Effect of Potassium on Growth, Yield and Nutrient Uptake under Rice-Lentil Cropping System in Acid Soil

Potassium deficiency is a major constraint in rice-lentil cropping systems on acidic soils, where intensive cultivation and imbalanced fertilization accelerate nutrient depletion. Inclusion of pulses in rice-based cropping system improves soil health and increase system productivity benefitting both the rice and pulse crop. This study evaluated the effects of K fertilization on crop performance and nutrient availability in acidic soils from 2022 to 2024.

The study was conducted in Lourembam, Thoubal District, Manipur (24.644573°N, 94.074931°E; 769 m above sea level) under Central Agricultural University, Imphal, Manipur during 2022–2023 and 2023- 2024. The field experiment was laid out in randomized block design (RBD) with 7 K levels (0, 10, 20, 30, 40, 50, 60 kg K₂O ha^-1) and 3 replications with rice (var. RC Maniphou- 13) during the Kharif season, followed by lentil (var. IPL-316) during Rabi season without additional fertilization. The crop for each treatment was harvested and threshed separately and yield per plot was recorded.

Results revealed that 40 kg K₂O ha^-1 with recommended N and P significantly improved rice plant height, tiller number, filled grains, grain and straw yield and K uptake (P<0.05). Lentil grown after 50 kg K₂O ha^-1 in rice showed the highest seed and stover yield, despite receiving no direct fertilization. Overall, this research provides a strong foundation for optimizing potassium use in acid soils and sets the stage for more advanced, data-driven approaches to nutrient management in sustainable cropping systems.