Estimating Percent Residue Cover Using the Line-Transect Method

Leaving crop residue on the soil surface is one of the easiest and most cost-effective methods of reducing soil erosion. Research in Nebraska and other midwestern states has shown that leaving as little as 20 percent of the soil surface covered with crop residue can reduce soil erosion by one-half of what it would be from residue-free conditions. Greater amounts of residue cover will further reduce erosion. Many Conservation Plans specify crop residue management or residue left on the soil surface as the primary erosion control method. Generally, the amount of cover required after planting ranges from 30 percent to as much as 85 percent. Thus, it is important to accurately determine percent residue cover to verify effective erosion control and compliance with a Conservation Plan. Residue cover cannot be estimated merely by looking across a field. Such estimates, often attempted from the road or edge of the field, grossly overestimate the actual amount of cover. Accurate estimates of residue cover can only be obtained from measurements taken within the field, while looking straight down at the soil and residue. Crop residue management, or leaving residue on the soil surface, is the most cost-effective method of reducing soil erosion available to Nebraska farmers. Accurate measurements of percent residue cover are needed to determine if enough cover is present to adequately reduce erosion and to comply with a Conservation Plan. The line-transect method is one of the easiest and most accurate methods of determining percent residue cover

Estimating Percent Residue Cover Using the Line-Transect Method

Leaving crop residue on the soil surface is one of the easiest and most cost-effective methods of reducing soil erosion. Research in Nebraska and other midwestern states has shown that leaving as little as 20 percent of the soil surface covered with crop residue can reduce soil erosion by one-half of what it would be from residue-free conditions. Greater amounts of residue cover will further reduce erosion. Many Conservation Plans specify crop residue management or residue left on the soil surface as the primary erosion control method. Generally, the amount of cover required after planting ranges from 30 percent to as much as 85 percent. Thus, it is important to accurately determine percent residue cover to verify effective erosion control and compliance with a Conservation Plan. Residue cover cannot be estimated merely by looking across a field. Such estimates, often attempted from the road or edge of the field, grossly overestimate the actual amount of cover. Accurate estimates of residue cover can only be obtained from measurements taken within the field, while looking straight down at the soil and residue. Crop residue management, or leaving residue on the soil surface, is the most cost-effective method of reducing soil erosion available to Nebraska farmers. Accurate measurements of percent residue cover are needed to determine if enough cover is present to adequately reduce erosion and to comply with a Conservation Plan. The line-transect method is one of the easiest and most accurate methods of determining percent residue cover

Slot Injection of Herbicides

Injection of thiocarbamate herbicides into a slot created by a coulter was evaluated during a 3-year study in southeastern Nebraska. Control of shattercane, the dominant weed, with the slot injector was similar to conventional double disk incorporation. In both tilled and untilled surface conditions, the slot injector placed the herbicide into the soil with minimal disturbance of the soil and residue. Herbicides which are normally broadcast applied were band applied, reducing chemical costs by two-thirds

Tillage Systems for Row Crop Production

Selecting the tillage system best suited to a particular farming situation is an important management decision. Formerly, the traditional system was a moldboard plow operation followed by several secondary tillage operations before planting. This system can be appropriate for poorly drained soils having little or no slope and low erosion potential. However, plowing has several disadvantages . The potential for soil erosion is high on sloping lands, and labor and fuel requirements can be substantially higher than with other tillage and planting systems. Today, conservation tillage systems are used to reduce preplant tillage operations, thus reducing soil erosion and moisture loss while saving labor and fuel. The label conservation tillage represents a broad spectrum of farming methods, and is most often defined by the amount of residue cover remaining on the soil surface. The minimum amount recommended is 20 to 30 percent after planting. Research in Nebraska and other Midwestern states has shown that leaving at least this much residue will reduce erosion by more than 50 percent of that occurring from a cleanly tilled field. To achieve effective erosion control, this minimum residue cover should be maintained during the critical soil erosion period between spring seedbed preparation and crop canopy establishment. Conservation tillage does not necessarily require new equipment. Most conventional farm implements can be used. For corn, grain sorghum, or wheat residue, one or two passes with a field cultivator, disk, or chisel plow will usually leave more than the 20 percent minimum cover. Additional operations reduce the amount of residue, and thus reduce erosion control. Other tillage and planting systems such as ridge-plant (till-plant) and no till leave even more residue, and thus offer greater erosion control. However, no-till planting is the only method that consistently leaves the minimum surface cover in the more fragile and less abundant soybean residue. No single tillage system is best for all situations at all times. Selecting the best tillage system for a particular soil and cropping situation requires matching the operation to the crop sequence, topography, and soil type. Rotating systems to coincide with crop rotations often provides an excellent combination. For example, a no till system could follow soybeans while a chisel or disk system might follow corn. This tillage rotation provides the best erosion control following soybeans, and provides an opportunity for some tillage in the less fragile and more abundant corn residue

