Tillage and Seeding

this unit of study deals with the various aspects of tillage and seeding in crop production tillage is the manual or mechanical stirring of soil tillage systems describe the tillage operations or steps used to prepare the land for planting and growth of crops methods of tillage and seeding have greatly varied from the earliest recorded history of Agriculture where simple tillage tools were used to the mechanically intensive and complex agricultural systems although methods of tillage widely varied throughout the world the goals and purposes remain the same you should now stop the VCR and study the section entitled goals and purposes of tillage systems in your text then return to the VCR for further tutoring one of the main goals and purposes of tillage is to prepare an adequate seed bed for rapid crop establishment an adequate seed bed is hard to define because it may vary for different crops and for the environment in which they are grown generally warm soil with adequate moisture aeration and soil conditions provides good seed to soil contact and is characteristic of a good seed bed the goals of tillage may also include incorporation and mixing of crop residues manure chemical fertilizers or pesticides in the soil weed control may also be a goal of tillage and may be conducted before the crop is planted between planting and emergence or after the crop has emerged conserving soil and water for future generations is another important goal of tillage systems tillage in general increases erosion potential because the ground cover is disturbed however different tillage systems can be selected that leave more crop residue on the soil surface and to help reduce soil loss and conserve and improve water quality the next section for study is tillage vocabulary you should now stop the VCR and study the section on tillage vocabulary in your text and return to the VCR for further tutoring the terms primary tillage and secondary tillage are frequently used and may be easily confused two main differences between primary and secondary tillage are the depth of tillage and type of implement primary tillage is usually deeper and the equipment is usually more heavily constructed for the initial tillage of an undisturbed soil the purpose of primary tillage is to bury residues and to break up the soil the depth of tillage is usually 15 to 36 centimeters the purpose of secondary tillage is leveling and firming the soil in the final stages of seedbed preparation the depth of secondary tillage is usually 5 to 15 centimetres there are many implements used in primary and secondary tillage disc plows and moldboard plows two primary tillage implements have similar functions they invert and mix the soil the moldboard plow uses a curved steel plate called the moldboard to invert the soil and bury residues the widespread use of the moldboard plow has probably changed the course of Agriculture more than any other tillage implement the moldboard plow is very effective in breaking sodded ground and burying surface residues but those attributes have largely contributed to severe soil erosion the chisel plow is also a primary tillage implement however it has been designed to leave more residue on the soil surface to help control erosion chisel plows or variations of the chisel plow are widely used in all areas of farming heavy crop residues such as stalks that remain field after corn harvest England can plug up the chisel plow or reduce its efficiency therefore stocks may be disked or chopped into smaller pieces a combination chisel plow has disk blades or Coulter blades attached in front of the chisel plow to avoid a separate preliminary disking operation the sweep plow also called the stubble mulch plow has been used in dryer farming areas it does not bury surface residue however it will loosen lower layers of the soil and destroy the roots of growing weeds the crop stubble on the soil surface remains undisturbed and helps prevent wind and water erosion of the soil the stubble also helps catch snow which results in more soil moisture for planting the following spring a powered rotary tiller is similar in function to the garden rotary tiller however it's bigger and constructed for field use it leaves a very fine seed bed but too much tilling can powder the soil which results in crusting after a heavy rain Lister betters can also be used as primary tillage implements the v-shaped moldboard can throw soil into ridges or beds thus leaving an alternating Ridge furrow situation some factors to consider in primary tillage are depth and time of primary tillage deep primary tillage generally has not resulted in any yield increases and therefore shallower primary tillage would be more economical because of fuel savings in some cases in areas that receive winter freezing and thawing heavy flat soils with small slopes are frequently tilled in the fall this is because soils are usually drier in the fall and the freezing and thawing action can help break up compacted soil in general practice however delaying tillage until the spring is recommended reduced the potential for soil erosion secondary tillage implements mainly consist of various Haros and field cultivators the tandem disc harrow commonly referred to as a disc is one of the most widely used secondary tillage implements in the u.s. disking helps mix crop residue into the soil breaks up clods and tills to a depth of 8 to 15 centimeters an offset this Carol is also a disc but is heavily constructed mainly for primary tillage therefore it is often used to break up undisturbed soil until much deeper than the tandem disc area this is an example of where tillage terminology can be confusing even though both the offset disc harrow and the tandem disc harrow are called discs their purposes are often different field cultivators are similar to chisel plows except they are lighter constructed and are operated at a shallower depth and have many more shanks and shovels than chisel plows field cultivators are widely used throughout all farming areas in the US and in many instances are replacing the use of the tandem disc harrow spring