Building Soils for Better Crops, 2nd Edition

	Putting It All Together generally, the type of soil management that gives the greatest immediate return leads to a deterioration of soil productivity, whereas the type that provides the highest income over the period of a generation leads to the maintenance or improvement of productivity. Charles Kellogg, 1936 In this chapter, we'll give some guidelines on how you can promote high quality soils by adopting practices that maintain or increase soil organic matter, develop and maintain optimal soil physical conditions, and promote top-notch nutrient management. In earlier chapters of Part Two, we discussed many different ways to manage soils, crops, and residues, but we looked at each one as a separate strategy. In the real world, we need to comine a number of these approaches and use them together. In fact, each practice is related to, or impacts, other soil heath promoting practices. The real key is to modify and combine them in ways that make sense for your farm. We hope that you don't feel as confused as the person on the left in the drawing on the next page. If the thought of making changes on your farm is overwhelming, you can start with only one or two practices that improve soil health. Not all of these suggestions are meant to be used on every farm. Decisions on the farm need to support the economic bottom line. Research shows that the practices that improve soil health generally also improve the economics of the farm, in some cases dramatically. However, you need to consider the fact that the increased returns may not be immediate. After implementing new practices, soil health may improve at a slow rate and it may take a few years to see improved yields. A "learning period" is probably needed to make the new management practices work on your farm. Permit yourself to make a few mistakes. Changing management practices may involve an investment in new equipment. For example, changing till age systems requires an investment in new tillage tools and planters, and the bottom line may not improve immediately. For many farmers, the short-term limitations may keep them from making these changes, even though they are hurting the long-term viability of the farm. Big changes are probably best implemented at strategic times. For example, when you are ready to buy a new planter, consider a whole new approach to tillage as well. Also, take advantage of flush times, when you receive high prices for products, to invest in new management approaches. However, don't wait until that time to make decisions. Plan ahead, so you are ready to make the move at the right time. General Approaches There are many options for making soil management changes in different types of farming systems. Let's go over the general approaches that can be used for most types of agriculture. If at all possible, use rotations that utilize grass, legume, or a combination of grass and legume sod crops, or crops with large amounts of residue as important parts of the system. Leave residues from annual crops in the field or, if you removed them for composting or to use as bedding for animals, return them to the soil as manure or compost. Use cover crops when soils would otherwise be bare to add organic matter, capture residual plant nutrients, and reduce erosion. Cover crops also help maintain soil organic matter in resource-scarce regions that lack possible substitutes to using crop residues for fuel or building materials. Raising animals or having access to animal wastes from nearby farms gives you a wider choice of economically sound rotations. Rotations that include perennial forages make hay or pasture available for use by dairy and beef cows, sheep, and goats. In addition, on mixed crop-livestock farms, animal manures can be applied to cropland. It's easier to maintain organic matter on a diversified crop-and-livestock farm, where sod crops are fed to animals and manures returned to the soil. However, growing crops with high quantities of residues plus frequent use of green manures and composts from vegetative residues helps maintain soil organic matter even without animals. You can maintain or increase soil organic matter more easily when you use reduced-tillage systems, especially no-till, instead of the conventional moldboard plow and disk system. The decreased soil disturbance under reduced tillage slows the rate of organic matter decomposition and helps to maintain a soil structure that allows rainfall to infiltrate rapidly. Leaving residue on the surface encourages the development of earthworm populations, which also improves soil structure. Compared with conventional tillage, soil erosion is greatly reduced under minimum-tillage systems, which helps keep the organic matter and rich topsoil in place. Any practice that reduces soil erosion, such as contour tillage, strip-cropping along the contours, and terracing, also helps maintain soil organic matter. Even if you use minimum-tillage systems to leave significant quantities of residue on the surface and decrease the severity of erosion, you also should use sound crop rotations. In fact, it may be more important to rotate crops when large amounts of residue remain on the surface. Decomposing residues harbor many insect and disease organisms. These problems