Abstract
The chemical forms of K, Mn, Fe, Cu and Zn in soil of a vegetable cropping field of clay loam brown lowland soil which have received the two level of mono-application of cattle or pig feces compost for 29 planting times during 15 years was examined by a sequential extraction procedure. Reference field cropping management was mono application of chemical fertilizer without any organic matter. Total contents of these elements were analyzed by hydrofluoric acid digestion method. The dilute hydrochloric acid (0.1M) extraction was also carried out to assess what chemical forms of the sequential extraction were corresponding to the dilute acid extractable amount. Total content of K and Fe of the compost plot was not significantly different from the chemical fertilizer plot, but, that of Mn tended to be higher in the compost plot. Total content of Cu of the compost plot except for the plot of higher level of pig feces compost was almost same to the chemical fertilizer plot. Total content of Zn of the higher level of cattle feces compost plot and the both plot of lower and higher level application of pig feces compost was significantly higher than the chemical fertilizer plot. The most of K was in the form of crystalline for all treatment plot, and in comparison with the chemical fertilizer plot, the relative proportions of chemical form of exchangeable, inorganic matter- and organic matter-bound were larger in the compost plot. Manganese was found to be relatively higher proportion in organic matter-bound form, comparing to Fe, and the proportion of inorganic matter-bound form in the compost plot was higher than that of the chemical fertilizer plot. More than 99.7% of Fe was in the form of oxides bound and crystalline form, and compost application resulted in a larger proportion of organic matter-bound form. Cu was found to be predominantly in oxides bound and crystalline form, and the proportion of organic matter-bound form of the compost plot was certainly larger than the chemical fertilizer plot. Zn was dominated in crystalline form and the proportions of inorganic matter- and organic matter-bound form in the compost plot was significantly larger than those of the chemical fertilizer plot. The proportion of 0.1M-HCl extractable K in the compost plot was much higher than that of the chemical fertilizer plot, and the dilute acid extracted the amount comparable to the sum of exchangeable and inorganic matter-bound form, and did not extract organic matter-bound form. The proportion of dilute acid extractable Mn in compost plot was tended to be higher than that of the chemical fertilizer plot, but the extractable proportion was comparable to only exchangeable and inorganic matter-bound form. Only very small proportion of Fe was extracted by the dilute acid, and the proportion was larger than the sum of exchangeable, inorganic matter- and organic matter-bound form, indicating the dilute acid dissolve a portion of oxides bound form. Copper in soil of the chemical fertilizer plot was extracted at the proportion comparable to the sum of exchangeable, inorganic matter- and organic matter-bound form. But, Cu in soil of highly compost applied plot which had relatively higher proportion of organic matter-bound Cu, the dilute acid could not extract most of the organic matter-bound form. Zinc in chemical fertilizer plot soil was extracted only small portion by the dilute acid. But, Zn in soil of increased Zn concentration by compost application was extracted at most 37.7% for higher application of pig feces compost. The dilute acid extracted Zn at a rate of little over proportion than the sum of exchangeable, inorganic matter- and organic matter-bound form, which dose contrast with Cu extractability.
