Data/hora: 23/09/2024 17:47:53

Biblioteca(s): 	Embrapa Pantanal.	
Data corrente: 	04/07/1996	
Data da última atualização: 	04/07/1996	
Autoria: 	FERGUS, I. F.; MARTIN, A. E.; LITTLE, I. P.; HAYDOCK, K. P.	
Título: 	Studies on soil potassium. II. The Q/I relation and other parameters compared with plant uptake of potassium.	
Ano de publicação: 	1972	
Fonte/Imprenta: 	Australian Journal of Soil Research, v.10, p.95-111, 1972.	
Idioma: 	Inglês	
Conteúdo: 	Setaria (Setaria sphacelata cv. Nandi) was grown in 10 surface soils, of contrasting properties, in pots until (after repeated harvesting of tops) plant growth virtually ceased. Uptake of potassium by tops and roots was correlated with change in exchangeable potassium during cropping, initial exchangeable potassium, and with quantities of potassium predicted from the immediate Q/I relations of the soils. Some initially nonexchangeable potassium was absorbed from seven of the soils by the plants, such that these soil quantity parameters (which were statistically equivalent) predicted two-thirds of the total potassium uptake averaged over all soils. Potassium uptake was also correlated with soil potassium soluble in constant-boiling hydrochloric acid, and with potassium extracted by a cation exchange resin (both of which predicted about twice the plant absorption). For six of the soils, uptake of initiallyu non-exchangeable potassium was correlated with the quantity of total potassium present in each pot in the <0.1 um clay fraction. The intensity of soil potassium (measured in dilute calcium chloride solution from the immediate Q/I relation) was reduced on all soils by exchausive cropping to a mean value for the equilibrium activity ratio (ARo) of 4.7 x 10 -4 mole 1/2 1.-1/2 (AG= -4500 cal equiv.-1); it was suggested that the observed variations in this value were unlikely to prohibit its use for practical soil testing, except for the prediction of the quantity parameter for those soils for which the form of the isotherm is altered by croping. A tentative value for the potential of soil potassium at which setaria has an adequate average potassium concentration in its tops was - 3600 cal equiv.-1 (ARo 2.1 x 10 -3 mole1/2 1.-1/2). 	
Palavras-Chave: 	Estudo; Plant uptake; Soil potassium; Study.	
Thesagro: 	Planta; Potássio; Solo.	
Categoria do assunto: 	--	
Registro original: 	Embrapa Pantanal (CPAP)	
Exemplares: 	CPAP - (32594-1) - ADD - SP - -- - SP2960 -  - 2960 - DIS