spike and tine tooth Haros are lightly constructed secondary tillage implement that prepare the final seed bed the operating depth is generally less than eight centimeters when seeding small seeded crops good seed to soil contact is important for proper germination and establishment to help prepare a fine seed bed for good seed to soil contact roller Packers are sometimes used to help further break up clods and prepare a very smooth soil surface roller Packers are essentially surface implements and do not stir the soil there is some risk of compacting soils using a roller Packer particularly in soils that can be easily compacted or if the roller Packer is used just before an intense beating rainfall this may result in a soil crust developing at the soil surface which can hinder the emergence of germinated seedlings another important part of tillage vocabulary is the terminology used to describe general types of tillage systems tillage systems is a term that refers to the nature and type of tillage sequences one may use to prepare the soil for planting unfortunately tillage systems terminology is not standard among or within different farming regions for example in the Midwest Corn Belt region of the u.s. conventional tillage to prepare corn ground for soybean planting usually refers to the sequential use of the moldboard plow disc harrow and spike toothed Harrow to prepare the seed bed however many farmers in this region are using chisel plows and other implements to prepare corn ground for soybean planting therefore the meaning of conventional tillage can vary over time and region other examples of the ambiguity in tillage systems terminology is the term minimum tillage minimum tillage for one farmer may seem to be extensive tillage to another farmer the terms mulch tillage conservation tillage minimum tillage and reduced tillage have all been used to describe tillage operations that try to utilize crop residues to reduce soil erosion the tillage system term used may simply reflect local usage names of tillage systems may refer to the nature of tillage such as full width no-till or Ridge till other names may refer to the objectives of the tillage systems such as minimum tillage reduced tillage or conservation tillage the next topic for study is the section on tillage methods in this section specific tillage systems used in various parts of the US are described we have divided these methods into clean or conservation tillage systems based on the amount of surface residue left at planting time and full width strip or no-till based on degree of surface tillage you should now stop the VCR and study this section in your text and return to the VCR for further tutoring clean tillage systems utilize moldboard or disk plows for primary tillage to essentially bury all the surface crop residues therefore residues will certainly not interfere with the planting operation however the soil is very irritable because of the absence of the protective surface residue clean tillage is also full-width tillage so the entire area is worked into a seed bed which is also a good seed bed for weed emergence conventional tillage in the Midwest Corn Belt region of the u.s. typically implies the following sequence of tilling fall or spring mouldboard ploughing disking or field cultivating two to four times and harrowing with a spike spring or tine tooth Harrow one or two times because of the many trips across the field fuel consumption tillage time involved and soil compaction can be problems these disadvantages can be partially alleviated by using plow and combined secondary tillage where several secondary implements can be hooked together to avoid extra trips across the field plow and strip till planting uses special planters to provide secondary tillage immediately ahead of the planting unit on plowed ground to combine secondary tillage and planting into one operation plow and strip till planting leave the middle of the row or inter ozone in a rough ploughed condition the loose rough soil helps reduce weed germination and emergence in the inter rows own by lowering the seed to soil contact necessary for weed seed germination loose soil in the inter rows own also allows faster water infiltration ideally the only compacted area is the row zone reduced tillage methods following primary tillage are most successful on spring plowed soil thus spring tillage and planting may be somewhat delayed from slow soil warm-up due to surface residues compared with methods that include fall plowing there can be many combinations of tillage implements used to create a clean tillage effect simply by increasing the number of tillage trips across the field for example disking and harrowing land previously grown to soybeans using four to five separate operations will essentially bury most of the surface residue therefore good management in addition to selecting the right tillage implements is needed to effectively use crop residues to protect the soil from wind and water erosion the remaining tillage methods are examples of systems used to meet conservation tillage objectives conservation tillage systems include full width strip and no-till methods which leave 30% or more of the soil surface covered with crop residue at planting time this definition does not mean that 30% of the crop residue is left on the soil surface of planting time this important difference means that no matter what level of surface crop residue you start with 30% of the soil surface must be covered with residue at the time of planting unlike clean tillage systems conservation tillage systems do not use the moldboard plow for primary tillage to bury surface residues rather implements are used to preserve enough surface residue to protect the soil from erosion forces in chisel plow systems the chisel plow substitutes for the moldboard or disc Clow the entire area of the soil surface is tilled and more of the crop residue is left to prevent soil erosion in fields with heavy crop residue a disking or stalk shredding operation may be used prior to chiseling to cut and reduce residues or a combination chisel plow may be used to avoid the