An analysis of soil cultivating with harrow. New harrow will give much better crop

Introduction

Every grain grows only from which conditions the single grain has. It does not help one grain that the neighbor grain has excellent growing conditions if it doesn’t have splendid growing conditions on its own. Therefore the seedbed must give quite equal an optimum conditions for all the grains if you shall get even sprouting and high crop. But do today’s tine cultivators give you that? From experience gained by participating with the spring season through many years I am convinced that harrows can be greatly improved. An analysis of how the harrow works and its technology became an interesting experience.

The whole area must be harrowed

I investigated one of the most recognized harrow brands in the marked (one that I myself have used through many years) with regard to how homogeneous it cultivates the soil. The result you can see on the figure. It is 4 inches (10 centimeters) between each tine and each has 4 cm width. That means clearly spoken, that when you have run the harrow ones, you have harrowed only 40 % of the area. 60 % of the area has passed free in the dead zones between the harrow tines. My son said that he had to try to sight to get a harrow tine to hit tuft of grass in the field because the tuft would often else bow aside and be just as unhurt after he has run over it. I the figure you can see how little the harrow deals with the area. Surprised? Check your own harrow and see how much of the entire area it covers. The harrow must, after my opinion, be shaped in such a way that it cultivates the entire area when you pass the first time to reduce the driving to as little as possible and to get an even seedbed. Because, if you run twice you will still only have harrowed 64 % of the total area with todays harrow example. This, in fact, appears to me to be too bad because you can not compensate for this (as simple probability calculation shows) for a poor harrow by harrowing twice. Everyone should therefore design their harrow in such a way that the harrow the whole area and harrow it more even because it will result in better crop and less weed.

Figure. The placing of the harrow tine seen from above. Normal solution from well generally) recognized manufacturer. Here you can see how little of the area that really will be harrowed. Take particular notice of the large areas (60 %) that not will be cultivated by any harrow tine.

Even harrowing depth over the entire area

One other important characteristic that you must obtain is to cultivate down to approximately the same depth over the entire area and it is very important to get as equal seed dept for every grain and thus even humility that in its turn gives even sprouting. This you will only obtain if the soil is evenly cultivated down below the approximate 4 cm depth that every grain should be placed at. In order to get the best possible humidity you should rather not cultivate particularly deeper than the seed depth either. But today’s harrows at least crush the lumps someone will claim. Even this is not ideal on today’s well recognized tine harrows. The tines have so nice rounded profiles in the front that lump and weed will be treated all too gently. Why they are rounded so nicely is not good to know, but if I shall speculate over it, it is a heritage from earlier time’s primitive harrows. The harrow tine shapes have changed surprisingly little from the ones that was made in the beginning of the past century. Some of them have even rounded tine profiles in the front as if they still should have been made from wood.

How should an ideal harrow be shaped?

The first commandment is that it really cultivates all parts of the area quite equal. Every grain straw only gets a root length of 3-6 cm and thus it is of vital importance that no small parts of the area remain uncultivated at the same time as no parts must be harrowed too much. The same pass for the weed. Here, no parts of the area must be untouched so that the weed can grow in competition with the corn crop. Have you run over the area once so must each part of the area be cultivated in such a way that each grain got equal growing conditions. This will result in better crop and less weed. The harrow tines should be sharp edged and vibrate as much as possible to destroy lumps and weed and thus make an ideal seedbed. This we have achieved by making the tines much longer than our competitors, by shaping the harrow tines with a different profile on the spring steel in the tines and with a different bowing profile on the tines.
It is few ”substances” that exist in so varying harnesses and many consistencies as soil. Therefore we feel that it will be advantageous to produce the harrows with 3 different tines. ”Normal” stiffness for all normal soil types. ”Hard” for hard soil types like clay and ”light” for soil that is easy to cultivate like instance sand. This we can safely do because most farmers have broadly one soil type and the ones that have more must choose from their toughest soil type. The tines will in addition get a hold to the frame without use of nuts and bolts to increase the strength of the hold and because the strong vibrations might result in loosening bolts. By making ”unstable” harrow tines we achieve that the tines on a ”normal” harrow has an elasticity of 50 times longer out in the side direction and 6 times more in driving direction than the ”reference harrow” from our competitors.

