Tillage Practices - A Guide

2. Abstract Tillage has been used for millennia to prepare the soil prior to sowing many of the annual grain crops. It involves applying power to break up and rearrange the entire topsoil structure. It has the primary aim of destroying weeds and pests but is also important for incorporating, redistributing or releasing nutrients and making the soil texture suitable for seed sowing, seed germination and for easy penetration of seedling roots. Introduction The English word “tillage” is derived from the OldEnglish “tillen” which means “to toil”. With only human or animal power available, it took a long time and much toil to till even moderate-sized areas of land. When tractors became available, larger areas could be cultivated per person. Tractors and their increasing power also made it possible to expand cropping areas into more difficult soils. In time this created problems in less robustly structured soils with many loamy and fine-textured topsoils weakening within a few years of tractors replacing animal teams for tillage. Fortunately, such weakening is reversible. In the absence of tillage, structural stability of soil aggregates improves after several years under, for example, subterranean clover pasture. Surface water runoff can increase following tillage on many soils, causing increased water erosion particularly on sloping cropland. Erosion by wind is also increased by tillage because the topsoil is left bare and loose. Other potentially undesired effects of tillage include reducing soil organic matter through oxidation and deleterious effects on soil micro flora and fauna, also leading to reduced soil structural stability and increased surface runoff and water or wind erosion. If it were possible to retain the desired effects of tillage while reducing or removing the problems it can generate, that would be a major step forward. 1.0Tillage practices have a direct correlation to soil health Farmers have a direct impact on soil quality through many of their field practices, including tillage. Many areas, including Michigan, have experienced a heightened sense of awareness of the importance of soil quality. Farmers have a direct impact on soil quality through many of their field practices, including tillage. Soil erosion from wind and water increases as tillage of a field increases. Though the soil may not move off the field, it will be moved from higher to lower elevations, causing some parts of the field to be less productive. According to the Michigan State University Extension, compaction is also a common side effect of tillage – at the soil surface, the plow layer and the subsoil. Crusting at the surface happens when unprotected wet soil particles are pounded together to form a thin, dense surface layer. This hard surface inhibits water from infiltrating down through the soil profile. It will also increase the potential for water runoff after rain or snow.

3. Compaction at the plow layer not only causes problems with production but also makes seedbed preparation more labor-intensive. Compacted soils require a secondary tillage followed by a packing tool to make a good seedbed and ensure a good plant stand. Every pass over the field – for any type of tillage or by other farm tools – can break up soil aggregates and reduce the ability of the soil to hold moisture. Heavily tilled fields may have a good seedbed for planting, but any rainfall after planting may cause the surface to seal, resulting in surface compaction. Some soil at this point will harden, reducing plant viability. Soils will soften when it rains again, but plants will suffer as soon as it dries out. Subsoil compaction, or plow pan, is compaction below the tilled surface layer. The pressure of tillage equipment pressing on the subsoil can cause this. The pressure of tractor tires on moldboard-plowed furrows also can cause subsoil compaction. The effect of subsoil compaction can be exacerbated when fields are tilled when they’re wet. Many farmers are addressing the compaction problem by using a minimal tillage system. There are several types of minimal tillage systems with various degrees of soil disturbance. With no-till, the soil is not disturbed during planting and a high amount of crop residue remains on the soil surface. With ridge- till, the seedbed is prepared on ridges. The soil between the ridges is undisturbed, and the residue is left between the ridges. Mulch-till involves a minimal amount of disturbance prior to tillage. Chisel plowing is a common type of mulch-till. An important part of all of these practices is that residue is left on the field. Michigan State University Extension educator Paul Gross visited several fields throughout IsabellaCounty during the fall of 2012 and measured the amount of residue left after various tillage types. His findings are illustrated in the accompanying photos, which show that limited tillage greatly reduced compaction. Fall tillage is a common practice on many Michigan farms. Farmers should understand how this and other tillage practices affect their soils and their subsequent crops. The challenge is that no two farming

