| Compound Iron Fertilizer had a striking effect on correcting fruit tree (apple, pear and peach) iron deficiency chlorosis. In order to reveal the transformation and Fe provision mechanisms of this fertilizer in calcareous soil, to optimize its formula and to improve its availability and utilization efficiency, soil incubation and pot cultivation methods were used in this research. The iron provision mechanisms , transformation and their abilities to adjust soil factors of several iron fertilizers were investigated in these experiments as well as bio-availability. Soil incubation experiment presented the results that compound iron fertilizer could improve organic matter content in contrast to the significantly decrease of pH value and carbonate content in soil. In addition, compound iron fertilizer had a little reguiation ability for soil bicarbonate in the course of incubation. The function in regulating soil factors and the high availability of iron contained of compound iron fertilizer are the major mechanisms to promote Fe provision power in calcareous soil. This affected the transformation and dynamic balance of iron in soil, and DTPA-Fe was striking improved. The compound iron fertilizer could increase the contents of exchangeable iron (Exch-Fe), carbonate-bound iron (Carb-Fe), manganese-oxide-bound iron (MnOX-Fe) and organic binding form Fe (OM-Fe), making their distribution coefficients larger than FeSO4 treatment. This is the display of iron provision mechanisms of compound fertilizer in soil iron fractionations. The results indicated that compound iron fertilizer delayed the unavailable process of iron in soil, so the unavailable iron proportion decreased and iron availability was promoted. There were striking correlated between DTPA-Fe and MnOX-Fe. The same conclusion was obtained between Exch-Fe, Carb-Fe and MnOX-Fe. Exch-Fe, Carb-Fe, MnOX-Fe and OM-Fe are the main sources of DTPA-Fe. There were negative correlations between DTPA-Fe Carb-Fe, MnOX-Fe and pH , and positive correlation between OM-Fe and OM. From pot experiment results, something can be seen that compound iron fertilizer could improve the biological properties of Peanut, increase the iron concentration and total amount iron in Peanut and Rape. The iron content was strikingly influenced by different level treatments of compound iron fertilizer. High concentration of available iron is closely related with the dynamics of iron fractionations. The DTPA-Fe was striking influenced by different compound iron fertilizer applying 56 levels, increasing with the growth of fertilizer quantity used in experiment. This trend could also be seen on MnOX-Fe , OM-Fe ,and amorphous iron-oxide-bound iron (AOFe-Fe), instead of Carb-Fe and Exch-Fe. Under the absorption of Peanut and Rape, striking correlation between MnOX-Fe and DTPA-Fe could also be found, this indicated that MnOX-Fe is the most important provider of all iron fractionations. AOFe-Fe functions as a index of iron available or unavailable process. Experiment results indicated that Rape has powerful absorption and activation ability to soil iron compared with Peanut. After cultivating Rape, Exch-Fe (available directly) was not detected due to its absorption in contrast to manganese-oxide-bound Fe and AOFe-Fe (available indirectly) were significantly increased. At the beginning of cow dung application, DTPA-Fe, MnOX-Fe were lower than FeSO4 treatment instead of AOFe-Fe, Exch-Fe and Carb-Fe , while OM-Fe changed little. As time wen... |
PDF Full Text Request