Gary Peterson, Colorado State University
Professor Gary Peterson is not only a person of deep knowledge, but also an open conversationalist, capable of captivating practitioners with original ideas and the simplicity of clear thought. At a conference in Dnepropetrovsk, where Peterson read this report, he instantly grew friends and new acquaintances, he was invited to visit, to farms, and he responded sincerely, because a week of stay on this land was enough for him to fall in love with Ukraine.
Precipitation and atmospheric evaporation demand
In arid conditions, natural precipitation is the only available source of moisture. Semi-arid regions such as Eastern Europe and Western Asia receive variable and limited rainfall. Therefore, the successful cultivation of crops in non-irrigated soils depends on adequate water storage in the soil to maintain the crop until the next rainfall. Crops in rainfed areas rely solely on water in the soil accumulated between rainfall, and because of unreliable rainfall, water accumulation in the soil is extremely important for cropping crops in rainfed lands.
There are three principles of moisture accumulation:
1) water accumulation - preservation of precipitation in the soil;
2) water retention - the preservation of water in the soil for later use by crops;
3) efficient use of water - efficient use of water to obtain an optimal harvest. It is only recently that we have technology that has significantly changed the approach to rainfall management in rainfed areas. When mechanical tillage was the only way to control weeds and prepare the seedbed, managing sediment build-up and retention in the soil was very labor intensive. The cultivated fields were not covered at all and were significantly affected by wind and water erosion. Intensive tillage has many negative effects on the soil itself, including a decrease in the amount of organic matter and damage to the soil structure. Using reduced tillage and no-till allows us to efficiently collect and store water. In most cases, when reduced tillage and no-till systems are well established, they lead to more sustainable crop production in rainfed areas. This article will look at the principles of catching sediment and storing it in the soil.
Water accumulation
Water conservation begins with the accumulation of incidental precipitation (rain or snow). Water accumulation must be maximized within the economic constraints of a given situation. The principles governing soil properties that affect the ability to store moisture are as follows: soil structure, aggregate formation and pore size. We will also look at the interaction of water storage and retention versus evaporation. For example, shortening the time for water to stagnate on the soil surface and move moisture deeper into the soil reduces the potential for evaporation. This is especially important in regions where there is a great potential for evaporation following rainfall in summer.
Visualization of precipitation trapping
We must try to ensure that the water contained in the raindrop immediately falls into the gaps between the soil aggregates and is retained there for further use by the crop. First, let's imagine capturing precipitation in terms of a raindrop that hits the surface of the soil and penetrates deep into the ground (Figure 1). Note that the longer the gaps between soil aggregates are open, the less water is obstructed and absorbed faster, thus the accumulation of precipitation will be excellent.
The entry of water into the soil, at first glance, looks like a very simple process, when the incoming water simply displaces the air present in the soil. However, in reality, this is a complex process, since The rate of water infiltration into soil is influenced by many factors, such as soil porosity, soil water content and soil profile permeability. Water retention is a complex phenomenon as the maximum infiltration rate is reached at the beginning of precipitation and then rapidly declines as water begins to fill the pore space on the surface.
Soil texture strongly influences the infiltration rate, but soil texture cannot be changed with management. A large number of macropores on the surface (large pores), like those found in coarse soils (sandy loams, etc.), increase the rate of moisture infiltration. Soils with a fine structure (silty loams and heavy clay loams) usually have fewer macropores (small pores), and, therefore, the infiltration rate on such soils is lower compared to soils with a coarse structure.
Soil aggregation also controls the size of soil macropores. Thus, soils with the same structure, but with different degrees of aggregation, can differ significantly in terms of the size of macropores. Fortunately and unfortunately, the degree of soil aggregation can be changed through management methods such as no-till, crop residues, which help to restore aggregation. It is extremely important to remember that finely textured soils, such as silty loams or heavy clay loams, remain well structured so that there are open paths for water to move downward. Remember, any technology that reduces the structural size will reduce the pore size at the surface and therefore limit the penetration of water into the soil. The best thing about this is a structure that can resist change. Weakly structured soils quickly lose their ability to absorb water if the structural aggregates break down and the pores on the soil surface become smaller. This can happen either due to too intensive soil cultivation, or due to natural phenomena, such as rain.
The soil surface itself should be of interest for management, since the conditions at the soil surface determine the ability to trap moisture. When working in drought conditions, our goal is to use techniques that result in increased infiltration in a realistic and cost-effective manner within a defined cropping system.
Visualizing the effect of a raindrop
What really happens when a drop hits the soil surface? The size of the droplets depends on the strength of the thunderstorm, which, in turn, is predetermined by the climate of a particular geographic region. The diameter of the droplets varies from 0.25 to 6 mm (the average is about 3 mm), and now compare the diameter of the droplet with the diameter of the soil aggregates into which this drop falls, and the soil, in turn, is not covered with anything; the size of soil aggregates is usually less than 1 mm. When a droplet with a diameter of 3 mm, flying at a speed of 750 cm / s, hits an aggregate with a diameter of less than 1 mm, the damage is often very significant. If we bring this to relative mass, then this phenomenon is similar to the fact that a car weighing 80 kg crashes into a person weighing 1600 kg, moving at a speed of 27 km / h. Wind-blown rain, which accelerates the droplet speed, leads to greater impact, because a drop accelerated by the wind carries with it a charge of energy 2.75 times more than rain in calm conditions. It is quite obvious that soil aggregates will be destroyed, especially if they are constantly hit by raindrops during thunderstorms of any duration. The energy of raindrops negatively affects the structure of the soil surface, literally "exploding" soil aggregates. When the aggregates explode, the remaining small particles clog the macropore space of the soil and the infiltration rate decreases (Fig. 2). Obviously, during a short or mild thunderstorm, the effect of raindrops will be less. No-till provides a solution to this dilemma, because With this technology, plant residues remain on the surface, protecting the soil surface from the effects of rain drops.
