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

Lu, Dianjun, Huan, Weiwei, Yan, Taotao, Wang, Yiliu, Jiang, Chaoqiang, Zhang, Xiang, Chen, Xiaoqin, Wang, Huoyan, Zu, Chaolong, Zhou, Jianmin
Zeitschrift für Pflanzenernährung und Bodenkunde 2017 v.180 no.6 pp. 659-666
Nicotiana tabacum, biomass, calcareous soils, cost effectiveness, farmers, field experimentation, leaves, potassium, potassium fertilizers, rhizosphere, soil separates, sorption, tobacco
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.