Minimum Tillage Changes Planters & Cultivators

For centuries, farmers had plowed their entire field, turning the ground over. Later they broke the large clumps left by the plow into fine, particles providing the ideal seed bed. The seeds were planted in rows that were wide enough for a horse to walk through so that the weeds could be cultivated and killed.

In the 1950s and 60s, scientists and progressive farmers started asking a fundamental question — If rows are closer, can a seed still germinate and grow? Do we need to prepare the entire field as a seedbed?

Research led to some startling answers. Most seeds only need a couple of inches of finely worked, firm soil around them to germinate and grow. Researchers also remembered the lessons of the Dust Bowl days of the 1930s. Dry, finely-worked open fields can become dust storms very quickly, and some crop residue from the previous year’s crop can protect the fields. Conservation practices had already changed planting practices for most farmers — they now waited until just before spring planting to plow. The new research forced a new question — Why do we need to upset 500 to 1,000 tons of soil per acre with a moldboard plow when in reality we will use only about 8 percent of it for a seedbed?

The answer came back, We don’t need to plow that much, especially when herbicides are now available to keep down weeds.

At first, manufacturers like Allis-Chalmers developed “wheel track” planting systems. The idea was to plow the ground and follow immediately with the planter unit, eliminating a discing operation that used to break up the rough plowed soil. In the wheel track system, the tractor’s tires and a series of wheels on the planter broke down and packed the rough plowed soil and then the planter followed in those tracks.
The rough ground between rows caught and held rainfall and made it harder for the wind to pick up dust particles and dry out the topsoil.

The next step was to eliminate the plowing altogether.

William Luebbe (left) says that he was ready to accept the new research on minimum-tillage systems. He says his family was rotating between soybeans and corn when he noticed a peculiar pattern in the field. “I noticed that in the following crop of corn, it wasn’t even,” he says. “It was kind of up and down. Some of it was a little taller. But, I noticed all of it [the taller corn] was every six rows… It had been in beans the year before, and the combine left more of the trash every six rows as we went. And that conserved enough moisture so that you could see it in the crop growth the following year.”

In a more systematic way, the researchers had seen the same phenomenon. They developed planting and tillage systems that used stubble on the field to conserve moisture.

After the fall harvest, the residue of the old crop was left on the field. In the spring, new herbicides were used to keep down the weeds. Then, new planters came through with a series of tools mounted. First, there was a fluted, sharp round disc blade known as a “coulter.” The coulter would cut through the old stubble and the flutes would break up the rough soil and leave a 2½ inch band of fine soil. Usually, a fertilizer unit was next. The planter unit followed placing the seeds at the desired depth and spacing. Then the furrows were covered over and compacted.

These changes in planting and pesticide management practices had obvious consequences on cultivation technology. Leaving the stubble in between the rows and using herbicides to keep weeds down meant there was little if any need to cultivate the crops between spring planting and fall harvest. But it took a while for farmers to change centuries of agricultural practice.

Much of the research supporting minimum tillage practices was done in the 1960s, but it took some time for word of the results to filter out to the manufacturers and their customers. Some of the first minimum tillage equipment came out in the late 60s, but changing cultivation techniques involved an investment in new machines and faith that the new techniques would work. Gradually, over the last quarter of the 20th century, minimum- and no-till technology gained acceptance.

In the meantime, many farmers continued to cultivate and manufacturers adapted their cultivators to the new row widths and other changes. As tractors got bigger, cultivator units went from two- and four-row capacities all the way up to 12-rows. The next big debate was where to put the units. Through the early years of development, most cultivators had been mounted ahead of the operator where the farmer could watch each cultivator and make sure it didn’t plow out the plants he was trying to grow.

But as the cultivators got bigger and as ag engineers produced machines to tighter tolerances, cultivators were moved to the rear of the tractor. Simple guide systems were added to the front of the tractor, and gradually the farmers learned to trust the machines, keeping their eyes forward, rather than turning around all the time and steering the tractor and cultivator out of the middle of the row.

The new machines were great, but Dan Stork found out growing up that a eight-row cultivator only multiplied a kid’s chance of getting something wrong. “Dad was very particular,” he says. “You could be off a couple inches in the two-row [cultivator] and you were just off a couple inches. But if you’re off two inches every row, and you get up to eight rows, of course, then you’re 16-inches off. And I remember a few times having a little discussion with my dad about all the corn that I cultivated out that I shouldn’t have.”

Written by Bill Ganzel, the Ganzel Group. First published in 2007. A partial bibliography of sources is here.