四、水稻土的硫肥力 (一)水稻土中硫的状况远在一百三十年前就已肯定了硫是植物生长的必要元素之一。然而自五十年代后期起,国际上对水稻土的缺硫报导逐渐减少了,甚至在美国硫研究所1971年发表的硫肥对各种作物的肥效报导中也未包括水稻。直至七十年代中期以后,世界各地又不断出现水稻土缺硫的报告,如1972年,IRRI的研究人员发现印尼水稻矮缩的原因是土壤缺硫。1973年美国农 Sulfur fertility of paddy soils (i) The status of sulfur in paddy soils has been affirmed one hundred thirty years ago that sulfur is one of the essential elements of plant growth. Since the late 1950s, however, there has been a gradual reduction in the number of reported sulfur deficiency in paddy soils. Rice was not even included in the fertilizer efficiency reports of sulfur fertilizers on various crops published by the Sulfur Institute in 1971. Until the mid-1970s, reports of sulfur deficiency in paddy soils all over the world continued to appear. In 1972, for example, IRRI researchers found that the reason for the dwarfing of rice in Indonesia is the lack of sulfur in the soil. 1973 American farmer