One cause of yield decline could be related to
declining SOC and its associate fractions in acid soils.
Three decades of continuous soybean–wheat cultivation
revealed a significant loss of active fractions of C and N
with control, N and NP fertilization. The POC and PON
were also lower with concomitant decrease of C and N
decay rate of aggregates, which led to lower nutrient
supplying capacity. Organic matter in the clay + silt
fraction (