Low weight

Harrows ought to have as low weight as possible to give as little soil packing as possible. Measurements shows that a tractor with 4-wheel traction can pull about 4/10 of its own weight. Out of this you can use a 4500 lbs (2000 kgs) lighter tractor if you save 1800 lbs (800 kgs) on an 18 ft (6 meters) harrow. Or a larger harrow with the present tractor size. Is it really possible to reduce the harrow weight that much? In our opinion, yes. By being very conscious about designing the frames in such a way that the steel strength in the frames is very efficient utilized we can achieve this even if every harrow tine has got much longer lengths. Our calculations shows that we get enough strength in our harrows with a harrow weight of 1800 lbs (800 kgs) where we see that today’s harrows weight more than 3600 lbs (1600 kgs). Less weight of frame parts and stag will also result in a more price friendly solution that compensate for the increased use of high quality spring steel in the tines and top quality hardened steel in the tine edges.

High-speed harrow

A harrow should be able to be driven with high speed because it then works better. In addition you will of course harrow larger areas in shorter times with the same equipment. If you can increase the speed from i.e. 4.5 mph (7.5 km/h) to 6 mph (10 km/h with a 18 ft (6 meters) wide harrow, the area you harrow will increase from 10 to 14 acres (4.5 to 6.0 hectare) with the same equipment. You can here save lots of time and money in a busy spring time season. How can you then achieve this? One of the problems I have experienced by trying to harrow with high speed is that the harrow has a tendency to start swinging from side to side, mainly because of the loose connection that is in use today. I have often wondered why it is so important to have the harrow connected so flexibly between the harrow frame and the tractor. It is often made from chain or rings. For me it looks almost like this is a heritage from past times when they used horses to pull the harrows. Less flexible connection would provide that the harrow runs more even and doesn’t become unstable at higher speed. That gives the possibility for larger speed and more pleasant running. The harrow tines must stand to hit stones even with fairly high speed without being damaged. Here comes another important argument for having much longer harrow tines in excellent quality spring steel. The tines will spring away (sort of stone release) without getting damaged. By having low weighted harrow the wheels can also be made smaller without increasing soil pressure. This will also save costs and reduce the price.

Production

Because no one of the today’s farming equipment producers makes harrows with such qualities, we have decided to start production of such a Flat harrow when we see that the interest is large enough so it will be possible for us to run an effective serial production. The new harrow can unfortunately nor either be demonstrated before it is patented because it is many patentable solutions in the concept. Serial production and patenting are today quite essential in order to be able to deliver top products at a reasonable price so that you also can get your chare of the saving.
How much can you earn by getting a Flat harrow next time you need a new harrow you must evaluate yourself. You know your own soil and can therefore best evaluate how large harvest loss you get each year because of poor harrowing, much driving uneven and late sprouting and areas with lots of weed and lump. Here it is room for huge positive surprises.

Reflections

We have either not during the study of harrows been able to not do some reflections as we saw the possibilities for improvements. During this work we got associations to the height jumper Richard Fosbury with his high jump technique ”Fosbury flop”. He started as known to study how the leg muscles had to work in order to get the best possible high jump result. In 1968 when he for the first time demonstrated his new technique it was laughter on the tribune because”everyone” knew how to jump height. But it became more silent as all the competitors missed and he continued to increase the height further, set new world record in height jump and won the most that year inclusive Olympic games. Today everyone jump by this technique.

Why this sample? Because it shows that it is not always the established who have right and that you can reach incredible results on well known areas if you are studying forces and techniques in detail without automatically accepting that the established techniques always are right. As we analyzed the harrow technique, the forces and movements we recognized that they where far from optimum and that it is great possibilities for improvements on an area where little has happened through long period of time. The moral you should draw from this are that it rather seldom is profitable just to copy an earlier solution. Unfortunately it is you as an user that will suffer from less crop than necessary every year. Surely a bit annoying seen from now on, but then it is even more important to do something about it now, as fast as possible. If you are interested or have views you are invited to contact us on email:flagro@fladby.com.

© Tron-Halvard Fladby/ 2006.05.29