|Looking north west towards a neighbours late barley crop, the barley is just about to come out in head:|
|Looking south east|
The next photo is some corn on another property (not mine) that is suffering from phosphorus deficiency. You will notice that it mostly affects two rows. These are the centre rows in my planter where I couldn't get the fert openers closer than 100mm from the seed openers due to the three point linkage. The corn here was sown with 100Kg of DAP (90 lb/acre) so there should be enough phosphorus, it's just that the plants haven't found it yet.
|Phosphorus deficient corn - Vam deficient? Long fallow Syndrome|
A soil test taken 5 years ago showed a Colwell P of 75, however it is very acid with a pH of 5.0 (4.2 in CaCl). I think that the problem is related to the previous crop - canola. Canola does not host VAM, vesicular arbuscular mycorrhizae, a beneficial fungi that makes phosphorus and zinc more available to crops like corn and sorghum. Check out this link for more info: http://www.daff.qld.gov.au/26_5395.htm