Sun Joe TJ604E 16-Inch 13.5 AMP Electric Garden Tiller/Cultivator,Black

 Sun Joe TJ604E 16-Inch 13.5 AMP Electric Garden Tiller/Cultivator,Black

• Powerful: 13. 5-Amp motor cultivates up to 16 in. Wide x 8 in. Deep
• Durable: 6 Steel angled tines for maximum durability and performance
• Easy storage: handle folds for convenient storage and easy transport
• Wheel-adjustment: 3-position wheel adjustment

BASIC PRINCIPLES OF TILLING

"Soil preparation" is the physical manipulation that is applied with the intention of modifying those characteristics that affect the sprouting of the seeds and subsequent stages of growth of the crop. These characteristics determine the plant-soil-water-air relationships, which will affect the development of plants.

Soil characteristics that affect plant growth

a)  Soil structure.  It is the ordering of the soil particles, understood as such, not only the individual mechanical elements such as sand, silt and clay, but also the aggregates that have been formed into smaller fractions by mechanical action. The productivity of a soil depends to a large extent on its structure, therefore, the first objective of all primary tillage operations is to modify it to obtain a porosity that allows good gas and air circulation in the soil, facilitating growth. and root penetration.

b)  Soil aeration. It is important to decide the fineness of the tillage. Crops can only grow vigorously in an environment with good aeration, that is, where the concentration of carbon dioxide around their roots is low and that of oxygen is high. Therefore, the rates of transfer of carbon dioxide from the root zone to the atmosphere, as oxygen from the atmosphere to the root zone, are properties of the soil of fundamental importance for the crop. By increasing the volume of pores with the plow, the conditions of air movement in the soil are improved, causing a decrease in the content of carbon dioxide. However, excessive or poorly performed tillage destroy aggregation and increase soil density, reducing porosity,

In a vertical section of a soil, it is observed that at different depths there are layers of different appearance, called horizons and their set make up the soil profile.

• Horizon A: Darker, better structure, good pore content.
• Horizon B: Subsoil, accumulation of soluble substances and colloidal matters, with lower fertility than horizon A.
• Horizon C: Original material, less affected by physical, chemical and biological agents. It is the least fertile horizon.

c)  Compaction.  Compaction is a problem that occurs in those soils whose structure is prone to destruction due to the effects of tillage and / or the action of water (rain or irrigation). Some degree of compaction can be beneficial, but when it is excessive, it can result in detrimental effects on soils and on the growth of cultivated plants. By reducing their porosity, it hinders the movement of roots, gases and water.

Soil compaction is the result of gravity, rain, and traffic. Of these, only the latter can be regulated by man and its action is "more severe" when organic matter is scarce, since the humus acts as a cement to give stability to the soil aggregates. As it is not possible to suspend the movement of agricultural equipment on the ground, methods must be used that tend to reduce the amount of work carried out on them. The effects of compaction increase with machinery traffic and even more so if the soil is loose at the time of starting work. This effect is also increased, when the soil has been worked with an intermediate moisture content (friable soil), a point at which it presents its maximum ease of loosening but also

The weight of the agricultural machinery and the working speed, together with the vibration of the drive unit, favor the general compaction of the soil, especially where practices that deteriorate its structure have been carried out. When a heavy tractor is used for tillage work, each "pass" causes two tracks in strips of approximately half a meter each. With subsequent work from the fourth pass, it is assumed that the ground is completely covered with tracks. The first pass of a tractor over freshly plowed soil has been shown to compact ten times more than a second or subsequent pass.

Therefore, it is advisable to "match" the traces of the subsequent passes so as not to generalize the damage and at the same time reduce the work to a minimum. It is recommended that the weight of the tractor and implements gravitate as little as possible on the ground, using wide tires with low pressures, especially when working on wet soils. The repeated use of the disc and / or moldboard plow at the same depth, compacts year after year the bottom of the furrow and forms a hard layer 3 to 4 centimeters thick, commonly known as "plow foot". This compaction limits root penetration, slows the movement of water and air in the soil profile and consequently causes drainage and erosion problems.

Another situation that requires special subsoil tillage treatment occurs in permanent grasslands subjected to direct grazing. The compaction produced by trampling animals is even more severe than that generated by machinery traffic, since the weight is distributed over a smaller surface in contact with the ground. This is particularly important in potato crops, which are generally used as a rotation head, after pasture.

