Conservation tillage works!

Biological farming is getting better by the day, thanks to intelligent and observant farmers.

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As we saw last time, farmers are great agricultural scientists – they just don’t see themselves as such. In their minds ‘true scientists’ are on a much ‘higher level’. This misconception needs to be put right. When farmers start to think of themselves as scientists, progress will accelerate. The first step is for farmers to understand what science is and their role in advancing it.

To paraphrase Prof Theuns Erasmus’s definition from last time, agricultural science is “the body of knowledge that helps us understand how agriculture works”. With this in mind, it’s clear why some farmers are great scientists – they have a profound holistic knowledge and insight into how to be highly productive. Few ‘academic scientists’ would be able to match them if put in their position.

Changing his ways
In my previous column, I promised to re-tell the story of Jack Human, who almost single-handedly changed the face of agriculture in the Southern Cape. He brought into being a whole new body of knowledge that has made agriculture in this region not only much more profitable, but also far more sustainable. Jack farmed near Heidelberg (his son has now taken over). Rainfall there is a mere 350mm a year.

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To make crop farming even more difficult, this rain falls throughout the year. Add to this the fact that soils are for the most part very shallow – 200mm to 300mm deep – and full of stones! If you had asked me before I met Jack if it was possible to have healthy earthworm populations in this region, I would have given you an emphatic “No!”

Like most other farmers, Jack used to prepare his soil for planting by using either a disc plough or heavy disc after burning the winter grain stubble. But freak torrential rains in early 1980s, which caused the Laingsburg disaster, forced him to change the way he did things.

He woke up one morning to find horrific erosion on lands that had recently been prepared for planting. The road below one land was so covered in topsoil that it was impassable. Jack decided there and then to stop his risky tillage practices. He pioneered conservation tillage in the region and developed superior equipment to handle his difficult soils. He also built contours on all the lands. Until then, this was deemed unnecessary because of the low rainfall.

Rotational cropping
What I like most about Jack’s farming changes is that he instituted a sound rotational cropping system based on a perennial legume (lucerne) pasture, which was utilised by his Merino flock. Half the 1 000ha farm was planted to lucerne in a five-year rotation programme. Little did he realise at the time what a huge impact this would have on the build-up of the biological fertility of his soil, and how much this would save on fertiliser costs.

The improvement in the crops after the lucerne phase was immediately apparent. Jack soon realised that he could reduce his nitrogen levels on crops that followed the pasture phase. It took about a decade for those earthworms to show up, however. Earthworms are, as most readers will know, the barometer of soil life, because they feed on micro-organisms. Soil life produces nitrogen and plays a major role in increasing the availability of all other nutrients as well as growth stimulants.

Jack ran into a problem with excess nitrogen. The combination of what the soil was producing biologically and that which he applied (between 40kg/ha and 60kg/ha) resulted in the grain crops growing too luxuriantly, detrimentally affecting grain yields. As Jack put it: the wheat outgrew itself. He had an academic soil scientist conduct nitrogen fertiliser trials. One of these revealed that Jack could grow a 3,7ton/ha wheat crop with zero nitrogen fertilisation and that an application of 8kg/ha of nitrogen was optimum!

Hopefully, now you can see why I say Jack is an outstanding agricultural scientist – the largest part of his farming career was spent developing knowledge that’s enabled many other farmers in SA to produce better crops and animals at a lower cost on a sustainable basis.

John Fair is a leading expert on pastures and founder and head of the SA Biofarm Institute in Harrismith. Contact John on 058 622 3585 or at [email protected]. Please state ‘Biological farming’ in the subject line of your email.