Protection of soil aggregates from the influence of rain drops
Water retention can be carried out at an adequate level if we can keep the pores on the soil surface open. Therefore, protecting soil aggregates from rain droplets is the key to maintaining maximum water capture for a given soil situation (Figure 3).
No-till, keeping plant residues on the surface, is a partial answer to how to protect soil aggregates. In Figure 3, you can see how the crop residues absorb the energy of the raindrops so that the soil aggregates remain intact. Thus, water infiltration takes place normally. By controlling weeds with herbicides, we can simply control weeds without mechanical treatment, leaving our soil as protected as possible from the effects of rain energy.
Under no-till, soil cover is maintained all year round because the total soil cover is the sum of the cover from the growing crop itself and the cover from the residues. Obviously, soil cover is very dynamic and can range from 0% to 100% within a single growing season, depending on which crop is currently growing and which tillage technology is being used. During sowing, for example, the soil cover consists only of plant residues. As the crop grows, coverage is already mainly carried out by the foliage of the crop itself. When the cover created by the crop itself takes on the impact of a drop of rain, just like plant residues, the water smoothly rolls down to the soil surface with a much lower energy charge, therefore soil aggregates are subject to less destruction, the pores on the soil surface remain open, and infiltration is maintained at an appropriate level. As the crop grows, the amount of plant residues decreases, because natural decay occurs due to the activity of microorganisms. When the cover created by the growing crop begins to shrink, residues again become the main soil protection and the cycle ends. Remember that mechanical tillage, during and after crop growth, reduces the amount of plant residues on the surface, and, consequently, the protection of the soil surface.
The benefits of water accumulation due to the cover are most noticeable in regions with summer precipitation; for example, the growing cycles of maize (Zea mays L.) or grain sorghum in the Great Plains of North America occur when 75% of the annual rainfall falls. Conversely, rain-fed regions with little rainfall in winter (the Pacific Northwest in the United States) do not have a well-developed cover when most of the rain falls. However, early formation of crops planted in the fall to obtain at least partial soil cover is recognized as a good soil protection and a way to control water outflow during the winter months.
Other effects of crop residues on water retention
In addition to absorbing droplet energy and protecting soil aggregates from destruction, crop residues physically block the outflow of water, reduce evaporation levels during rain, allowing water to enter the soil profile before outflow begins. General water infiltration is a consequence of how long water will be in contact with the soil (a time of opportunity) before it starts flowing down a slope. Increasing this time component is a key management tool in water storage. The main principle of increasing the "time of opportunity" is to prevent the outflow of water, slow it down, and thus provide the opportunity to stay in contact with the soil for a longer time, and, therefore, to be absorbed. Crop residues on the soil surface increase the “opportunity time” because physically block and slow down the outflow of water. Contour seeding also enhances the benefit of crop residues in slowing down the outflow of water because ridges play the role of mini-terraces.
Duley and Russel (1939) were among the first to recognize the importance of soil protection with crop residues. In one of their experiments, they compared the effect of 4.5 t / ha of stacked straw with an equal amount of embedded straw and uncovered soil on moisture accumulation. Moisture accumulation accounted for 54% of rainfall with stacked straw, compared with 34% when straw was covered and only 20% with uncovered soil. Their experiment did not separate the effects of crop residues into components such as soil protection, evaporation and water blocking, but comments suggest that maintaining porosity and physically blocking water significantly reduced moisture outflow during thunderstorms and were major contributors to increased water accumulation during thunderstorms. season.
Data from the study by Mannering and Mayer (1963) clearly show a protective mechanism of plant residues affecting the infiltration rate in silty loams with a slope of 5%. After four simulations of rain for 48 hours, the soil covered with 2.2 t / ha of crop residues had a final infiltration rate that was not much different from the initial one. The researchers found that the straw absorbed the energy from the droplets and spread it out, preventing the soil surface from crusting and blocking.
Demonstration of the negative impact of machining
Soil aggregation decreases with an increase in the intensity of tillage and / the number of years of cultivation (Fig. 4). Mechanical tillage has a negative effect on soil aggregates for two main reasons: 1) physical crushing, which leads to a reduction in the size of the aggregates; 2) an increase in the levels of oxidation of organic matter, which occurs due to the destruction of macroaggregates and the subsequent discovery of organic compounds by soil organisms. The distribution of the sizes of aggregates also changes in such a way that microporosity increases due to macroporosity, which leads to a decrease in the rate of infiltration. The degree to which mechanical tillage affects infiltration is governed by a complex interaction of the type of tillage, climate (especially rainfall and temperature) and time, together with soil characteristics such as structure, organic structure and organic matter content. Therefore, long-term cultivation of any soil reduces the resistance of the aggregates to physical destruction, for example, exposure to raindrops and mechanical tillage of any kind. However, both clay minerals in the soil and organic matter stabilize soil aggregates and make them resistant to physical destruction. A decrease in the amount of organic matter reduces the stability of the aggregates, especially if it is already low.
