In making the transition from conventional to conservation tillage, the most common mistake is using the same fertilizer program.
Prior to adopting a conservation tillage system, soil pH and nutrient levels should be tested and adjusted to meet recommendations (contact your local Cooperative Extension Service office for recommendations). For no-tillers in particular, these adjustments are critical to retain soil quality benefits while avoiding the use of full-width tillage in the future.
Conservation tillage leaves the soil cooler and wetter. Cooler soils alter the availability of nutrients as well as the plant's ability to use them. That's why adjustments are essential.

The fundamentals
There are seven keys to successful nutrient management in conservation tillage systems (in addition to timing and method of fertilizer application):

1. Soil test on a regular basis. P, K, and lime (plus N in drier regions) recommendations should be based on realistic yield goals and accurate soil tests. The interval for soil testing varies among regions of the U.S. and depends on crop rotation, soil type, irrigation, and other factors. Check with your local Cooperative Extension Service agent for more information.

2. Lime to neutralize soil acidity. This is important in conservation tillage, especially where surface applications of N and P fertilizers are used. Lime rates may need to be adjusted and applications be more frequent in no-till systems. For example, if 4 tons of lime are needed it would be better to apply 2 tons over two years than 4 tons at once.

3. Base P and K fertilizer rates on 6-8 inch deep soil samples. If P and K deficiencies (or other nutrients) are corrected prior to switching to conservation tillage, problems should be minimal. If not corrected, then fertilizer placement techniques such as deep banding or surface stripping may provide some advantage. To avoid soil erosion, this technique should be used on soils with slopes of less than 6%.

4. Monitor nutrient content of the lower portions of the old tillage zone. This is important in continuous conservation tillage, where incorporation of nutrients is limited. If depletion of nutrients in the lower portion occurs, deep banding or deep tillage of fertilizers can correct this problem. Consider that roots feed just under surface residue in conservation tillage and may not have to be deep to be effective.

5. Use starter fertilizer. While the nutrient responsible for a starter response (usually N) varies by location, yield response is consistent throughout much of the eastern U.S. Phosphorus placed as a row starter may be most efficient because it may be used by the plant before being tied up in the soil.

Table 10. Effect of tillage on starter fertilizer (nitrogen) response of corn

Tillage system	Number of yield responses	Average yield response over 11 experiments bu/ac
Conventional No-till	1/11 8/11	0.9 7.8

(Purdue University)

6. Manage nitrogen to enhance efficiency. N management, especially in corn production, is probably the key to a successful fertilizer program for conservation tillage. In general, N fertilizer should be placed below the residue to avoid the loss of nitrogen (through volatilization or runoff). Studies show the most efficient time for applying the majority of N for no-till corn production is at planting or after planting. Significant N loss results from applying too early.

Soil test on a regular basis.

7. Take credit for N from legumes. Legumes can be a valuable source of N for corn and cereal crops. Many states make some credit for N fertilizer recommendations for N contributions of the previous legume crop in the rotation, or a legume cover crop or intercrop.

Regional note on #7: In the southern Midwest and Southeast, no adjustment in legume N credits are needed when conservation tillage is used. In the upper Midwest (Minnesota, Wisconsin, Michigan, North and South Dakota), credits for legume N are tied to specific tillage systems and their effects on crop residue decomposition.