may be worse in monoculture with no-till practices than with conventional tillage. Test your soils regularly and apply lime and fertilizers only when they are needed. Testing soils every two or three years on each field is one of the best investments you can make. Make sure that you properly credit the N contribution of a decomposing sod or the N, P, and K contributions from manures. If you keep the report forms, or record the results, you will be able to follow the fertility changes over the years. Monitoring soil test changes will help you fine-tune your practices. Soil testing laboratories usually charge extra for an organic matter determination, but it's worth the money every few years just to track changes. Also, if you're interested in soil microorganisms, there is now a laboratory that can help you. In dry areas, salt accumulation may be a problem. You may need to use gypsum or other leaching salts. Also, maintain your pest scouting efforts and keep records over the years. This allows you to evaluate improvements in this area.   It's the Combination... Farmers are learning that the combination of reduced tillage, cover crops, and better rotations can have a dramatic effect on their soil and the health of crops. They are finding that, by combining practices, they are reducing pest damage, improving soil tilth, vastly reducing runoff and erosion, increasing soil organic matter, and producing better crop growth. Each practice by itself is worthwhile. However, the greatest strengths and benefits are derived from combining a number of key practices. For example, on the Groff farm, it's the combination of good rotations, integrating livestock with crops, using no-till and cover crops that all work together to produce high-quality soil and crops.   There is no substitute for taking a little time each year to observe your soils for such things as indications of compaction, the presence of earthworms, the health of roots or other indicators we discussed in chapter 20. The saying "The farmer's footprint is the best fertilizer" can be modified to "The farmer's footprint is the best path to improved soil health." If you don't already, begin to regularly observe and record the variability in crop yield across your fields. As equipment changes are made, you might consider buying a yield monitor that allows you to track yields on a field. Or, simply take the time to track production from the various sections of your fields that seem different. Compare your observations with your soil sampling plan, so you can be sure that the various areas within a field are receiving optimum management. Perhaps the hilltop or sideslope would benefit from additional manure or compost, while none is needed in other portions of the field. What Makes Sense on Your Farm? What makes sense on any individual farm depends on the soils, the climate, the nature of the farm enterprise itself and the surrounding region, potential markets, and the family's needs and goals. The specific details of implementing general management approaches depend primarily on the type of farm enterprise: grain or vegetable crops only, integrated crop-livestock, organic or not, etc. Most grain crop farms export a lot of nutrients and are managed with a net loss of organic matter. However, these farms provide a great deal of flexibility in adopting alternative soil management systems because there is a wide range of equipment available for grain production systems. You can promote soil health easily with reduced-tillage systems, especially no-till and zone-till, instead of the conventional moldboard plow and disk system. Well-drained, coarse-textured soils are especially well adapted to no-till and zone-till systems, and the finer-textured soils do well with ridge-tillage or zone-tillage systems. Regardless of the tillage system that is used, you should try to travel on soils only when they're dry enough to resist compaction. However, managing no-till cropping on soils that are easily compacted is quite a challenge because there are few options to relieve compaction once it occurs. Maintaining controlled traffic zones or using some tillage to break up compacted layers may be necessary on such soils. Even if you use minimum-tillage systems that leave significant quantities of residue on the surface and decrease the severity of erosion, you also should use sound crop rotations. Consider rotations that utilize grass, legume, or a combination of grass and legume perennial forage crops. Raising animals on what previously were exclusively crop farms, cooperating on rotations and manure management with a nearby farm, or growing forage crops for sale to a beef or dairy farm gives you a wider choice of economically sound rotations and at the same time helps to cycle nutrients better. Incorporating these innovations into a conventional grain farm often requires investment in new equipment and creatively looking for new markets for your products. There also are many opportunities to use cover crops on grain farms, even in reduced tillage systems. Organic grain crop farms do not have the flexibility in soil management that conventional farms have. Tillage choices are limited because of the reliance on mechanical methods instead of herbicides to control weeds. On the positive side, organic