水保所知识产出(1956---)知识库

土壤中微量元素的有效性研究已成为农业和环境科学领域关注的焦点。施肥是微量
元素进入土壤的一个重要途径，明确和揭示施肥与土壤微量元素有效性之间的关系可为
农业生产实践提供科学参考依据。本文研究了长期施肥条件下土壤微量元素含量、形态、
分布特征及其变化情况，分析了影响土壤微量元素有效性的因素，探讨了土壤微量元素
有效性变化产生的机制，所取得的主要结论如下：
（1）长期种植作物和施肥均降低了土壤 pH 值和碳酸钙含量，增加了土壤有机质含
量。2015 年苜蓿连作耕层土壤 pH 值降低最多，较裸地相比降低了 0.44 个 pH 单位。粮
豆轮作系统中耕层土壤碳酸钙含量较 2002 年相比降低了 48%。苜蓿连作耕层土壤有机
质积累显著，与裸地相比增加了 134.9%。施肥增加了土壤有效磷含量，粮豆轮作系统
中氮磷有机肥配施 0-15cm 和 15-30cm 土壤有效磷含量和不施肥相比分别提高了 34.3 倍
和 11.69 倍。连续施肥条件下土壤胡敏酸与富里酸比值均大于 1。施用有机肥增加了土
壤还原性物质总量，其中粮豆轮作系统中氮磷有机肥配施耕层土壤增加较多，较不施肥
相比增加了 107.14%。
（2）作物种植和施肥均增加了土壤有效铜、铁含量。施肥可提高土壤有效锰含量。
苜蓿、小麦连作以及施用有机肥可显著提高土壤有效锌含量。与 2002 年相比，2015 年
耕层土壤有效铜、锰含量增加量最大的分别是小麦连作系统中单施有机肥 0.69 mg kg -1 、
粮豆轮作系统中氮磷有机肥配施 58.91%。苜蓿连作耕层土壤有效锌、铁含量较 2002 年
相比分别增加了 1.95 倍和 2.05 倍。
（3）土壤中微量元素的主要存在形态是矿物态，锰的氧化物结合态所占比例也较
大。2015 年和 2002 年相比，铜、锌、铁的形态分布变化不大，而锰的形态分布变化较
大，表现为矿物态和交换态锰的占比有所提高，碳酸盐结合态、氧化物结合态、有机结
合态锰的占比有所降低。
（4）长期种植作物和施肥对土壤锌、铜的活化作用很小，但交换态锰和铁的含量
都有所增加。2015 年苜蓿连作耕层土壤交换态锰增加最显著，较裸地相比增加了 8.03
倍。粮豆轮作系统中氮磷有机肥配施耕层土壤交换态铁增加较多，较不施肥相比增加了84.36%。各形态铜、锌含量随作物种植和施肥年限的增加而增加，但矿物态铜仅在施用
化肥时有所增加。小麦连作系统中单施有机肥耕层土壤碳酸盐结合态、氧化物结合态、
有机结合态铜增加较多，较 2002 年相比分别增加了 2.01 mg kg -1 、1.7 mg kg -1 、3.54 mg
kg -1 。苜蓿连作耕层土壤氧化物结合态锌增加较多，较 2002 年相比增加了 94.26%。作
物种植仅降低了碳酸盐结合态锰含量。苜蓿连作 0-15cm 和 15-30cm 土壤碳酸盐结合态
锰含量降低较多，较 2002 年相比分别降低了 59.95 mg kg -1 和 35.65 mg kg -1 。小麦连作
系统中 15-30cm 土壤有机结合态锰增加显著，较裸地相比增加了 2.63 倍。小麦连作系
统土壤各形态铁都有所增加。不施肥情况下，小麦连作系统中 0-15cm 和 15-30cm 土壤
碳酸盐结合态铁较 2002 年相比分别增加了 114.52%和 183.69%、有机结合态铁分别增加
了 1.08 倍和 3.3 倍。施肥大都降低了土壤各形态锰和铁的含量。粮豆轮作系统中单施磷
肥耕层土壤有机结合态锰增加显著，较不施肥相比增加了 8.2 倍。
（5）长期作物种植和施肥条件下土壤 pH 值与有效铜、锰、锌、铁之间显著负相关，
有效磷、胡敏酸、富里酸与之相反；土壤有机质、还原性物质总量与有效铜显著负相关，
与有效锰、锌、铁则相反；土壤水分与有效铜、锌呈正相关，而与有效锰、铁呈负相关。
与 DTPA-Cu、Mn、Zn、Fe 含量之间直接通径系数最高的分别为土壤水分 0.781、胡敏
酸 0.652、有机质 0.895、有机质 0.83。与 DTPA-Cu、Mn、Fe 含量之间直接负作用较高
的分别为还原性物质总量-0.509、富里酸-0.595、碳酸钙-0.501。
（6）长期作物种植和施肥条件下交换态铜、锰、铁与有效量间呈正相关，且对有
效量的直接通径系数也最高，分别为 0.829、0.445 和 0.122，故交换态是土壤有效量的
直接和主要来源。碳酸盐结合态铜与有效铜呈正相关，且与交换态铜间接通径系数最大
0.479，表明它可以通过向交换态铜的转化而增加土壤中有效铜的含量。矿物态铜与有效
铜直接通径系数较高 0.571，可视矿物态铜为土壤有效铜来源的储备库。碳酸盐结合态、
有机结合态与有效锰、锌、铁的相关系数、直接通径系数均为正值，表明这两种形态是
土壤有效量的来源。氧化物结合态锌与有效锌显著正相关，也是土壤锌的有效来源。
（7）长期施用微肥增加了土壤有机质、还原性物质总量。2015 年施用铜肥表层土
壤有机质和还原性物质总量增加最多，较对照相比分别增加了 25%和 24.74%。施用微
肥后土壤碳酸钙、有效磷、胡敏酸、富里酸含量大都有所降低。施用铜肥 0-15cm、15-30cm
土壤碳酸钙含量降低最显著，较对照相比分别降低了 32.35%、41.25%。施用锌肥表层
土壤有效磷含量降低最多，降低了 55%。施用微肥后胡敏酸和富里酸比值均小于 1。施
用锰肥表层土壤胡敏酸含量降低最多，降幅为 77.87%。施用锌肥亚表层土壤富里酸含
量增幅最大，增加了 2.27 倍。
长期施用微肥后，土壤铜、锌的全量及有效量增加显著，表层积聚现象明显。2015
年表层土壤全铜、全锌含量较对照相比分别增加了 131.82%和 108.71%；有效铜、锌含
量较对照相比分别增加了 6.03 倍和 6.97 倍。全锰、有效锰含量并没有明显增加。2015
