www.sare.org publications building-soils-for-better-crops-3 soil-testing-for-nitrogen Soil Testing for Nitrogen Soil samples for nitrogen tests are usually taken at a different time and using a different method than samples for the other nutrients (which are typically sampled to plow depth in the fall or spring). In the humid regions of the U.S. there was no reliable soil test for N availability before the mid-1980s. The […]
www.sare.org publications building-soils-for-better-crops-3 sources-of-confusion-about-soil-tests Sources of Confusion About Soil Tests People may be easily confused about the details of soil tests, especially if they have seen results from more than one soil testing laboratory. There are a number of reasons for this, including the following: laboratories use a variety of procedures; labs report results differently; and different approaches are used to make recommendations based on […]
www.sare.org publications building-soils-for-better-crops-3 accuracy-of-recommendations-based-on-soil-tests Accuracy of Recommendations Based on Soil Tests Soil tests and their recommendations, although a critical component of fertility management, are not 100% accurate. Soil tests are an important tool, but they need to be used by farmers and farm advisors along with other information to make the best decision regarding amounts of fertilizers or amendments to apply. Soil tests are an estimate […]
www.sare.org publications building-soils-for-better-crops-3 taking-soil-samples Taking Soil Samples The usual time to take soil samples for general fertility evaluation is in the fall or the spring, before the growing season has begun. These samples are analyzed for pH and lime requirement as well as phosphorus, potassium, calcium, and magnesium. Some labs also routinely analyze for organic matter and other selected nutrients, such as […]
www.sare.org publications building-soils-for-better-crops-3 sources-7 Sources Hanson, B.R., S.R. Grattan, and A. Fulton. 1993. Agricultural Salinity and Drainage. Publication 3375. Oakland: University of California, Division of Agriculture and Natural Resources. Havlin, J.L., J.D. Beaton, S.L. Tisdale, and W.I. Nelson. 2005. Soil Fertility and Fertilizers. Upper Saddle River, NJ: Pearson/ Prentice Hall. Magdoff, F.R., and R.J. Bartlett. 1985. Soil pH buffering revisited. Soil Science Society […]
www.sare.org publications building-soils-for-better-crops-3 remediation-of-sodic-alkali-and-saline-soils Remediation of Sodic (Alkali) and Saline Soils The origin and characteristics of saline and sodic soils were discussed at the end of chapter 6. There are a number of ways to deal with saline soils that don’t have shallow salty groundwater. One is to keep the soil continually moist. For example, if you use drip irrigation with low-salt water plus a surface […]
www.sare.org publications building-soils-for-better-crops-3 soil-acidity Soil Acidity Background Many soils, especially in humid regions, were acidic before they were ever farmed. Leaching of bases from soils and the acids produced during organic matter decomposition combined to make these soils naturally acidic. As soils were brought into production and organic matter was decomposed (mineralized), more acids were formed. In addition, all the commonly […]
www.sare.org publications building-soils-for-better-crops-3 cation-exchange-capacity-management Cation Exchange Capacity Management The CEC in soils is due to well-humified (“very dead”) organic matter and clay minerals. The total CEC in a soil is the sum of the CEC due to organic matter and due to clays. In fine-textured soils with medium to high-CEC clays, much of the CEC may be due to clays. On the other […]
www.sare.org publications building-soils-for-better-crops-3 summary-and-sources-13 Summary and Sources Summary Both N and P are needed by plants in large amounts, but when soils are too rich in these nutrients, they are environmental hazards. And although N and P behave differently in soils, most sound management practices for one are also sound for the other. Using soil tests (and for N on corn the end-of-season lower […]
www.sare.org publications building-soils-for-better-crops-3 planning-for-n-and-p-management Planning for N and P Management Table 19.2: Comparison of N and P Management Practices Nitrogen Phosphorus Use fixed-rate approaches for planning purposes and adaptive approaches to achieve precision. Test soil regularly (and follow recommendations). Test manures and credit their N contribution. Test manures and credit their P contribution. Use legume forage crops in rotation and/or legume cover crops to fix […]