建土壤磷肥连续效应的研究

当季作物只利用磷肥的很小部分。在旱作条件下,残存在土壤中的大部分磷肥,不断转为非活性磷;随时间的延长,磷肥对后作的连续效应不断降低。改为水田时,旱作物未吸收的磷素,将释放进入活性磷库中,使作物吸磷量急剧上升。四季作物磷肥累加回收率将大大超过当季回收率,最高达56.86%。因此,要注重当季的施磷效果,又不容忽视磷肥的连续效应。土壤磷库水平与作物吸磷量的关系密切。在旱作条件下,作物吸磷量占 Olsen-P 量的1/4～1/3左右;在水田则可超过 Olsen-P 量的1～2倍以上。土壤总磷库(全磷量)虽然对当季作物吸磷量的影响没有达到显著水准,但对四季作物的总吸磷量和生物产量则有极显著正相关,相关系数分别为γ=0.6192、0.6530。为此,提高土壤磷库水平在生产上是有重要意义的。

THE CONTINUAL EFFECT OF PHOSPHATIC FERTILIZER IN THE SOILS OF FUJIAN PROVINCE

Corps assimilated only small amount of applying phosphatic fertilizer from the soil.Under dry farmland condition,the phosphatic ferilizer that remained in the soil gradually changed into the non-active phosphoric sink as time increased and the delayed effect of phosphatic fertilizer on the crops decreased.By turning the dry farmland into paddy field,the phos- phorus that were unable to be consumed by the crops usually released and formed the active phosphoric sink.The amount of phosphorus uptake by the crop evidently increased. Applying the phosphatic fertilizer evidently incrcased the level of phos- phoric sink in the soil.The accumulative rate of recovering phosphatic fer- tilizer in the four crops evidently surpassed the rate in one crop and the maximum tate was 56.86%.So not only attention must be paid to the offect of phosphatic fertilizer application on one crop but also the continual effect of the fertilizer. The level of phosphoric sink of soil was closely correlated with the amount of phosphorus in the plant.Under the dry farmland condition,the amount of phosphourus uptake the crop was 1/4～1/3 of the Olsen-P,but in the paddy field the amount of phosphorus in the rice plant was two to three times over Olsen.Although the total phosphoric sink(the amount of total phosphorus)was not corlelated to the amount of phosphorus uptake by one crop,the total amout of uptake by the four crops and the weightht of dry matter were significantly correlated to the total phosphoric sink.The cor- relation coefficients appearcd 0.6192 and 0.6530 respectively.So,it is important in practice that increase of the phosphoric sink in the soil promoted production.