Cropping System-driven Changes in Phosphorous Fractionation and Soil Fertility in Acid Soils
Boishali Dutta
Department of Soil Science, College of Agriculture, Assam Agricultural University, Jorhat, Assam, India.
Kulendra Nath Das
Department of Soil Science, College of Agriculture, Assam Agricultural University, Jorhat, Assam, India.
Binoy Kumar Medhi
Department of Soil Science, College of Agriculture, Assam Agricultural University, Jorhat, Assam, India.
Bhabesh Gogoi
Advanced Centre for Integrated Farming System Research, AICRP on IFS, AAU, Jorhat, Assam, India.
Anindita Das
Krishi Vigyan Kendra, Cachar, Assam Agricultural University (Jorhat), Silchar, Assam, India.
Aditya Bezbaruah
Department of Agriculture, Govt. of Assam, Assam, India.
Bitopan Das
Department of Agriculture, Govt. of Assam, South Salmara-Mankachar, Assam, India.
Sushmita Konwar *
Faculty of Agricultural Sciences and Technology, Assam down town University, Guwahati, Assam, India.
Arunima Goswami
Department of Agronomy, College of Agriculture, Odisha University of Agriculture and Technology, Bhubaneswar, India.
*Author to whom correspondence should be addressed.
Abstract
Phosphorus (P) availability in acidic soils is predominantly influenced by its transformation into various inorganic and organic forms, which are further affected by cropping systems and associated nutrient management. The present study was conducted at the ICR farm, Assam Agricultural University, to assess the distribution of different P fractions in acid soils under seven intensive cropping systems, with three replications in a randomised block design, following five consecutive years of cultivation. Soil samples (0–30 cm) collected from each cropping sequence were analysed for major soil properties, available nutrients, total P, organic-P and different inorganic P fractions, including saloid-P, Al-P, Fe-P and Ca-P. Continuous cultivation improved soil pH, organic carbon and available N, P2O5 and K2O compared with the nearby uncultivated soil (virgin soil). The different phosphorus fractions varied significantly across the cropping-system soils. The inorganic P distribution was dominated by Fe-P, followed by Al-P, Ca-P and saloid-P, irrespective of the cropping system. The contributions of the P fractions to total P followed the order Fe-P > Al-P > Org-P > Ca-P > Sa-P. Correlation analysis indicated strong associations between soil pH and Fe-P and Al-P, whereas organic-P was positively associated with soil organic carbon. Thus, the findings demonstrated that five consecutive years of intensive cultivation and associated nutrient management substantially affected soil phosphorus pools and their distribution, highlighting the significance of balanced nutrient management and diversified cropping systems in sustaining different P pools in acidic soils.
Keywords: Acid soils, intensive cropping systems, phosphorus fractionation, soil fertility, iron-bound phosphorus, aluminium-bound phosphorus, saloid phosphorus, organic phosphorus, soil organic carbon, nutrient management