By Dr. Donald Eckert
Soil and water are two critical components of crop production. Our agronomic crops depend on soil for physical support and to provide the water and nutrients necessary for optimum performance. The characteristics of Ohio soils vary tremendously from place to place, even within the same field, and as characteristics change, management practices necessary for optimum production and environmental protection may change also. Producers should know how soil properties influence production and which management practices are best suited to the particular soils found on their farms. Characteristics of the soil series found in Ohio can be found in the Soil Survey bulletins usually available from the local Soil and Water Conservation District, Ohio State University Extension, or Natural Resource Conservation Service offices. Information for individual soil series is also available on-line at: www.dnr.state.oh.us/soilandwater/soils/soilsinfolinks.htm.
Efficient water management is perhaps the most important aspect of crop production. Crop yields are affected adversely by the presence of too much or too little water, and unfortunately, many Ohio producers are faced with both problems in the same year. Researchers at the USDA-Agricultural Research Service’s North Appalachian Experimental Watershed near Coshocton have shown that Ohio crops may use the following amounts of water during a typical growing season:
In a typical year, precipitation exceeds crop water use in winter, spring, and autumn. During the spring, excess soil water may even interfere with field operations and early crop development. During summer months, however, crop needs often exceed precipitation, and the crop must rely on water stored in the soil from previous rains. Therefore, an ideal water management system permits maximum intake and storage of water in the soil profile, but also provides a means of draining any excess water quickly from the soil.
Drainage class is probably the most important soil characteristic influencing choice of management options, and failure to consider drainage when planning production programs is a common reason for poor crop performance. The term drainage refers to how long during the year soils are saturated at or near the soil surface. Though the characteristics of Ohio’s topsoils vary widely across the state, many of our subsoils transmit water very slowly. When water enters the soil faster than it can be removed (as can happen in winter and early spring when vegetation is dormant and evapotranspiration is minimal), it may become trapped in the soil due to the low permeability of the subsoil, and a zone of saturation may form at or near the soil surface. The presence of such a saturated zone can affect root health, soil fertility, and our ability to work the soil safely. Due to the importance of this phenomenon, all Ohio soil series are classified by drainage. The more common drainage classes include:
Drainage improvement, though expensive, is among the most profitable actions a crop producer can take. Improving drainage on more poorly drained soils expands production options, reduces many problems, and usually improves yields in wet and dry years alike. Crop rooting, soil biological activity, fertility, and water-use efficiency can all be improved by removing excess water from soils. Drainage can be improved in a number of ways—by grading land to eliminate low spots and promote managed runoff, installing surface drains and ditches to collect water and channel it safely off the field, and installing perforated plastic pipe below the soil surface to collect and remove excess water from the soil profile. Installing such practices and structures requires detailed analysis and procedures. Producers are urged to consult drainage contractors and specialists for assistance. Further information on drainage improvements can be found at: ohioline.osu.edu/aex-fact/0320.html.
Surface soils with relatively low organic matter and high silt concentrations often form hard, impermeable crusts that interfere with seedling emergence and restrict the intake of mid-season rainfall. Important agricultural soils, including Blount, Canfield, Cardington, Crosby, and Fincastle fall into this category. Hard crusts form when raindrop impact destroys weak aggregates at the soil surface, causing the surface to disintegrate and dry into a solid, impermeable mass. Young seedlings may not be able to generate force sufficient to break through the crust and may be trapped and die underground. Fracturing early season crusts with a tool such as a rotary hoe may facilitate emergence and increase stand significantly.
Crops growing on crusted soils may suffer moisture stress if the soil has not stored enough water prior to crusting to support the crop until maturity. On such soils, preventing or eliminating crusting can increase water infiltration and yield, often significantly. Mechanical inter-row cultivation, which breaks up an existing crust, will usually raise yields on crusting soils. On soil where crusting is not a problem, however, cultivation may be of benefit only in controlling weeds. Cultivation should be deep enough to break up the crust, but not so deep as to damage plant root systems.
