Abstract

                                Soil enzymes play vital role in nutrient mineralization and their activity in soil is an excellent sensor in predicting the nutrient supplying capacity to plants. A field experiment was conducted to study the effect of long-term fertilization and maize hybrid on seasonal and temporal changes in soil enzyme activities (phosphatase and dehydrogenase). There were ten treatments each replicated four times viz., T1- 50 % NPK, T2 - 100% NPK, T3 - 150% NPK, T4 - 100% NPK + hand weeding, T5 - 100% NPK + ZnSO4, T6 - 100% NP, T7 - 100% N alone, T8 - 100% NPK + FYM, T9 - 100% NPK (-S) and T10 - Control. The results showed that during monsoon fallow period, dehydrogenase activity increased, while phosphatase activity recorded lower values after monsoon rainfall. Unlike phosphatase activity, dehydrogenase activity followed a declining trend as growth stages of hybrid maize (Co-6) proceeds. Among the treatments, 100 % NPK + FYM @ 10 t ha-1 (T8) recorded the highest activities of these enzymes emphasising the importance of integrated nutrient management in improving biochemical properties of soil, thereby sustaining the soil health over long run.

Key words : Long-term fertilization, Maize hybrid, Soil enzyme activity.