年和 2001 年相比，全锰含量增加幅度小于 12%；2015 年 30-45cm 土层有效锰含量和对照相比增幅最大 26.54%，其它土层增幅均小于 6%。施用微肥后土壤交换态铜、锌占全
量的比例增加显著，不同形态锰占全量的比例变化不明显。土壤各形态铜、锰、锌含量
随施肥年限增加而增加，尤其是表层土壤，矿物态锰则相反。表层土壤氧化物结合态、
碳酸盐结合态铜增幅较大，较对照相比分别增加了 23.46 倍和 16.35 倍。各土壤性质与
有效铜、锰、锌间相关性不显著，但对微量元素形态有所影响：胡敏酸与除交换态铜之
外的其它形态铜以及有机结合态锰都显著负相关；富里酸与氧化物结合态锌显著正相
关。有效铜与碳酸盐结合态、氧化物结合态、有机结合态铜显著正相关；交换态铜载荷
在第二主成分里最大，这四种形态是土壤有效铜的来源。有效锰与交换态锰显著正相关；
第一主成分里氧化物结合态、有机结合态锰的载荷较大，这三种形态与土壤有效锰关系
密切。有效锌与交换态、氧化物结合态、有机结合态锌显著正相关，对有效锌贡献较大。
（8）施用微肥与土壤微量元素有效量之间存在以下相互作用关系：锌抑制铜，但
铜不抑制锌；锰利于铜，而铜抑制锰；锌抑制锰，但锰不抑制锌；锰肥有利于土壤中有
效铁含量的增加。
关键词：微量元素；有效性；施肥；轮作；土壤性质；黄土高原

The availability of trace elements in soils has become a focus in the fields of agricultural
and environmental sciences. Fertilization is an important way for trace elements to enter the
soils. Clarifying and revealing the relationship between fertilization and the availability of
trace elements in soils can provide scientific reference for agricultural practice. In this paper,
the contents, fractions, distribution characteristics and changes of trace elements in soils under
long-term fertilization were studied, the factors affecting the availability of trace elements in
soils were analyzed, and the mechanism of the changes was explored. The main conclusions
were as follows:
（1）The soil pH value and CaCO 3 content were decreased after long-term crop planting
and fertilization, while the content of soil organic matter was increased. The largest decrease
of soil pH value was observed at 0-15 cm depth in the continuous alfalfa cropping system,
which was decreased by 0.44 pH units compared with the fallow soil in 2015. In the
crop-legume rotation cropping system, soil CaCO 3 content was reduced by 48% compared
with that in 2002 at 0-15 cm depth. Soil organic matter accumulated significantly in the
alfalfa continuous cropping system, and it was increased by 134.9% at 0-15 cm depth
compared with the fallow soil. Fertilization increased the available P content in soils,
compared with the no-fertilizer control, the application of N and P fertilizers and manure
resulted in 34.3 times and 11.69 times increase in the crop-legume rotation cropping system at
0-15 cm and 15-30 cm depths, respectively. The ratio of humic acid and fulvic acid in soils
was more than 1 under continuous fertilization. The application of manure increased soil total
reducing substance, the crop-legume rotation cropping system had a 107.14% increase under
the application of N and P fertilizers and manure at 0-15 cm depth compared with the
no-fertilizer control.
