-Pb含量分别下降了5.92%、16.7%、9.24%和17.9%;培养60 d时,以上处理DTPA-Pb含量与对照相比下降比例分别为6.15%、17.6%、14.5%和16.4%,而磷酸盐施用30 d后再施用一半石灰的处理DTPA-Pb含量下降14.2%。与铅相比,稳定措施对镉的有效性影响较小,仅有石灰单独施用和磷酸盐施用30 d后再施用一半石灰处理DTPA-Cd含量显著低于对照(P 0.05),降低比例分别为2.54%和5.51%。以上结果表明,对于铅冶炼污染石灰性土壤,磷酸盐配合膨润土施用、磷酸盐施用后一段时间再施用石灰均可促进镉、铅的稳定,磷酸盐配合石灰施用可降低土壤磷的风险。     

VA菌根真菌对石灰性土壤不同形态磷酸盐有效性的影响

用32P示踪法研究了VA菌根真菌对石灰性土壤不同形态磷酸盐有效性的影响。结果表明，VA菌很真菌显著增加了玉米吸收肥料和土壤的磷量。菌根植物和非菌根植物都可不同程度地吸收利用土壤中的Ca2-P、Ca8-P、Fe-P和Al-P，VA菌根真菌增加了玉米对它们的吸收。试验结果还表明，施Ca10-P时接种VA菌很真菌对玉米生长的促进作用比施用其它磷酸盐明显，但Ca10-P不能直接被玉米植株所利用。说明VA菌根真菌能提高土壤中的有效性磷（Ca2-P和Al-P）和缓效性磷（Ca8-P和Fe-P）的有效性。     

石灰和磷酸盐结合稳定石灰性重金属污染土壤的研究

为了探讨磷酸盐和石灰对重金属污染土壤的稳定效果,采用铅冶炼污染石灰性土壤(镉、铜、铅和锌全量分别为4.12、81.0、455和115 mg·kg-1)、设置磷酸盐和3个不同石灰用量及磷酸盐和石灰同时施用及间隔15 d施用的处理,培养后测定土壤性质。结果表明,两种添加剂间隔15 d施用且石灰用量为250和500 mg·kg-1时,土壤pH和磷有效性均高于同时施用处理。两种添加剂间隔15 d施用时,土壤镉有效性显著低于二者同时施用时(P<0.05,低6.63%～11.82%)、土壤锌有效性显著高于同时加入的处理(P<0.05,高17.64%～28.39%)。两种添加剂的不同施用方式对土壤铅和铜的有效性影响较小。石灰用量为1000 mg·kg-1且两种添加剂间隔15 d施用时,土壤镉和铅有效性最低。以上说明,对于石灰性镉污染土壤,磷酸盐和石灰的施用方式对土壤镉的稳定效果存在重要影响。     

石灰性土壤无机磷有效性的研究

本文概要地介绍了作者推荐的关于石灰性土壤无机磷分级体系的建立依据,并将该分级体系中的Ca₂-P、Ca₈-P和Ca₁₀-P与张守敬的土壤无机磷分级体系进行了比较。根据对土壤中无机磷形态的分析,以及系列的生物试验结果,对石灰性土壤中不同形态无机磷的有效性进行了初步评价。     

石灰性土壤无机磷分级的测定方法

本分级体系适用于石灰性土壤、中性土壤以及无机磷酸盐中磷酸钙占有较大比例的土壤或其它沉积物。     

干湿交替过程中石灰性土壤磷吸附和解吸的变化

培养试验表明：淹水便石灰性土壤磷吸附量增加，沙土尤为显著，被吸附的磷容易解吸，对作物仍然有效；回旱后土壤对磷的吸附量减少，但解吸量也小，施用稻草能降低石灰性土壤对磷的最大吸附量（Ｘｍ）和结合能常数（ｋ），淹水后作用更明显。     

石灰性土壤无机磷分级方法的应用

土壤磷素形态的分级,对研究磷素形态转化及有效性,对了解土壤供磷状态,指导磷肥的合理施用等都是极其重要的。石灰性土壤无机磷的分级,过去一直沿用张守敬等(1957)的方法^[1],但该法对石灰性土壤中占主要成份的Ca-P没有从有效性上进一步分级。     

