Abstract
Intensive rice-based systems are mining soil potassium (K) due to negative K balances. Conservation Agriculture (CA) practices may increase yield and economic return of rice-based systems but there is limited understanding of their effects on K pools and balances. This study evaluated crop productivity and K input–output balances under contrasting rice-based intensive cropping and long-term CA. The comprised three factors- (a) soil disturbance (strip planting, SP and conventional tillage, CT); (b) residue retention (low, LR, 20 cm by plant height and high, HR, 50 cm) and; (c) K application-100% K (recommended dose, RD), 50–75% K of RD (low dose, LD), and 125–150% K of RD (high dose, HD). The long-term experiment initiated in 2010 and soil samples were collected in 2018 after 24th crop and 2020 after 30th crop of triple cropping system. The K balances for the 2018 cropping cycle were negative, ranging from − 47 to − 82 kg ha−1 yr−1. In the 2020 cycle, when the high K dose was increased from 125 to 150% of RD, the negative K balance was significantly reduced in SP-HR-HD (− 19 kg ha−1 yr−1) while 23–35% higher cropping system yield was achieved. Leaching was a significant K loss pathway. Overall results indicate that minimum soil disturbance and increased crop residue retention had significant positive effects on cropping system yield and K balance. However, to achieve neutral K balance in intensive rice-based cropping systems, increased recycling of K from crop residue, higher doses of K addition or lower K losses are needed.
