NUTRIENT BALANCES AS AFFECTED BY INTEGRATED NUTRIENT AND CROP RESIDUE MANAGEMENT IN COTTON-WHEAT SYSTEM IN ARIDISOLS. III. POTASSIUM

Abstract

Potassium (K) uptake, uptake trend and apparent balances as influenced by integrated nutrient and crop residue management were investigated in a five-year field experiment on two calcareous soils, i.e., Awagat (coarse loamy) and Shahpur (fine silty) in cotton-wheat sequence. Total K uptake by cotton and wheat plants differed significantly due to nutrient management treatments, i.e., farmers’ fertilizer use (FFU); balanced nutrient management (BNM); integrated nutrient management (INM); and balanced nutrient management plus green manuring (BNM+GM). Minimum mean K uptake (kg ha⁻¹) by cotton with FFU was 87.1 in Awaga and 108.1 in Shahpur. Corresponding maximum mean K uptake with INM was 115.1 and 132.2, respectively. Nutrient treatments effect on K uptake by wheat was similar to cotton. Potassium uptake was further enhanced by crop residue recycling. Potassium uptake by both crops exhibited non-significant trends and large negative apparent K balances were observed in both the soils.

Keywords:

• integrated nutrient management
• K concentration
• K uptake
• K uptake trends
• apparent K balance
• cotton-wheat system

ACKNOWLEDGMENTS

Financial support for this field-cum-laboratory investigation was provided by the Ministry of Science & Technology, Government of Pakistan, through the Pak-Kazakh Joint Research Fund Project. The authors are indebted to the Central Cotton Research Institute, Multan and the Pak-German Institute for Cooperative Agriculture, Multan for invaluable support in this challenging field research endeavor. We are also grateful to M. Inayat Khan and M. Asif Ghumman for guidance and support in experimental design and statistical analysis of data and to M. Tauseef Tabassum and Zulfqar Ali for assistance in laboratory analytical work.