Using a tillage system that leaves crop residue on the surface also reduces crusting. Residues reduce direct raindrop impact and promote biological activity at the soil surface, which maintains permeability and promotes greater infiltration (see Table 2-1). Increasing mid-season infiltration is likely the major reason why no-tillage practices increase yields to the extent they do on well-drained soils subject to crusting.
| Table 2-1: Effect of Tillage and Soil Cover on Water Infiltration for a Dry Wooster Silt Loam Soil Under Simulated Rainfall (OARDC, 1964). The Wooster Soil Crusts Severely. | ||
| Tillage System and Residue Cover | Infiltration Rate After 1 Hr. | Total Infiltration After 1 Hr. |
|---|---|---|
| cm/hr | cm | |
| Plowed, disked, cultivated, bare | 0.66 | 1.80 |
| No-till, bare | 0.28 | 1.22 |
| No-till, 40% cover | 1.17 | 2.34 |
| No-till, 80% cover | 2.64 | 4.39 |
Driving on soils when they are too wet can cause compacted layers to develop in the soil profile. Such layers can restrict rooting to shallow depths and reduce percolation of excess water following rain. This situation can cause the upper layer of the soil to become saturated more quickly than normal and may also prevent roots from obtaining nutrients and water from deeper in the soil during dry periods. Both effects are detrimental to yield. Compaction problems seem to be increasing in Ohio, likely a result of heavier equipment and loads, coupled with warmer winters that reduce opportunities for deep freezing and thawing.
Surprisingly, much compaction occurs when soils are moist, not saturated. Unfortunately, this condition is common in mid-spring and fall, when timely fieldwork is critical. Because it is almost impossible to avoid working in fields when they are sensitive to compaction, producers need to take as many steps as possible to minimize damage to the soil. These include inflating tires to proper pressure (ohioline.osu.edu/aexfact/0530.html ); reducing axle loads, particularly during harvest; and limiting the area driven upon (i.e., controlling traffic). Several additional tips for reducing compaction can be found at: ohioline.osu.edu/agffact/0113.html.
Most Ohio soils contain significant quantities of clay and are subject to smearing and clod formation if they are worked when wet. Working wet soils can often create very large clods that may persist and interfere with production throughout the growing season. Poor seed-soil contact (and impaired germination) is a major problem that results from planting into a cloddy soil. Planting into wet soils may also create other unfavorable conditions, including smeared seed furrows that are impenetrable by young roots, or furrows that reopen upon drying, exposing the seed and severely limiting germination. Planting should always be delayed until soils are crumbly and good seed-soil contact can be obtained.
Ohio is not usually considered to be a dry state, but periods of dry weather are often capable of stressing crops and reducing yields. Rainfall usually exceeds crop water use during spring and early summer. However, in most areas of the state, late-season water use by crops exceeds what is supplied by precipitation, creating the potential for stress unless a reserve of moisture has been accumulated from previous rains. Several practices can help make the best use of the water available throughout the growing season.
Practices that promote vigorous rooting allow plants to explore the soil to a maximum extent and utilize much of the water in the soil profile. Obviously, practices that limit compaction will limit the occurrence of impenetrable zones in the soil. Subsurface drainage improvements on wet soils allow roots to penetrate more deeply into the soil and make better use of water deeper in the profile. Rotating crops can also promote more extensive rooting by reducing root predation by soil insects and pathogens, and possibly by reducing the concentrations of autotoxic substances in the soil.
Crop residues on the soil surface do more than increase infiltration on crusting soil; they also reduce evaporation of soil water. This results in more soil water being potentially available for crop use. Adopting tillage and cropping systems that leave significant quantities of residues on the soil surface is beneficial, particularly on well-drained soils; however, on more poorly drained sites, such systems are most effective when used in conjunction with a drainage system that quickly removes excess water as it accumulates. Yield reductions can occur if too much water accumulates in the soil.
Proper timing of forage harvests can save large quantities of water for later growth. As forage crops approach the recommended stages for cutting, the amount of dry matter produced for every gallon of water used declines rapidly. Water is being used to maintain plants, rather than to support further accumulation of useful forage. Harvesting at the recommended time reduces the total amount of water used by that cutting, conserving moisture to support future growth.
Matching plant densities to soil conditions helps convert the water available into the best possible yields. Whereas high densities may be appropriate on soils rarely subject to drought, such as Kokomo or Pewamo, densities on sands, eroded knobs, and other drought-prone soils should be lower. This allows the overall population of plants to make the most grain per gallon of water available. When planting at low densities, it is important to plant varieties that have an acceptable yield potential at lower populations.
