Potassium status and fertility evaluation of major upland soils in northeastern part of China
1999
Han, J.L. (Kyushu Univ., Fukuoka (Japan). Faculty of Agriculture) | Egashira, K.
Potassium status and fertility of major upland soils of the northeastern part of China was evaluated for soils collected at Jilin and Liaoning provinces, covering Meadow soil, Black-colored soil, Dark-brown forest soil, Sols lessives, and Saline soil which occupy more than 80% of the upland field. Total and mineral K contents ranged from 21.1 to 25.8 and from 20.6 to 25.0 g kg(-1), respectively. Mineral K occupied 92 to 99% of the total K and its main source was estimated to be K-feldspars, based on the significant and positive correlation between mineral K and sand contents. Nonexchangeable K was measured by extraction with hot 1M HNO3 for 10 min, and its content was in a range of 264 to 971 mg kg(-1), occupying 1 to 4% of total K. Content of nonexchangeable K was significantly and positively correlated with mica and clay contents. Content of exchangeable K, including water-soluble K, was ranged between 66 and 974 mg kg(-1) and occupied 0.3 to 4% of total K. It was highly significantly and positively correlated with cation-exchange capacity and organic matter content. Potassium fertility of upland soils was roughly evaluated based on the contents of nonexchangeable and exchangeable K. It was in the order of easterncentralwestern agricultural divisions for soils in Jilin province and lowest for a soil in Liaoning province, and in the order of Black-colored soilMeadow soilSols lessives, Dark-brown forest soil for soils in the eastern division of Jilin province. Potassium fertility was controlled first by the mica content which is mainly derived from eolian dust from inland China and Mongolia, and by contents of 2:1 mixed-layer minerals, through contribution to cation-exchange capacity, and of organic matter
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