I am a small farmer, 18 acres, with big ideas. Although the farm has been a somewhat successful truck farm, I am getting too old for the intensive management and am trying to convert to an organic no-till row cropping system. The experience I have with crimping a cover crop and no tilling into it, has led me to search to find an alternative weed methodology. Flaming, steaming, alternative herbicides have been assessed, but I think the best chance is to develop an in-between row mower: minimal soil disturbing.
No-till farming has numerous benefits over conventional farming: improved soil quality, less soil loss, less fuel. Organic farming has its benefits: no herbicide use, socially desirable and higher prices.
Combining those two is a challenge. Organic weed control in row crop situations is cultivation based; in no-till it is herbicide based.
Yet many farmers are trying for this holy grail as can be evidenced from the many SARE grants that focus on no-tilling vegetables into killed cover crop mulches.
Growing row crops in this way is challenging: row crops stay season long in the field, as opposed to vegetables that have a shorter life span.
The cover crop holds the weeds back for a little while but eventually the weeds will come up in between the row. Due to the high residue conventional cultivation is not possible. I want to develop an alternative weed control method: a three-point-hitch mounted 2-row mower that can be used for in-between row weed control. The design will be such that it can be scaled up to a 6-row application.
I want to develop an in-between hydraulically driven two-row mower that is inexpensive and effective and can be easily scaled up to 4 or 6 row and be used in row crops like beans and corn.
I want to make the design an open source design: I want to be able to provide design dimensions and drawings to anyone that is interested.
I want to use the mower at my farm.
I want to demonstrate and discuss the mower at my farm, and at field days at MU research center.
As described I am looking at building an in-between row mower to manage weeds that break through the crimped cover crop. Burning is not an option as the crimped weed mat may catch fire. The Rodale Institute has made great strides with the no-till organic row crops approach and has developed a specific crimper roller tool to kill the cover crop (usually rye) before the crop is no tilled into the cover crop.
I can replicate the crimping of the crop by merely driving over it with a two-row no-till planter. But I have not been able to replicate their yield success. I think that the Rodale people have been working the ground a lot longer, and have decreased their weed seed bank so substantially that escaped weeds growing through the mat, in between the row weeds is less of an issue for them than it is for me.
To make the construction of this mower as simple as possible I have gone with the choice for a hydraulic system: a hydraulic pump that runs off the PTO and drives the individual units, basically lawn mowers that run on hydraulic fluid.
I have thought about using a direct mechanical drive off the PTO shaft, but you’d have to come up with a transfer mechanism to drive 3 individual motors. (or 7 on a 6 row mower) and you ‘d have to come up with a different mode of turning the mowers.
There is a company that is developing an in-between-row mower unit that uses individual sickle bars of say 25 inch wide. But this is beyond my mechanical and engineering abilities.
The process of developing the mower has been relatively straight forward: buy a cultivator and use as many parts as you can; use a solid plate of metal to mount the motor on and use the same plate to be mounted to the individual cultivator.
Educational & Outreach Activities
I have interacted by email with a couple of interested farmers, but as the mower is not finished and tested yet, no outreach has been undertaken.
It is my intention to participate in field days at the MU research farms, to organize my own field day in conjunction with SWCD and Kerry Clarks’ research from MU. At the field day I will have the detailed drawings for handouts.
This in-between-row mower is to be used in organic no till where row crops have been no-tilled into a crimped cover crop, or in conventional row crop farming where the in-between-row weed pressure of herbicide tolerant weeds is too great. The in-between-row mower project is running behind schedule and going over budget. But what is new in the world of grants and deadlines? In addition to the one two-row mower for the SARE project I have started building a six-row mower for the University of Missouri. Consequently progress has been made, process bottlenecks have been found, technical issues have been isolated and are being addressed. As this is a progress report no final drawings are provided yet.
Some notes and observations on In-between row mower components.
– BLADE/ MOWER
One of the first things to be decided was the mower blade width. How close can a farmer cultivate? How close can a farmer mow? Cultivation is more forgiving than mowing. A shank or shovel can be 4 inches away from a plant, but still provide excellent weed control as the soil is thrown up towards the base of the plant.
As we are not sure of what is practically possible we have opted for a conservative 22 inch blade. This does leave about 3 inches on either side of the stems of the plants, as these do have a nominal thickness and are not perfectly straight once germinated. (It is understood that once we show the validity of mower weed control this system can be updated with automated GPS and you may get within an inch of the crop). Mower blades come in a variety of shapes, quality and thickness but are readily available. The idea is to make this mower with off the shelf parts, but right off the bat: you have a hydraulic motor on which you want to attach a lawn mower blade. It helps to have a machine shop in town, the part is simple, but probably beyond the precision ability of a farmer.