Of these two basic soil properties that regulate the formation of aggregates, mechanical tillage in any form affects the content of organic matter. The degree of practicality of altering the organic matter level will vary depending on the conditions. the level of organic matter is largely determined by two processes: accumulation and decomposition. The first is determined mainly by the amount of organic matter introduced, which is highly dependent on precipitation and irrigation. The second is mainly temperature. The goal of maintaining or increasing organic matter levels is easier to achieve in cool, humid conditions than in hot and dry conditions.
The "freshness" of organic matter compounds is necessary for the stability of the aggregates. In soil ecosystems, newly added or partially decomposed plant residues and their decay products, also known as “young humic substances”, create a more “mobile” array of organic matter. Older or more stable humic substances, which are more resistant to further decay, create a "stable" body of organic matter. It is generally accepted that a mobile body of organic matter regulates the supply of nutrients in the soil, especially nitrogen, while a mobile and stable body affects the physical properties of the soil, for example, the formation of aggregates and structural stability. The formation of a mobile and stable array is a dynamic process that is regulated by several factors, including the type and amount of organic matter applied and its composition.
There has been a lot of interest in determining how soil cultivation affects the structural development and maintenance of soil in relation to organic matter content, especially with the advent of no-till technology. An increase in the intensity of soil cultivation increases the loss of organic matter from the soil and reduces the aggregation of the soil.
Snow accumulation and melt water retention
Many dry lands receive significant annual precipitation in the form of snow. Effective accumulation of snow water has two characteristics: 1) trapping snow itself and 2) trapping melt water. Since snow is often accompanied by wind, the principles of trapping snow are the same as those used to protect soils from wind erosion. Crop debris, windbreaks, strip cultivation and artificial barriers were used to maximize snow trapping. The basic principle of these devices is to create areas where the wind speed from the leeward side and the barrier is reduced, thus trapping snow particles from the other side of the barrier. Repetitive barriers, such as standing stubble, keep the wind above the surface of the crop residues, and therefore the "trapped" snow remains unreachable for subsequent wind movements.
Research by scientists from the Great Plains of the United States showed that standing stubble retained 37% of winter precipitation, and fallow fields without plant residues retained only 9%. The proportion of the field covered with plant residues on the vine obviously influences the collection of snow. Scientists studying the effect of sunflower cut height on snow retention have found a strong correlation between stored moisture in the soil and cut height: the higher the cut, the more snow is captured.
The introduction of no-till technology has made it possible to significantly improve snow catching with the help of plant residues on the vine. Prior to the introduction of no-till, the mechanical treatment required to control weeds led to a decrease in the proportion of crop residues on the vine and the overall proportion of soil coverage in crop residues, and therefore to a decrease in snow capture.
Capturing snowfall remains the simplest part of accumulating the snow moisture resource; capture of melt water is much less predictable and manageable. For example, if the soil freezes before it snows, the water is less likely to be absorbed than when the soil is not frozen. In northern latitudes, soils usually freeze before snow falls. Moreover, the depth of soil freezing depends on the amount of water in the soil in autumn, as well as on the insulating effect of snow, which increases with increasing depth of snow cover. Dry soils freeze deeper and faster than wet soils, but frozen dry soils reduce water outflow compared to wet soils.
Maintaining infiltration when the soil freezes before snowfall and / or winter rains is difficult. The levels of infiltration of frozen soils are determined by two factors: 1) the structure of the frozen soil, i.e. small granules or large aggregates similar to concrete, 2) the water content of the soil during frost. Soils that are frozen with low moisture content do not interfere with water penetration. the aggregates leave enough room for infiltration. Conversely, soils frozen with a high water content freeze into massive, dense structures (like concrete) and practically do not allow water to penetrate inside. Sudden thaw and rain on such soils can lead to large outflow and erosion. The accumulation of winter precipitation can be maximized using the following principles: 1) trapping snow with plant residues on the vine; 2) maximization of macropores on the surface during those periods when the soil is frozen.
Synthesis of the principles of water storage
Favorable conditions for infiltration at the very surface of the soil and sufficient time for infiltration are keys to efficient water storage. However, the most important principle is to protect the soil surface from droplet energy. During the winter months in temperate zones, when large leaves have not yet appeared to absorb the energy of the drop and allow water to pass through, vegetation (plant residues) has the function of reducing outflow levels. The coating absorbs droplet energy, protects soil aggregates and increases the size of macropores, which in turn reduces outflow. Moreover, during the growing season of the crop, the water content of the soil in small amounts ensures a good infiltration rate.
Water retention in soil
After the water has been collected, the evaporative property of the air begins to "pull" it out. Therefore, even if no crops are present in the field, the soils lose moisture due to evaporation. In this section, we will demonstrate how no-till affects soil water retention after we have collected enough moisture during rainfall. The protective property of plant residues increases infiltration because they not only protect soil aggregates, but at the same time affect the rate of evaporation, especially during the initial stages of evaporation, after precipitation.