The possibilities of compaction are greater in soils with a clay texture and in those with a low content of organic matter. Overworking that leaves the soil finely soft (especially with disc harrows) favors compaction and should therefore be avoided.

d)  Organic matter. Organic matter increases aggregation and improves the structure of soils. Continuous tillage practice has been shown to destroy aggregation and deteriorate its structure, simultaneously reducing its organic matter content. The incorporation of organic matter into the "topsoil" of the soil by plowing crop stubble and / or degraded natural or artificial pastures enhances the soil structure and reduces the negative effects of compaction. The same goes for the use of manure and liming. For organic matter to break down quickly, the stubble must be broken into small pieces and allowed to dry on the surface before being buried. It is also recommended, to speed up this process, add approximately 80 to 100 kg. nitrogen per hectare,

e) Soil moisture.  It is one of the factors that has the highest incidence in soil preparation work, both in plowing and scraping. Moisture makes the soil present more or less resistance to the penetration of the implements, it also gives it plasticity characteristics that allow it to adhere to the tillage implements, hindering their action. In very humid soils, traction is affected by increasing slippage and increasing power requirements, due to the great resistance it offers when moving the plow.

A soil with low moisture content is hard. As the humidity increases, it softens and breaks down easily. The friable consistency represents the optimal humidity condition to carry out the tillage of the same. This condition is recognized in practice by taking soil in your hand and making it easily disintegrate when pressed, without leaving any remains attached to it. Very wet soil forms a ball when "kneaded" and soils the hand with the wet clay that sticks. A too dry soil forms very hard clods that are very difficult to break up.

When the moisture content increases excessively, the floor becomes plastic, adhesive and very difficult to disintegrate, the action of the scrapers being useless. This is closely related to the type of soil. Sandy soils do not present these problems, but as the clay content increases, it is important to consider working the soil in friable conditions, as it is very difficult to manage. Clay soils require great dedication, because they quickly lose moisture in spring, being difficult to loosen.

From the above, it can be deduced that the soil's softness is closely linked to its moisture content and, therefore, the opportunity to carry out the work is more important than the number of times. A job done at the right time can have a definitive effect on obtaining the desired degree of fluffiness. However, it should not be forgotten that the moment when the soil is easier to compact, coincides with its friable condition, so it is advisable to avoid excessive traffic in order not to reach an excess of compaction.

OBJECTIVES OF SOIL PREPARATION

• Release and remove the soil to create favorable conditions for the circulation of water and gases in the arable area of ​​the soil, at the same time facilitating the root development of the crop to be established.
• Generate optimal soil loosening conditions for seed germination.
• Control and destroy weeds that compete with the crop.
• Increase the moisture retention capacity of the soil.
• Eliminate those insects that constitute pests, their larvae, eggs and places of development.
• Incorporate plant residues, fertilizers and lime promoting an increase in bacterial activity and an increase in organic matter.

There is no priority order of importance in the proposed objectives, given the enormous variety of soil, weed, pest and humidity problems present in the fields throughout the country.

OPTIMAL SEEDING BED

The seedbed corresponds to the entire soil profile that is altered by tillage work and its function is to create the ideal conditions for sowing, germination of the seed and subsequent development of the crop. In it, two zones are distinguished that obey different objectives and therefore require different characteristics: the seed zone and the root zone.

Optimal characteristics and conditions of the seed zone

The seed zone is the superficial one and must allow the increase in surface temperature and adequate humidity provided from the lower layers of the soil. Soil preparation generally begins in winter and when planting this area should present the following characteristics:

a) Depth : The land for a potato planting must have a surface layer of 8 cm. suitably soft, allowing aeration and accumulation of sufficient temperature for sprouting. Further down there should be a layer with higher moisture content, 15 to 20 cm. on which the seed tuber is deposited. These first centimeters of soil constitute the sprouting zone, therefore a good job of this part of the soil will ensure the best emergence of the plants.

b) Softness:  The degree of softness of the soil must be related to the size of the seed. When the clods are too large, good contact is not established with it, due to the air pockets that surround it and isolate it, they prevent the transfer of the humidity and temperature necessary for sprouting. The clods must not exceed 3 cm in diameter. The excessive fluffiness of the seed zone is not favorable either, since it destroys the structure facilitating the compaction produced by the water.

c)  It must be free of weeds , champas and live plant residues on the surface. Weeds compete with the crop for nutrients from the soil, water, and light.

d) Compaction:  It must be firm enough so that the planting machine can regulate the depth and thus allow a uniform location for the seed. In no case is it advisable for excessive compaction to occur in this area, which may limit root penetration and water and air circulation.

e) Humidity : It must have the necessary humidity to allow a good germination and development of the seedlings. Excessive tillage in the seed zone ventilates the soil and dries it quickly.

f) Temperature : In the potato-producing area this aspect is very important since the seed tuber to sprout requires temperatures above 9ºC in the soil. This happens from August onwards and especially if the paddocks have a northern exposure.