Soil Compaction I Where, how bad, a problem

Soil compaction is a more common problem now than it was 15 years ago, regardless of the tillage system used. Producers now use heavier tractors, larger implements, bigger combines, earlier spring tillage, reduced tillage, and no-till planting systems. While all of these have a potential to increase compaction, the major cause of the problem is conducting field operations when the soil is too wet. Most think about tilling wet soils in the spring as being the major problem, but harvesting a too-wet field in the fall can cause just as much compaction. Large combines and auger wagons can have loads exceeding 20 tons per axle. Continuous no-till has also created concerns regarding soil compaction and potential yield decreases. A study in Minnesota that compared no-till and other tillage systems used for 10 years on a clay loam soil showed the greatest soil density for the no-tilled soil. A study in Illinois indicated more compaction with no-till and other reduced tillage systems than with moldboard plow or chisel systems. Generally speaking, no-till is undesirable on a fine textured soil which has poor internal drainage or on a soil that has marginal tilth at the outset. On top of the soils themselves, the residue cover with no-till conserves moisture and slows soil drying, which can further complicate the problems of compaction when no-till is used on poorly drained soils. Soils with good structure, high organic matter, and good internal drainage are less likely to have compaction problems. Also, in low-rainfall areas, such as the Great Plains, compaction is less likely to be a problem than it is in areas of more moisture. The biggest single cause of compaction is the degree of wetness in a field when work is performed in or on that field. Defining compaction Compaction can be defined as the moving of soil particles closer together by external forces exerted by humans, animals, equipment, and/or the impact of water droplets. Packing the soil particles together results in the loss of pore space within the soil. This, in turn, leads to poorer internal drainage and aeration. Under many soil conditions compaction leads to slower water infiltration, which results in greater runoff and soil loss from both rainfall and irrigation. Compaction effects on the crop include reduced plant growth, especially root development, decreased crop yield , and delayed maturity

Tillage Systems for Row Crop Production

Selecting the tillage system best suited to a particular farming situation is an important management decision. Formerly, the traditional system was a moldboard plow operation followed by several secondary tillage operations before planting. This system can be appropriate for poorly drained soils having little or no slope and low erosion potential. However, plowing has several disadvantages . The potential for soil erosion is high on sloping lands, and labor and fuel requirements can be substantially higher than with other tillage and planting systems. Today, conservation tillage systems are used to reduce preplant tillage operations, thus reducing soil erosion and moisture loss while saving labor and fuel. The label conservation tillage represents a broad spectrum of farming methods, and is most often defined by the amount of residue cover remaining on the soil surface. The minimum amount recommended is 20 to 30 percent after planting. Research in Nebraska and other Midwestern states has shown that leaving at least this much residue will reduce erosion by more than 50 percent of that occurring from a cleanly tilled field. To achieve effective erosion control, this minimum residue cover should be maintained during the critical soil erosion period between spring seedbed preparation and crop canopy establishment. Conservation tillage does not necessarily require new equipment. Most conventional farm implements can be used. For corn, grain sorghum, or wheat residue, one or two passes with a field cultivator, disk, or chisel plow will usually leave more than the 20 percent minimum cover. Additional operations reduce the amount of residue, and thus reduce erosion control. Other tillage and planting systems such as ridge-plant (till-plant) and no till leave even more residue, and thus offer greater erosion control. However, no-till planting is the only method that consistently leaves the minimum surface cover in the more fragile and less abundant soybean residue. No single tillage system is best for all situations at all times. Selecting the best tillage system for a particular soil and cropping situation requires matching the operation to the crop sequence, topography, and soil type. Rotating systems to coincide with crop rotations often provides an excellent combination. For example, a no till system could follow soybeans while a chisel or disk system might follow corn. This tillage rotation provides the best erosion control following soybeans, and provides an opportunity for some tillage in the less fragile and more abundant corn residue