Irrigation is not widely used on field crops in Ohio, but a more frequent occurrence of erratic rainfall and yield losses due to moisture stress over the past 20 years has caused more producers to consider it. Some factors to evaluate before investing in irrigation include:
Soil erosion is a major concern in Ohio and throughout the world. Erosion reduces field productivity and contributes significantly to water-quality problems. The most common form of erosion is sheet or interrill erosion, which removes a thin, almost invisible layer of topsoil from the field. Recent advances in crop production, such as improved varieties, improved cultural practices, and increased use of fertilizers, have masked the decline in inherent soil productivity resulting from sheet erosion. Muddy streams, gullying, and the continued growth of clay knobs in some fields, however, are evidence of Ohio’s significant erosion problems.
Most Ohio fields can tolerate erosion at rates of three to five tons of soil per acre per year because new soil is constantly being formed from underlying parent material. Many fields, however, are eroding at much higher rates. The rate of erosion is affected by many factors, including rainfall characteristics, tillage and cropping practices,physical characteristics of soil, and slope (both length and angle). Such factors affect both water and wind erosion (particularly important in northwestern Ohio).
Even if erosion rates are below tolerable limits, it is often desirable to reduce erosion further. On the lake-plain soils of northwestern Ohio, for example, erosion rates are normally far below those considered hazardous to productivity. However, a large portion of the soil eroded in this region finds its way into streams and causes sediment-related problems. This sediment may also carry large quantities of plant-available phosphorus that can accelerate eutrophication, causing algal blooms, odor and taste problems, hypoxia, and other deteriorations of water quality. In such cases, erosion control measures are needed to maintain clean water as well as to preserve the soil resource.
Controlling soil erosion should be a high priority in any crop production system. Different situations require different approaches. The best method or combination of methods should be chosen in each case. Further information and technical assistance is available from Ohio State University Extension (ohioline.osu.edu ), the Natural Resources Conservation Service (www.nrcs.usda.gov ), and the Ohio Department of Natural Resources and affiliated local Soil and Water Conservation Districts (www.dnr.state.oh.us/soilandwater/ ).
Contour cropping reduces erosion and is most effective on deep, permeable soils and on gentler slopes (2% to 6%) that are less than 300 feet long. The effectiveness of contouring diminishes greatly on steeper or longer slopes because runoff water frequently breaks over rows. Contouring can reduce erosion losses up to 50% compared with up-and-down-hill tillage on slopes of from 2% to 6%. On steeper slopes (18% to 24%), contour cropping without supplementary practices reduces erosion losses by only about 10%. Grass waterways are usually necessary to carry the runoff water safely from the contour rows.
Strip-cropping, the practice of alternating contour strips of sod and row crops, is even more effective than contouring alone, often reducing erosion to one-fourth of that resulting from up-and-down-hill tillage. Strip widths and sequencing should be governed by slope angle and length.
Terraces are channels and ridges built across slopes to intercept and divert runoff water, shortening the effective length of a slope. Terraces are generally more effective than either contouring or strip-cropping and are designed especially for longer slopes. Most terraces in Ohio are designed with gradual slopes to lead water safely into grass waterways or other suitable outlets. The number and spacing of terraces depend on the soil type, slope, and cropping practices. Terraces should by designed by qualified soil conservation technicians. New, improved designs allow easier farming with modern machinery and reduce the number of point rows.
Grass waterways are natural or constructed outlets or waterways protected by grass cover. They serve as safe outlets for runoff water from contour rows, terraces, and diversions. Natural drainage areas are good sites for waterways and often require a minimum of shaping to produce a good channel. They should be designed to be wide and flat to accommodate farm machinery and be able to carry the runoff safely from the watershed above.