preliminary disking or stalks writing operation secondary tillage may include several passes with a disc or field cultivator in Harrow several secondary tillage operations may be combined or attached together to minimize the number of tillage passes in chisel plow systems chisel plow systems are widely adapted and very popular in the u.s. in some cases because of remaining surface residues chisel plowed soil may warm up more slowly in the spring compared with conventionally tilled soil chisel plows can bury twenty to 75% of the residue so using this system on soils with little residue may result in a clean tilled effect in the disc and plant system which is widely used on soybean ground the disc harrow is used as the initial tillage operation in some situations heavier discs are offset discs are used as the primary tillage operation in many cases the field cultivator is substituted for the disc harrow the field may be disc or field cultivated once or twice followed by harrowing and planting field cultivators or discs may have attached Haros to minimize tillage trips this system is particularly popular on soybean ground because there is little soybean residue left on the field after harvesting and the system buries less residue than chisel plow systems strip rotary tillage uses power driven rotating blades that cut and mix soil and residues rotary tillage can be performed in full width or in strips depending on the type of rotary tiller and for primary or secondary tillage depending on the operating depth till planting also uses the strip tillage concept tillage and planting is done in a one pass operation using a tilt planter with disc row cleaners or other tools that clear a strip of soil ahead of the planting unit the till plant system can be used on ridged or non ridged soil ridging also called listing and bedding transforms of flat soil surface into a ridge furrow condition listing tools used to create furrows in the lister planting system can be used to create ridges ridging soils is usually conducted in the previous year during row cultivation for weed control Ridge tillage encourages faster warming of soil on the ridge and utilizes crop residues in the furrows of the inter rows own to improve water infiltration weed control and erosion control this practice is often used in poorly drained soils no-till also called slot planting or zero till planting is an increasingly popular system used on ridged or non ridged soils no primary or secondary tillage operations are conducted instead special no-till planters are used that have tillage tool attachments that cut through residues until a very narrow 5 to 8 centimetres strip or slot immediately ahead of the planting unit an example of such an attachment would be these Coulter blades double disc opener x' open a v-shaped slot in the soil the seed is planted and press wheels firm the soil for good seed to soil contact no-till systems represent the least amount of tillage conducted before the seed is planted because the system is a one-pass operation and only a narrow slot is tilled it saves time fuel labor and leaves much of the soil surface and crop residue undisturbed this system is extremely effective in reducing soil erosion this system may result in lower spring soil temperatures on poorly drained soils due to the insulating effect of surface residues to avoid this problem farmers have ridged soil and used Ridge planting with no-till planters no-till systems may also increase the dependence on chemical weed control and change the insect and disease problems compared with conventional tillage systems the next topics for study are the sections on tillage operations for special situations and tillage for weed control you should now stop the VCR and study the section in your text and return to the VCR for further tutoring subsoil een uses a heavy chisel like implement to break up impervious layers in some soil types subsoil een is regularly used to break up very compacted soils due to excessive wheel traffic or on soils that naturally form compacted layers however the value of regular subsoil een in many temperate soils that undergo freezing and thawing during winter conditions is controversial winter freezing and thawing of soils helps break up compacted soils and the regular use of a subsoil and implement can itself compact soils at the lower level of the operating down generally scientists believe that subsoil een used on a regular basis is not needed for most areas in the Midwest but it can be useful in some situations under different soil and climatic conditions for example it has been useful in soils with dense hard pans that are frequently found in southeastern United States weed control is a very important aspect of crop production tillage before planting and cultivation after crop emergence are often used to control weeds herbicides may not completely control weeds and can have variable results depending on the environment soil type and many other factors therefore tillage before and cultivation after planting has been used to help control bothersome weeds farmers often use a disc to kill weeds before planting sometimes vigorous tillage is needed to destroy weedy species that have become firmly established during the past season a rotary hoe can be used after planting but before emergence to destroy newly emerging weed seedlings the rotary hoe is not designed for row cultivation therefore the implement can damage the crop but the damage is usually much less than from uncontrolled we grow tillage for weed control can also be used after planting and after the crop has emerged the rotary hoe can be used for this purpose too again some crop damage may occur but many newly emerging weed seedlings have shallower root systems than the crop and can be uprooted more easily row cultivation is used after crop establishment to help control weeds the row crop cultivator is widely used for this purpose this implement may use shovels or sweeps spring teeth or ground driven rotary finger wheels weeds between crop rows can be destroyed while minimizing injury to crop plants sometimes smaller weeds within the crop