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Cobalt in the form of vitamin B12 is required by 亚博体育官网无法取款animals and humans.In plants it does not appear to be required by non-legumes.It is essential for nitrogen fixation by Rhizobium and thus is indirectly required by legumes.

In practical agriculture its importance lies in the ability of different soils to supply sufficient of the element for efficient nitrogen fixation by clovers on the one hand and for ruminant nutrition on the other.在爱尔兰,元素含量低的土壤主要由酸性火成岩形成,例如花岗岩和流纹岩,from sedimentary rocks such as sandstones and conglomerates and from metamorphic rocks as typified by quartzites,片岩和片麻岩。Peat soils are also inherently low in cobalt.石灰岩土壤中的钴含量,根据母岩的纯度而变化很大。页岩土的含量从低到很高,取决于页岩是砂质(砂质)还是泥质(粘质)。Cobalt levels in Irish soils formed from a variety of parent materials are shown in Table 1 (Fleming,1978).

图1.低钴土壤

表1:不同母材形成的土壤的cobolt(mg/kg)含量
Parent material No.of soils Range 平均值
基本火成岩 7 63-170 十二点八
云母片岩 5 10.4-14.2 十二点六
页岩 五十六 1.6~18.4 八点二
石灰石 278 1.8 - 17.5 6.0
砂岩 七十五 0.5 -13.8 三点六
Gneiss 0.2 -4.4 二点四
花岗岩 七十九 0.3 - 17.5 二点一
Blown Sand 十九 0.2—1 零点四
The soil samples were received from agricultural advisers.Sampling depth was 10 cm.用浓盐酸从土壤中提取钴。Thus the figures are essentially total values.

Distribution of low cobalt salts and the effect of manganese on cobalt availibitly

沃尔什绘制了低钴土壤(低于5 mg/kg)图。等。1952(图)。1)。This serves to pinpoint areas where the risk of cobalt deficiency in stock is high.Such maps however do not reveal the true extent of risk areas.有许多土壤的总钴含量很高,但牧场的可用性很差。这在石灰岩和页岩土中尤为明显,主要原因是土壤锰含量高(fleming,1983).这里我们有一个很好的例子,说明了土壤中一种微量元素与另一种微量元素的相互作用。Research in Australia highlighted the significance of various forms of manganese dioxide in binding soil cobalt (McKenzie,1967;Adams.,1969)。

二氧化锰矿物通常以极细的形式存在于土壤中,导致其吸收能力与其质量含量完全不相称。这些化合物的晶体结构使它们很容易将钴离子容纳到非常稳定的结构中。简而言之,the availability of cobalt in high Mn soils is severely restricted even in soils with high total Co contents.

灰化作用对表层土壤中钴的含量影响很大。在灰化作用过程中,钴从表层浸出,沉积在富铁B层。许多山地土壤,already inherently low in cobalt,被灰化作用进一步耗尽。这些土壤经常被覆盖泥炭覆盖,如果不采取补救措施,山区绵羊的钴缺乏可能是一个问题。The effect of podzolization on soil cobalt is shown in Table 2 (Finch and Ryan,1966).

Soil analysis for cobalt

除非同时进行锰的平行分析,否则对CO的土壤分析几乎没有价值。只有当两种分析都可用时,才能预测可能的牧草含量或应用钴可能产生的效益。Various extractants have been employed in the estimation of plant-available cobalt.Some such as dilute acetic acid are very useful on acid soils but have in our experience proved of little value on limed soils

表2:灰化对土壤含钴量的影响
土壤系列 Parent material Horizon Co (mg/kg)
Knockaceol 老红砂岩 A1 1
有限公司。Limerick A2 1
B2 (ir)
B/C

Cobalt and Irish Soils

钴(co)在营养中的重要性是因为它对动物而不是植物是必需的。亚博体育官网无法取款It is especially important for ruminants as,没有CO,rumen bacteria are unable to synthesise the cobalt-containing vitamin B12.植物营养,cobalt does not appear to be necessary for non-legumes but,because it is essential for nitrogen fixation byRhizobium,它是豆类植物间接需要的。动物对钴的需求随动物类型和年龄而变化。亚博体育官网无法取款Co requirement of common farm ruminants are in decreasing order as follows: weaned lambs > adult sheep > young cattle > mature cattle.Cobalt deficiency is therefore classically associated with sheep but in very deficient soils cattle can be affected.除了补充钴后的生长改善外,生育能力的提高也有记录(Alderman,1963).

