Tillage not only stimulates soil organisms to feed on the organic content of the soil, but also scrambles the soil particles, damaging the soil’s natural structure. Each soil form has a distinct structure or alignment which ensures there is sufficient, but not excessive aeration, and paths for water to flow down into the profile at the fastest rate possible. When we till the soil, all this is broken down and the alignment disturbed. A n extreme case is where we form mud.
Water penetration is rapid to the point where the newly tilled soil has been disturbed and then it becomes saturated until the rate of water penetration is vastly impeded and aeration badly affected. If you want proof of this, seek out a newly ploughed land where there is undisturbed veld alongside and check the difference after a heavy downpour. Once the tilled soil has become saturated, the aeration status can be so affected that we can create favourable conditions for a number of pathogenic organisms which cause root diseases.
This may only be temporary in some cases but be enough to cause losses. The natural realignment of soil particles can take a long time and is influenced by the soil composition. Organic matter, different clays, fungal activity and the crop’s root system are some factors which interact. One can even see a vast difference between newly ploughed soil after rain and bare soil that’s been in that condition for some time. Farmers sometimes refer to this as the soil telling them that it’s ready for planting.
Leaving cultivation behind after realising that cultivation doesn’t really improve growing conditions in the soil, we can take a good look at what we are trying to achieve in each case instead of cultivating out of tradition or habit, believing it’s the right thing to do. When we are on the bed system, as many vegetable farmers are after a crop of beetroot, it’s traditional to plough, rip or perform some other form of total tillage before bedding and rotavating for the next crop. Instead we could use the same beds to plant lettuce or cabbage without any cultivation.
After the crop of beetroot, the soil would be just about becoming well-aligned when it’s scrambled again before the next crop. Not only are we wasting money on diesel and equipment, but we are not doing our soil a favour. On top of this, without tillage the land is immediately ready for planting after harvesting, come rain or whatever weather conditions. he whole idea is so terribly controversial that I can barely convince a farmer to set a small piece of land aside to see for himself. have proved it for myself over and over. basic fertiliser is required in the form of either chemical fertiliser or manure, it can be placed on the beds before transplanting, without incorporation. – Bill Kerr ((016) 366 0616 or e-mail [email protected]). |fw