4. systems are exactly the same, so farmers need to find a way to reduce tillage that will work for their individual farms. Some may need to use more than one tillage practice in their crop rotations. 2.0 Types of Tillage Tillage operations are broadly grouped into two types based on the time. Types of Primary Tillage Depending upon the purpose or necessity, different types of tillage are carried out. They are deep ploughing, subsoiling and year-round tillage. Deep Tillage Deep ploughing turns out large sized clods, which are baked by the hot sun when it is done in summer. These clods crumble due to alternate heating and cooling and due to occasional summer showers. This process of gradual disintegration of clods improves soil structure. The rhizomes and tubers of perennial weeds (world's problematic weeds viz., Cynodon dactylon and Cyperus rotundus) die due to exposure to hot sun. Summer deep ploughing kills pests due to exposure of pupae to hot sun. A deep tillage of 25-30 cm depth is necessary for deep rooted crop like pigeonpea while moderate deep tillage of 15-20 cm is required for maize. Deep tillage also improves soil moisture content. However the advantage of deep tillage in dry farming condition depends on rainfall pattern and crop. It is advisable to go for deep ploughing only for long duration, deep rooted crops. Depth of ploughing should be related to the amount of rainfall that it can wet. Subsoiling

5. Hard pans may be present in the soil which restrict root growth of crops. These may be silt pans, iron or aluminium pans, clay pans or -man-made pans. Man-made pans are tillage pans induced by repeated tillage at the same depth. Root growth of crops is confined to top few centimetres of soil where deep penetration of roots is inhibited by hard pans. For example, cotton roots grow to a depth of 2 m in deep alluvial soil without any pans. When hard pans are present, they grow only up to hard pan, say 15-20 cm. Similarly, vertical root growth of sugarcane is restricted due to hard pans and it is not compensated by horizontal spread. Subsoiling is breaking the hard pan without inversion and with less disturbance of top soil. A narrow cut is made in the top soil while share of the subsoiler shatters hard pans. Chisel ploughs are also used to break hard pans present even at 60-70 cm. The effect of subsoiling does not last long. To avoid closing of subsoil furrow, vertical mulching is adopted. Year-round Tillage Tillage operations carried out throughout the year are known as year-round tillage. In dry farming regions, field preparation is initiated with the help of summer showers. Repeated tillage operations are carried out until sowing of the crop. Even after harvest of the crop, the field is repeatedly ploughed or harrowed to avoid weed growth in the off season. Secondary Tillage Lighter or finer operations performed on the soil after primary tillage are known as secondary tillage. After ploughing, the fields are left with large clods with some weeds and stubbles partially uprooted. Harrowing is done to a shallow depth to crush the clods and to uproot the remaining weeds and stubbles. Disc harrows, cultivators, blade harrows etc., are used for this purpose.

6. Planking is done to crush the hard clods to smoothen the soil surface and to compact the soil lightly. Thus the field is made ready for sowing after ploughing by harrowing and planking. Generally sowing operations are also included in secondary tillage. Layout of Seedbed and Sowing After the seedbed preparation, the field is laid out properly for irrigation and sowing or planting seedlings. These operations are crop specific. For most of the crops like wheat, soybean, pearl millet, groundnut, castor etc., fIat levelled seedbed is prepared. After the secondary tillage, these crops are sown without any land treatments. However, growing crops during rainy season in deep black soils is a problem due to ill-drained conditions and as tillage is not possible during the rainy season. Broadbed and furrows (BBF) are, therefore, formed before the onset of monsoon and dry sowing is resorted to. For some crops like maize, vegetables etc., the field has to be laid out into ridges and furrows. Sugarcane is planted in the furrows or trenches. Crops like tobacco, tomato, chillies are planted with equal inter and intra-row spacing so as to facilitate two-way intercultivation. After field preparation, a marker is run in both the directions. The seedlings are transplanted at the intercepts.

7. Layout of Seedbed AFTER CULTIVATION The tillage operations that are carried out in the standing crop are called after tillage. It includes drilling or side dressing of fertilisers, earthing up and intercultivation. Earthing up is an operation carried out with country plough or ridge plough so as to form ridges at the base of the crop. It is done either to provide extra support against lodging as in sugarcane or to provide more soil volume for better growth of tubers as in potato or to facilitate irrigation as in vegetables. Intercultivation is working blade harrows, rotary hoes etc., in between the crop rows so as to control weeds. Intercultivation may also serve as moisture conservation measure by closing deep cracks in black soils. 2.0Plow Moldboard plowing can provide soil pulverization and nearly complete burial of weed seeds and residue. Secondary tillage operations, such as disking or field cultivation, allow for uniform incorporation of fertilizers and pesticides and smoothing of the soil surface. Additionally, crop cultivation for weed control is usually practiced. Soils that tend to be wet arewell suited for a fall moldboard plow system. Plowing speeds up warming and drying of these soils, thus avoiding spring delays. Although vulnerable to erosion, wet soils are often relatively flat, thus soil loss caused by runoff may not be a major concern. With fall moldboard plowing, more time is available in the spring for additional tillage operations. However, on steeper slopes, the