G91-1046 Conservation Tillage and Planting Systems

Tillage system descriptions and comparisons are included here. Moldboard plowing, followed by such secondary tillage operations as disking and harrowing, was once the most common, or traditional, tillage system before planting. Soil erosion potential from rainfall on sloping lands was great and requirements for labor and fuel were high compared to other tillage and planting systems. One of the most commonly used tillage systems in Nebraska today is two diskings followed by field cultivation. Unfortunately, the potential for soil erosion may be great because the number of tillage operations involved may not leave adequate residue cover for erosion control. Today conservation tillage systems reduce soil erosion and moisture losses while saving labor and fuel. Conservation tillage can represent a broad spectrum of farming methods, provided at least 30 percent of the soil surface remains covered with crop residue following planting. Research in Nebraska and other midwestern states has shown that leaving at least 30 percent residue cover reduces erosion from water by more than 50 percent, as compared to a cleanly tilled field

G91-1046 Conservation Tillage and Planting Systems

Tillage system descriptions and comparisons are included here. Moldboard plowing, followed by such secondary tillage operations as disking and harrowing, was once the most common, or traditional, tillage system before planting. Soil erosion potential from rainfall on sloping lands was great and requirements for labor and fuel were high compared to other tillage and planting systems. One of the most commonly used tillage systems in Nebraska today is two diskings followed by field cultivation. Unfortunately, the potential for soil erosion may be great because the number of tillage operations involved may not leave adequate residue cover for erosion control. Today conservation tillage systems reduce soil erosion and moisture losses while saving labor and fuel. Conservation tillage can represent a broad spectrum of farming methods, provided at least 30 percent of the soil surface remains covered with crop residue following planting. Research in Nebraska and other midwestern states has shown that leaving at least 30 percent residue cover reduces erosion from water by more than 50 percent, as compared to a cleanly tilled field

G95-1132 Estimating Percent Residue Cover

This NebGuide briefly describes the direct observation, line-transect, photo comparison, and calculation methods that are used to estimate the percentage of the soil surface covered with crop residue. Leaving crop residue on the soil surface is the easiest and most cost-effective way to reduce soil erosion caused by water and wind. Residue reduces water erosion by lessening the impact of the raindrops, thus reducing the amount of soil that is detached. It also slows flowing water, reducing the amount of soil that can be transported. Residue helps reduce wind erosion by reducing wind velocity near the soil surface and by trapping soil particles carried by the wind. Many conservation plans that were developed to meet conservation compliance provisions of the 1985 Food Security Act and the 1990 Food, Agriculture, Conservation, and Trade Act (Farm Bills) specify crop residue management as the primary method for erosion control. Four methods direct observation, line-transect, photo-comparison, and calculation are frequently used to estimate percent residue cover

RESIDUE MANAGEMENT TO CONTROL SOIL EROSION BY WATER

The Erosion Process Erosion of topsoil begins when water detaches individual soil particles from clod and other soil aggregates. A single raindrop may seem insignificant, yet collectively, raindrops strike the ground with surprising force. During an intense storm, rainfall can loosen and detach up to 100 tons of soil per acre and can be especially erosive when residue mulch or vegetation are not present to absorb their impact. Two problems often occur during rainstorms. The rate of rainfall can exceed the rate at which water can enter the soil and raindrop impact forces can partially seal the soil surface. In the first in distance, the excess water either collects on or runs off the soil surface and in the second, less water can infiltrate into the soil, causing more runoff. This runoff will travel downhill, carrying soil particles with it. Runoff from steeper areas flows at greater velocities and may transport considerable amounts of soil. Further, longer slopes have greater flows because water is concentrated from a larger area. As runoff flow across unprotected soil surfaces, additional soil particles are dislodged, thus creating even more soil erosion. Residue Reduces Erosion Crop residue helps protect the soil surface from raindrop impact. It. also reduces surface crusting, sealing and rainfall-induced soil compaction, all of which increase water runoff by reducing infiltration. In addition, runoff is reduced because pieces of residue form a complex series of small dams and obstructions that slow the runoff. Years of research show that no-till planting systems, which leave the greatest amount of residue cover, can reduce soil erosion by 90 to 95 percent of that occurring from cleanly tilled systems. As little as a 30 percent residue cover can reduce erosion by 65 percent as shown in the illustration. Prior land use, crop canopy and surface roughness also influence erosion from different tillage and planting systems, but residue cover is the single most important factor