Nitrogen Management for Grains Throughout the Season
Nitrogen (N) is the most limiting nutrient for the production of wheat. Due to this fact and the possible environmental problems related to its use, nitrogen use efficiency (NUE) plays a fundamental role in sustainable grain production. NUE is the ratio between grain yield and the amount of nutrient provided by the fertilizer. N fertilizer represents a significant cost in wheat production and may cause negative impacts on the environment through leaching and N2O emissions. Management practices to help farmers increase productivity and reduce production costs should be studied to ensure agricultural sustainability. In this sense, studies indicate that the development and use of wheat cultivars with higher N efficiency can contribute to a reduction in applied N amounts without decreasing grain yield.
There is no other nutrient as important as N to attain high yields of wheat with acceptable grain protein. Proper N management requires an understanding of the seasonal N needs of the crop and a realistic estimate of the yield potential. An accurate estimation of available N in the soil, a step many producers skip, is important to determine how much N is needed to maximize yield. Available N during early vegetative through boot growth stages affects yield potential, while N applications after the boot stage are primarily used to increase protein. A late-season N application is often needed to achieve protein standards for hard red and white wheat and durum wheat. Plant tissue testing shows promise for predicting the need for a late-season N application.
The nitrogen needs of a wheat plant, as well as most plants, change dramatically over the season, and are commonly thought of as occurring in three distinct phases. Cumulative nitrogen uptake in wheat follows a sigmoid, or “S” shaped, curve giving rise to the three phases. Early-season N uptake contributes to yield primarily and has minimal effect on grain protein. It is critical not to short the plant during this critical early-season time period to realize full yield potential. In addition, early-season N applications can be important to break down residue from the previous crop.
Yield potential is determined by three factors:
- the number of head-bearing tillers per unit area,
- the number of kernels per head and
- the size of individual kernels.
Of these, the density of head-bearing tillers is by far the most significant. Therefore, an adequate supply of N throughout the vegetative growth stages is critical to reaching maximum potential yield. N at tillering is important because it obviously affects tiller density, and N during jointing is important because of its influence on the number of kernels per head. In contrast to early-season N, late-season N has minimal impact on yield because tiller density and kernel number have already been established. Late-season N can improve yield slightly in deficient plants because it can increase individual kernel size and bushel weight somewhat. Of the three factors affecting yield, kernel size is the least important. However, late-season N can have a significant impact on protein concentrations.
There are lot of potential products we can fit into the cycle of a grain crop. Slow-release N can help provide early-season nitrogen in the plants. CoRoN® 25-0-0 is a controlled-release liquid fertilizer with readily available nitrogen for your wheat crop. CoRoN’s unique formulation stays wet longer, allowing more nitrogen to be taken into the plant. With CoRoN, there is minimal volatilization or crystallization. CoRoN is visible on the leaf long after other nitrogen products are gone, supplying your crop with the needed nitrogen to ensure bountiful yields. Because of these same properties, CoRoN makes an ideal tank-mix partner for many crop protection products. Tests have demonstrated the benefits of using CoRoN in conjunction with fungicides and insecticides. Contact your local Helena representative for more information on how CoRoN can meet your nitrogen needs.
- David Gehrts, Product Manager