Abstract In a 5-year experiment on a yellow-brown loam of medium Mg status, finely ground dolomite, serpentine, and talc-magnesite, from Nelson, were compared as Mg sources when topdressed once on pasture at rates providing 110, 220, and 440 kg total Mg/ha. Calcined magnesite (MgO) at the highest rate of Mg and limestone (L) at 4200 kg/ha were also included. Dry matter yields were determined at grazing height, and the experiment was conducted under the technique of mowing with return of clippings. In a second experiment managed under a total removal system, with replacements of P and S (in superphosphate) and K (in KCI) only, dolomite and MgO were compared at rates providing 31.5, 63, and 126 kg Mg/ha, repeated after 21 months, and measured over 4 years. Samples from all yield cuts were analysed for Mg, Ca, K, Na, P, and total N. In both experiments responses in total yields were very small. Overall, MgO increased herbage Mg concentrations more than did dolomite. It had its maximum effect on herbage Mg in...
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机译：摘要在一项为期5年的中等镁含量黄褐色壤土实验中，比较了来自尼尔森的细磨的白云石，蛇纹石和滑石菱镁矿以110、220和120总Mg / ha 440公斤。还包括以最高的镁含量煅烧的菱镁矿（MgO）和4200 kg / ha的石灰石（L）。在放牧高度确定干物质的产量，并在割草并剪草的技术下进行实验。在总去除系统下进行的第二项实验中，仅置换了P和S（过磷酸盐）和K（在KCI中），比较了白云石和MgO的速率，分别提供了31.5、63和126 kg Mg / ha， 21个月，历时4年。分析所有减产样品中的Mg，Ca，K，Na，P和总氮。在两个实验中，总产的响应非常小。总体而言，MgO比白云石增加了牧草中Mg的浓度。它对牧草中的镁有最大的作用。
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