大豆重迎茬减产的原因及农艺对策研究Ⅲ.重迎茬大豆的土壤养分与养分吸收

通过连续8年在黑龙江省6个生态区9个9区固定轮作场圃综合试验，试验区专项研究，框区，盆栽试验，实验室分析，以及大量的大面积生产调查，发现大豆重迎茬种植，根部病虫危害加剧，在影响重迎茬大豆生长发育，产量品质的诸多因素中，所起的作用最大，杀灭土壤中的病菌和害虫，重迎茬大豆的产量不比正茬低。在减缓重迎茬损失的各种调控措施中，以杀灭土壤中病，虫为主要目标的土壤处理剂和种衣剂效果最好。这一切都说明根际土壤病虫害加剧是大豆重迎茬减产的主要原因。

STUDY ON THE REASON REDUCING PRODUCTION OF SOYBEAN PLANTED CONTINUOUSLY AND THE WAY TO GET MORE OUTPUT Ⅲ. Harmfulness of Diseases and Pests

The experiments had been carried out by 8 years in 9 rotation nurses with 9 plots and series of field experiments in 5 ecological regions of Heilongjiang Province since 1993. In the same time, the investigation was made in soybean fields. The result showed that: Harmfulness of diseases and pests in the soil around roots of soybeans planted continuously became more serious, and it was the most important in the facts to effect growth and development of soybeans planted continuously. When the funguses and pests of soil were killed, the output of continuous soybeans was not as low as that of rotation soybeans. Among the methods to control the production reduce of continuous soybeans, the best one was soil treatment and seed coat that could kill diseases and pests in soil. It is the main reason to reduce output of soybeans planted continuously, that diseases and pests in soil around roots become more serious.