（2）Soil available Cu and Fe contents were increased by crop planting and fertilization
for many years. Fertilization could improve the available Mn content. The alfalfa, wheat  continuous cropping system and the application of manure could significantly improve the
available Zn content. The largest increases of the available Cu, Mn contents at 0-15 cm depth
in soils were respectively in the wheat continuous cropping system under the application of
manure (0.69 mg kg -1 ), the crop-legume rotation cropping system under the application of N
and P fertilizers and manure (58.91%) in 2015 compared with that in 2002. The alfalfa
continuous cropping system made soil available Zn and Fe contents increase by 1.95 times
and 2.05 times than that in 2002 at 0-15 cm depth.
（3）The main fraction of trace elements in soils was mineral-bound, oxide-bound Mn
also had the larger proportion. Compared to 2015 and 2002, the changes of the proportions of
Cu, Zn, Fe fracions were not obvious, while the change of Mn fractions was larger, the
proportions of mineral-bound, exchangeable Mn increased, and the proportions of carbonate-,
oxide-, organic matter-bound Mn decreased.
（4）The activation of Zn and Cu in soils was very small through long-term crop planting
and fertilization, but the contents of exchangeable Mn and Fe were increased. Exchangeable
Mn was increased significantly in the alfalfa continuous cropping system at 0-15 cm depth in
2015, which was 8.03 times larger than that in the fallow soil. The application of N and P
fertilizers and manure increased considerably exchangeable Fe more than the no-fertilizer
control in the crop-legume rotation cropping system at 0-15 cm depth, and the increase was
84.36%. The contents of Cu and Zn fractions were increased with the increase of crop
planting and fertilization years, but the mineral-bound Cu was increased only when the
chemical fertilizer was applied. The carbonate-, oxide-, organic matter-bound Cu were
increased considerably in the wheat continuous cropping system under the application of
manure at 0-15 cm depth, which were increased by 2.01 mg kg -1 , 1.7 mg kg -1 , 3.54 mg kg -1
compared with that in 2002, respectively. The alfalfa continuous cropping system increased
soil oxide-bound Zn at 0-15 cm depth, the increase was 94.26% compared with that in 2002.
Crop planting only reduced carbonate-bound Mn content. Carbonate-bound Mn content
reduced more than that in 2002 in the alfalfa cropping system at 0-15 cm and 15-30 cm depths,
which were decreased by 59.95 mg kg-1 and 35.65 mg kg-1 respectively. The wheat
continuous cropping system increased organic matter-bound Mn significantly at 15-30 cm
depth; the increase was 2.63 times compared with the fallow soil. The different fractions of Fe
in soils were increased in the wheat continuous cropping system. Carbonate-bound Fe were
increased by 114.52% and 183.69%, organic matter-bound Fe were increased by 1.08 times
and 3.3 times respectively at 0-15 cm and 15-30 cm depths compared with that in 2002 under
no fertilizer. Fertilization almost decreased the contents of different Mn and Fe fractions. The
crop-legume rotation cropping system significantly increased organic matter-bound Mn, and  the increase was 8.2 times compared with the no-fertilizer control.
（5）Soil pH value had significant negative correlation with the available Cu, Mn, Zn, Fe
under long-term crop planting and fertilization, the available P, humic acid, fulvic acid were
opposite. Soil organic matter, total reducing substance significantly negatively related with the
available Cu, and the available Mn, Zn and Fe were on the contrary. Soil moisture positively
related with the available Cu and Zn, but it had negative correlation with the available Mn and
Fe. The highest direct path coefficients with DTPA-Cu, Mn, Zn and Fe in soils were soil
moisture (0.781), humic acid (0.652), organic matter (0.895) and organic matter (0.83),
respectively. The higher negative direct path coefficients with DTPA-Cu, Mn and Fe were
total reducing substance (-0.509), fulvic acid (-0.595), CaCO 3  (-0.501).