Characteristics and optimal conditions of the root zone It

corresponds to the deepest zone from where the extraction of nutrients, water and air that the plant needs for its growth takes place, and must meet the following characteristics:

• a) It requires less fluffing than the seed zone.
• b) It must have a granular structure that allows easy activity and root penetration.
• c) It should not be compacted to allow better water retention and greater air movement in the soil.
• d) It must be deep enough to allow the roots to have a wide area of ​​development (up to 25 to 30 cm).

This area must be removed by deep plowing, only this being enough to leave it in good condition. However, the plowing work should not exceed 28 to 30 cm. depth of soil, it is advisable to eliminate all the compactions present at the bottom of the arable soil (plow foot) that limit root development and the movement of water in it.

SOIL PREPARATION METHODS AND TYPES OF TILLAGE

a) Traditional tillage:

It is the soil preparation system that was used in a traditional way, and in some cases it is still carried out by small farmers. It is characterized by the repeated use of the moldboard plow, with which crosses and recruits are made that invert the soil, followed by a significant number of harrows with disc or nail harrows. In each plow pass a large amount of soil is moved, leaving the surface without vegetation cover.

The "cross" corresponds to the second plowing that is applied to a soil in the same season, this is carried out perpendicular to the first plowing. It is a practice that is identified with traditional farming and that does not always have a clear justification; However, when it is used it is mainly to solve the following situations:


Rectify a hole of irregular depth, and defective investment.
Deepening the "seed bed" when, due to the characteristics of the soil, it is not possible to achieve the desired depth with the first plow.
Loosen the soil that has been compacted by the rains. This case is common in the preparation of clayey soils (vegas).


Extract moist soil from the lower layers, burying the clods that have formed on the surface, as a way to facilitate loosening. If the previous points are analyzed, it is possible to verify that the cross can be eliminated in most cases, since most of them are the result of inappropriate soil management practices.

b) Conventional tillage: Soil  preparation system that uses moldboard or disc plows to give the working depth and invert the soil and a limited number of harrows with disc or nail harrows, vibro-cultivator, rotary cutters, rotators, etc. It differs from the traditional system by eliminating the work of crossing and recruza. In the same way, it moves a large amount of soil, and leaves the surface without vegetation cover.

c) Minimum tillage:  Faced with the large number of problems created by over-tilling, new methods of soil preparation are proposed, inspired by the principles of minimum tillage, which tends to reduce the traffic of machinery through the field.

To apply minimum tillage procedures, no special or sophisticated equipment is required. Common implements are used, arranged in tandem (one behind the other) and applied at the right time and in relation to the moisture content of the soil. Nor is more power required, since the tractors have enough reserve to cover the extra demand that means attaching an additional implement such as those mentioned.

The most frequent cases involve the execution of two or more tasks simultaneously, coupling several tillage implements to the tractor in tandem. Tractor, plow, subsurface roller and nail harrow coupled in line, often achieve a suitable seedbed in just one operation on some soils. Other examples could be: a subsurface roller or a nail harrow attached behind the plow, to prevent clod formation in medium to heavy soils; A nail harrow or a simple wooden harrow behind the disc harrow makes it possible to achieve a more finished soil loosening, while also sealing it on the surface to prevent moisture loss.

Currently the national agricultural machinery market offers a series of equipment that is based on this principle of minimum tillage, such as the combined harrow of nails and rollers; in addition to the strategic use of the vibrocultivator, rotary mills, rotators and chisels with stubble incorporators. The trend has been to replace the use of the moldboard and disk plows with the chisel plow, to give the depth of work, moving a small amount of soil from the profile and replacing the inversion of the soil with the chemical control of the vegetation or "Chemical fallow".

The best results with minimal tillage are achieved on medium textured soils. Heavy soils make it difficult for equipment to move because of its hardness, when the moisture content is low, and because of its adhesiveness, when it is too wet. These methods, however, can be applied on all arable soils, after eliminating natural obstacles such as stones and logs, in favorable humidity conditions. At present, tillage for potato cultivation has been reduced to such an extent that there are rotary mills that with just one pass allow the soil to be in suitable conditions for planting.



Another aspect to consider is the improvement of the planting opportunity, especially when it is prepared with a rotary cutter pass, which allows synchronizing the soil preparation with the planting. Only the surface that will be planted the next day will be prepared, thus becoming independent of the climatic conditions.
Despite the improvement of mechanization technology for tillage, the success of minimum tillage systems depends largely on the efficiency of the operator, quality of work and physical characteristics of the soil at the time of applying these methods.

d) Zero tillage : As in the case of cereals, the reduction of tillage in the potato crop has reached the extreme of eliminating it completely, thus creating a zero tillage system. In this case, the crop is established directly on the ground, covering the seed with a dense layer of stubble or cereal straw, which allows it to be protected from environmental factors such as light, wind and low temperatures, thus facilitating the development of the crop. Because planting and crop management are done manually, the system is limited to small areas.

