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研究指出,在石灰性土壤上,磷肥用量和土壤有效磷增量两者间呈直线关系,直线的斜率称为“磷肥指数”。同时,这个土壤有效磷增量又随施磷后的时间大体上按指数函数关系衰减,可以用“减半期”表示。 在同一地块或在不同地块上,磷肥肥效与土壤有效磷的自然对数呈直线负相关(其中同一地块的相关系数r=0.9531,不同地块r=0.7467)。这种函数关系表明磷肥肥效的演变趋势是,新施磷肥的肥效将因长期大量施磷肥使土壤有效磷提高而逐渐下降,亦将随施磷后间隔较长时间不施磷,使土壤有效磷下降而肥效再次提高。 在石灰性土壤中磷肥需要量取决于土壤有效磷和磷肥指数。实验确定的土壤需磷量和计算的土壤需磷量密切相关(相关系数r_(盆栽)=0.953,r_(大田)=0.932)。
The study pointed out that in calcareous soil, there is a linear relationship between the amount of phosphate fertilizer and soil available phosphorus increment, and the slope of the straight line is called the “phosphate index.” In the meantime, the increment of available P in the soil decreases with exponential function after phosphorus application, which can be expressed as “halving period”. In the same plots or in different plots, the correlation between fertilizer efficiency and the natural logarithm of soil available P showed a linear negative correlation (r = 0.9531 for the same plot and r = 0.7467 for different plots). The functional relationship shows that the evolution trend of the fertilizer efficiency is that the fertilizer efficiency of the newly applied phosphate will be gradually decreased due to the increase of available phosphorus in the soil due to long-term large-scale application of phosphorus fertilizers, and no phosphorus will be applied for a long time after the phosphorus application. Declining and fertilizer efficiency increased again. Phosphate fertilizer requirements in calcareous soils depend on soil available P and P fertilizers. The experimentally determined soil phosphorus demand is closely related to the calculated phosphorus demand (correlation coefficient r_ (pot) = 0.953, r_ (field) = 0.932).