8. potential for soil erosion by water throughout the winter and spring is great because surface residue in not available to protect the soil. Likewise, in drier climates, the potential for soil erosion by wind is greater without residue cover. Spring plowing reduces the potential for wind and water erosion throughout the winter, but the labor and time requirements in the spring can offset these advantages. Furthermore, spring plowing may produce clods, which require unplanned tillage operations to develop a seedbed. Excessive soil moisture losses, especially in dry years, is another disadvantage with spring plowing and the associated secondary tillage operations. 4.0 Tillage or No-Tillage: High Yields or Soil Health? The growing emphasis on soil health could be a deciding factor in what type and how much tillage farmers will utilize in the future. Dealers who haven’t picked up on the push for “soil health” in the last few years haven’t been paying enough attention. When you see mention of ag-related trends in media like the New York Times, it’s probably not because they were looking to write something about agriculture (“Farmers Put Down the Plow for More Productive Soil,” New York Times, March 9, 2015). In all likelihood, the collective volume of coverage soil health is getting in local, regional and ag media somehow got their attention.

9. In many cases, for the general public and mainstream media, when discussing issues such as this, it tends to center on conservation, the environment and “regulation of agricultural pollution.” For the farmer, the issue is far more pragmatic. A Texas farmer, who switched to no-tillage in 2005 for his 6,000 acres, was quoted in the article, and put the issue into “farm” perspective: “My goal is to improve my soil so I can grow a better crop so I can make more money. If I can help the environment in the process, fine, but that’s not my goal.” Farm equipment dealers and manufacturers who make tillage tools are dragged into the debate because conventional tillage practices are often cast as the villain when the discussion turns to soil health. To paraphrase Shakespeare’s Hamlet, “To till or not to till, that is the question.” That’s to say, to purchase tillage equipment or not to purchase tillage equipment is becoming the question. It’s one that is near and dear to the hearts and wallets of many dealers and equipment makers. Do farmers who have consistently produced high crop yields by using conventional tillage have to give it up to attain a high level of soil health? Or is there a middle ground that can produce high yields while improving soil health? Soil Health: A New Fervor The amount of recent attention devoted to soil health is clearly beneficial as a precursor to increasing crop yields that will be required to feed the extra mouths that will need to be fed in the next 20-30 years. This year has been designated as the International Year of Soils. According to USDA, this year of

10. awareness aims to increase global understanding of the importance of soil for food security and essential ecosystem functions. “I think part of the excitement is the catchiness of the new term. Years ago we called it soil quality and now it’s soil health,” says Tony Vyn, professor of agronomy at Purdue University. “Part of it is also the growing concern for hypoxia (oxygen depletion) in the Gulf of Mexico and the phosphorous going into Lake Erie.” These factors, he says, would seem to indicate that there’s significant nutrient loss from the soil taking place, including phosphorous and nitrogen. “This and increased societal scrutiny have advanced the notion that we need to increase our attention to soil health.” He says that farmers need to placate these concerns by emphasizing the positive things they’re doing through farm practices to hold soil, sediment and phosphorous in place. Vyn cites practices like no-till and strip-till that improve nutrient cycling through crops, as well as the use of cover crops to avoid nutrient losses to air and water. “We’re learning more and more about soil microbes that we have never known before. And if we give them a good home they work for us,” says Jodi DeJong-Hughes, an extension educator at the University of Minnesota. “It’s only in the last 5-7 years that we have really talked about soil health. For many farmers, it’s a really new concept. With a new practice, many farmers will watch other farmers try it out first. If they are successful, then they’ll give it a try too.” For Paul Jasa, an extension engineer at the University of Nebraska-Lincoln, all of the talk about soil health is a wake up call to farmers and the rest of the industry. “Soil health disappeared from the radar screen when large scale farming really took over and farmers could buy technology and we didn’t have to worry about soil health.” Jasa says prior to 1950, everybody was an organic farmer. All of the pesticides, fertilizers and technology weren’t available. Farmers practiced diversity through crop rotation. They utilized things like green manure cover crops that boosted soil health.

