Corn Fertilizer Requirements
First of all, you have to consider the soil condition of your field through semi-annual or annual soil testing before applying any fertilization method. There are no two identical fields in the world, and thus, nobody can advise you on fertilization methods without considering your soil’s test data, tissue analysis, and field history. However, we will list some standard fertilization programs that many farmers use worldwide.
For every ton of whole plant corn harvest, we remove from the soil about 25 kg of N, 5 kg of P and 20 kg of K. As a rule of thumb, in some cases, we may need to supplement about 100 kg N, 280 kg of P2O5, and 100 K2O per hectare, in order to have a satisfactory corn yield for the years to come. However, it is very important to understand which nutrient is necessary for plant growth and at which stage. Otherwise, if you apply a nutrient at the wrong time, you may harm your crop.
Basal Fertilization – Starting with Phosphorus
Since only Phosphorus is absolutely necessary during the first stages of root development, corn producers usually integrate the entire P and some small amounts of Nitrogen and Potassium as basal fertilization. According to Cornell University (1), applying large amounts of K or N at this stage may result in significant problems. Urea and diammonium phosphate (DAP) can cause seedling injury and should not be used in the starter band to eliminate this risk. If you used to grow Fabaceae, such as beans, lentils, etc., in the same field, the amount of Nitrogen in the soil should be sufficient for the first stages of Corn development.
Nitrogen – The plant needs most of it later
Corn is considered a heavy nitrogen user. Nitrogen requirements are different during the various growing stages of the plant. Nitrogen is an essential element for the crop, and this element is the one that regulates the plant’s growth rate and yield. According to Mississippi State University (2), nitrogen should be added at different times according to crop needs. This split application method reduces the likelihood of considerable nitrogen loss due to wet weather before the crop can use it. Corn seems to use less than 10 % of its nitrogen before rapid vegetative growth begins. In Mississippi, this growth spurt usually happens in late April through mid-May, depending on the planting date and seasonal temperatures. Thus, farmers can use nitrogen more efficiently if they apply only a small portion just after plants emerge. Then, they add the bulk of nitrogen fertilizer just before the growth spurt, when the plants need it most. Mississippi State University’s standard nitrogen recommendation is to apply no more than one-third of the total nitrogen near planting/crop emergence. Then, someone can apply the remaining nitrogen about 30 days later. Early fertilization can waste a lot of nitrogen, especially if there’s a long period of wet weather before rapid corn growth begins. Nitrogen loss because of saturated soil happens mostly through denitrification, particularly in heavy, clay soils.
Corn also needs potassium for sustainably good yields. However, since only 25% of the absorbed K is stored in the kernels and removed during harvesting, you may not need to offer additional potassium to your crops. The rest 75% returns to the soil through remainings integration. However, if you harvest the entire plant (silage harvest), you may need to apply additional amounts. According to Cornell University, potassium can accumulate to very high levels in heavily manured cornfields. This K can be used by the next crop in the rotation. If K is needed, starter N+K2O should be limited in the fertilizer band to prevent salt injury. According to the University of Mississippi, you can also apply potassium fertilizer in the fall because, like phosphorus, potassium is relatively immobile in most soils. But potassium leaches on sandy soils with cation exchange capacity (CEC) less than 8.0. Spring application is recommended on these soils.
Zinc and Iron
According to Colorado State University, Zinc availability decreases with increasing soil pH, and most Zn deficiencies are reported on soils with pH levels higher than 7.0. Zinc deficiencies are found on soils leveled for irrigation where the subsoil is exposed, or on soils with high levels of free lime. Incorporation of manure in these exposed subsoils may correct Zn deficiencies, as well as improve soil structure.
According to Colorado State University, the availability of iron (Fe) decreases with increasing soil pH, but most soils are adequately supplied with available Fe for corn production. Iron deficiencies are most likely to occur on highly calcareous soils (pH higher than 7.8) or on soils leveled for irrigation where the subsoil has been exposed. Visual symptoms of Fe chlorosis are yellow striping of younger leaves.
Foliar Fertilization for N and K
Apart from soil fertilization, foliar applications can also be a choice, especially in order to promote future grain formation. Many corn farmers have reported that they use 13-3-44 at the stage of 7-9 leaves, and they repeat 3 weeks later. The concentration is about 2% and they spray about 200 liters per hectare. Of course, these are just some common patterns that you should not follow without making your own research.
Maize Fertilizer Requirements