Potential importance of the subsoil for the P and Mg nutrition of wheat
Potential importance of the subsoil for the P and Mg nutrition of wheat
复制标题
底土对小麦磷和镁营养的潜在重要性
作者：
H. Kuhlmann;G. Baumgärtel
本文介绍了一种定量测定春小麦从30 cm以上底土中吸收磷、镁潜力的方法。小麦种植在人工表土（不含植物有效磷或镁的沙子）上，这种表土叠加在氮素缺乏的黄土底土上。德国。施入不同量的磷镁肥后，耕层土壤磷镁供应量发生变化。从底土中吸收的P和Mg被计算为总植物吸收（通过植物分析测定）和从表土中去除的P和Mg的量（通过土壤分析测定）之间的差异。从下层土壤吸收的磷增加到总吸收磷的37%至85%，减少在表土中的磷供应。通过扩散的潜在供应的计算表明，与CAL提取的P2 O 5在底土中的含量为9毫克100克-1，供应从底土是唯一可能的，如果考虑到根毛的影响。该方法还表明，春小麦对镁的总需求量可由典型黄土底土的镁供应来满足。从底土中吸收的镁减少到总吸收的33%，增加镁供应的表土。
A method is described which allowed the quantification of the potential uptake of P and Mg from the subsoil (>30cm) by spring wheat. Wheat was grown on an artificial topsoil (sand with no plant available P or Mg) which was superimposed on loess subsoils in N. Germany. The supply of P and Mg in the topsoil was varied by application of different quantities of P and Mg fertilizer. Uptake of P and Mg from the subsoil was calculated as the difference between total plant uptake (determined by plant analysis) and the quantities of P and Mg removed from the topsoil (determined by soil analysis). P uptake from the subsoil increased from 37% to 85% of total P uptake, with decreasing P supply in the topsoil. Calculations of potential supply by diffusion showed that, with a CAL-extractable P2O5 content in the subsoil of 9 mg 100g-1, supply from the subsoil was only possible if the influence of root hairs was considered. The method also showed that the total demand for Mg by spring wheat could be satisfield from the supply of Mg from the subsoil of typical loess soils. Mg uptake from the subsoil decreased to 33% of total uptake with increasing Mg supply in the topsoil.