Adopting a conservation-tillage-based production system requires careful forethought. These systems require more careful management than conventional, plow-based systems, and much of this extra management takes place in the office rather than in the field. Over time, extra management becomes second nature, and many farmers have reported increasing yields as they have switched to conservation tillage, not necessarily as a direct result of the new system itself, but simply as a result of better overall management. When planning and implementing a major change in tillage system, these factors should be considered:
Conservation tillage systems leave at least 30% of the soil surface covered with a plant-residue mulch (remains of the previous crop or a cover crop) after planting. This is achieved using tillage tools that do not invert the soil (chisel plows, disks, field cultivators, etc.), but rather shatter or mix it shallowly. Often, a field can be prepared for planting with only one pass of a tillage tool. Many producers adopt conservation tillage because it saves time and fuel, while reducing labor requirements; however, the mulch left on the soil surface also provides significant erosion control.
Because the residue cover associated with no-till reduces evaporation of soil water, eliminating one avenue for removal of excess moisture, drainage improvements may be needed on many soils to obtain the best yields in a conservation tillage system. Yields under conservation tillage often are more adversely affected by poor drainage than those under conventional tillage. A combination of tile and surface drainage is ideal on soils requiring drainage; however, any drainage improvements are usually beneficial.
Soil characteristics greatly influence the crop yields obtained using no-till and other forms of conservation tillage. While it may be possible for a few producers to produce a crop (and even make money) using these systems on any field, maximum returns are normally achieved by matching the proper tillage systems to the soil at hand. In general, as soil drainage becomes better, tillage can be reduced further.
Well-drained soils, such as Wooster, Fox, Miamian-Celina, or Morley-Glynwood, often become moisture deficient as the growing season progresses. The mulch provided by no-tillage planting normally conserves some water and maintains infiltration on these soils by reducing crusting. As a result, the yield potentials of such soils are usually higher under no-till than under moldboard plowing. Intermediate tillage, such as chisel plowing, usually produces yields intermediate between moldboard plowing and no-till.
Somewhat poorly drained soils, such as Blount, Crosby, and Fincastle, can be no-tilled with careful management. These soils produce the best yields under no-till if they are systematically drained and crops are rotated. If drainage is not provided, chisel-plowing may provide the best yields under conservation tillage. If adequate drainage and residue are present, yields produced with conservation tillage should be equal, on the average, to those obtained by plowing, though different systems may produce the highest yields in different years. These soils crust severely, and in some cases, use of a carefully managed cover crop may be necessary when planting into soybean stubble to ensure adequate surface protection and infiltration. This latter point is most important during the first few years of no-till on such soils.
Poorly drained soils that respond to subsurface drainage improvements, such as Kokomo, Pewamo, and Hoytville, may be adapted to no-till production. Improved drainage and crop rotation are essential to producing top yields. If drainage and rotation are not used, yields under no-till may be much lower than had the field been plowed. No-tillage soybeans may be successful if drainage and rotation recommendations are followed and precautions for preventing Phytophthora root rot are taken. Soils such as these are considered to be among the most productive in Ohio when plowed and will produce very high yields under conservation tillage as well, if managed properly.
Wet, poorly drained soils, such as undrained Hoytville, or soils that do not normally respond well to tile, such as Clermont, Mahoning, and Paulding, are not normally recommended for no-tillage because surface residue often creates severe moisture excesses. Ridge planting may offer a more attractive alternative on such soils because the elevated ridge dries more quickly in the spring and may allow for significantly earlier planting, which can raise yield potentials. Crop rotation is a must on these soils to avoid low yields, regardless of tillage system used.
No-tillage and ridge-planting systems should not be used in fields with zones of significant soil compaction. While repeated use of no-tillage in a cash-grain rotation may alleviate a compaction problem eventually, a producer may go broke waiting for the effect, which can take several years. Compaction should be eliminated before initiating no-till. Following a controlled traffic pattern can prevent future compaction problems.
A well-managed cover crop is beneficial in certain no-tillage situations. The purpose of the cover crop is to provide extra residue where little residue is present after harvest. The extra residue improves erosion control and also reduces soil crusting.
A cover crop should always be planted after a corn silage harvest on soils prone to erosion and crusting, particularly if no-till planting is anticipated the next year. The use of a cover crop after corn harvest for grain is of questionable value and is not normally recommended because the corn stover usually provides enough residue for erosion and crust control. Cover crops may be needed following a soybean harvest if residue levels are not high enough to provide adequate erosion or crusting control, though the benefit of this practice may vary from field to field and should be evaluated on an individual basis. The need for a cover crop for crusting control should decline after several cycles of a corn-soybean rotation because organic matter builds at the soil surface and tends to reduce crusting. Cover crops are not usually necessary on non-crusting soils.
