A heterogeneous potassium supply enhances the leaf potassium concentration of ridge‐cultivated tobacco grown in calcareous soil

• Published in: Journal of plant nutrition and soil science 2017-12, Vol.180 (6), p.659-666
• Main Authors: Lu, Dianjun, Huan, Weiwei, Yan, Taotao, Wang, Yiliu, Jiang, Chaoqiang, Zhang, Xiang, Chen, Xiaoqin, Wang, Huoyan, Zu, Chaolong, Zhou, Jianmin
• Format: Article
• Language: English
• Subjects: Calcareous soils; Fertilizers; Field tests; Leaves; Nicotiana tabacum; placement; plant‐available K; Potassium; Rhizosphere; Soils; space heterogeneity; Tobacco
• ISSN: 1436-8730; 1522-2624
• DOI: 10.1002/jpln.201700023

The high potassium (K)‐fixing capacity of calcareous soils with homogeneous K supply limits crop K concentration. The objective of this study was to determine the increase in the leaf K concentration of tobacco (Nicotiana tabaccum L.) with a heterogeneous K supply. Two field experiments were conducted from 2013 to 2015 with five K rates applied in homogeneous environments and one K rate applied in varying fractions of soil volume (from 0% to 100%) in heterogeneous environments. Under ridge culture, leaf biomass was not significantly affected by homogeneous (K rate) or heterogeneous (patch size) K management. Under homogeneous conditions, increasing the K supply to three times the standard rate used by farmers (249 kg K ha−1) increased leaf K concentration significantly, but the effect was limited and not cost‐effective. Heterogeneous supply of K fertilizer at the standard K rate in patches of 0–40% of soil volume outperformed homogeneous K supply in terms of leaf K concentrations. Furthermore, K fertilizer mixed in intermediate soil volume fractions of 1–20% resulted in higher leaf K concentrations than the smallest (0%) and larger (30–40%) soil fractions. However, such K‐rich patch application should be managed precisely with specific placement due to the sharp reduction in available K with increasing distance from the fertilizer. To maximize the sorption of immobile K, the match between the uptake volume of the rhizosphere and the area available for K diffusion is important.