土壤钴含量

Soils with inherently low concentration of Co are formed mainly from acid igneous rocks,即花岗岩和流纹岩,from sedimentary rocks such as sandstones and conglomerates and from metamorphic rocks as typified by quartzites,片岩和片麻岩。由石灰石形成的土壤的一氧化碳浓度随母岩的纯度而变化。来自页岩的土壤中CO的浓度取决于页岩是砂质(砂质)还是粘土质(泥质)。Peats always have low concentrations of cobalt.

Podzolization

Podzolization strongly influences the content of cobalt in top soils.在灰化作用过程中,钴从表层浸出,沉积在富铁B层。许多山地土壤,already inherently low in cobalt,被灰化作用进一步耗尽。这些土壤经常被覆盖泥炭覆盖,如果不采取补救措施,山区绵羊的钴缺乏可能是一个问题。

土壤排水

土壤中微量元素的迁移受多种因素的影响,在温带地区,排水起着重要作用。这在钴的情况下尤其如此,通常在排水不良土壤的潜育层中发现的可提取CO量比在相同母材上排水良好土壤的相应深度中的可提取CO量大。沃尔什等。(1956)发现在排水不良的土壤中,10 percent of the total Co was extractable with dilute acetic acid,而在排水良好的土壤中,同一母质只去除了总CO的2.6%。Such increases in extractable Co are reflected in increased plant uptake from poorly drained soils.Mitchell.(1957年)对比了来自排水良好和排水不良的苏格兰土壤的混合和纯草群,发现在排水不良的土壤上生长的牧草中的一氧化碳是其5到8倍。从排水不良的土壤中增加钴的可利用性的原因在于与钴有关的铁和锰氧化物的分解或风化。在排水条件差的还原环境中很容易发生故障。亚博体育平台是黑彩

影响牧草钴状况的因素

A typical example of the effect of one element on another element is the influence of manganese (or more correctly the oxides of manganese) on the availability of soil cobalt.锰的氧化物带有很高的负电荷,except under extremely acid conditions,并且有很大的表面积-与它们的重量成比例,-和,因为钴离子的大小和电荷,have very high sorption capacities for the latter.微量营养元素中,CO最容易被氧化锰的表面吸引,最终被困在其晶格结构中,因此无法被植物利用。在排水条件差的情况下,土壤孔隙被水填满,而不是产生空气的还原条件。因此,锰氧化物的稳定性减弱,由此产生的矿物分解释放捕获的CO,然后可供植物吸收。石灰化及其产生的ph值增加有相反的效果。

不同的草原物种含有不同数量的钴。一般认为三叶草的含量超过草。然而,当有充足的一氧化碳供应时,这是正确的,当一氧化碳供应受到限制时,反过来可能获得。Among the grasses themselves,黑麦草(黑麦草)黑麦草通常比其他物种(如鸭茅)含有更多的一氧化碳。(鸭茅属和蒂莫西(Phleum)(赖斯和米切尔,1964年),但是差异通常是边际的,特别是当CO的一般水平较低时(fleming,1963).爱尔兰牧场的含量通常在0.02到0.11 mg/kg之间。对于羔羊来说,牧草中CO的理想水平为0.1 mg/kg。由于牧草的任何土壤污染都会产生显著的影响,因此很难获得牧草中真正的CO含量数据。除非牧草中的一氧化碳含量附有土壤污染程度的说明,否则它们是毫无意义的。

