A K^+-selective electrode and a Na^+-selective electrode were used to construct a measuring cell without liquid-junction for the determination of the ion activ
The reserve of soil nutrients is limited.In case of irrational use of land,nutrients would be depleted sooner.Before the 1950s the low grain production in China
<正> INTRODUCTION Nitrogen is a key component of soil organic matter. Only when we have succeeded in characterizing the major part of organic N-containing compo
<正> As early as the 1950s, there had already been reports on the δ 15N value of some chemical fertilizers (Hoering, 1955). Since Kohl and his co-workers (1971