Sources, Amounts, and Forms of Alkali Elements in Soils

Scott, Alex; Smith, S. J.

doi:10.1007/978-1-4612-4682-4_3

Cited by 24 publications

(15 citation statements)

References 89 publications

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“…Some of the applied potassium fertilizers to such soils often becomes unavailable or slowly available to the plants (Scott and Smith, 1987) due to fixation of K + by soil particles. This fixed K + may be released from soil particles into soil solution when the concentration of K + is lowered in soil solution although this release is often too slow to meet the plant's requirement.…”

Section: K + and Na + Dynamics In Soilmentioning

confidence: 99%

Potassium–sodium interactions in soil and plant under saline‐sodic conditions

Wakeel

2013

Z. Pflanzenernähr. Bodenk.

184

104

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About 7% of the total land around the globe is salt-affected causing a great loss to agriculture. Salt stress refers to the excessive amount of soluble salts in the root zone which induce osmotic stress and ion toxicity in the growing plant. Among toxic ions, sodium (Na + ) has the most adverse effects on plant growth by its detrimental influence on plant metabolism in inhibiting enzyme activities. An optimal potassium (K + ) : Na + ratio is vital to activate enzymatic reactions in the cytoplasm necessary for maintenance of plant growth and yield development. Although most soils have adequate amounts of K + , in many soils available K + has become insufficient because of large amounts of K + removal by high-yielding crops. This problem is exacerbated under sodic or saline-sodic soil conditions as a consequence of K + -Na + antagonism. Here K + uptake by plants is severely affected by the presence of Na + in the nutrient medium. Due to its similar physicochemical properties, Na + competes with K + in plant uptake specifically through high-affinity potassium transporters (HKTs) and nonselective cation channels (NSCCs). Membrane depolarization caused by Na + makes it difficult for K + to be taken up by K + inward-rectifying channels (KIRs) and increases K + leakage from the cell by activating potassium outward-rectifying channels (KORs). Minimizing Na + uptake and preventing K + losses from the cell may help to maintain a K + : Na + ratio optimum for plant metabolism in the cytoplasm under salt-stress conditions. It would seem a reasonable assumption therefore that an increase in the concentration of K + in salt-affected soils may support enhanced K + uptake and reduce Na + influx via HKTs and NCCSs. Although very useful information is available regarding K + -Na + homeostasis indicating their antagonistic effect in plants, current knowledge in applied research is still inadequate to recommend application of potassium fertilizers to alleviate Na + stress in plants under sodic and saline-sodic conditions. Nevertheless some encouraging results regarding alleviation of Na + stress by potassium fertilization provide the motivation for conducting further studies to improve our understanding and perspectives for potassium fertilization in sodic and saline-sodic environments. : Exogenously supplied compatible solutes rapidly ameliorate NaCl-induced potassium efflux from barley roots. : Loss of the AKT2/3 potassium channel affects sugar loading into the phloem of Arabidopsis. Planta 216, 334-344.Demidchik, V., Maathuis, F. J. M. (2007): Physiological roles of nonselective cation channels in plants: from salt stress to signaling and development. New Phytol. 175, 387-404. Demidchik, V., Tester, M. (2002): Sodium fluxes through nonselective cation channels in the plasma membrane of protoplasts from Arabidopsis roots. Plant Physiol. 128, 379-387. Demidchik, V., Shabala, S. N., Coutts, K. B., Tester, M. A., Davies, J. M. (2003): Free oxygen radicals regulate plasma membrane Ca 2+ and K + -permeable channels in plant root ce...

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Section: K + and Na + Dynamics In Soilmentioning

confidence: 99%

Potassium–sodium interactions in soil and plant under saline‐sodic conditions

Wakeel

2013

Z. Pflanzenernähr. Bodenk.

184

104

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“…1). Further, some fractions of applied K to illite and vermiculite rich soils K may get fixed by soil particles making it unavailable or slowly available to plant roots (Scott and Smith, 1987). Nonetheless, K in fixed fractions may become available to plant roots when released into soil solution particularly at low soil K levels (Cox et al, 1999), but is too slow release may not meet the plant-growth requirements.…”

Section: Introductionmentioning

confidence: 99%

Potash Use for Sustainable Crop Production in Pakistan: A Review

Wakeel¹,

Rehman²,

Magen³

2017

IJAB

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“…Application of K + fertilizer to soils containing illite and vermiculite clay minerals often leads to fixation of some of its fraction by soil particles. This fraction then becomes unavailable or slowly available to the plants (Scott and Smith, 1987). The fixed K + can be made available to plants by its release from soil particles into soil solution when the concentration of K + is lowered in soil solution (Cox et al, 1999), but in many cases this release is too slow to meet the plants requirement.…”

Section: Introductionmentioning

confidence: 99%