row can be buried under the soil from this operation the next topic for study is the section on general considerations in adopting tillage techniques you should now stop the VCR and study this section in your text and return to the VCR for further tutoring there are many factors that should be considered when adopting different tillage systems tillage methods affect the physical chemical and biological properties of soil soil and climatic factors also influence the suitability and success of different tillage systems therefore if new tillage methods are adopted changes and other management practices must be considered changing from clean tillage to conservation tillage implies that more crop residues will be left on the soil surface crop residues can interfere with proper seed placement in the soil and providing good seed to soil contact newer planters have been designed that can more effectively plant in heavier residue soils methods of fertilizer application may change or the manner in which crop pests are controlled for example soil tillage effectively controls persistent weeds under no-till systems some perennial weeds may become more troublesome because of the absence of tillage requiring changes in weed control management conservation tillage systems that leave more surface residues generally lower spring soil temperatures and increase the soil moisture content this may be an advantage in warm dry regions or a limitation and higher rainfall areas with short growing seasons tillage systems that concentrate crop residues on the soil surface generally improve organic matter tilt and activity of microorganisms and earthworms in the topsoil over an extended period of time one of the primary concerns in adopting different tillage methods is the effect on soil erosion there is no doubt that soil erosion rates are directly linked to the amount of bare soil exposed to erosion forces as you might expect primary tillage operations such as mouldboard ploughing can bury 90% or more of surface residues secondary tillage operations such as disking may bury 50% or more therefore avoiding unnecessary tillage or selecting different tillage implements can be very effective in reducing soil erosion net profit over a period of time is a major concern when changing tillage systems crop yields are very important in determining profitability of different tillage systems but one must also consider other factors such as costs and fuel labor equipment and soil erosion even with the uncertainties associated with changing tillage systems more and more farmers are using no-till and other conservation tillage practices that reduce soil erosion and maintain profitability the next topic for study is the section on seeding objectives the section on demonstration exercises in seeding in your text supplements the principles discussed in this section you should now stop the VCR and study the sections on seeding objectives and a demonstration exercises in seeding in your tech and return to the VCR for further tutoring good seed beds allow proper depth placement seed to soil contact planting rate and distribution of seed proper depth placement of seed during seeding is very important different crops have different emergence potentials for example corn emerges better than soybeans from deeper planting soybeans emerge better than alfalfa when planted at deeper depths in general planting depth should be shallower for crops with smaller seeds and epithelial emergence in soils with higher clay content and soils that are cooler with higher moisture content good seed to soil contact is another objective and seeding the seed should be in contact with well pulverized firm soil however the surface of the soil should not be packed good seed to soil contact is necessary for the seed to absorb moisture from the soil to begin the germination process you may recall that the percent germination and purity of the seed lot are very important in determining planting rate seeding rate should be adjusted to compensate for the pure live seed of the seed lot pure live seed in other words is the amount of viable seed of the desired variety however adjustments in planting rate depend on the competitive ability of each crop optimum planting rate for maximum seed yield is usually greater for smaller less competitive varieties than for larger more vigorously growing varieties this is also true for tillering or branching species versus a non tillering or non branching species tillering or branching species can be planted at lower rates lower planting rates will lower plant population for area but tillering or branching can maintain adequate numbers of reproductive inflorescences considering the competitive ability of a plant species or variety is also very important when planting mixtures of species particularly with mixtures of forage species that are often used improper planting rates can give an already aggressive species too much competitive ability over other species in a forage mixture environmental factors are very important in determining planting rate and distribution for example in tillering crop species the amount of tillering will be generally lowered in infertile dry sandy soils there may be a good environment during later seed filling but if a plant did not Tiller normally during the tillering stage there may not be enough stalks or seed heads to result in high yield if enough seeds had been planted the yield may have been higher soil aeration also affects seedling emergence corn generally withstands poor soil aeration better than soybeans poor soil aeration is usually a result of too much moisture in the soil a waterlogged situation thus some species are damaged more from poor aeration than our other species time of planting affects the optimum seeding rate for instance research has shown that oats produced more yield from higher rates of planting only at late dates of planning when warm weather kept the amount of tillering to low earlier seeding dates required lower planting rates for optimum yields as a general rule earlier dates of planting are best for high yield because the crop can utilize more