Demonstration of evaporation of water from soil
Evaporation occurs because the air demand for water is always high, even in winter, in relation to the soil's ability to retain water. In other words, the air potential is always negative in relation to the soil potential. Warm air has a greater ability to retain moisture than cold air. Thus, as the temperature rises, the evaporation potential increases. Evaporation is greatest when the soil is moist (high water potential) and the air is dry (i.e. low relative humidity). When the soils dry out at the surface, water rises to the surface to replenish the evaporated water (Figure 5). With constant evaporation, the distance traveled by the water increases, which reduces the rate of flow of water to the surface in the form of liquid or vapor, the rate of evaporation decreases, and the soil surface remains dry (Fig. 5). Finally, water only begins to move towards the soil surface in the form of vapor, which results in a very low evaporation rate. Each subsequent precipitation starts the evaporation cycle anew, because the soil surface becomes wet again.
In addition to air temperature, other atmospheric influences such as solar radiation and wind affect evaporation. Solar radiation gives energy to evaporation, and wind speed affects the vapor pressure gradient on the soil-atmosphere horizon. High humidity and low wind speed result in a lower vapor pressure gradient on the soil-atmosphere horizon and thus lower the evaporation rate. As the relative humidity decreases and the wind speed increases, the evaporation potential gradually increases. On a windy day, moist air is constantly replaced by dry air on the soil surface, leading to faster evaporation.
The evaporation of water from the soil goes through three stages. Most of all water is lost at the first stage, and at subsequent stages the level of losses decreases. Evaporation in the first stage depends on environmental conditions (wind speed, temperature, relative humidity and solar energy) and the flow of water to the surface. Losses are significantly reduced during the second stage, when the amount of water on the soil surface is reduced. During the third stage, when the water moves to the surface in the form of steam, the speed is very low. The greatest potential for reducing evaporation levels lies in the first two stages.
Let's demonstrate how plant residues left on the soil surface affect the evaporation of water from the soil. Obviously, they will reflect solar energy, cooling the soil surface, and also reflect the wind; both of these effects will reduce the initial rate of evaporation of water (Fig. 6).
Plant residues on the soil surface, present in no-till technology, significantly reduce the level of evaporation in the first stage. Any material, such as straw or sawdust, or leaves or plastic sheeting spread over the surface of the soil, will protect the ground from the effects of rain energy or reduce evaporation. The orientation of crop residues (on the root, laid mechanically or in the form of a cover) also affects the evaporation rate, because orientation affects aerodynamics and reflectivity, which in turn affects the solar energy balance at the surface. An example of the efficiency of using plant residues is given in the scientific work of Smika (1983). He measured the loss of water from the soil during a 35-day rainless period. Losses were 23 mm from uncovered soil and 20 mm with plant residues laid, 19 mm with 75% laid residues and 25% standing residues and 15 mm with 50% laid residues and 50% standing residues on the surface.
The amount of residues was 4.6 t / ha and the standing residues were 0.46 m in height.
The reader should remember that plant residues do not stop evaporation, they delay it. If a lot of time passes, and precipitation does not fall, the soil under plant residues will begin to lose as much water as uncovered soil. The only difference is that uncovered soil will lose water quickly, and plant residues will decrease the rate at which water will leave the soil (Fig. 7).
The benefits of slowing evaporation with crop residues in a no-till system can be demonstrated using the data in Figure 7. Suppose it rains on day 0, ie. and uncovered soil (line indicated by diamonds) and soil covered with plant residues (line indicated by squares) are in the same conditions in terms of moisture content. After 3-5 days, very rapid evaporation has occurred on uncovered soil and the surface will be almost air dry. In contrast, soil covered with plant debris has a much lower evaporation rate and does not dry out until 12-14 days after rainfall. Now, let's imagine another rain falls on the seventh day; since uncovered soil is already dry on the seventh day, rain must re-wet the dry soil before moisture retention begins. If it rains very briefly, only the amount of water that has evaporated will be replenished. In contrast, the soil that was covered with plant debris evaporated very slowly, so by the seventh day the soil under the plant debris is still moist (shown in Fig. 6). This means that if it rains on the seventh day, it does not need to wet the dry soil (there is none), so the water immediately begins to move deep into the soil, and its accumulation occurs.
Slowing down evaporation with crop residues in no-till systems helps to retain moisture because the soil surface dries more slowly. However, if it does not rain for an extended period, soil covered with plant debris will not retain more moisture than uncovered soil.
The reader should understand that even if there is a long time between rains and evaporation dries up the soil, plant residues are beneficial in any case. they will protect the soil from the energy of the raindrops when it rains again.
