Let’s consider some hard facts in a simplified manner .
An acre of land is 4000m² . Let’s assume an effective rooting depth of 20cm or 0.2m .
The effective soil volume that affects crop production is 800m³ .
If we put this soil in 10m³ tanks or 10 000 , it would fit into 80 such tanks .
Ph acidity is determined by higher concentration of H+ the higher it is in a given soil, the lower the pH or towards 1.
DAP fertiliser is victimised because of it’s NH+ nature .
DAP fertiliser is 18kgs N and let’s assume its all in NH+ form .
Ideal DAP fertiliser application for maize is 2 bags per acre or 250kgs per ha which farmers rarely use despite kenyan soils being low in Phosphorous.
Lts put 18kgs Nitrogen that is in a 100kgs of DAP into 80 tanks of 10m³ each of soil .
How many grams would each tank get ?
225g per tank .
An acid has a sharp taste and therefore we can use taste in our example . Let’s assume you put 225g of sugar into a 10 ,000 litre tank full of water , would it even taste sugar ?
The ammonium in 225g in 10,000lts of soil would be too scattered to register any significance shift in a ph meter .
Soil acidity in many parts of Transzoia and Uasin gishu is mainly affactor of leaching and mineralisation than the use of DAP fertiliser.
On another note .
The results from soil analysis lab indicates the available nutrients. If the nutrients are available in a stable soil , there are no hungry element fixtures waiting for you to apply Phosphorous in order to fix it into insoluble compounds eg Calcium phosphate . Such reaction takes time and the assumption that the DAP applied in the soil becomes unavailable in low ph is a also not factual.
DAP is a very good fertiliser.
Credit: David Ndegwa