Soil preparation times

Soil preparation must be planned well in advance, with the aim that sowing is not delayed by this concept. Most of the delays in planting are due to winter rains and excessive soil moisture, which prevents mechanized tillage from starting as early as desired, limiting the time available to prepare the soil, added to the fact that the decomposition of the waste buried by the plow is slow.

These considerations make it advisable to start the work of soil preparation for sowing in autumn (chopping and incorporation of the residues with plowing), then continue in winter or at the end of winter with superficial scrapes (control of the germination of weed seeds) and finish during the last month before sowing, deepening the break with a chisel plow (without inverting), leveling and conditioning the seed area. In general, the early potato planting date is July and the mid-season is August.

In the case of plain soils, soil preparation begins in October, once the humidity level has decreased. In the coastal sector, the sun and the prevailing south wind in spring dry the soil quickly, especially in the case of soils with a loamy-clay texture, with a great tendency to form clods. That is why the soil preparation must be done quickly, taking advantage of the friable soil condition. If clods do form, due to the action of the sun and the wind, it is best to plow with a moldboard or disc to bury them and "bring to the surface" moist soil in better condition to be broken up.

MACHINERY FOR PREPARING SOILS FOR SOWING

There is a wide variety of equipment for breaking, breaking up, leveling, compacting the soil, breaking clods, controlling weeds and shredding stubble residues from the previous crop. Most of these equipments are of different design, but they have been conceived to solve the same problem (disc plows and moldboards, vibro cultivator tandem harrow), or to act under specific soil conditions.
To determine the most suitable soil preparation method and correctly choose the equipment to use, it is necessary to clearly define the characteristics of the seedbed to be achieved, and to know the effects of the available tillage equipment.

Deep work equipment

Soil breaking equipment is classified according to its action: plows that invert the profile of the soil (discs and moldboards), plows that mix it (rotary) and plows that do not alter it (chisels and subsoilers).

a) Plows that invert the profile of the soil: These are those that are made with disc and mouldboard plows. Both teams invert the ground, but with different results, mainly due to their different design. Its operating characteristics cause differences in the quality of the plow, in relation to the inversion, softening and subsequent leveling of the ground.

The most important operating characteristic of disc and chute plows is their ability to bury manure, plant residues, degraded pastures and others. Both teams perform best in the presence of previously cut meadows to avoid "jamming" in the breaking units. The moldboard plow makes an excellent soil investment when operating on land that has not been recently plowed. When used on loose floors, you just move it sideways without inverting it. The opposite happens with the disc plow, it reverses a loose soil very well, causing unevenness of micro relief when used on meadow.

In soils with the presence of obstacles (stones, logs, roots, etc.) that are humid and with a clay texture, the disc plow performs better, since when turning, the breaking unit avoids obstacles and presents less resistance to the soil (the earth sticks less to the disc). Without the presence of these soil limitations, it is preferable to use the moldboard plow that protects the leveling, a factor that can be important when driving irrigation water.

b) Plows that mix the soil profile :

Rotary plows are breaking implements that require great dedication to use, because they subject the soil to excessive manipulation and can alter its structural characteristics. However, when these are used adapting the revolutions to the characteristics of the soil, they turn out to be highly efficient due to their speed and simplicity of use.

The blades attached to a rotor that rotates driven by the tractor shaft, cut pieces of soil and throw them against the plow housing to complete their loosening. The size of the pieces of soil depends on the speed of movement and the revolutions of the rotor. Most designs offer a wide range of rotor revolutions since they are equipped with a gearbox for that purpose. This implement can be used for the chopping of residues and for the destruction of clods, but it requires great power from the tractor's power take-off shaft and alters the structure of the soil, producing an exaggerated softness.

c) Plows that do not alter the soil profile : Chisel and subsoiler plows are tillage equipment that allows the soil to be disintegrated without altering its profile, cracking it by means of the action of one or more chisels attached to a rod or arm attached to a tool holder frame. The difference between both teams lies in the robustness of the structure, depth of work and number of chisels.

• This type of work requires relatively dry soils for soil cracks or fractures to occur. Wet floors would be cut by the chisel like a knife, without producing the cracking effect of
• drying. However, dry soil offers greater resistance to plowing, which translates into a high demand for power, which increases in direct proportion to the depth of work and the number of chisels on the implement.
• The chisel plow is the right tool to destroy “plow foot” type compaction, improve water retention and protect the leveling and structure of the soil. Its main advantage is to deepen the seedbed without inverting the soil or causing unevenness in its surface, which indicates that it can be used first to condition the seed area and later to the desired depth. The separation between the chisels is determined by the length of the cracks or fracture lines produced, the important thing is that the cracks intersect enough to ensure a uniform treatment of the soil.