膨润土和磷肥对石灰性土壤无机磷形态转化及有效性的影响

对山西石灰性土壤无机磷的形态、加入外源磷后无机磷形态的转化及施加膨润土后对提高磷素的有效性进行了初步探讨 ,结果表明 :山西石灰性土壤中磷素以无机磷为主 ,而无机磷中以Ca P为主 ,Ca10 P和Ca8 P占无机磷总量的 85 % ,Ca2 P仅占 4 42 %。土壤加入外源磷后 ,Ca2 P有所增加 ,其次是Ca8 P、Ca10 P、Fe P ,Al P和O P增加很少。施加膨润土后使加入外源磷的土壤无机磷都有所增加 ,其中Ca2 P增加最明显 ,Ca8 P、Al P、Fe P增加较多 ,而Ca10 P和O P增加最少 ,说明施用膨润土是实现土壤无机磷释放的主要途径     

三种施肥模式对石灰性土壤培肥的影响

试验在中国科学院封丘农业生态实验站的石灰性潮土上进行 ,在氮、磷、钾固定用量和比例的基础上 ,选定全施有机肥、全施化肥、有机肥和无机肥配合施用三种处理。结果表明 ,这三种施肥模式都显著地提高了土壤全氮和速效氮、土壤全磷和有效磷、土壤全钾和速效钾含量。有机肥在提高土壤全氮和速效氮含量方面效果明显优于无机肥 ,对土壤速效磷含量的影响也高于无机肥 ,但是对土壤全磷含量的增加效应上不如无机肥大。无论是有机肥中的钾还是无机肥中的钾 ,对土壤全钾的贡献没有明显的差别 ;但是在土壤速效钾方面 ,无机肥中的钾对其影响大于有机肥中的钾。有机肥和无机肥的配合施用是提高石灰性潮土土壤肥力更好的方法。     

石灰性土壤无机磷的形态分布及其有效性

本文应用蒋柏藩和顾益初(1989)提出的石灰性土壤无机磷的分级方法,对我国北方主要的石灰性土类进行了无机磷形态分级的研究,并对其有效性作出了初步评价。供试的甘肃、陕西和河南的16种土壤的无机磷形态的分布情况为:Ca₂-P平均占无机磷总量的1.34%,Ca-P占9.91%,Al-P占4.27%,Fe-P占4.40%,O-P占10.9%,Ca₁₀-P占69.1%。生物试验的结果表明:Ca₂-P型的磷酸盐是最有效的,也是作物磷素营养的主要来源;Ca₈-P、Al-P和Fe-P可以作为缓效磷源;Ca₁₀-P和O-P只是一种潜在磷源。本研究为石灰性土壤无机磷的研究和磷肥的合理施用提供了理论依据。     

RESPONSE OF SOYBEAN TO SOIL APPLIED SULFUR AND BORON IN A CALCAREOUS SOIL

A greenhouse experiment with soybean grown on sulfur (S) and boron (B) deficient calcareous soil was conducted for two years in northwest India to study the influence of increasing sulfur and boron levels on yield and its attributing characters at different growth stages (55 days, maturity). The treatments included four levels each of soil applied sulfur viz. 0, 6.5, 13.4, 20.1 mg S kg^?1 and boron viz. 0, 0.22, 0.44, 0.88 mg B kg^?1 at the time of sowing. The highest dry matter yield at 55 days after sowing, DAS (19.3 g pot^?1) and maturity (straw yield ?25.2 g pot^?1 and grain yield ?7.3 g pot^?1) was recorded with B_0.44 S_13.4 treatment combination. The combined applications of sulfur and boron yielded highest oil content with B_0.44S_13.4 (21.7%) treatment level. Chlorophyll ‘a’ and ‘b’ increased significantly with successive levels of sulfur and boron addition at 55 DAS. The mean sulfur and boron uptake in straw and grains increased significantly with increasing levels of sulfur and boron up to 13.4 mg kg^?1 and 0.44 mg kg^?1 and decreased non-significantly thereafter. At both the growth stages, a synergistic interactive effect of combined application of sulfur and boron was observed with B_0.44 S_13.4 treatment level for sulfur and boron uptake in straw and grains.     

深浅施肥的肥料氮在碳酸盐土壤中的转化

利用15_N示踪技术,采用不同追施方法研究碳铵、硫铵、尿素在碳酸盐土壤中的转化表明:在种植作物条件下,肥料氮施入土壤后所发生的矿物固定与生物固定具有负相关关系.由于施用方法不同,肥料氮的矿物固定和损失不同,深施氮素矿物固定与损失呈显著负相关(r=—0.8359)。肥料氮在土壤中转化固定有助于减弱氮素的损失。后茬作物对残留氮的利用与生物固定态氮的多少关系不大。但与矿物固定和无机氮总量之和有密切关系。     