11. “We became lazy managers with the introduction of commercial fertilizers, pesticide to kill pests and herbicides to kill weeds. We ignored the importance of a healthy soil system and started doing it with technology instead,” he says. Jasa points to the emergence of glyphosate-resistant weeds as a more recent example of how the industry has gotten lazy when it comes to soil health. “Unfortunately, a lot of our technology serves as a band aid. We are treating the symptoms. We’re not treating the problem itself.” He likens issues of soil health to human health. “My doctor says my cholesterol is too high and I need to lose some weight. It’s a lot easier for me to take a cholesterol-lowering pill than it is to exercise and watch what I eat.” Tillage & Tradition DeJong-Hughes from the University of Minnesota places herself on the tillage side of the debate, but with a big qualifier — farmers need to reduce it. “If you reduce your tillage, you will improve your soil health. Whether or not a farmer looks at reducing their tillage depends on their goals and perceptions. Do they believe profit and reduced tillage are separate goals? Do they believe the only way to get the highest yield is to aggressively till? Or do they believe improving soil health will ultimately improve profit and yields?” She says another aspect of reducing tillage that should get farmers’ attention is it goes hand in hand with reducing costs. “I’ve seen that by reducing tillage we won’t lose yield, however, we decrease our inputs, especially fuel and labor, plus it improves soil health. Once farmers see this and get used to it, they usually keep going in that direction.” DeJong-Hughes estimates that about 70% of Minnesota farmers utilize a disc ripper, disc chisel and/or a chisel plow, which she considers “conventional tillage” and which leaves less than 30% residue compared to a moldboard plow, which leaves less than 15%. “It wasn’t that long ago that moldboard plowing and leaving the soil black with no ‘trash’ made you a good farmer. We’re trying to show there are new ways to leave more residue.” She says the biggest battle in getting farmers to look at new techniques is tradition. “Never underestimate tradition. If their dads did it and their dad’s dad did it and it worked for them, then why change?” When conventional farmers see residue levels created by 3 years of corn-on-corn, they’ll probably pull out their plows, says DeJong-Hughes. “I’m trying to show them that there are other ways to manage residues without a plow. If they have a corn/bean rotation, they have a lot more options.” Regardless of circumstances, DeJong-Hughes is recommending to the farmers she’s working with that the best approach to tillage is to reduce its depth, number of passes and aggressiveness. “I’m pushing for the least amount of soil disturbance possible. I’ve suggested that some of them take a look at vertical tillage to manage heavy residue build-up.”

12. What she’s leaning toward is getting her farmers to consider strip-till. “It’s not going to be ideal for everyone, but I think it’s the best marriage of no-till and full-width tillage. You can get the seed bed to warm up while leaving 50-60% residue to protect and build soil health. With strip-till, you incorporate your nutrients so they’re not sitting on top of the soil, and, if needed, you can also till in lime. In between the row, you have full residue where you get all your soil health benefits, including erosion protection, water infiltration and water-storing capacity. “It’s a long list of benefits for farmers. It’s a wonderful way to reduce tillage but still produce high yields,” says DeJong-Hughes. When it comes to “pure” no-till, she doesn’t promote it because it is at a yield disadvantage unless it’s done on sandier soil. “On really nice growing seasons, no problem. When we have a cold and wet spring, we have research that shows no-till gets hit hard, even in southern Minnesota.” On the other hand, she acknowledges that in states west of Minnesota, Iowa and Missouri that have very little rainfall, no-till can be an excellent solution. “My state and east have a lot more rainfall — 2-3 times more —and we don’t need to preserve the soil moisture like others have to do. In the spring, we need to get our soil to dry out.” Though he would prefer that farmers avoid the conventional tillage practices many utilize, Francisco Arriaga, assistant professor & extension soil scientist at the University of Wisconsin-Madison, says there are times when some level of tillage is necessary. He points to this past year when farmers in different parts of Wisconsin needed to harvest in less than ideal conditions; it was too wet. “They called concerned about compaction and rutting issues to the point where their ground was not level, so they didn’t have a good seedbed. In this scenario, tillage is about the only way you can go about it. “It’s bad enough that they’re probably going to have to do some discing, and what I recommend then is to check to see if there’s any subsoil compaction. There might be some areas where they have to do some subsoiling. This is a prime example of not being able to avoid tillage. When conditions are not the best and it’s time toharvest, the farmers must get in the field. It’s a business after all and they have to get their crops out,” says Arriaga.

