Dung sums

[MattR]

RB209 gives a figure of 2.4 kg/t total sulphur for cattle fym, but "no data" for sulphur in horse fym - does anyone have a rough value please?

Also, how do you go about factoring dung applications into fertiliser requirements, particularly with regard to total vs available nutrients?

Might sound obvious, but for example I've got maybe 8t/ac cattle fym in a heap to spread on my spring barley ground. According to the table below (rb209) that would give 28 - 98 - 35 (P - K - S) in units/ac of available nutrients. If I was just buying compound I would be aiming for say 40 u/ac P and 55-60 u/ac K for a maintenance dressing. In that dung the available P is 28 but the total P would come to around 50 units - presumably it's the total that's important when it comes to determining what is sufficient for maintenance, as you're replacing crop offtake?

 

[robbie]

What is your soil index for p and k???

At maintainance and above use total P and K figures for index below maintainance (2-) use available figures.

For crop supply I'd ignore the sulphur figures as that's not necessarily going to be available when the crop needs it, I always think of S and Mg along with trace elements as just a bonus and not rely on them for the crop.