5. Conclusions
The study concludes that the tillage increases net N mineralization
and net nitrification rates in the soil of a hot humid tropic
region. However, the increase is the highest in the frequent till and
the lowest in the long term zero till treatment. Simultaneously
with the increase in the net soil N mineralization rate, SOC declines
due to the tillage treatments. But, the decline is the highest in the
frequent till and the lowest in the long term zero till treatment.
Like the SOC, tillage reduces also MB-C, however, the reduction is
the highest in the frequent till and the lowest in the long term zero
till treatment. In the low till treatment, the SOC is nearly equal to
that in the short term zero till treatment, but net N mineralization
rate is greater particularly during the wet season when plant’s
demand for nitrogen in the tropics is high. These trends indicate
that low tillage can be a good option for SOC build-up and soil
fertility management in the hot humid tropics. However, the
trends can be confirmed and logical conclusions can be drawn only
after long-term experimentation.