Publication Date:
1984-02-01
Description:
Potassium deficiency in grapes, as well as in other fruit crops grown on soils in the Niagara peninsula, is a common and often serious problem. Ap horizon samples from 12 of these soils and grape petiole samples from nine of the soil locations were analyzed to elucidate the behavior of the soil K and its availability to grapes. The soils ranged in texture from sandy loam to silty clay and their clay mineralogy was relatively uniform with mica as the main layer silicate. Vermiculite was quantified by potential K fixation methods and was concentrated in the clay. Up to 5.8% vermiculite was present in the soils which seemed to be sufficient to reduce K availability by K fixation. Amounts of exchangeable K extracted with NaCl or NH4Cl were relatively high (0.46–2.09 meq/100 g) but were not correlated with K uptake by grapes. Energies of K exchange obtained from immiscibly displaced soil solutions were closely related to vermiculite contents and amounts of K fixed after air drying. Energies of K exchange and ratios of exchangeable K over exchangeable Ca + Mg were highly correlated with K uptake by grapes. Soils with energies of K exchange less than or equal to −2800 cal/equiv. or K exch./(Ca + Mg) exch. equal to or more than 7% appeared to have adequate amounts of available K for grapes. These two analyses therefore show promise for predicting K availability to grapes. Key words: Exchangeability of K, energy of K exchange, fixation of K, soil mineralogy, availability of K to grapes
Print ISSN:
0008-4271
Electronic ISSN:
1918-1841
Topics:
Geosciences
,
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