Demonstration of the effect of soil cultivation on moisture evaporation
When the soil is mechanically cultivated, the moist soil opens up to the surface. This means that rapid evaporation begins immediately after processing (Fig. 8). Obviously, if mechanical treatment is used to control weeds, it will waste moisture because constantly exposes wet soil to rapid evaporation on the surface. In contrast, no-till, which uses herbicide-based weed control, does not lead to evaporation because there is no impact on the soil. The soil remains wetter at the surface, and therefore the next rain will not rewet the dry soil, but will penetrate deeper into the soil and accumulate for future use.
conclusions
The key to effectively capturing water is the favorable conditions at the soil surface so that water can enter the soil immediately, as well as those (conditions) that allow sufficient time for infiltration. The most important principle for achieving the penetration of water into the soil is to protect the surface from the energy of rain drops. The no-till system provides coverage with growing crops and crop residues. The coating absorbs droplet energy, protects soil aggregates and increases the size of macropores. At the same time, this coating slows down the outflow, thereby increasing the accumulation of water in the soil for use by subsequent crops. To maintain the maximum amount of accumulated moisture, evaporation must be minimized. No-till reduces evaporation because With this technology, plant residues remain on the surface, which reduce the temperature of the soil and raise the wind above the soil. The use of water by weeds is a waste of moisture that could be available to cultivated plants. Mechanical tillage usually stops weeds immediately, but exposes wet soil to the atmosphere, resulting in increased evaporation losses. When using a no-till system, weed control is carried out using herbicides, which prevents harmful effects on the soil compared to mechanical tillage, while water accumulates in the soil. This is especially important in countries like Ukraine, where most of the precipitation falls in summer.
The soil, constantly shaded by several crops, loses several times less water.
The larger the sand particles in the soil of your site, the more difficult it is to keep moisture in it. The water passes through the soil like a sieve. Fertile and structured soil stores and retains it much better.
So, what can you do to somehow keep moisture in the soil longer?
-To increase moisture-holding the ability of sand is added to it crushed clay and various organic fertilizers.
Since on sandy soil water quickly seeps into the depths, without lingering in the upper layers, it should not be watered as abundantly as clayey, but much more often.
During drought, try not to disturb the soil as much as possible: any loosening contributes to additional evaporation of moisture.
If the soil is very dry, water in several passes: First moisten the surface layer and wait a few minutes, then water again - the water will seep below without spreading over the surface.
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On hot spring days, when there is still a lot of moisture in the depths of the soil, you can use the so-called reverse watering: cover the soil near the plants with black plastic wrap and sprinkle it with a layer of earth 2–3 cm. During the day, the film heats up, and moisture rises from the lower soil layers to the upper ones. It condenses on the film that has cooled down overnight and goes back to the soil.
In late autumn, when evaporation decreases, it is necessary produce water-charging irrigation, to protect the root system of plants from frost in case of snowless winters.
To moisten the soil of plants in containers fill a wide container with water, in which, in turn, put pots and hanging baskets for a while. Thus, all the soil in the container is soaked through and the plant receives a large amount of moisture.
It is also an excellent way to urgently resuscitate already damaged plants with a dried earth clod. This method of moisturizing is not harmful even in the hottest hours, because water does not get on the leaves. After a similar procedure, the water from the container can be poured under some bush, because useful substances from the soil of the containers have accumulated in it.
If you can afford irrigation systems, invest in a modern drip or jet system instead of a traditional sprinkler. Water in such systems, thanks to the timer on the tap, appears at the right time (for example, late in the evening), even in your absence, gets to the roots of plants and is absorbed to the last drop, without being wasted on watering neighboring weeds.
Pay attention to this:
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Preservation of moisture in the soil
The problem of a reduced level of soil moisture after a drought is becoming one of the most pressing issues in planning work. Harold van Es, a crop and soil expert at Cornell University and author of Building Soils for Better Crops, is actively researching the issue. According to him, most farmers, after short annual droughts, regularly face a lack of moisture in their soils.
This is also the topic of SARE's recent Water Efficient Use on Your Farm report. It notes that land management is an important factor in the drought problem.
Indeed, many farmers at the end of last summer spoke of extremely unfavorable soil conditions. “When you were digging,” comments Jim Callison, an Illinois farmer. - then the shovel just bounced off her like concrete. " He discusses the expediency of tillage in such conditions: “The corn pulled so much water out of the ground that it hardened. Until it gets at least a little moisture, we can walk over it with the opener. "
The SARE study says now is the right time to consider organic matter in the soil, as this is the key to good moisture.
As noted in the report, with an increase in organic matter in the earth, its micropores increase. When decomposing, plant residues and other reclamation components create viscous substances that bind soil particles and create space between them. In addition, the characteristics of the organic matter alone allow water retention. “By changing the micropores of the soil, you change its ability to retain moisture. - confirms the idea of van Es. "Plants will get more moisture with a good, loose soil structure than with a dense soil."
Ways of increasing organic matter in the soil have long been widely known: the introduction of manure, compost, sowing cover crops. Less intensive tillage is also effective. Another option is to diversify the crops sown.
SARE's findings are encouraging. By reducing the intensity of tillage or switching to another crop rotation, you can increase the moisture level in the soil by 10% - 20%. Direct-sowing farmers find their land more resistant to drought. Pennsylvania farmer Steve Groff even received the commendation recorded in the SARE report for applying no-till and planting cover crops to improve the soil. "The negative effects of the drought," he says, "appeared on my farm a few days later than in the neighboring ones." Eileen Kladivko, an agronomist at Purdue University, also notes that after a drought, it is especially important to increase the dose of organic matter in the soil, which compensates for the lack of plant residues. At the end of last summer, she recommended the use of cover crops for fall planting. Such crops, she said, will help offset the cost of nitrogen fertilization and increase the amount of organic matter.