In order to be able to adjust the width of the mower blade (by buying different sized ones), you have to be able to adjust the width of the mower box. ( As I think that an open box without at least side guards would be too dangerous to operate.) The front end of the box is open to prevent the weeds from being bent down below the mower blade. The back is open so that residue can leave the mower without clogging up.
The mower box is made out of three different pieces. A flat 3/8th sheet of steel on which the hydraulic motor is bolted is the base of the mower. It is thick enough not to bend and is used to mount the individual mower to the toolbar gang. On the sides there are two pieces bolted — bolted pieces are flat pieces that were bent with a brake. To be able to bend the metal it had a maximum thickness of 1/16th, something I already regret. In hindsight, either the 90 degree angle has to be welded with thicker metal, or this part has to be made in a different way or outsourced. At this time the mower has not been field tested yet, but the thin material may not withstand too much abuse.
The actual design of the mowers, dimensions and metal thickness will be compiled in a set of building drawings to be handed out at the field days.
In order to reduce cost for the in-between-row mowers I purchased two old cultivators. A four row cultivator (five gangs) and an eight row cultivator (nine gangs), both set up on thirty inch spacing. They were both cut, one to three gangs wide, and one to 7 gangs wide. Second hand cultivators are very inexpensive; you start with something that is solid and strong enough to carry the weight of the individual mower box with minimal sideways movement, although you have to be careful with the heavily used cultivators as those do have more “slop” in them. The cultivators mount to the tractor with a common three point hitch.
There exist many different cultivators: if you start with used cultivators the design will not be exactly the same. The mower box will be the same but you have to adjust how you connect the mower box to the cultivator unit/shanks. It would be ideal to have the mowers mounted on a high boy so you mow as late as you can just before canopy of crops. But as this is practically prohibitively expensive we did settle on using cultivators behind tractors. The limiting factor for mowing will be the axle height of the tractor. In order to get more clearance the vertical bar to which the cultivator gangs are attached was made taller.
A hydraulic engineering firm was engaged in the design and choice of hydraulic components. The design is free but the stipulation then is that you have to order parts through their dealerships. But once you have a working prototype and a working design, you can then shop for the individual components. Below is the hydraulic schematics for the 6-row mower, for the 2-row mower remove the top 4 mowers, the flow divider/uniters.
The first component is the hydraulic pump which has to be sized correctly (to volume and pressure). It is mounted on the PTO, just like you would a sprayer pump. For the 2-row mower the pump runs at 12 gallon per minute, the 6-row at 22 gpm. From the pump the fluid goes IN SERIES (!) through the three hydraulic motors. It is here that you need the engineering to make sure that there is enough pressure and volume to operate the three motors. Maybe a parallel layout will work but it does mean that you will need two extra manifolds: one to split to the individual motors and one where the flows come together again. In a parallel layout fluid will look for the path of least resistance which may lead to one of the mowers not working as well as the others. By going in series you send the same volume through each pump but you have to make sure there is enough pressure at the last motor to be in the optimally functioning range of the motors.
For the 6-row mower it is not possible to put all the motors in series: if you send the same volume in series through 7 motors the pressure gradient will not work.
So for the 6-row mower you need to split up the flow in two groups: one side will have 3 motors, the other side 4 motors.
This flow divider is a special component, and it is expensive.
After the PTO pump there is a pressure relief valve to protect the hydraulic motors, the fluid goes through the motors, into a radiator, through a hydraulic filter, into a so called cyclone unit. This cyclone unit is a relatively new development in the hydraulic world: it reduces the air out of the hydraulic fluid and can thus replace the much larger reservoir that is filled with oil. There is a cost saving in reducing the total volume of oil and not using a metal hydraulic storage tank.
All motors have a drain/bypass valve to protect the seal in the motor, these lines do come together in a small manifold, which goes into the bottom of the cyclone.
These are the components…. and then you get into the hydraulic hoses that connect everything. It’s not the hoses themselves, but rather the connectors that are crimped on that runs into expenses.
The PTO works, the pump works, it has pressure built up, but there is a pressure relief valve that may be the problem, either it is all the way open, or all the way closed, and it prevents circulation. I did make a video that I am sharing with the engineer, hopefully he can instruct me as to where the snag is. I just got the tractor back so I can hook it up again; without a tractor it is really difficult to diagnose.