The subsoiler plow works under 30 cm of depth and is very useful to destroy natural compactions or those produced by the traffic of machinery or animals. It is also used in order to improve drainage, adding a pellet in the boot of this equipment to make underground galleries (mole plow). In this case, as an exception to the rule, work is done on damp soil, since it is not primarily of interest to loosen or crack the soil, but rather to manufacture underground galleries to remove excess water.

The use of the subsoiler on dry soil produces cracks of varying lengths depending on the implement used, humidity and soil texture. To determine the spacing distance between "subsoiler passes", the length of the cracks must be calculated using a trench and the spacing between "passes" should be arranged so that they intersect. The correct working depth of the subsoiler is also of vital importance, since if the boot works very deep and not in the compacted area to be cracked, the work is ineffective. In view of the intense traffic of machinery, typical of modern mechanized agriculture, it is recommended to subsoil the soils every 4 to 5 years.

Equipment for surface work

The basic function of surface work is to prepare the seed area through the use of various types of implements. Soil loosening, leveling, weed control, and the necessary compaction to ensure good crop establishment are its main objectives.

Modern agriculture has a wide range of equipment to fulfill this function, among which are disc harrows, nails, springs, scaffolding, vibro-cultivators, rotary cutters, rotary rakes, levelers, micro-relief levelers, rollers and others.

a) Disc harrow:  It is a very common tool in our environment and widely diffused throughout the mumps area. It is used mainly to loosen the soil and control weeds in the seed zone. There are two basic models that differ in the availability of discs and chassis bodies: offset offset disc harrows and tandem disc harrows.


The "efficiency" of the disc harrow depends on several factors:
• weight of the equipment
• size, concavity, cutting edge and angle of attack (lock) of the discs
• working speed
• soil moisture content.

This equipment works by cutting narrow strips of soil with lateral displacement of the same to cause its loosening. In addition, they cut the plant residues of the roof into pieces of variable size, depending on the dimensions of the equipment, soil condition and the locking of the harrow bodies. With regard to weed control, this equipment acts on the newly emerged seedlings, uprooting them so that the sun and the wind complete their destruction. It is also possible to use this equipment to chop the meadows as a pre-incorporation task.

Whatever the purpose of its use, it is desirable that the disc harrow acts at the maximum permissible speed and superficially to condition the seed area (tandem harrow). The off-set harrow is more efficient due to its design and weight, which is why it is recommended for use in heavy soils loosening and for the superficial chopping of stubble or vegetation cover. With a heavy off-set harrow properly locked acting on a light soil, a deep work similar to a plow can be carried out that only allows to loosen the soil without inverting it.

Special care must be taken to avoid the excessive use of this equipment, since its aggressiveness considerably affects the structure of the soil, and its cutting nature multiplies asexually reproducing weeds, such as chépica, blackberry and others. There is no justification to use a disc harrow to achieve the desired softness, when operating on loamy textured soils that are easily disintegrated, since there are other equipment with lower operating costs and greater efficiency and quality of work, such as combined harrows. of nails and rollers, vibro-cultivators and others.

b) Combined harrows :

They are highly effective equipment for the adaptation of the seed area. Except in very justified cases, this equipment displaces the disc harrow in its wide range of jobs, due to its cheaper cost and superior performance. Its action is based on the principle of minimum tillage that postulates the performance of several tasks in a single operation. Combination harrows are offered in versions with springs or vibro-activators and with rigid nails. The use of vibro-cultivators is recommended to carry out work a little deeper (10 cm.), In view of its greater aggressiveness, but both models satisfactorily fulfill the mission of conditioning the seed area.

The use of a combined harrow, like the plow, and like all the equipment that works in the seed zone, softening the soil and controlling weeds, is most effective when moving over 8 km / hour, which allows a large capacity of work. Another combination harrow design recently incorporated into national agriculture is the shaft driven rotary nail harrow that takes power from the tractor.

There are a wide variety of designs of the breaking unit, highlighting the horizontal axis rotor system with nails or hoes and the vertical rotating and oscillating nails. The mechanical action of great force that is exerted on the soil, gives this equipment special conditions for the loosening of clods and chopping of meadows, especially under extreme conditions (dry clay soils and dense and hard meadows). Although it is the best tool available to chop grass meadows prior to their incorporation with soil preparation work, it is not convenient to generalize its use, since it consumes a lot of motor energy and puts a special effort on the tractor system. of transmission.

It is not recommended to use a rotary cutter to loosen light-textured soils that disintegrate easily or to control newly emerging seed-breeding weeds, since a combination harrow of fixed nails or springs and rollers can do this at low cost and very quickly, without using the axle, it takes power from the tractor.

c) Spring, nail and roller harrows : They are also very useful to fine-tune the finish of the seed bed. The first two are preferably used to control germinating weeds in their early stages of development. Like combination harrows, it is desirable to operate at high speeds to obtain good soil loosening and weed eradication. The rollers, whether smooth or corrugated, surface or subsurface action, seek to complete the loosening of the soil and compact the seedbed to give it the firmness it needs to support the seeder unit.

