Starter fertilizer is always important on low testing soils and can be beneficial for early planting in cold wet soils regardless of soil test level. At higher soil tests and as we get later into the season when the soils are warmer, the probability of getting an economical response to a starter becomes much lower. If it gets warm and looks like it is going to stay warm, if soils have optimum or higher nutrient levels, and if the overall nutrient needs of the crop are being met with other fertilizer, starter could probably be eliminated to speed up planting with little risk. This does not mean cutting overall fertilizer requirements; this is simply shifting the method of application to speed up planting. If starter is eliminated make sure that there is adequate early season nitrogen for the crop. If there is no manure application, then at least 1/3 to 1/2 of the crop N requirement should be applied near to planting time. This could be just some ammonium sulfate (up to 300 lb/A) applied near the row in place of a starter, it could be all or a significant amount of the crop N requirement applied either dribble or injected 4–6 inches from the row at planting, or as a broadcast application which is the least efficient option.
If N were applied early in anticipation of early planting, there is the potential that a significant amount of that could be lost by now. Since it has also been fairly cold which may have limited microbial activity in the soil and thus reduced nitrification and the potential for leaching and denitrification losses. For early applied N, this year would probably have been a good year for using a nitrification inhibitor. As we get later, unless it remains extremely wet, the potential benefit of a nitrification inhibitor goes down.
If small grain fields or grass hayfields did not get their normal N at green-up they will still benefit from N applications. This should be high priority as soon as soil conditions are acceptable. If N fertilizer has not yet been applied for corn, no major change in management should be needed unless planting is delayed to the point where yield potential is significantly reduced. Then a rate reduction may be warranted. The general recommendation is that if no manure is applied, then at least 1/3 to 1/2 of the crop N requirement should be applied near to planting time. The balance can be sidedressed. Fall, winter, or early applications of manure to fields with cover crops should retain much more N than fields with nothing growing during this wet period. If manure has been applied, then some N in the starter plus the soluble manure N should be adequate to get the crop to sidedress time.
The real question is how much N we should apply given the spring we have experienced. This is the kind of year with so much uncertainty about N, when in-season N tests like the PSNT and the chlorophyll meter tests will be extremely useful. See: Agronomy Facts #17 Pre-sidedress Soil Nitrate Test for Corn and Early Season Chlorophyll Meter Test for Corn. There is no simple answer to this question. Make some guesses about whether or not we have lost some of our N, what our yield potential is, how we plan to apply any additional N, and then make some adjustments in our N rates based on that. That hopefully will get us in the ballpark. Then if we want to do better than just be in the ballpark, we can use the PSNT or chlorophyll meter to either confirm that our guesses were correct or guide any additional N we may need as a corrective treatment. Alternatively we can just make sure we have adequate N for the early season and then plan to sidedress the balance based on the results of these tests.
Many farmers have barely begun to apply manure yet unless they have had to “rut” some on because the pit is full. From a very narrow fertility point of view late application is good because there is less chance of losing the manure nutrients before crop uptake. But the real problem is just getting it spread, a quickly as possible, while doing the minimum amount of damage to the soil or crop so that we can get on to planting.
I have gotten some questions about post planting applications. The main problem with this is the physical effects of trying to spread manure in a planted field such as running down rows with big manure spreaders, cutting in and out of fields at the end of loads, and compaction. If the corn is emerged, there can be problems with physically smothering the plants with a heavy application, especially something like dairy manure. This is less of a concern with poultry and swine manure but then there are chemical concerns with all of these manures from salt injury in the soil and burning emerged plants. Both of these will be minimized if there is a good soaking rain right after application. Along this same line, if manure is applied and the crop is planted very soon after, there can be salt injury which can reduce germination, especially with poultry manure. Usually, a half inch of rain between manure application and planting is safe.
Since most manure storages are open to the rain this is adding significantly to the volume of manure, and also diluting the nutrients. Thus, basing your manure nutrient planning and accounting on previous manure analyses will probably over-estimate the nutrients being applied. If you are applying the same rate as always, you may need to adjust any supplemental fertilizer nutrients up a little to compensate or you may want to increase the rate of application as another way to compensate. If you take a manure sample at spreading time this information can be helpful for later adjusting at-planting or sidedress N applications based on the lower manure nutrient content.