SP FAQ - Power requirement
This is a commonly asked question. On flat-to gently rolling ground and light soils Cross Slot openers require about 7 -9 engine horsepower per opener. Hillsides and heavier land may require 8-12 hp per opener.
Yes. Not only is it reduced at slower speeds, it is often reduced (almost halved) with the time a given field has been under no-tillage.
The easiest way to understand what happens is to imagine that the soil is like a lot of loose bricks. When they are scattered randomly you cannot walk across them because they move continuously. And if you were to pull a vertical tine through them it would meet little resistance as the bricks would part easily.
But if you then stacked them properly they will withstand enormous vertical loads without movement. But a vertical tine would still pass easily through them in a sideways direction because they would still part easily.
This is exactly what happens to the structural units of soil. They build themselves like well-fitting, but un-cemented bricks.
The penalty is not as much as you might imagine because Cross Slot openers are usually (and in fact, thrive on being) pulled faster than most other openers (up to 16 km/hr or 10 mph) which consumes power. In any case, it is the price operators pay to get superior biological results, especially the certainty of reliable crop stands and the likelihood of superior crop yields. If an operator sees no-tillage only as a cheap option, then that operator will never achieve crop yields approaching what is possible with tillage or with Cross Slot no-tillage.
The process of tillage makes drilling the seed a relatively easy and cheap procedure. When tillage is eliminated, no tillage then becomes a very demanding operation. Nonetheless the total energy you put into sowing each hectare is much less under no-tillage (by about 75%) than under tillage. The problem is that it is all applied in one pass, compared with several passes with tillage. This means one large tractor has to be used with no-tillage. And no-one has yet found a way of achieving consistent success with no-tillage without using a sophisticated seeding machine.
The only way to see the value of Cross Slot machines in their true perspective is to talk with current owners. A survey of New Zealand owners was carried out in 2001. It covered some 40,000 hectares (100,000 acres) drilled with Cross Slot machines over a period of 4 years (8 seasons) in some 6,000 separate fields, sowing a very wide range of crop and pasture species into an equally wide range of soil and residue conditions. Operators were asked to rank the percentage of their crops that turned out equal to or above the district average yields, and those that were below district average yields. In the latter case they were also asked to identify the causes of impaired crops. There was no gain for operators answering in any way but honestly.
90% of crops had been at or above district average yields. Some crops topped national yields and many topped district yields.
9% of crops had been below district average yields due to poor management (inadequate weed or pest control, too early planting, driver error etc i.e. non-drill problems).
1% of impaired crops were identified as machine problems, and one of those problems (tire tracks of drills causing seedling emergence problems) has already been eliminated.
In other words the Cross Slot machines proved to be 99% failsafe!
We are not aware of any comparable surveys of other no-tillage machines anywhere in the world, nor of the failsafeness of tillage itself, but we doubt if any would come up to this standard. Who, for example would claim that tillage has ever been 99% failsafe over the years?
No! There are examples of big and expensive no-tillage machines that turned out to have added very little to the failsafeness of no-tillage. And some smaller cheaper machines that achieved success in specific conditions. But it is hard to find operators of small cheap machines who are confident of achieving success all of the time with no-tillage machines.
We are saying that sophistication (not to be confused with size or complication) is always cost-effective.
There have been no-tillage openers from reputable manufacturers that required up to 14 adjustments per opener to cope with different soil and residue conditions. Such openers required a high level of operator skill to be successful. There are also well-known no-tillage openers for which operators can buy some 13 different after-market attachments designed to improve their performance. These are examples of complication. Just read some of the questions on the Internet chat session sponsored by No-Tillage Farmer magazine (USA) for evidence of the knowledge and skills being exchanged between operators in this regard as they constantly seek to improve the performance of their machines.
Cross Slot no-tillage openers have only three adjustments, and one of these is made from the tractor cab and is automated anyway. The only adjustment usually needed when going from one soil condition to another is the downforce applied to the openers. No opener modifications are ever necessary to cope with different types or levels of surface residue, wet or dry. Seeding depth may have to be adjusted when going from one crop to another, but fertilizer and seed separation occurs regardless of soil or surface conditions or forward speed.
This is sophistication.