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Fluid Journal : Fluid Journal 1999-2001
2 Fluid Journal Fall 1999 progress. Plant analysis can determine if nutrients are being absorbed by plants. Accurate records on soil test results and locations of the sample allow subsequent tests to be taken from the same areas of fields. When changing tillage or fertilizer placement systems, soil test levels at different depths in the profile should be carefully monitored. If shallow or reduced tillage or no-till is used, the top two inches (for determining pH, especially) should be sampled separately. A second sample of the top 6- to 7-inch layer (for determining P and K needs) should be taken. Soil pH at the surface is critical in reduced tillage systems and affects herbicidal activity, early plant growth, and nutrient availability. Phosphorus and K stratification can occur, with high availability near the surface and sharply lower levels below 6 inches. Under low rainfall conditions. P and K could be subject to poor utilization because of the lack of moisture at the surface. This positional unavailability problem may be corrected with occasional deep tillage. Sampling subsoil occasionally may provide useful management information. Some soils have very low P and/or K levels in the subsoil. Continuous cropping can further deplete these levels to the point where they limit production. This is especially true under reduced tillage systems where roots tend to be more shallow and nutrients do not move as readily down the soil profile. Corrective action may require occasional deep tillage or deep placement of fertilizer materials. Maintaining adequate nutrient levels in the subsoil helps crops to root deeper and to better utilize water and nutrients during dry seasons. Fertilizing soils should be planned on the basis of soil tests, previous crops and yields removed, and yield goals that have been established for each field, If soil tests are maintained at a high level, timing and method of application will be less critical, increasing the number of options available. Climate While climate is similar within a given region, it does have an impact on whether a farmer in one region can adapt a tillage system that is being used in another. Rainfall, rainfall distribution, temperature cycles, etc., influence whether a given tillage system would be a good choice. Weather factors may need to be assessed each year to determine if plans should be changed. For example, if deep tillage in the spring is planned and the weather stays wet, the plan may need to be altered. Soil and climatic conditions (cold soil temperatures, soil compaction, excess soil moisture) can also influence the need for starter fertilizers and must be considered along with soil nutrient availability. Finances Financial considerations can limit the options available for tillage and fertilizer placement. Even if it is decided that tillage systems should be changed, finances may dictate delaying the change. It is still important to have the option of a long-range plan to cover equipment changes as replacements are needed. Computer software Evaluation of tillage and fertility management systems for different soil types and management can be enhanced with the use of decision-aid programs for personal computers. Management models have been developed by many universities, the USDA, Agriculture Canada, and industry sources. Some models concentrate on evaluating adaptability of systems to soil type and climatic region. Others handle economic analysis and crop budgets for various management systems. As data bases and management decision software have become more readily available, they have become common management tools for farmers and consultants. Setting goals Every farmer should have clear goals defined for his operation. Goals form the foundation upon which management decisions can be made. Profit. Business plans should be developed around a profit goal and might include overall profit for the farm or a profit per unit of yield. Yield. Fertility decisions, hybrid/ variety selection, and other management decisions must be made on the basis of a yield goal. It is important that the yield goal be realistic with respect to the resources available. The goal should be based on past experience. It should be above the historical average for a given field. Risk associated with setting yield goals should be carefully considered. Some practices and goals have a higher risk and should be selected with that in mind. Resources -- soil, climate, finances, etc -- will help determine the acceptable level of risk. Environmental. Considerable attention has been focused on selecting best management practices (BMPs) for different soils and crops. Environmental goals should include reduced runoff, control of wind erosion, and efficient use of fertilizers and chemicals for the protection of groundwater. Practices that work toward environmental goals may sometimes conflict with production and economic goals. Fortunately, however, there are many more cases where practices that lead to increased yield and profits also lead to more responsible attention to the environment. The FFF expresses gratitude to the Potash & Phosphate Institute for allowing it to draw from its materials for this article.
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