陕西省锰肥应用分布的研究

INVESTIGATION ON THE DISTRIBUTION OF SOILS DEFICIENT IN Mn AND APPLICATION OF Mn FERTILIZER IN SHAANXI

本文研究了土壤有效锰(DTPA-Mn)含量与作物产量之间的关系。试验结果表明,土壤有效锰含量和作物产量密切相关。有效锰含量较低,施锰肥就有较好反应。因而,根据锰肥对作物产量的反应,初步将土壤中有效锰分为:最低;较低;低;中等;丰富五级。在全省范围內,在陕北和关中大面积土壤需施锰肥,而陕南土壤有效锰较丰富,需施锰肥面积小。土壤缺锰面积与钙质土壤的分布是一致的。此外,土壤有效锰含量和土壤pH值、碳酸钙含量呈负相关。在钙质土中,土壤有效锰易被吸附,所以含量较低。

Owing to difference in relief and climate between the north and south of the province, the distribution of the soils in Shannxi are different; most of the soils are neutral and slightly alkaline in reaction but a part of slightly acid soils are distributed in south Shannxi. Previous experiments conducted in 1961—1980 by the authors had proved the effect of Mn fertilizezr on most of the soils in this province. The present paper deals with the gradation of available Mn in soil, reasonable application of Mn fertilizer in the soils of various districts of the province, the distribution regularity of Mn in soils and the conditions of applying Mn fertilizer. For studying the relationship between the available Mn content in different soils and the crop yield, 51 plot trials and 20 pot experiments for the effect of Mn fertilizer on the yield of wheat and corn planted on soils with different available Mn content were carried out. Results of experiments showed that the content of soil available Mn was significantly correlated with the yields of crop; the lower the content of available Mn in soil, the better the responce of crops to Mn fertilizer; consequently, according to the response of crops to Mn fertilizer, the available Mn (DTPA-Mn) in soil and application of Mn-fertilizer were divided into five levels, i.e. the lowest level (<3.0ppm) being the grade urgent need for Mn fertilizer, the lower level (3—5 ppm) being the grade of need for Mn fertilizer, the low level (5—10 ppm) being the grade of need for Mn fertilizer acording to actual conditions, the medium level (10—15 ppm) being sufficient for the crops need, and the high level (>15ppm) being no need of Mn fertilizer. It has been found that there is a large area of the soils deficient in Mn and needed to apply Mn fertilizer in northern and middle Shaanxi, but the available Mn (DTPA-Mn) is rich in the soils in southern Shaanxi. The distribution of the soils deficient in Mn is quite consistent with that of calcareous soils. Experiment results also showed that the contents of available manganese in soil was negatively correlated with the pH value of the soil and content of calcium carbonate in the soil, and the manganese in soil was so easily adsorbed in calcareous soil that the available manganese was lower.