Long-term effects of integrated application of organics and chemical fertilizers on transformation of copper (Cu) into various chemical pools and their availability under maize–wheat cropping system were investigated in the ongoing long-term fertilizer experiment initiated in 1972 at the research farm of Chaudhary Sarwan Kumar Himachal Pradesh Agricultural University on an acidic soil in the Western Himalayas of India. The continuous use of chemical fertilizers alone for 36 years brought about marked depletion in all forms of copper except organically bound Cu (Cu-III) compared to buffer plots. Integrated use of organics and chemical fertilizers gave higher content of Cu forms over chemically treated plots except Cu occluded by free oxides (Cu-IV). Residual Cu was the most dominant form of copper contributing about 62% of the total Cu. Organically bound Cu (Cu-III) was the most important fraction of copper contributing toward DTPA (diethylene triamine pentaacetic acid) extractable Cu. Content of DTPA-extractable Cu increased over control when chemical fertilizers were applied in conjunction with different organics, whereas DTPA-Cu content declined over control with application of chemical fertilizers alone for the last 36 years.

中文翻译：

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土壤中铜的含量及其对典型 hapludalfs 下玉米 - 小麦种植系统中铜的可用性和吸收的贡献

1972 年在美国农业部的研究农场进行的长期肥料试验研究了有机物和化肥综合施用对铜 (Cu) 转化为各种化学物质库的长期影响及其在玉米 - 小麦种植系统下的可用性。 Chaudhary Sarwan Kumar Himachal Pradesh 农业大学位于印度喜马拉雅西部的酸性土壤中。与缓冲地块相比，连续使用化肥 36 年导致所有形式的铜明显枯竭，除了有机结合的铜 (Cu-III)。除了被游离氧化物 (Cu-IV) 吸留的 Cu 外，有机物和化肥的综合使用比化学处理的地块的 Cu 含量更高。残留铜是最主要的铜形式，约占总铜的 62%。有机结合的铜 (Cu-III) 是铜中最重要的部分，有助于 DTPA（二亚乙基三胺五乙酸）可提取的铜。在过去的 36 年中，当化肥与不同有机物联合施用时，DTPA-可提取铜的含量高于对照，而单独施用化肥时 DTPA-Cu 含量低于对照。