13. He believes crop rotation is an ideal approach to minimize tillage and discourages farmers from planting corn-on-corn for more than 2 seasons. In instances when they plant corn after corn for 3 or 4 years, some tillage to address residue buildup will improve yields somewhat, Arriaga says. “This was the original purpose for developing vertical tillage. It was a pretty good way of addressing the residue without disturbing the soil too much,” he explains. “But it was meant to be a one-pass operation. A lot of people are doing multiple passes, sometimes in the fall, sometimes fall and spring, and this can actually be detrimental. It varies a lot, depending on the manufacturer and the setup of the implement. It can create severe disruption of the soil, which, in my view, is not a good thing.” Till/No-Till Middle Ground? While many soil scientists and extension engineers would prefer that farmers avoid tillage whenever possible, others believe strongly that it’s often necessary and good, and some believe the middle ground is where vertical tillage comes in and sets the stage for a farmer to initiate the use of no-till and strip-till. “Corn is a good example of a crop that really likes tillage if it can get it, and it will respond accordingly by producing high yields,” says Tom Evans of Great Plains Mfg., a maker of tillage and seeding equipment. “It’s a different matter if you’re on highly erodible land. Then too much tillage can add to the problem. “So regarding your question to till or not to till, the answer is yes,” he says. But rather than only discussing conventional tillage vs. conservation tillage, Evans says there are really three categories that need to be brought into the conversation: conventional tillage, vertical tillage and no-till. He goes on to say, conventional tillage, which would typically include a moldboard plow, a disc harrow and a field cultivator, “needs to cease. Conventional tillage restricts the root system in a lot of crops because it causes density changes in the soil profile and it’s prone to erosion. When it comes to pure conventional tillage, I believe it’s a negative for everybody.”

14. Evans maintains that vertical tillage is the ideal method for creating soil density and healthier soils. “It makes a uniform density as deep as possible and that depends on the farmer’s ground. The idea is to get as much of the soil profile as practical to a uniform density. To do this, the first time you’re probably going to run a subsoiler as deep as practical, 12, 14, 16 inches deep to reset the profile.” Evans makes a point of stressing the use of a subsoiler, not a v-ripper. “A subsoiler will actually pick the soil up and set it back down and bury no residue if it’s run properly. A v-ripper with a parabolic shank, on the other hand, is designed to roll the soil over, so it will disturb it way more than what an inline subsoiler would do. “Vertical tillage doesn’t work against no-till, it works with no-till,” he explains. “If a farmer is going to convert to no-till, the first thing he should do is take an inline subsoiler and reset the profile of the soil and then no-till on top of it. He may not have to subsoil again for years. But that will reset the profile to a uniform density while you’re no-tilling on top of that.” It’s All About the Soil Joe Dedman, vice president of agronomy for Monty’s Plant Food Co., is a proponent of no-till and he has another theory on the growing attention to soil health. He says, “We’ve pretty much brought everything that we have in our arsenal to the marketplace, including new chemistries, new genetics and new varieties. And of course, farmers are paying for that stack of genetics they have in that seed to help protect it from insects and diseases. At the same time, we’ve not made the jump in yield that should come along with all this new technology. People are saying, ‘There’s something missing here.’ What we’ve been missing is paying attention to thehealth of our soils.” Dedman also serves on the soil research team at Soil Renaissance, a branch of the Noble Foundation. He says they’re working to formulate standards to measure soil health which allow producers to know the condition of their soil, which can affect its production capabilities. What people are beginning to discover, Dedman explains, is the more they treat their soils like living organisms and maintain and feed them, the more it benefits the soil’s biology and the more its biology will increase. “The more it increases, the more it lends to soil health,” he says. “Then you see better crop yields, better crop quality and better seed test weights. All of these things go together with soil health, and conservation tillage goes hand-in-hand with better crop yields and soil health.” The more attention soil biology and soil health get, the more conventional tillage will be scrutinized. He explains that the soil ecosystem builds networks. Earthworms dig channels through the soil and deposit all kinds of nutrients and break nutrients down. Conventional tillage destroys these networks every year when farmers prepare a seedbed. So the biology must to be rebuilt every season, according to Dedman. “The more emphasis that is put on soil health and the more data that begins to get released, I believe it will show the tremendous advantage of not tilling the soil as much as we have been. By growing the soil ecosystem to its maximum potential, we will take yields a lot higher than we’ve ever been able to do. That’s because it’s all about the soil,” he says. “Even though tilled soil warms up sooner, it also exposes the biology that’s in the soil on the surface to too much heat and too much light,” says Dedman. “You could say it kills them. I want the numbers to go up when we’re talking soil health. Soil health is related to undisturbed soil or where there’s very little

