Ah, yes, Mr. Brown. What I have been trying to tell people for many years here.

Here is a link that might be useful: About soil pH

Have you? Tell people what, exactly?

There are many contributors to soil acidification, two of the biggest being leaching of mobile metal ions (e.g., Ca), and the ongoing use of a number of high N fertilizers. Plants do exude organic acids from their roots, which helps mobilize many plant nutrients for absorption. In healthy soils in an aerobic environment, those organic acids should be decomposed fairly easily over time. From the video it seems their biggest problem was soil compaction, which concentrates things and reduces aeration which slows further degradation.

Speaking of compaction, if we let those monster outfits run over our gardens, we would have compacted areas likely...although my amended beds can handle my walking on them easily..

It's an issue of soil texture as well, in this case, right? In a quite sandy soil even with big machinery you'd never get sufficient compaction to reduce leaching enough to move a neutral soil to pH5 due to the build up of exudates from crop roots, nor probably even the acidulation from fertilizers.

The gentleman from NC no doubt has a far better grasp on the matter than me, and I will bow to his expertise.

That said, I believe texture/drainage plays a big role when coupled with irrigation/rainfall. In high moisture environments highly porous soils can leach metals and their basic counterions. The problem is exacerbated by acid rain and high nitrogen fertilizers (e.g, your favorite FL soils), which favors loss of calcium and carbonate. When that soil is very retentive for Ca, it tends to remain alkaline in spite of high moisture (e.g., my TX gumbo clay soils). For a real change of perspective, consider the clay soils of the arid SW US - both calcerous and high in sodium because of the very limited rainfall.

My SWAG on the organic acid buildup on the soils noted in the video is that it is a reflection of an anaerobic condition as a result of compaction. The typical low molecular weight organic acids will degrade readily in an aerobic environment. Composting is a great example of that - pH will drop to ~ 5 in the early stages of aerobic thermophilic composting, but will readily returns to 7 or a tad higher in a few days.

That's what caught my attention, TX, is that in the case of what they are talking about in the end of the video, the acid condition is caused by basically the opposite of the cause I am used to, that is lack of drainage rather than excessive drainage. I would never have thought that soil would become more acid due to lack of drainage.

pnbrown - I may be wrong here, but I don't think it is a lack of drainage per se, but rather a lack of aeration. If the soils that were showed were indeed the soils they were discussing on their farms, it sure looked like some heavy clay soil to me. In the field one of the brothers talked about where the pH was too high, his long-term solution was to improve drainage via tiling. Their real point was to understand the root cause of the problem(s), then attack and solve that problem.

How deep the compaction goes is an issue too. Heavy compacted soils lack good aeration during the spring season. The roots are limited until the tilth improves.. During an ideal season of frequent moderate rains, the soil structure can improve, but flooding and then drought can make a hard soil.

Lowering the soil saturation level by tiling can greatly improve the depth of the root zone. These roots help to open channels in the soil and fiberize the deeper soil. horizon.