The machinery market offers a wide variety of equipment for surface shavings, both motor and animal traction that allow the user to select the tool according to its energy availability. As for the types of rollers most used in our environment, they range from wooden ones, metal ones that can be filled with water and those with a combined action of a spray roller with a double run of corrugated rollers and a spring harrow between them, considered an excellent team to destroy clods and finish the refinement of the seed area.

d) Micro-relief levelers or rakes: Micro-relief levelers are generally used to leave the soil in conditions that allow precision planting, such as beets. In the case of potato sowing, rails or rakes can be used to fine-tune the seed bed at the end of soil preparation. They are generally used after planting to clear the seed furrow left by the planting machine or to compact and smooth the soil surface when planting is done manually.

SPECIFIC PROBLEMS IN SOIL PREPARATION

In potato production there are no relevant problems in soil preparation, which hinder or affect the establishment of the crop, although the preparation work has been carried out with simple machinery or animal traction. The problems generally appear at the time of mechanized harvest, in which the potato is bagged; and it is related to the formation and presence of clods, which behave the same as a tuber, so when carrying out a mechanized harvest with bagging, a large part of them pass into the sack, which later arrive at the winery.

Clay soils with a tendency to lump formation

a) Factors that favor the formation of clods:  The formation of clods occurs due to the loss of soil moisture and depends on the texture of the soil and the prevailing climatic conditions (wind). The higher the clay content, the more difficult it is to work the soil and therefore prepare a fluffy seed bed.
Clods do not exist naturally in the soil, being the result of poor work done by man. The plows carried out on clayey soils that are too humid and inopportune scrapes accelerate the drying process of the soil, increasing the surface exposed to the wind and sun, facilitating the formation of clods.

Farmers often do not start scraping to loosen the soil until they have finished all the plowing they want to do in the season. This means that the plowed soil is exposed to the wind and the sun for a long period, giving the opportunity for it to dry out more in the part exposed to the air. The work of scraping with discs on this soil condition separates the dry blocks from the wet ones, giving rise to clods, the size of which depends on the clay content of the soil and the leveling achieved by plowing. Moldboard plows allow for a more orderly inversion of the terrain, and are less prone to clod formation.

The presence of hard and dry clods forces the farmer to carry out an excessive number of scrapes with the intention of loosening them, objectives that are not always achieved, increasing tillage costs and accelerating the loss of soil moisture.

b) Methods to avoid the formation of clods:

• I) Plow and track at the right time in relation to the percentage of soil moisture using subsurface rollers behind the plow to level and offer less contact surface to the wind.
• II) When the soil is friable, carry out a single harrow to achieve the desired softness. It is recommended to use combination nail harrows and sub-surface rollers immediately after plowing.
• III) Use wooden rakes and / or rollers attached behind a disc harrow to "iron" the ground and prevent moisture loss.

The opportunity of the scrapes in relation to the moisture content of the soil is essential to avoid the formation of clods.

c) Methods to destroy clods on dry soils in the entire topsoil.

• I) Irrigation: Return the moisture lost to the clod to bring it to a friable level that is easy to fluff through artificial irrigation. This method, however, delays cultivation and increases the number of soil preparation tasks, since it is inevitable to re-plow the soil to loosen it and destroy the compaction produced by irrigation.
• II) To soften the dry clod by means of the impact of motor-powered equipment, for example, the rototiller or rotary plows.
• III) Pressure exerted on the dry clods by a leveling equipment or roller. The latter case has given excellent results using the leveler - chisel plow combination on very clay dry soils. Also in the above cases, it is appropriate to use a chisel plow after watering or after the rototiller, in order to deepen and loosen the soil.

d) Methods to destroy clods on dry soils in the superficial layer (8-10 cm) and humid in the base.

• I) If there is no humidity in the first centimeters of the soil, there is sufficient humidity in the lower layers of the soil, it can be rolled to introduce the clods in the humid zone and then trace it, when the clods have
• been impregnated with enough moisture to recover friable condition.
• II) It is also possible to resort to "crossing" to bring moist soil to the surface and be able to soften it later, by means of superficial scrapes.
• In summary, it is important to carry out the scraping work in a timely manner, which will subsequently soften the soil based on a high number of tasks, since this implies a misuse of equipment and high operating costs.

Soils with a high degree of infestation of seed-reproducing weeds
a) Contamination of the soil with weed seeds : It is practically impossible to eliminate the problem of seed-reproducing weeds by applying mechanical tillage methods, due to the permanent infestation of new weed seeds brought by the wind, irrigation water and animals. Soil preparation is only intended to retard weed development to give a growth advantage to the crop to be established.

