Potassium supplying capacity of a red soil from eastern India after forty-two years of continuous cropping and fertilization

• Published in: Geoderma Vol. 341; pp. 76 - 92
• Main Authors: Das, Debarup, Dwivedi, B.S., Datta, S.P., Datta, S.C., Meena, M.C., Agarwal, B.K., Shahi, D.K., Singh, Muneshwar, Chakraborty, D., Jaggi, Seema
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.05.2019
• Subjects: Alfisol; Crop yields; Long-term fertilizer experiment; Non-exchangeable potassium; Quantity/intensity relationship; Release kinetics; Crop yields; Ver; Ill; Ks; Long-term fertilizer experiment; CK0; Ktotal; EK0; INR; Alfisol; ΔG0; Quantity/intensity relationship; ΔK0; Knex; FYM; EKmin; KL; b; Non-exchangeable potassium; Kws; CK; AReK; CKS; CKR; bR; bS; Release kinetics; Knitric; Sm; PBCK
• ISSN: 0016-7061; 1872-6259
• DOI: 10.1016/j.geoderma.2019.01.041

Fertilizer use in Indian agriculture is skewed towards nitrogen (N) and phosphorus (P), and farmers generally neglect potassium (K) input ignoring K requirement of crops. We, therefore, studied the long-term effect of imbalanced fertilization (i.e. without K) on K supplying capacity of a kaolinitic red soil (Typic Haplustalf) after 42 years of intensive cultivation. Soil samples (0–15 and 15–30 cm) were collected after the completion of 42 cropping cycles from an on-going long-term fertilizer experiment located at Birsa Agricultural University, Ranchi, India, from six treatments, viz. control (unfertilized), fertilizer N, NP, NPK, 150% NPK (1.5 times of NPK) and NPK + FYM (NPK + farmyard manure), along with adjacent uncultivated land. Soil K pools, clay minerals, quantity-intensity relationship and K release kinetics along with grain yield and K uptake of soybean and wheat were studied. Among the treatments, NP treated soils showed the lowest amounts of labile (KL) and non-exchangeable K (Knex). Equilibrium activity ratio (AReK) and non-specifically held K (−ΔK0) were also lowest under NP treatment. The gap between equilibrium exchangeable K (EK0) and minimum exchangeable K (EKmin) was minimum under NP. Cropping and fertilization-induced transformation in clay minerals was noticed wherein continuous neglect of K fertilizer led to a decrease in illite content with a concomitant increase in interstratified minerals. On the other hand, noticeably lower alteration in clay minerals and comparatively less depletion in overall K-supplying capacity of soil were recorded under K addition as compared to imbalanced fertilization (i.e. without K). Soybean showed a significant positive response to K application. The study thus underlined the necessity of adequate K input for the sustenance of soil health, inherent K-supplying capacity and crop productivity. •We studied long-term effect of cropping with or without K input on soil K-fertility.•Imbalanced fertilization with respect to K caused depletion of soil K pools.•Imbalanced fertilization adversely affected quantity, intensity and K release rate.•Continuous neglect of K addition led to distortion in clay minerals.•Cropping with K addition maintained much better K-supplying capacity of soil.