Midseason Application of Nitrogen, Potassium and Magnesium
for Improved Yields
Protein and carbohydrate production is critical for high yields and quality crops, especially in grains and fruits. Proteins and carbohydrates are made in the leaves, stems, and roots of plants before moving into the fruit and seed. Three essential plant nutrients (nitrogen, potassium and magnesium) are especially needed as the fruit and seed are maturing to ensure quality and high yields. During rapid grain and fruit development the need for these nutrients may exceed the plant roots’ ability to take up these nutrients from the soil. This can be the case even when there are abundant nutrients in the soil. This is one reason tissue testing is important in midseason to determine which nutrients, if any, are limiting crop performance. The uptake of these nutrients from the soil may be limited by soil pH (too high or too low), soil chemistry (e.g. too high calcium levels), or that the roots may not have the capacity to take up enough nutrients to meet the needs of the rapidly growing crop. To bypass these uptake issues foliar application of these nutrients offers a more effective means to get these nutrients into the plant.
Nitrogen
The issue with nitrogen is not the quantity applied, but is the efficiency of the nitrogen fertilizer that is applied. This is especially so with crops like corn, which use a lot of nitrogen. Dr. Fred Blackmer of Iowa State University spent most of his life trying to find ways to reduce the quantity of applied nitrogen needed to produce a bushel of corn. He found that most growers apply more than enough nitrogen to crops, but the crops do not use this nitrogen efficiently. By midseason most nitrogen in the soil is in the nitrate form, which is when fruit and grains begin to form. Crops can readily take up nitrate, however, molybdenum is required in the plant tissues to convert this nitrate into ammonium. Ammonium is then used to make proteins needed by the crops. To understand the nitrogen status of a growing crop do a tissue test to determine the levels of nitrate, Total N, and molybdenum. If nitrate levels are high and molybdenum is low, then the crop cannot use the nitrate nitrogen that is in the crop. If nitrate and total nitrogen (Total N) levels are low, then nitrogen application may be needed. If molybdenum is low in the plant tissues, then foliar applying AgriGuardian Moly™ (4 oz per acre is usually adequate) to get the full benefit of nitrate in the plant, and thereby increasing the protein content and the yield of the crop.
Potassium
This nutrient is needed throughout the growing season to regulate water uptake by the roots, and consequently the uptake of soil nutrients. It is also involved with the conversion of nitrate to ammonium inside the plant. Potassium is critical for the movement of carbohydrates, proteins, and other essential compounds from the roots, stems, and leaves into the developing fruit and seed. Without adequate potassium in the crop, yield may dramatically reduced. The demand for potassium increases greatly as the crop begins to mature. This demand often exceeds the capacity of the roots to take up enough potassium to meet the crop's needs. This is especially the case when low soil pH, high calcium, high magnesium, and/or high sodium reduce available potassium for uptake by the crop. The “peak demand” period for potassium occurs most often during fruit enlargement and grain fill. Since root uptake is often the limiting factor, foliar application is the most effective way to get potassium into the crop. To understand the potassium status of a crop have both soil and tissue tests done.
Magnesium
The most critical role of magnesium is as the center atom of the chlorophyll molecule. Chlorophyll is responsible for photosynthesis and the source of energy used in the formation of carbohydrates and resulting growth. Magnesium also has a role similar to potassium in the movement of carbohydrates from the leaves, stems, and roots into developing fruit and seed. It is also involved in the formation of proteins in the plant. Magnesium's peak demand period is when crops begin maturing, and large amounts of magnesium are used in the development of fruits and grains. As with potassium, roots may not be able to take up enough magnesium to meet the crop’s needs. If magnesium is low, then magnesium will be removed from the chlorophyll molecules to supply the growing fruit and seed. Once magnesium is removed from chlorophyll, photosynthesis ceases, and the leaves prematurely turn yellow and die. This reduces the overall quantity of carbohydrates produced by photosynthesis by the plant and reduces the available carbohydrates for fruit and seed growth. The bottom line is that yield is reduced. As with potassium, since root uptake is often the limiting factor, foliar application is the most effective way to get magnesium into the crop. To understand the magnesium status of a crop have both soil and tissue tests done.
AgriGuardian Nutra-Boost® was developed to provide both potassium and magnesium as foliar application. It also contains sulfur, which helps the crop tolerate environmental and other stresses. Sulfur deficiency has become more and more common with increasing efforts to remove sulfur from the atmosphere. There is a synergy among potassium, magnesium, and sulfur in the overall health and performance of crops. AgriGuardian Nutra-Boost® increases yield with numerous crops (for example by enhancing ear fill in corn and pod fill with soybeans). The product is typically foliar applied at 1 gallon per acre to the crop just before or during the early stages of fruit and seed development, e.g. pre-tassel stage with corn. The product may also be used when the plant is young and the root system is small and limits nutrient uptake.
For more information on AgriGuardian Moly™, AgriGuardian Nutra-Boost® or other AgriGuardian™ products, please contact your local AgriGuardian™ distributor or visit AgriGuardian.com.