• The weeds that seed in the abandoned stubble and those transported by irrigation water are the only ones possible to control by man, since they are deposited on the surface of the soil and are buried with the plowshares and distributed uniformly throughout the profile arable.
• Despite the entire profile of the seedbed being contaminated, only the seeds that are in the first few centimeters can germinate and the rest waits stratified for their opportunity to germinate. The seed can retain its germination power for several seasons as long as the conditions are not in place for it to be activated.

b) Measures to control weed contamination

• I) Use adequate cultural rotations in order to create unfavorable environments for the development of weeds.
• II) Process, with clearing equipment, the stubble immediately after the harvest is finished and repeat the operation as many times as necessary, to prevent the weeds from seeding.

c) Opportunity to control germinating weeds : The weed seeds present on the surface are activated by the humidity and temperature of the soil, a phenomenon that occurs when this area is prepared for cultivation. Once the germination of the weeds is activated, the process is irreversible, that is, from that moment the situation can be controllable.

• Being easier to control the weed when it is germinated or just emerged; It is advisable to do a leveling work 10 days before sowing to provoke the germination of the weed seeds, with the compaction and loosening effect of this equipment.
• Soil moisture also has a great influence on the effectiveness of weed control by harrowing. If the soil is very wet or it rains after raking, the action is canceled, since the roots of the uprooted weeds return to their initial position. If the soil is dry, there is no point in scraping since the seeds have not yet been activated.

d) Weed control methods with harrowing tasks : The weed control carried out by the different types of harrows mentioned above, consists of uprooting the seedlings and leaving their bare roots exposed to the action of the sun and the wind for their definitive destruction. It is a mistake to think that the mission of these teams is to crush or chop the weeds, destroying them with blows. From the foregoing, the importance of tracking growth and humidity at the right time, to obtain a successful control, follows.

• Each movement of the soil removes new weed seeds to the surface layers, leaving them in conditions to germinate, so it is advisable to carry out the soil preparation work from greater to less depth, in relation to the control of germinating weeds. It is not intended to carry out deep work after surface scrapes that have the mission of controlling weed seeds germinated on the surface, since this work will deposit new weed seeds brought from lower layers, canceling the action of the previous control.

It is advisable to plow only once and do the job well, to avoid a cross that would have the effect of nullifying the control of germinating weeds carried out by the scrapers. After this plowing and when soil moisture is advisable, increasingly superficial scrapers should be administered, preferably using combined harrows of nails and springs, of great efficiency and performance. From the point of view of germinating weed control, one scrape after another should not be applied, since it is necessary to allow time for the weed seeds that were in a favorable position to germinate.

Soils with meadows

It is common to find seed beds with a large amount of residues from the paste on their surface, which makes the operation of the seeder machine difficult. This problem is caused by directly breaking the meadow with a disc plow and distributing residues or grass champas throughout the profile. From that moment the problem of the champas is out of control, since a new plow to bury the residues of the surface, can remove those that are already buried.
Despite the number of scrapes applied after plowing, the champas will remain in the profile for two main reasons:

to. The harrow needs a hard surface to hit the grass against in order to cut it into small pieces and the loose soil, removed by the plow, will act as a shock absorber preventing this objective from being achieved.
b. The decomposition of organic matter is very slow in the south, where this problem is typical, such that the waste persists for several months without decomposing.
In the case of natural grasslands, it is convenient to crush the weeds superficially with a disc harrow, rototiller, or rotary cutters, expose them to the action of the sun and wind for a few days, and then incorporate them with a deep plowing work. It is recommended to do these tasks at the end of summer. Plowing can be replaced by the use of chemical fallow.

The scraping should be practiced superficially in the first 8 cm of the ground, so as to always have a hard surface against which to hit, to get a better cut of the champa. In the case of using a tandem disc harrow, which is more effective than the offset harrow for this task, it should be adjusted with a low angle of attack (lock) and proceed to carry out the work 2 to 3 times, passing in a crossed direction. In the same way, it can be replaced by a vibro cultivator that can be more efficient and faster. The harrow passes must be spaced apart to allow the action of the wind and sun on the debris.

For the subsequent incorporation of the chopped material, it is preferable to use a disc plow, since it inverts the soil very well when it is loose and without the mooring of the root mass of the pasture.

Soils with vegetative reproduction weeds

To prepare soils that have a vegetation cover with vegetative reproduction weeds such as chépica, onion grass, yarrow, among others; One must be very careful in the selection of tillage implements, since the rotary discs and harrows chop the roots, spreading weeds that multiply very easily. In these cases, the use of tools such as the mouldboard plow and the nail and spring harrow to uproot the chépica is recommended. Chemical fallow with the use of Glyphosate (Roundup, Rango) is a very good alternative in this situation since it efficiently controls grass weeds. When there are more complicated broadleaf weeds, Glyphosate can be mixed with 2,4-D (amine or ester), Ally, Ajax, Aliado, Tordon 24-K, MCPA.