（6）Exchangeable Cu, Mn and Fe positively correlated with the available Cu, Mn and
Fe, and the direct path coefficients were the highest, which were 0.829, 0.445 and 0.122,
respectively, therefore exchangeable fraction was the direct and major source of the available
Cu, Mn and Fe in soils. Carbonate-bound Cu had the positive correlation with the available
Cu, and the indirect path coefficient between carbonate-bound Cu and exchangeable Cu was
largest (0.479), which indicated that it could increase the content of the available Cu in soils
by the transformation to exchangeable Cu. The direct path coefficient between mineral-bound
Cu and exchangeable Cu was 0.571; it showed that mineral-bound Cu could be regarded as
the repository of the available Cu in soils. The  correlation coefficients, direct path coefficients
between carbonate-bound, organic matter-bound and the available Mn, Zn and Fe were
positive, which indicated that these two fractions were the source of the available Mn, Zn and
Fe in soils. Oxide-bound Zn was significantly positively correlated with the available Zn, and
it was also an available source of zinc in soils.
（7）The long-term application of microelement fertilizer could increase the soil organic
matter, total reducing substance, the increases were the largest under the application of Cu
fertilizer in surface soils in 2015, which were 25% and 24.74% respectively. The application
of microelement fertilizer made soil available P, CaCO 3 , humic acid and fulvic acid contents
almost decrease. The contents of CaCO 3  at 0-15 cm and 15-30 cm depths were decreased
significantly, and the decreases were 32.35% and 41.25% respectively compared with the
control. The application of Zn fertilizer resulted in the available P the largest decrease in the
suface soil, the decrease was 55%. The ratio of humic acid and fulvic acid was less than 1
after the application of microelement fertilizer. Humic acid content was reduced most under
the application of Mn fertilizer in the surface soil, and the decline was 77.87%. The biggest
increase of fulvic acid content was found at 15-30 cm depth under the application of Zn
fertilizer, the increase was 2.27 times compared with the control.  The contents of total Cu, Zn and the available Cu, Zn in soils were increased
significantly after long-term application of microelement fertilizer; the phenomenon of
surface accumulation was obvious. The contents of total Cu, Zn were increased by 131.82%
and 108.71%, the available Cu, Zn were increased by 6.03 times and 6.97 times in the surface
soil compare with the control in 2015. The changes of soil total Mn, the available Mn were
not obvious. Compared to 2015 and 2001, the increase of total Mn was less than 12%.
Compared with the control, the available Mn at 30-45 cm depth was increased most, the
increase was 26.54% in 2015, and the increases of other soil depths were less than 6%. The
proportion of exchangeable Cu, Zn in the total Cu，Zn had a significant increase after the
application of microelement fertilizer, while the change of the proportion of different Mn
fractions in total Mn was not obvious. The contents of Cu, Mn, Zn fractions were increased
with the increase of fertilization age, especially in the surface soil, but the mineral-bound Mn
was opposite. The oxide-, carbonate-bound Cu had a larger increase in the surface soil, which
were 23.46 times and 16.35 times higher than that in the control soils. Soil properties had no
obvious correlation with the available Cu, Mn, Zn, while had some influences on the fractions
of trace element: humic acid was significantly negatively correlated with other Cu fractions in
addition to exchangeable Cu and organic matter-bound Mn; fulvic acid had a significant
positive correlation with oxide-bound Zn. There was a significant positive correlation
between the available Cu and carbonate-, oxide- and organic matter-bound Cu, the largest
load of the second principal component was exchangeable Cu, thus these four fractions were
the source of soil available Cu. The available Mn was significantly positively correlated with
exchangeable Mn; the loads of oxide- and the organic matter-bound Mn were larger in the
first principal component, which indicated that these three fractions were closely related to the
available Mn in soils. The available Zn had significant positive correlation with exchangeable,
oxide- and organic matter-bound Zn; it showed that these three Zn fractions had greater
contribution to the available Zn.
（8）The interactions between applying microelement fertilizer and soil available trace
elements were as follows: Zn restrained Cu, but Cu did not restrain Zn. Mn was beneficial to
Cu, while Cu restrained Mn. Zn restrained Mn, but Mn did not restrain Zn. Mn fertilizer was
conducive to the increase of the available Fe in soils.
Key words：trace element, availability, fertilization, rotation, soil property, the Loess Plateau