SULFUR APPLICATION EFFECTS ON SOIL PROPERTIES IN A CALCAREOUS SOIL AND ON SUGARCANE GROWTH AND YIELD

High pH soils limit availability of pH sensitive nutrients including phosphorus (P), even though abundant levels are present. Application of such nutrients to the soil is ineffective because they quickly get tied up in unavailable forms. Elemental sulfur (S) application in a narrow band to lower root zone pH and increase nutrient availability to the crop is a possible economically feasible solution. A four year field study was conducted in which S was applied to sugarcane (Saccharum spp.) at rates up to 1120 kg S ha^?1 each of the 1st three years in a band using different application methods. Sulfur application effects on soil pH were gradual, causing only a slight reduction in the application zone after one year; but was long lasting, resulting in continuing substantial declines in soil pH in an adjacent zone four years after the first S application. Soil available P, sulfate (SO₄)-S, and salinity levels increased with increasing S applied. Sugarcane plant growth, as indicated by leaf area index during the grand growth period responded to moderate S application levels. Sugarcane yields increased linearly in the plant crop, but showed quadratic responses to S applications in the 1st through 3rd ratoon crops. Initial soil available P levels prior to the first treatment application were at the critical level considered adequate for crop requirements, yet growth and yield increases in response to S application suggest that the critical available soil P levels for sugarcane may be higher than previously established. Sulfur application at rates beyond those necessary to produce maximum yields resulted in salinity problems which probably reduced yields. The ‘stool splitter’ application method, which slices the plant stool using a coulter and places the fertilizer directly in the middle of the furrow caused crop damage and stand loss which persisted for the remainder of the sugarcane crops. Based on the results of this study, a single application of elemental S at up to 1120 kg S ha^?1 directly below the seed cane at planting is recommend for sugarcane on a calcareous soil, with no additional applications in later crops.     

GROWTH AND IRON-MANGANESE RELATIONSHIPS IN DRY BEAN AS AFFECTED BY FOLIAR AND SOIL APPLICATIONS OF IRON AND MANGANESE IN A CALCAREOUS SOIL

Manganese (Mn) deficiency may be induced by adding large quantities of iron (Fe), provided that soil manganese is marginally deficient. Results of a greenhouse study showed that iron soil application did not influence shoot dry matter yield of dry bean due to the fact that the iron:manganese ratio in aerial parts of dry bean was higher than 0.4. A foliar spray of 2% iron sulfate significantly reduced it probably due to the high level of shoot iron and iron:manganese ratio greater than 4. Iron application decreased concentration/uptake of shoot manganese due to the iron-manganese antagonistic relationships. Mangenese soil application is not an effective method in correction of manganese deficiency induced by iron fertilizers. Iron did not affect root manganese uptake, indicating that manganese absorption was not affected by iron application. Both manganese/iron soil tests are recommended in calcareous soils with manganese soil test in marginal range.     

干湿交替过程中石灰性土壤无机磷的转化及有效性

盆栽试验和培养试验结果表明：淹水能显著提高石灰性土壤磷含量，其作用顺序为，两合土〉淤土；淹水促使土壤无机磷组分中Ｃａ２－Ｐ、Ｃａ８－Ｐ含量增加，说明石灰性土壤淹水后土壤磷有效性的提高主要是Ｃａ－Ｐ体系的活性提高所致。回旱后，土壤速效磷值明显降低，土壤无机磷组分中，Ｃａ２－Ｐ、Ａｌ－Ｐ、Ｆｅ－Ｐ组分均呈降低趋势，土壤无机磷向难溶态转化。淹水降低了外加磷肥的肥效。     

石灰性土壤小麦根际pH及磷动态变化的研究

本文采用网隔栽培室种植小麦,置于人工气候室内生长,对不同温度条件下土小麦根际及距根不同距离土体中ｐＨ,Ｏｌｓｅｎ-Ｐ及无机磷组分动态变化进行了研究。主要结果有:（１）根际及０～３ｍｍ土体ｐＨ较低,而３～８ｍｍ和８～５０ｍｍ土体ｐＨ较高;（２）Ｏｌｓｅｎ-Ｐ含量为根际＜０～３ｍｍ土体＜３～８ｍｍ和８～５０ｍｍ土体,温度升高,各土层Ｏｌｓｅｎ-Ｐ含量呈降低趋势;（３）距小麦根系越近,Ca2-P、Ａｌ Ｐ、Ｆｅ-Ｐ和Ca8-P含量越低,Ｏ-Ｐ和Ca10-P变化不明显;随时间延长和温度升高,Ca10-P含量有所增加,Ca2-P、Ａｌ-Ｐ、Ｆｅ-Ｐ和Ca8-P含量有所降低,Ｏ-Ｐ含量变化不大