HI Lloyd : In what form does Al exist when the PH is above the cutoff point?
How does calcium get depleted? Does it leach away like the inorganic N ? Regards TaChung Huang -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of Lloyd Charles Sent: Thursday, October 10, 2002 7:04 AM To: [EMAIL PROTECTED] Subject: Re: Nutrient blockers ----- Original Message ----- From: Roger Pye <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Thursday, October 10, 2002 5:54 PM Subject: Nutrient blockers > Does anyone know whether aluminium locks calcium up in soils? > > roger > -- > Hi Roger Other way round!!- calcium locks up aluminium - Its a chain of events - calcium depletion - then low pH - then the acidity makes aluminium available - Al is a +++ so its some of the last to come unstuck. So you are not going to have available aluminium at toxic levels unless you have the extreme low pH that comes with a serious lack of calcium (or magnesium in a real sandy soil). This will be at pH less than 4.5 calcium chloride - in our red soils we can go as low as 4.2 before serious trouble - in your country probably 4.4 would be the cutoff point. . Aluminium levels rocket upwards as the pH drops that last half point or so. So the aluminium is a result of a lack of available calcium not the cause of it. Cheers Lloyd Charles
