Long-term Impact of Soil Test and Targeted Yield Based Nutrient Management on Vertical Variability in Carbon Fractions of a Vertisol under Rice-wheat Cropping Sequence

Aim: To study the Long-term impact of soil test and targeted yield based nutrient management on vertical variability in carbon fractions of a Vertisol under rice-wheat cropping sequence.

Place and Duration of Study: This research trail was conducted during rabi season of 2020-21 in an on-going research programme of AICRP on STCR initiated during 2008 at the Research Farm of Jawaharlal Nehru Krishi Vishwa Vidyalaya, Jabalpur.

Study Design: The study has consisted of six treatments of nutrient management practices based on soil test and targeted yields of rice and wheat (T1: Control; T2: GRD; T3: T.Y. 50 and 45 q ha-1 for rice and wheat; T4: T.Y. 60 q ha-1; T5: T.Y. 50 and 45 q with FYM 5 t ha-1 for rice and wheat and T6: T.Y. 60 q with 5 t FYM ha-1) at different soil depths (0-15, 15-30 and 30-45 cm) which were replicated four times in a randomized block design.A total of 72 post- harvest soil samples of wheat were subjected to determination of carbon fractions across the soil depths.

Results: Results revealed that Carbon fractions in soil were significantly altered by nutrient management practices over soil depths. However, the highest contents of organic and inorganic carbon fractions in soil were obtained under T6 having highest yield target of 60 q along with FYM 5 t ha-1 and the lowest in control. The results showed that contents of carbon fractions of soil were decreased with consecutive increase in soil depths except less labile carbon and inorganic carbon which increased with soil depths.