Over the past 200 years, revolutionary changes have taken place in the technology of growing crops. Laws for restoring soil fertility have been developed, the role of humus has been studied, a powerful industry for the production of mineral fertilizers and pesticides is working, new intensive varieties of agricultural crops have been developed and much, much more.
The transition from a planned system to market relations in 1993 affected agriculture most painfully. Much has changed in agricultural production. State and collective farms did not fit into market relations and ceased to exist. Instead of experienced chairmen of collective farms and directors of state farms, leaders of the market format came, having no experience in working with land. Most of them before that were not engaged in agricultural affairs at all. And the land requires a special and careful attitude towards itself, and therefore, not everyone succeeded right away.
Trying to reduce the cost of the products received, the new farm managers began to save at all stages of grain production: they work on worn-out equipment, mainly without the use of mineral fertilizers and pesticides, save on the quality of seed material, reduce the consumption of fuels and lubricants to a minimum, skipping the necessary technological operations.
Without meeting the deadlines and requirements of technology, with unjustified stubbornness, what is the guarantee of their well-being, and by and large the future of mankind, whose existence as a whole depends on the fertility of the earth, will be destroyed.
Resource-saving grain production technology has been exciting the minds of agricultural producers for more than one year. It can be noted that in recent years, more and more articles have begun to appear in print media about resource-saving technologies. Manufacturers of agricultural machinery also write such articles, bringing one of their machines under resource conservation. It is clear that resource-saving technology cannot be introduced with one seeder or one cultivator. Certain agronomic knowledge about resource-saving technologies is needed, it is imperative to have a set of special equipment that would meet the requirements of minitill and no till technologies. Having experience in working on the ground and a special set of equipment, the introduction of resource-saving technologies in a certain soil-climatic zone is, in principle, possible. But this will require more than one year of painstaking work and knowledge to achieve a result. Some farm managers think that resource-saving technologies are being introduced, as in good fairy tales, by a wave of the hand, and the fields will ripen right there, a harvest, say, 100 centners, without any knowledge, farming fundamentals and costs.
What are the realities today in our agriculture with a market economy? For the most part, agricultural producers have the bitterness of disappointment for their work. They look at their hard-won harvest and think. What to do with it? If there is a lot of grain, then there is nowhere to sell, dealers simply rob, and if there is a drought, then consider it lost. What's next?
According to numerous studies of the Research Institute of Agriculture, the change of the classical farming scheme to new resource-saving technologies is possible, I.E. Ovsinsky 100 years ago, also T.S. Maltsev and his followers and numerous research and development in the field of plant growing and field cultivation, both in our country and abroad. All of them agreed on one thing: it is not necessary to stress the active biological horizons of the soil by turning the layer, but on the contrary, it is necessary to activate the natural metabolic processes by means of shallow tillage with the preservation of stubble. When switching to non-moldboard tillage, a slow process of restoration of the biological active part of the soil begins - this is the process of decay of plant residues, with the formation of carbonaceous compounds, which is the main source of nutrition for microorganisms.
Scientific research institutes have long noted that the turnover of the seam causes an increase in soil mineralization due to an increase in the colony of microorganisms in the soil. Their activity leads to a powerful depletion of soil organic matter. Plowing to a depth of over 20 cm, according to these studies, must be accompanied by the application of nitrogen mineral fertilizers. The constant and necessary condition for this is the application of organic fertilizers in very high doses. If these requirements are not met, an increase in the number of microorganisms does not lead to the accumulation of humus, but, on the contrary, causes its depletion.
In addition, the work of many scientists shows that even with the maximum level of use of mineral fertilizers, the formation of grain crops is mainly 40-50% due to its own soil nitrogen. That is, the use of only mineral fertilizers will never help maintain a deficit-free balance of soil organic matter.
Microbiologists, having made long-term comparisons between different methods of cultivation, have established that to stimulate the microflora in the soil, an alternative to plowing with a seam turnover, it can be loosening the soil without turning the seam, to shallow depths, for example, a crevice to a depth of 30 cm. Under this condition, one can count on the maximum increase in the number of microorganisms in the uppermost soil layer, where the primary decomposition of plant residues occurs, that is, where the processes of primary humification are carried out. Thus, they led to the idea that when leaving plant residues on the soil surface, followed by mulching them with special working bodies no more than 2-3 cm and loosening the soil to shallow depths without turning the layer, it is possible to create good conditions for humification. In practice, this was proved by the Moscow Agricultural Academy, for 20 years they observed the dynamics of humus accumulation in the soil during surface tillage without turning the seam and a decrease in the humus content during plowing with seam rotation to a depth of 25 cm and by 25 cm with 15 cm subsurface loosening (A.M. Lykov and others). That is, if the financial situation of the farm cannot allow it to constantly apply large amounts of mineral and organic fertilizers to its fields, the agronomist of this farm is simply obliged to abandon plowing with a seam turnover, and the head of the farm should seriously think about the technical basis for surface tillage.
The accumulation of humus is not the only advantage that the transition to shallow tillage can bring. Recently, there have been reports of another phenomenon, with minimal processing with mulching of the soil surface with plant residues. This is the effect of the accumulation of dew in the soil.