Soils with compaction type «plow foot»

The compaction produced by the repetitive action of a plow that always works at the same depth, creates important problems for crops. It is advisable to perform subsoiling work at least once every 5 years to soils subjected to intense machinery work and / or with animals in direct grazing. In the same way, the permanent passage of the chisel plow should largely solve this problem, provided that the plowing is carried out on dry ground and at the speed recommended by its manufacturer. The method takes advantage of the characteristic of the chisel plow that does not alter the soil profile, to reverse the traditional process of plowing first and then tracking.

The residue is chopped, buried and the seed area is traced, and then chiselled in depth, taking advantage of the fact that the first centimeters are loose and offer less resistance to the implement. Another interesting aspect proposed in this method is the replacement of the disc harrow by the leveling harrow, which does an excellent job of tuning.

On soils with stubble on the surface

Chopping up the residue before plowing is always a good method because it uses the resource in favor of the soil and facilitates the investment of the plow. Not processing the residues complicates the operation of the plow and remains of the stubble remain on the surface.

ORGANIZATION OF MECHANIZED TILLAGE WORKS

One of the typical problems that farmers who want to start preparing a planting bed must face is the choice of the direction or direction of work. Several factors should be considered to solve this problem, among which are: the conservation and protection of the soil, the work capacity or performance of the equipment and the quality of the work carried out.

Factors determining the direction of work

a) Soil conservation and work direction:  When the soil is removed by the tillage implements, it can eventually be washed away by rain or irrigation water, and lost through erosion. If the plowing with discs or moldboards or other work that leaves grooves in the direction of work, is carried out on soils with a steep slope, the orientation of the contour lines or the direction of the least slope should be chosen. In this way it is avoided that the rainwater descends at high speed through the furrows, dragging the soil and forming cracks that are almost impossible to recover. In addition, the tractor or draft animals have greater difficulty working against the slope (uphill).

b) Direction of work and performance of teams:  The work capacity of a team, or the time it takes for it to cover a given area, is measured in hours per hectare or hectares per hour. The working capacity depends on the speed, working width and time lost in non-productive actions, such as turning on the paddock heads with the implement raised.

This last factor, which is also called field efficiency, affects the final performance of the equipment, since the width and working speed must be kept fixed depending on the power of the tractor. From the point of view of work capacity, to avoid lost time due to turns with the implement raised, the tasks should be oriented in the direction of the greater length of the paddock. Another technique that avoids excessive loss of time at the ends of the paddock is to leave wide heads to allow the tractor to turn without resorting to gear changes or use of the clutch, and to prevent unnecessary deterioration of the transmission system. They can also be left wide heads and sides, of equal measure, in order to later close the work by circulating around the worked ground.

c) Direction of work and quality of work

Plowing:  When this task is carried out with a chisel plow, which does not produce unevenness in the ground due to its symmetrical condition, its quality is not affected mainly by the direction of the work. The same does not happen with the disc and mouldboard plow that require a method to avoid unevenness on the surface. The cross that corresponds to a second plow to rectify or increase the depth of the seedbed, it is advisable to apply it in a direction perpendicular to the first one, in order to achieve a better penetration of the plow, provided that a raking to improve the surface leveling of the terrain

The subsoiler plow should preferably be used in the "direction" of the greatest length of land to improve performance. However, it is advisable to use it in the direction of the slope when its function is to improve the drainage of a flat floor.

Scraping:  As its function is to loosen and even the soil, it is convenient to apply it in a 45 degree direction to the plowing line; in this way, the tractor wheels are prevented from falling simultaneously into the traversed furrows, which causes sudden movements that impair operator comfort and machine maintenance. Furthermore, a better leveling effect is achieved than when operating in any other working direction. The combined harrows and rollers can be used in any direction since this does not influence the quality of your work, being more important in these cases, the performance of the equipment and the speed of movement.

Leveling:  Leveling a previously plowed and traced soil generally requires 2 to 3 passes with the equipment to achieve an acceptable correction of the micro relief.

Tillage reduction

Potato cultivation has been characterized by the excessive use of soil preparation work, mainly with traditional systems that implied the use of a moldboard or disk plow and the practice of crossing and recruiting.

Trials carried out in the 70s and 80s by INIA Carillanca and the Austral University of Chile indicated that it was feasible to reduce the number of soil preparation tasks without affecting crop yields. At present, such a reduction has been reached, that with only one work of a rotary cutter with 35 cm tines, it allows the soil to be left in conditions to carry out the planting of potatoes.