‘On-land ploughing is a breeze’

It has rained lightly, and that immediately stops the plough in its tracks on the heavy soil of the Hoeksche Waard, an island just south of the Dutch city of Rotterdam. “Just three millimetres of rain is enough to turn it into a quagmire, certainly on the heavy clay we have here. It’s completely different to when you plough in the furrow with a plough tyre.”

Ploughing in green manure (grass) using the Lemken on-land plough. The tractor stands on broad tyres at 0.9 bar in order to prevent soil compaction as much as possible. – Photos: Peter Roek

Potatoes, onions and sugar beets

Ampt works in the west of the Hoeksche Waard, south west of the Netherlands, with 2 colleagues, and the 3 of them grow potatoes, onions and sugar beet together. They work according to a principle of ‘we will all do our best’. No one keeps tabs on each other as the bigger picture is more important, and investments in machinery are divided up in proportion to the farmland of each individual grower. The three of them have 275 hectares in total.

The farm in the Hoeksche Waard has heavy clay soil. That means that a little rain will stop the plough in its tracks there and then. “Just three millimetres is enough to turn it into a quagmire.”

New Lemken 6-furrow plough

Their most recent acquisition, the new Lemken 6-furrow plough, fits into the business strategy of ensuring future yields by paying attention to the soil as much as possible, which means minimising soil compaction and ensuring sufficient water supply (during drought) or drainage (when it is wet). For on-land ploughing, the 210 hp tractor stands on 900/60 R-38 tyres at 0.9 bar.

If only one thing has become clear over the last 10 years, it is that Ampt has to identify starting points for improving cultivation of the soil. “A few years back, I often pushed for 12 tonnes of wheat per hectare. Sometimes I can still manage that, but at other times I only get 8 tonnes. My average harvest nowadays is 10 tonnes. I cannot make up for that loss with precision or variable-rate seeding.”

Profile: Name: Leen Ampt (47). Location: Zuid-Beijerland (NL). Farm: Leen Ampt’s farm is one of three farms making up the HAM association. The total land area is 275 hectares. The cultivation plan is made up of one quarter potatoes, one eighth onions, one fifth sugar beet and a little less than one half is grains, grass seed and dry field peas. The soil is heavy clay that is 30 to 60% elutriable. He also has a job selling agricultural machinery alongside the running of his farm.

“The crop overcomes variations in conditions by itself by sprouting to a greater or lesser extent. It is soil compaction that is the problem, and that is why we cannot manage to get any closer to 15 tonnes of wheat per hectare. Once the potatoes are finished, the wheat has to be sown. We try to sow under good conditions, but we have not been quite as successful in a wet autumn.”

Compaction inhibits growth

The compaction of the lower soil layers on many fields in the Hoeksche Waard is a cause for concern, as it inhibits crop growth. “We have been checking the soil very frequently with penetrometers to see how compacted it is. You cannot even probe down into the soil where you have driven in the furrow with your plough wheel.

Weather station with soil moisture sensor up to one metre deep. Ampt reads it using his smartphone. “This allows you to learn how water moves through the soil after it has rained or after it flows in via the drains.”

“I have concluded that driving through the furrow with a firm tyre has a negative impact on the subsoil, certainly when it is wet and you’re driving with slippage, which is the difference between your gearbox speed and what you are measuring with GPS. On heavy soil, I have often ploughed with 15% slippage, and with 10% on lighter areas of soil. I think 15% is a lot, and I won’t plough with it any higher than that. If it were to involve a few passes, we attach a tractor to it or otherwise take a ploughshare off.”

Objections to on-land ploughing

Ampt’s fellow farmers have some objections to on-land ploughing: are there enough days left with good weather conditions to plough heavy soil to be ready for sowing? There is no basis for that concern in Ampt’s view. “I had 8 to 10% slippage in early November when I was ploughing in green manure under the grain stalks. It is a breeze with GPS just on the tractor, and makes plough steering systems redundant.” What also matters is that when you have slippage on top, the soil becomes a little compacted but not the subsoil. “It is always less at 0.9 bar, and what’s more, you plough in that soil again.”

Should conventional ploughing have better results under certain conditions, he can change the plough hydraulically. And there are always the wheels with plough tyres in the shed. That won’t be without its problems, however. Apart from the disadvantage that the wheel in the furrow compacts the subsoil in the case of conventional ploughing, Ampt in fact noticed that exactly where the outermost wheel at 2.5 bar had passed, the furrow does not fall apart because the wheel had just pressed the soil together.

The compressor on the Beco Super 2200 tipping trailer, with automatic tyre pressure system. In less than 20 seconds, the tyre pressure changes from low in the field to high enough for transport by road.

Diagonally loosening

The positive experience of on-land ploughing with GPS is partly due to the fact that Ampt always loosens the wheel gauges diagonally first before ploughing. “We go over it with the subsoiler – not too deeply, say 30cm. It goes at an angle to the tracks and the direction of ploughing. That helps to prevent the tractor and the plough following the previous tracks.”

The crop farmer anticipates that on-land ploughing will contribute towards maintaining or even restoring the productivity of his soil. “It’s still subject to 3 conditions, though: early, level and dry. If you sow well in the autumn, you will reap the benefits in the spring.”