The essence of the phenomenon is simple: the higher the air temperature, the higher its humidity. For example, in a drought, when the air temperature reaches 50 degrees, each cubic meter contains 92 g of water. As soon as this hot air penetrates into the upper soil layer and cools there to a temperature of, say, 40 degrees, then due to physical laws, the amount of water contained in this air decreases to 55 g, the difference (92 g - 55 g) is equal 37 g is immediately transferred to the soil in the form of dew or condensation. Think of the instant sweating of a saucepan or bottle taken out of the refrigerator. The process of dew settling in the soil is ensured by the air permeability of the soil. It should be loose, capillary, shaded with mulch or a thin, no more than 5 cm loosened layer.
Dew catching technology is over 100 years old. So one of its authors I.E. Ovsinsky, when neighbors came to his fields, he wrote: “Some make the assumption that rain has fallen over my fields, others see some kind of mystery in this, while the matter is explained very easily and is achieved by the most simple means. Now I am not only calm, but also with some pleasure encounter this terrible scourge of agriculture - drought. With our surface plowing of 5 cm, such a mass of water is deposited in the soil that during the worst drought, there is dirt under the thin dry top layer. Our plants will surely sprout and grow without rain, and good weather will make it easier for us to work in the field, which often becomes an obstacle to rain ”.
So, let us summarize some of the results and consider the technology of minimum cultivation of the land using the example of grain crops using the complex of machines of Syzran-Selmash LLC.
Refusal from plowing with seam turnover. Autumn plowing, replaced by crevice. The depth of loosening with slot-cutters is from 20 to 30 cm, for this you can use the OPO-4.25 or OPO-8.5 cultivators manufactured by Syzran-Selmash LLC. It's just that in the fall, on the OPO cultivator, you need to replace the racks with paws and instead of them put the slot cutters through one rack. The frame design provides for the installation of slots. Cutters are available from the factory. This agricultural practice will allow to fully preserve and evenly distribute over the entire surface of the field, autumn and spring moisture for the future harvest in a meter layer of soil, and the lagging stubble between the cracks in the winter will help to retain snow. Diesel fuel consumption for crevice is 8-10 l / ha. Productivity OPO-4.25 with a 3-ton class tractor. 20-25 ha, OPO-8.5 with a 4-5 ton class tractor. 30-40 ha per shift A prerequisite for any autumn soil preparation is straw chopping. For this purpose, you need to use RIS-2 (rotary straw chopper).
In the spring, as the soil matures, in order to preserve moisture, control annual weeds and mulch the soil surface with straw residues, it is necessary to harrow in two tracks with heavy harrows across the cracks.
Before sowing spring crops, depending on the weediness of the field, one presowing cultivation is carried out, OPO-4.25 or OPO-8.5 to a depth of 6 cm. in this case, SZP-3.6 or AUP -18.07 can be used for sowing and seeder. If the fields are not heavily weedy, or the farm has a sufficient amount of herbicides, it is possible to sow without preliminary tillage on the stubble with the AUP-18.07 seeder.
Particular attention should be paid to the preparation of the soil for winter crops in clean fallow according to a moldboard-free scheme:
- - harvesting is carried out with chopping of straw,
- - crevice across slopes,
- - harrowing in spring with heavy harrows in two tracks across the slots,
- - the number of presowing cultivation per season depends on the weediness of the field.
The first cultivation for winter crops is carried out to a depth of 8-10 cm with cultivators OPO-4.25, OPO-8.5. All subsequent cultivation should be carried out with simultaneous mulching of the soil surface with plant residues no deeper than 5 cm. Such processing will allow the accumulation of moisture from the air in the soil.
The last cultivation before sowing should be carried out with the AUP-18.07 seeder to a depth of 6-7 cm with the simultaneous introduction of granular mineral fertilizers. What does it do?
You apply fertilizer to the area of future roots. By the time of sowing, fertilizers will dissolve and will be in an accessible form for plants. The seeder has exactly the same working bodies as the cultivator and cut the weeds at all, no worse than the OPO. Having rollers on the seeder will roll the soil well and draw moisture into the top layer of the soil.
With this agricultural technique, you reduce the intensity of field work in the autumn and especially during sowing winter crops. The productivity of the unit increases in the sowing of winter crops by increasing the capacity of the grain box due to the lack of fertilizers.
The introduction of starting doses of mineral fertilizers is of great importance to provide mineral nutrition and the formation of secondary roots of the sown crop, as well as to increase the efficiency of the decomposition of stubble and plant residues. As a rule, the yield after the application of straw to the fields decreases due to the high consumption of nitrogen by microorganisms, especially on poor soils with a low humus content. Therefore, in order to avoid a decrease in grain yield, it is required to apply at least 50-60 kg / ha in physical weight of complex mineral fertilizers simultaneously with sowing or 6-8 kg in physical weight of nitrogen fertilizers per 1 ton of introduced straw.
