Residual Effects Of Zinc And Manganese Sulfate On Growth And Zinc And Manganese Uptake Of Soybean Plants
2005
Asadi Kangar Shahi, A`li
A significant portion of chemical zinc and manganese fertilizers applied to calcareous soils is not absorbed by the first crop and may, therefore , affect the growth and chemical composition of the subsequent crops . This is called the residual effect of Zn and Mn. Soil tests may be used to predict such effects . The present experiment was conducted to study the residual effects of zinc and Manganese sulfate on the subsequent crop of soybean. Twenty soils of nourthern Iran (5-39% calcium carbonate equivalent), previosly treated with two levels of Zn ( 0 and 20 mg Zn kg-1 as ZnSo4) and Mn ( 0 and 30 mg Mn kg-1 as MnSo4) and under one crop of Soybean, was used in greenhouse to grow a subsequent crop of soybean without addittional Zn fertilizer but with uniform application of nitrogen , phosphorous and potassium. Soils were sampled before the subsequent crop and extracted with Zn extractant DTPA. Dry weight of plant tops and Zn concentration and uptake after eight weeks under the greenhouse conditons were used as the plant responses to residual Zn and Mn in soil . Statistical analyses showed that the overall effect of previosly- applied Zn and Mn on dry matter were nonsignificant , but seed yield , Zn concentration and uptake were significantly increased . The effects of applied Zn and Mn on dry matter and seed yield of the third crop in soils were nonsignificant, but Zn concentration and uptake were significantly increased. In the fourth crop, effect of Zn on dry matter was nonsignificat, but Zn concentration and uptake were increased.
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