Acidification of a kaolinitic Alfisol under continuous cropping with nitrogen fertilization in West Africa
Acidification of a kaolinitic Alfisol under continuous cropping with nitrogen fertilization in West Africa
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DOI：
10.1007/bf00010278
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发表时间：
1995-04
期刊：
影响因子：
4.9
通讯作者：
A. Juo;A. Dabiri;K. Franzluebbers
中科院分区：
文献类型：
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作者：
A. Juo;A. Dabiri;K. Franzluebbers
由于热带地区粮食需求的增加，氮肥的使用量增加，种植密度增加，这就要求设计和评估土壤酸化最小的可持续种植系统。本研究的目的是量化酸化的Oxic Kandiustalf与不同类型的氮肥在两种种植制度下免耕及其对作物性能的影响。连作玉米土壤化学性质研究和长爪豇豆（Vigna unguiculata（L.）Walp）轮作，分别以尿素（UA）、硫酸铵（AS）和硝酸铵钙（CAN）为氮源，在西非的尼日利亚进行了5年的试验。土壤化学性质与粮食产量和诊断植物养分浓度有关。对于三种氮源，玉米-豇豆轮作中土壤pH下降率为连续玉米的57±7.5%，连续玉米施氮量为施氮量的两倍。在连续种植玉米的土壤酸化率在五年中是大于AS比UA或CAN，并没有不同的UA和CAN在两种种植制度。随着AS，土壤pH值从5.8下降到4.5，在连续五年的玉米种植。交换性酸度随着施氮量的增加而增加，但没有达到限制玉米或豇豆生长的水平。返回到土壤表面的残留物可以通过提供有机配体的来源而降低可溶性和可交换性Al水平。土壤溶液锰浓度增加，氮肥的水平可能不利于作物生长。锰中毒的症状，观察豇豆叶AS适用于前玉米作物，但不是玉米植株。土壤酸化导致交换性Ca和有效CEC显著降低。在6年的种植期内，施氮肥的主季玉米产量，AS低于UA或CAN，但UA和CAN之间没有差异。与其他N源相比，AS的玉米籽粒产量较低，这归因于AS的pH值较低，且可提取的Mn浓度较高。当高岭土化的淋溶土用于连续种植玉米时，即使在免耕和作物残茬作为覆盖物返回的情况下，几年后土壤也可能酸化至pH值5.0或更低。对于这些缓冲性差的高岭土土壤，与连续种植玉米相比，免耕谷物-豆类轮作与司法使用尿素或CAN作为谷物作物的N源是更合适的系统。应避免使用AS作为N源。H Marschner Section editor
Increased use of N fertilizer and more intensive cropping due to the rising food demand in the tropics requires design and evaluation of sustainable cropping systems with minimum soil acidification. The objectives of this study were to quantify acidification of an Oxic Kandiustalf with different types of N fertilizer in two cropping systems under no-tillage and its effect on crop performance. Chemical soil properties in continuous maize (Zea maysL.) and maize-cowpea (Vigna unguiculata(L.) Walp) rotation were determined with three N sources (urea (UA), ammonium sulfate (AS) and calcium ammonium nitrate (CAN)) in Nigeria, West Africa, during five years. Chemical soil properties were related to grain yield and diagnostic plant nutrient concentrations. For the three N sources, the rate of decline in soil pH in maize-cowpea rotation was 57±7.5% of that in continuous maize, where double the amount of N fertilizer was applied. The rate of soil acidification during the five years was greater for AS than for UA or CAN in continuous maize, and not different for UA and CAN in both cropping systems. With AS, soil pH decreased from 5.8 to 4.5 during five years of continuous maize cropping. Exchangeable acidity increased with N fertilization, but did not reach levels limiting maize or cowpea growth. Return of residues to the soil surface may have reduced soluble and exchangeable Al levels by providing a source of organic ligands. Soil solution Mn concentrations increased with N fertilization to levels likely detrimental for crop growth. Symptoms of Mn toxicity were observed on cowpea leaves where AS was applied to the preceding maize crop, but not on maize plants. Soil acidification caused significant reductions in exchangeable Ca and effective CEC. Main season maize yield with N fertilization was lower with AS than with UA or CAN, but not different between UA and CAN during the six years of cropping. The lower maize grain yield with AS than with the other N sources was attributed to lower pH and a greater extractable Mn concentration with AS. When kaolinitic Alfisols are used for continuous maize cropping, even under no-tillage with crop residues returned as mulch, the soil may become acidifed to pH values of 5.0 and below after a few years. The no-till cereal-legume rotation with judicial use of urea or CAN as N sources for the cereal crop is a more suitable system for these poorly buffered, kaolinitic soils than continuous maize cropping. The use of AS as N source should be avoided. H Marschner Section editor