*3.2.6 Soil organic matter and soil pH*

The soil organic matter improves soil fertility by its influence on the chemical, physical, and biological properties of a soil. It was measured as an organic fraction of soil C. The soil organic C decreased in comparison to the initial value of 2.1%

#### **Figure 17.**

*Effect of integrated nutrition and FYM on soil carbon content in 0–30 cm depth.*

#### **Figure 18.**

*Effect of integrated nutrition and FYM on soil pH in 0–30 cm depth.*

measured in 1958, because crop residues have been removed from the field until 2009. Integrated nutrition increased soil C compared to only FYM application (**Figure 17**). Reduction of crop growth and low root biomass indicated by low yield (**Figure 10**) decreased soil C content at the treatment without any fertilizer. During 1959–1973, the soil organic C was not measured.

Liming of soil every 3 years with 1 tone CaO per ha increased soil pH compared to the initial pH measured in 1958 (**Figure 18**).