Season

有关牧草中钴的季节变化的证据似乎是矛盾的。Reith和Mitchell(1964)发现黑麦草的一氧化碳含量在秋季有所增加。在频繁切割和施氮条件下,fleming(1970a)记录到了下降。the Co content of perennial ryegrass ranged from 0.06 mg/kg in spring to 0.03 mg/kg in autumn.蜂群管理的变化可以很好地解释这些不同的发现。In practice the onset of cobalt deficiency in sheep often occurs in late summer or early autumn especially when 亚博体育官网无法取款animals are grazing regrowth material.

成熟期

弗莱明(1970A)发现多年生黑麦草的一氧化碳含量略有下降,但没有铜那么明显。Cobalt tends to concentrate in the seed heads of grasses and this may account for the relatively small change in content with increasing plant maturity.

浸灰

Liming decreases Co levels in pastures (Wright and Lawton,1954;赖斯和米切尔,1964).由于石灰化后植物成分发生变化,混合物种的牧场通常会显示出不同水平的CO。因此,必须注意确保样品能代表切屑。Lower Co contents were found in both ryegrass (especially) and clover following liming but the effect was not as pronounced with mixed species samples (Mitchell,1957)。

Management of cobalt deficient pastures

在土壤中施用钴盐可以提高牧草的共生状况。但是,这种方法的效率在不同的土壤中差异很大。在质地较轻的土壤和泥炭上,牧草对一氧化碳吸收的响应可能很大,但在质地较重的土壤上,通常情况相反。Whereas soil pH,粘土,有机质含量对确定从CO到牧草的有效性起着一定作用,如前所述,the oxides of manganese are more often the prime regulator of the movement of Co from soil to plant.澳大利亚研究(Taylor和McKenzie,1966;麦肯齐1967,1970;Adams.,1969)毫无疑问,锰氧化物是土壤钴的主要沉淀池。弗莱明(1983)报告了爱尔兰表层土壤和土壤剖面中钴和锰的关系,and on the effect of the application of cobalt sulphate to Irish soils of differing manganese status (Table 5).

通常以2 kg/ha的速度施用硫酸钴,如果整个放牧区都得到了处理,那么必须考虑到财政影响。In practice,在第一年,可能就足够处理三分之一的区域了,another third in Year 2 and the final third in Year 3.在此期间结束时,可能需要重复该周期。这里应该以一氧化碳的牧草分析为指导。如果土壤锰含量超过约400 mg/kg,the application of cobalt sulphate at 4 kg/ha will probably be effective for one season at most.在这种情况下,直接通过口服给药补充动物,亚博体育官网无法取款cobalt bullet administration,向供水中添加钴,use of cobaltized mineral licks or injection with Vitamin B12 must be considered.

表3:不同锰含量土壤上草的施用钴螺栓和钴螺栓含量
土壤参数 Soil 1 土壤2 土壤3 土壤4
酸碱度 6.5 5.5 6.7 六点四
粘土(%) 二十四 二十二 十一
org。C (%) 三点一 7.7 1.9
Co (mg/kg) 7.0 6.5 2.5
Mn (mg/kg) 一千一百六十七 八百三十七 二百一十三 七十
科索.7h2o Pasture Data
Applied (kg/ha) Co (mg/kg)
零点零二 零点零三 零点零三 0.05
一点三二 零点零四 零点零六 零点一一 零点一七

除非同时进行锰的平行分析,否则对CO的土壤分析几乎没有价值。只有当两种分析都可用时,才能预测可能的牧草含量或应用钴可能产生的效益。

亚博体育官网无法取款Animals at pasture may receive useful amounts of cobalt通过土壤摄取因此,钴缺乏的发生率可能在高储备率下而不是低储备率下。Differences in stocking rate may well be a factor in explaining yearly variations in the incidence or severity of cobalt deficiency.