of the growing season however there may be instances where later dates of planting result in higher yields planting date is often adjusted as a means of allowing a crop to escape some drought stress examples would be planning an early maturing variety early or a late maturing late to allow the crop to escape the time of the usual drought row fertilizer is applied during the planting operation three ways to apply RO fertilizers during the planting operation are with the seed or pop up to each side of the seed called split boot and to the side and below the seed called sideband some types of fertilizers have a high salt content that can damage germinating crop seeds if application rates are too high or if fertilizer is placed too close to the seed seed and seedling injury may occur this is frequently called fertilizer burn or fertilizer salt injury to avoid fertilizer burn many farmers use the side band method a good placement of RO fertilizer is approximately two inches to the side and two inches deeper than the seed species and varieties of crops can differ in their response when fertilizer is applied with the seed and a pop-up application for example germinating seeds and seedlings of soybeans are usually more sensitive to fertilizer burn than corn the last topic for study is planting methods you should now stop the VCR and study this section in your text and return to the VCR for further tutoring planting has been done by humans since the dawn of Agriculture the basic actions of planting are opening a furrow or slot in the soil properly spacing the seed placing seed in the soil firming the soil around the seed and covering seed with soil these steps are deceptively simple and logical yet they largely determine how successful planting and stand establishment will be whether planting by hand or using modern mechanized planting implements the value of any planting method or implement will be based on its ability to perform these five functions row crop planters are widely used to plant a variety of large seeded crops such as corn cotton soybeans and sunflowers different parts of the planter are designed to meet the goals of seeding the main parts of a row crop planter usually includes some type of tillage tool for instance a disk or Coulter blade to clear residue and provide some tillage a furrow opener such as a runner or disc opener opens a furrow in the soil double disc opener Tsar popular for planting and heavier trash and also to help provide better seed to soil contact a seed hopper and internal mechanism is needed to accurately meter seed spacing and placement a gauge wheel or some other device controls the depth of seed placement press wheels are important in providing good seed to soil contact and are designed to minimize severe soil compaction directly over the seed soil compaction and crusting can occur from the press wheels of any planter if soil conditions are right planting and moist but friable soil is ideal the row crop planter is usually equipped with insecticide and herbicide hoppers and applicators different planting patterns have been used for row crop planters the he'll drop pattern planting seed in groups of two or more probably originated from native Indian customs to ensure that at least one seed will germinate in a hill the check row pattern where seeds are placed equal distances within and between rows used to be very popular particularly before herbicides had been developed this allowed the farmer to cultivate the field in two directions to remove more weeds he'll drop and check row planting patterns are no longer used much in mechanized agriculture using chemical weed control the most widely used planting pattern of row crop planters is the drill pattern in the drill pattern seeds are individually placed in the row at a uniform distance that distance depends on the population per area desired broadcast Cedars and grain drills are used to plant crops in closed rows and for crops whose seed characteristics make it difficult to meter seed individually at accurate spacing for instance small seeded forages like alfalfa or crops with light Chaffey seeds like smooth broom grass soybeans although commonly planted with row crop planters can be planted with a grain drill to obtain very narrow rows at high plant populations the important parts of a grain drill are similar in function to row crop planters although the design is different the grain drill has hoppers for small or large seeded crops and for fertiliser discs furrow openers for seed placement depth controls and press wheels broadcast Cedars however are designed to randomly scatter seed in a uniform manner on the soil surface thus the seed bed needs to be completely prepared prior to seeding a separate shallow tillage operation following broadcast seating is necessary to cover seed with soil although fast in operation the broadcast method has many limitations for instance on windy days seed distribution is not good and may result in uneven strips of established legumes and grasses also seed depth soil coverage and seed to soil contact are almost totally regulated by the type of tillage following seedings specialized planters can be of various shapes and sizes and can be designed for special crops or planting situations in this case a tobacco planter is being used to transplant young alfalfa seedlings in a research field it is important to remember that even though new machinery is continually being designed the basic goals and objectives of seeding remain unchanged to best judge whether a new piece of equipment is worth the expense an evaluation must be made of how that new machine completed all of the objectives of seeding hopefully from this chapter you have developed a basic understanding of the goals implements and systems used in tillage and seeding even though the purposes of tillage and seeding remain unchanged over time the challenge is meeting these goals under different technologies in an environmentally responsible manner this is the end of the chapter on tillage and sealed you should now be ready to try the self-evaluation test at the end of the chapter in your text