Sowing dates for spring crops depend on the average annual meteorological forecasts. Agronomist, he should know about the average annual periods of the onset of soil and atmospheric drought and sow spring crops at the optimal time in order to avoid plants getting under the influence of drought in the phases of stemming and during the appearance of the flag leaf. The traditional sowing dates in a particular region do not always coincide with the average annual distribution of precipitation, namely, during the spring field work, when the effect of drought on the grain yield is maximal. For winter crops, the determining factor should be the expected weather conditions in the tillering phase, it is equally dangerous for plants when winter crops outgrow in autumn and leave weakened in winter.
As you can see, the technology of minimum tillage can become resource-saving, if the main condition is met: reducing the cost of carrying out agrotechnical operations, due to their combination, which becomes possible only if new multifunctional agricultural units are used.
One of the oldest agricultural engineering enterprises in the Russian Federation, LLC Syzran-Selmash, Syzran, Samara region, produces a set of machines for growing grain and leguminous crops using resource-saving soil-conserving technologies.
All plants, especially during the period of their rapid growth, need moisture. Plant organisms can take moisture only from the soil layer. Only a few isolated species of lianas are able to draw water, literally, from the air, but this is in a tropical humid climate, and not in our suburbs.
Therefore, the issue of moisture conservation, especially in the hot summer period, is more relevant than ever for every gardener. There are several simple old, but already half-forgotten methods, as well as modern ones that require investments in advanced technologies.
To keep moisture in the soil longer, it is necessary to close its outlet back to "freedom" - to the atmosphere. This can be done by combing the ground adjacent to the plants with a rake. This is convenient for potatoes, cabbage and single-stemmed fruit trees. In other cases, loosening of the soil is performed. The crust with straight holes collapses, and the passages in it become more intricate, which prevents all moisture from reaching the surface.
A fence made of dense material partly helps from blowing out useful moisture in the soil. Excellent and reliable fences are made from pergone stone. Looked at http://pergonen.ru/product/zabory/ - there are good solutions. This is a simple solution for making your homestead look solid for little money. The fence is mounted quickly, which is important when building large perimeters. Take shading as a moisture retention option.
The second method is to mulch the soil surface with a layer of sawdust or manure. For large areas it is possible to mow the grass from the side. Such a layer will help to retain moisture, stifle weeds and get dew when the temperature in the surrounding space changes.
Also, a study published in the SARE report "Effective use of water on your farm or ranch" suggests that by reducing the intensity of tillage or making a transition to a different crop rotation, it is quite possible to increase the level of moisture in the earth by 10-20%.
More modern means include a special mulching plastic wrap. Such protection allows moisture to penetrate into the soil, but does not allow it to get out back. In addition, such a system also allows you to prevent excess moisture from passing through, for example, from heavy rain. Given the high cost of the film, it is advisable to use it only for more expensive delicate crops such as garden strawberries.
The primary source of moisture supply to the earth is precipitation of the cold season, in particular, snow, frost, ice. In summer, this function is performed by groundwater. How to retain moisture and use it wisely? Tips for the southern regions
Water is the source of vital energy for all living things. By absorbing it, the plants restore their moisture reserves and receive a natural temperature regulator. In the process of thermoregulation, the plant evaporates up to 99% of all the water obtained, while using only 0.2-0.5% for the formation of vegetative mass. Over the past 30 years, the average annual air temperature in the south has exceeded the norm every season. The situation with precipitation is getting worse, for effective farming there is not enough 100-150 mm to the norm. Therefore, agronomists resort to different methods.
1. During spring field work in southern farms, they try to abandon cultivation. After harvesting the culture, a disk unit is started up, then deep moldboardless processing (stubble plowing) is carried out. After harvesting, a tractor moves behind the harvester, which discs the soil to a depth of 5-12 cm. To close the moisture, harrowing is mainly carried out. In the pre-winter period, autumn cultivation is carried out for better penetration of moisture into the soil and the operation is repeated in the spring.
2. On chernozems of medium granulometric composition, in order to preserve moisture, they try not to compact the soil and resort to technical methods: in the fall they carry out plowing, in the spring they remove the crust with a cultivator, carry out disking to a depth of 5-6 cm and harrow.
3. No-till technology allows you not to disturb the land, plus the fields are always covered with crop residues from previous crops. It is often said that the technology has disadvantages, for example, heavy rain can wash away plant residues that lie unevenly on the field. Theoretically, this is possible, but so far we have not encountered a similar situation in the southern regions.
4. When growing sugar beets in the fall, practitioners advise to level the field. After harvesting wheat, barley and other crops, disking to provoke weed shoots, then the main cultivation and deep loosening to a depth of 35 to 40 cm.Plowing for sugar beets is performed at a depth of 32 cm, for corn and sunflower - 27 cm as soon as it becomes possible to enter the field, cover the moisture by 5 cm.
5. In recent years, not a drop of rain may fall in the south for the whole summer. The average crop yield can be ensured by the observance of crop rotation with the mandatory content of fallows. To accumulate moisture, it is necessary to carry out non-irrigation deep loosening of the soil. Thanks to such processing, the yield increases by an average of 10% compared to plowing. To retain moisture, plant residues are left on the surface in the form of a mulch layer, and harrowing is carried out in early spring.
6. Do not forget about the traditional method - snow retention, which ensures the accumulation of winter moisture in the soil. As soon as snow falls on the field across the movement of the main winds, snow holders are installed. Also a good solution would be backstage from tall plants such as sunflowers or corn. (