15. soil disturbance to allow the ecosystem to continue to grow and to build and multiply. We need them to multiply to do all the work for us when we throw the fertilizers down or apply chemicals. We need those chemicals to break down for next year’s crop.” Regardless of the new technology to maximize yields, “It still goes back to soil health; feeding the ecosystem that’s in the field so it works for me,” he says. “There’s a whole new horizon that people are writing about and digging into and teaching. There are all kinds of things yet to be discovered about soil health.” Advocating for No-Till To say dedicated no-tillers are passionate about what they do would be an understatement. Boak of Salford says it’s “a bit like a religion. You get guys who start down the road to no-till and they work really hard to make it work for them. All of a sudden, they’re opposed to anybody who does tillage.” Jasa of the University of Nebraska. makes no apologies about his stance on no-tilling vs. conventional tillage. “If you think about it, Mother Nature never tilled her soil. She’s been growing things for a long time. She has the best soil structures anywhere because it’s never been tilled. That’s what we want to get producers to do in their fields as well.” He says when it comes to soil health, tillage is one of the things a lot of people are looking at because it really hasn’t been considered much before. “Tillage has always broken down soil health and destroyed some soil structure. No-till is the practice that’s going to build the soil health the best,” Jasa says. And so when it comes to no-till itself, “Once a farmer builds a good soil structure and no longer destroys it with tillage, soil health builds. More importantly, the structure allows water infiltration, air and gas exchange, and better root penetration. Once your soil gets healthy, the need for tillage sort of drops away. In the past, tillage begot tillage. If a soil was tilled and you didn’t have that air exchange, you had to till again to fluff it up to get some air exchange to get the plant up and growing. So if tillage was so good, why do you have to do it again next year? It’s a temporary fix,” says Jasa. But soil doesn’t get fixed by only parking the tillage implement. It often takes a couple of years before producers see the change and, according to Jasa, a lot of producers don’t have the patience, especially those who want to raise a single crop and be done with it. “If they’re willing to do cover crops, crop rotation and apply livestock manure, they can help jumpstart soil biology. Then no-till becomes a lot easier and a lot faster,” he says. What tillage does is “erase some management mistakes,” Jasa adds. “It made us lazy managers.” For example, if the farmer didn’t do a good job of weed control in the early season, he goes out and tills again. If he had a crust on his field, he went out and tilled it again, which left little or no soil structure, so the soil formed a crust again.” And while they can be valuable tools, Jasa says, Roundup Ready crops made lazy managers out of a lot of no-tillers. “In some cases, people switched to no-till or Roundup Ready technology because it took less management than tillage did. Unfortunately, those are the same producers who are having problems with glyphosate-resistant weeds. Roundup Ready technology is only a tool to be used, but it has been misused.”

16. When it comes to corn yield, Jasa explains that he’s had a set of tillage plots since 1981 that he uses to compare no-till to fall plow, fall chisel and spring disc. “The first couple of years until I got the soil biology working with me, the yields were statistically the same. After about 5 years, no-till has always been the most profitable statistically. Whether it’s been the highest yield or not isn’t that important. It’s more profitable because I don’t have the cost of tillage.” Reference Suitable methods of tillage for the farm | fao.org | Retrieved on 20.04.2020 from http://www.fao.org/3/y5146e08.htm Plough | Retrieved on 20.04.2020 from https://www.beroni.in/products/tillage/plough Reversible Mould Board Plough | https://www.fieldking.com/product-portfolio/plough/reversible- mould-board-plough/ Christina Curell, February 2014 | Tillage practices have a direct correlation to soil health | canr.msu.edu | Retrieved on 20.04.2020 from https://www.canr.msu.edu/news/tillage_practices_have_a_direct_correlation_to_soil_health Dave Kanicki, 2015 | Tillage or No-Tillage: High Yields or Soil Health? | farm-equipment.com | Retrieved on 20.04.2020 from https://www.farm-equipment.com/articles/11545-tillage-or-no-tillage-high-yields-or-soil-health Tillage :: Types of Tillage |agritech.tnau.ac.in| Retrieved on 20.04.2020 from http://agritech.tnau.ac.in/agriculture/agri_tillage_typesoftillage.html Plow | cropwatch.unl.edu | Retrieved on 20.04.2020 from https://cropwatch.unl.edu/tillage/plow Tilage | Retrieved on 20.04.2020 from https://farmease.app/category/tillage