Fall-seeded small grains make good cover crops. In Ohio, rye is the most popular. Rye should be killed when it is no more than 20 inches tall in the spring, unless one plans to harvest the cover crop for straw or feed prior to planting soybeans. Any time corn is planted into a grass cover of any kind, the field should be watched carefully for armyworm activity in May and June. Fall-seeded oats (that die over the winter) are often used as an alternative when only a light residue addition is wanted.
Planting is a critical operation in conservation tillage. Planter operation should be checked and corrected frequently. Not all planters plant under all conditions when adjusted by the book, and experience is often a better guide.
Evaluate soil and residue conditions carefully before planting. Soil should be slightly moist and crumble when squeezed. Planting into too-dry soil may cause penetration problems, too shallow planting, and failure of the seed slot to close. Planting into too-wet soil may result in poor seed-soil contact or seed furrows that reopen upon drying. All of these factors may reduce plant stands. Generally, farmers should delay no-till planting until late morning to allow residues moistened by dew to dry. Wet residues may be jammed into the seed slot, causing poor seed-soil contact and germination.
Seeding depth is important. In recent years, too shallow planting has produced poor root system development. Plant corn 1½ to two inches deep and soybeans ¾ to one inch deep. Running the coulter ½ to ¾ inch deeper than the desired seeding depth and then making appropriate adjustments of the seeding mechanism should aid in accomplishing these objectives.
Where to place rows is a continuing question. In general, new rows should be planted where material from old rows, particularly row stumps, will not interface with depth control. Row middles are subject to compaction by repeated wheel traffic, and planting into them should be avoided if stand establishment or crop development has been a problem in the past.
Fertilization practices for no-tillage or ridge planting are often similar to those recommended for conventional tillage. In particular, soil testing and plant tissue analysis should guide nutrient management. Some management recommendations for specific nutrients are given here.
Phosphorus—With corn, row placement of phosphorus (P) generally increases yields at lower soil-test levels. At adequate soil-test levels, and in almost all cases with soybeans, broadcasting is an acceptable production practice from a yield standpoint; however, row placement of phosphorus is encouraged, even in maintenance programs, as a water-quality-management practice.
Potassium—Crop response to row placement of potassium (K) has been more inconsistent than for phosphorus. Farmers using a row fertilizer program can include some potassium; however, in nearly all cases, broadcasting is an acceptable practice. Farmers are encouraged to pay close attention to K management in no-till and ridge planting, because K deficiency occurs more frequently in these systems than in plow-based ones.
Nitrogen—Nitrogen (N) management for no-tillage or ridge-planted corn can be a critical part of the production program. Surface broadcasting of large quantities of urea and UAN solutions should be avoided to prevent the possibility of significant nitrogen loss. Detailed nitrogen management is discussed in Extension Bulletin E-2567, Tri-State Fertilizer Recommendations for Corn, Soybeans, Wheat, and Alfalfa. Go to: ohioline.osu.edu/e2567/index.html.
Lime—It is important to maintain surface pH levels no lower than pH 6.0. This can be accomplished by frequently adding small amounts of lime to the soil surface. The lime should be applied in the fall and disked in lightly, if possible, to ensure quicker reaction.
Because some nutrients and acidity tend to accumulate at the surface of the soil in no-till fields, the methods used to sample are important. Two separate samples are recommended:
Specific recommendations for specific crops are given in Weed Control Guide for Ohio Field Crops, Extension Bulletin 789 (ohioline.osu.edu/b789/index.html ). Weed control may be the most critical phase of any no-tillage program. Many farmers notice a shift in weed species as they progress into no-till, most likely an increase in annual grasses and perennial broadleaves. Farmers should watch their fields carefully and modify their herbicide programs as shifts occur.
Most no-tillage and ridge-planting systems require a material that burns down existing vegetation at planting, except for early planted corn where no green vegetation is present. A fairly wide choice of burn-down materials is available; choice is usually dictated by time of year, stage of weed and crop growth, and weed species present. Careful selection and use of burn-down materials help avoid costly clean-up treatments later in the season.
