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A Study of Factors Affecting the Availability of Potassium in Red Bay Fine Sandy Loam, a Humic Paleudult

出版	University of Florida, 1968
URL	http://books.google.com.hk/books?id=QZaoIwAACAAJ&hl=&source=gbs_api

註釋Crops were grown in the greenhouse on samples of Red Bay fine sandy loam which had received various levels of potassium and a uniform lime rate followed by cropping and leaching for several years. Exchangeable potassium was related to the residual treatments but differences were samll and even the highest level was lower than recommended for maximum plant growth. Most of the residual potassium was expected to be in the difficultly or moderately fixed forms. There was also a treatment with high residual potassium levels, although potassium contents and uptake increased significantly with rates of residual potassium. Lime increased yields of cats, cabbage, and tomatoes. The yield increases were related to calcium, magnesium, iron, aluminum, and molybdenum contents of the plants and inversely related to the levels of zinc, copper, and manganese. Molydbenum and calcium were extremely low in the unlimed cabbage and tomatoes. Cabbage had a cupped leaf appearance. Two other virgin sources of Red Bay fine sandy loam having NH4 OAc-extractable potassium adequate for most crops were planted to cherokee wax beans at different potassium levels. These two sources did not respond to potassium. The source with pH 4.3 and 220 ppm NH4 OAc-extractable calcium gave a yield response to lime but not the source with pH 5.3 and 260 ppm calcium. These experiments showed that exchangeable potassium in itself may not be a measure of the potassium supplying power of a particular soil. Source A, a cultivated soil, deficient...................