论文部分内容阅读
本文以二年多田间试验(玉米)与一年~(32)P同位素标记肥料盆栽试验(小麦),先后证明对红壤旱耕地的速效磷提取法,酸性提取优于碱性提取。为了进一步证实上述试验结果,继续采用4种方法来确定红壤旱耕地速效磷的主要形态:(1)各级形态磷与3个参比标准之间的统计分析;(2)各级形态磷与10种提取方法结果之间的统计分析;(3)小麦盆栽后的土壤与空白土壤各级形态磷的差减;(4)同位素~(32)P平衡法与土壤磷分级分析相结合。四种方法的研究结果一致证明,红壤旱耕地的速效磷主要形态是Al-P而不是Fe-P;从而说明了酸性提取优于碱性提取的原因。因为Al-P是一种两性化合物,新沉淀的Al-P酸溶性较大,而Fe-P只可能碱溶。Mehlich,Ⅲ法是一种不分土壤类型与地区的通用提取剂,本试验的结果证明其同样适用于红壤旱耕地。本文最后推荐Brayl法与Mehlich Ⅲ法为红壤旱耕地上的速效磷提取剂,并针对玉米作物确定相应的磷养分丰缺指标。
In this paper, pot experiment (wheat) with more than two years of field trial (corn) and one year (32) P isotope labeling fertilizers has proved that the extraction of available phosphorus from the dryland of red soil is better than that of alkaline extraction. In order to further confirm the results of the above experiment, four methods were used to determine the main forms of available phosphorus in the dryland of red soil. (1) Statistical analysis of phosphorus at all levels and three reference standards; (2) Statistical analysis of the results of 10 extraction methods; (3) Difference of morphological phosphorus at all levels between soil and blank soil after potted wheat; (4) Balance of isotope ~ (32) P and soil phosphorus fractionation. The results of the four methods consistently proved that the main form of available phosphorus in dryland of red soil is Al-P instead of Fe-P, which indicates that the acid extraction is superior to alkaline extraction. Because Al-P is an amphoteric compound, the newly precipitated Al-P is more soluble in acid and Fe-P is only alkali-soluble. Mehlich, Ⅲ method is a common soil extractant regardless of soil types and regions, the results of this test proved that the same applies to red soil dryland. At last, Brayl method and Mehlich Ⅲ method are available as fast-acting phosphorus extractant on red soil dryland, and the corresponding indexes of phosphorus abundance and deficiency are determined for corn crop.