Farmers just beginning in ridge planting should use a complete no-tillage program for weed control. Over time, many have found that their cultivation practice allows them to modify herbicide programs and reduce rates considerably. The ability to do this is dependent on weed pressure and response of soil to cultivation (whether it crumbles or slabs). Farmers attempting to reduce herbicide rates in ridge systems should do so only on the basis of their own experience, not on the advice of others.
Corn production for grain or silage is possible on land reclaimed to modern standards after being surface-mined for coal in eastern and southeastern Ohio. Corn grain yields from Ohio mine-soil field trials have ranged from 18 to 143 bushels per acre. These studies were conducted over time at 13 different sites in five counties. The mean, 74 bushels per acre, was 62% of production from nearby unmined soils, and 80% of county average yields. Silage production is also slightly lower compared to production on natural soil. A significant factor implicated in the lower yields is that rooting tends to be shallower and more restricted on mine soil than on unmined soil, magnifying adverse effects of any moisture stress that might occur.
Keys to successful corn production on reclaimed land include selection of an acceptable mine soil; split-application of the nitrogen to improve N-use efficiency; no-tillage planting into forage sod or stalk cover to conserve soil moisture; and rotation of corn with forages and application of manure, where available, to improve physical properties of soil. Given the sensitivity of the crop to moisture stress, success with corn on mine soils also depends greatly on the amount and distribution of precipitation.
Fairpoint, Farmerstown, and Morristown mine soils have proven to be most adaptable to corn production. In contrast, Bethesda is not recommended for corn. For corn, one should select only those sites where the mixed topsoil-upper subsoil placed over the spoil is of silt-loam or silty-clay loam texture, avoiding surface layers with high clay content because they often produce poor stands.
Split application of nitrogen (one-half at planting and the remainder sidedressed four to five weeks later) can double the efficiency of nitrogen fertilizer on mine soils. An opportunity for increased denitrification on mine soils (due to early season wetness) means that application of all N at planting time often promotes severe N losses. Fertilizing and liming according to soil-test results provides corn with adequate phosphorus, potassium, calcium, and magnesium. No micronutrient problems have been identified for corn production on mine soils.
Both conventional plow tillage and no-tillage planting have been successfully used on mine soils. No-tillage is preferable because retention of previous crop residue is valuable for conserving soil moisture on mine soils, which tend to be droughty after drying in the spring. Also, no-tillage decreases the number of rocks brought to the surface. A forage-sod mulch and no-till planting usually provide the best soil and water environment for corn.
Rotating corn with forages on mine soils is encouraged because soil structure rapidly improves under forage cover. Severe compaction sometimes occurs when the spoil or topsoil material is moved when too wet during the reclamation process. Compaction restricts depth of rooting, and chisel ripping may not alleviate the problem. Severely compacted areas are best kept in continuous forage production.
Forages should be grown at least two seasons before beginning corn production. Heavy repeated applications of manure and/or municipal biosolids increase soil fertility and can enhance the structure of mine soils.
Very early planting is not recommended for mine soils because of their restricted internal drainage. Seedling emergence may be delayed in wetter, cooler mine soils, similar to corn response on natural soils with poor internal drainage. When planting on mine soils, farmers should select high-yielding adapted hybrids with strong emergence when grown on poor to moderately well-drained natural soils. Other desirable hybrid characteristics include good stalk strength and flexible ear size and number. Other aspects of corn production in mine soils should follow current Extension recommendations for natural soils.
Seasonal precipitation can affect soybean yields significantly on both the light-colored, natural soils and mine soils in eastern Ohio. Farmers might expect soybean yields on mine soils to be about 65% of those obtained on natural ones. With careful planting, plant densities should be similar to those obtainable on unmined sites. Narrow-row planting is recommended.
Farmerstown, Fairpoint, and Morristown mine soils have proved to be more satisfactory for soybeans than the more acidic Bethesda mine soil. No consistent nutrient problems have been associated with the production of soybeans on properly managed mine soils. Mine soils will likely lack sufficient populations of Rhizobia bacteria, so seed inoculation will usually be necessary to ensure nodule formation and nitrogen fixation on soybean (and other legume) roots.