farms already rely heavily on organic inputs through green and animal manures and composts to provide adequate nutrients to their crops. A well-managed organic farm usually uses many aspects of ecological soil management. However, erosion may remain a concern because many organic farms use clean and intensive tillage. It is important to think about reducing tillage intensity and perhaps invest in a better planter. New mechanical cultivators can generally handle higher residue and mulch levels and may still provide adequate weed control. Try to look into ways to increase surface cover, although this is a challenge without the use of chemical weed control. Alternatively, you should consider conventional erosion control practices, such as strip cropping, as they work well with rotations involving sod and cover crops. Diversified crop-and-livestock farms have an inherent advantage for improving soil health. Diversified crop-and-livestock farms have an inherent advantage for improving soil health. Crops can be fed to animals and manures returned to the soil, thereby providing a continuous supply of organic materials. For many livestock operations, perennial forage crops are a logical part of the cropping system, thereby reducing erosion potential and improving soil physical properties. Livestock-based farms also have some disadvantages. It is more difficult to adopt minimum tillage practices when sod crops are rotated with row crops, and the need to incorporate manure requires at least some type of tillage. You should still consider minimizing tillage by trying to inject the manure or chiseling it in, rather than plowing it under. Also, minimize soil pulverization by reducing secondary tillage and establishing the crops with no-tillage (or zone-tillage) planters. Preventing soil compaction is important on many livestock-based farms. Manure spreaders are typically heavy and frequently go over the land at very unfavorable times, doing a lot of compaction damage. Think about ways to minimize this. In the spring, allow the fields to dry adequately (do the ball test) before taking spreaders out. If there is no manure storage, building a structure to hold it temporarily allows you to avoid the most damaging soil conditions. Livestock farms require special attention to nutrient management, making sure that the organic nutrient sources are optimally used around the farm and that no negative environmental impacts occur. This requires a comprehensive look at all nutrient flows on the farm, finding ways to most efficiently use them, and preventing problems with excesses. Soil quality management is especially difficult on vegetable farms. Many vegetable crops are sensitive to soil compaction and often pose greater challenges in pest management. These cropping systems, therefore, can greatly benefit from improved soil health. Most vegetable farms are not integrated with livestock production, and it is difficult to maintain a continuous supply of fresh organic matter. Bringing manure, compost, or other locally available sources of organic materials to the farm should be seriously considered. In some cases, vegetable farms can economically use manure from nearby livestock operations or swap land with them in a rotation. Farms near urban areas may benefit from leaves and grass clippings and municipal or food waste composts, which are increasingly becoming available. In such case, care should be taken to insure that the compost does not contain contaminants. Vegetable cropping systems are generally well adapted to the use of cover crops because the main cropping season is generally shorter than those for grain and forage crops. There is usually sufficient time for growth of cover crops in the pre- or post-season to gain real benefits, even in colder climates. Using the cover crop as a mulch (or importing mulch materials from off the farm) appears to be a good system for certain fresh market vegetables, as it keeps the crop from direct contact with the ground, thereby reducing the potential for rot or disease. The need to harvest crops during a very short period before quality declines regardless of soil conditions often results in severe compaction problems on large vegetable farms using large-scale equipment. Controlled traffic systems, including permanent beds, should be given serious consideration. Limiting compaction to narrow lanes and using other soil-building practices in between them is the best way to avoid severe compaction damage under those conditions. The Future Each of the farming systems discussed above has its limitations and opportunities for building better soils. Although there are ways to improve soil health in any system, the details may differ. Whatever crops you grow, when you creatively combine a reasonable number of practices that promote high quality soils, most of your farm's soil fertility problems should be solved along the way. The health and yield of your crops should improve. The soil will have more available nutrients, more water for plants to use, and better tilth. There should be fewer problems with diseases, nematodes, and insects. By concentrating on the practices that build high quality soils, you also will leave a legacy of land stewardship for your children and their children to inherit and follow. Top