Choosing a Nitrogen Source for Forage Crops
The menu of nitrogen sources is quite large. However, all sources are not created equal. Nor do forage grasses, like bermudagrass, respond to each source the same way. There are reasons for this. Consider these facts when choosing the best agronomic and economic source of nitrogen for your crops.
Urea and urea containing sources like UAN (urea ammonium nitrate) are subject to a potential loss of some nitrogen due to volatilization (nitrogen escape as ammonia into the atmosphere). This loss results when urea and urea containing sources are unprotected. The loss is greater when the air temperature is high, under windy conditions, and where moisture comes in contact with the source to activate urease and the hydrolysis of urea. These sources can be protected with additives or by incorporation into the soil by tillage or with water from natural rainfall or irrigation. This loss can be as high as a quarter or third of the nitrogen applied. So, if possible, select sources that are not subject to nitrogen loss by volatilization or that are properly protected.
Some sources contain three to five percent sulfur along with their nitrogen. This is good because sulfur helps crops to better utilize the fertilizer nitrogen. In many regions of the country and for many crops sulfur is becoming the fourth major nutrient limiting high yield crop production. This amount of sulfur, three to five percent, seems to be adequate in meeting crop needs.
Nitrogen use effectiveness and efficiency are regulated by several conditions. One of these is to insure that other nutrients are readily available to the crop. Potassium and sulfur are two such nutrients that can restrict crop use of nitrogen if they are in short supply. Both are involved with a crop’s ability to use nitrogen to form quality plant proteins. A shortage of potassium is also closely associated with forage crop stand decline and winter injury.
Recent emphasis on higher and higher crop yield is placing greater stress on the total quantity of plant nutrients needed and the critical growth stages when these nutrients must be absorbed by the plants. Nitrogen, potassium and sulfur are three of those vital nutrients that must be “spoon fed” to the crop. If irrigation is available, they can be delivered in the water as needed by the crop.
A relatively new source on the nitrogen menu is the liquid 18-0-0-3. Research during the past three years shows it to be one of the best for forage grasses when properly applied. It contains three percent sulfur to help nitrogen to work best. It contains nitrogen in about equal amounts as the nitrate and ammonia form so quick response to forage grasses and pastures can be expected. And, another important agronomic factor is that it is not subject to volatilization loss of the nitrogen being applied.
So, from an economic viewpoint, 18-0-0-3 is a low cost solution fertilizer source. It contains sulfur, the nitrogen exists in both the nitrate and ammonium forms and the nitrogen is not subject to loss due to volatilization. Availability of this nitrogen source is widespread throughout the Georgia area. Check with your local fertilizer provider for more details.
The Wheat/Soybean Double Crop System
Advanced planning and timeliness of operations are two keys to top-profit double crop soybeans. At twelve to fifteen dollar a bushel, soybeans are no longer a second class crop. They deserve first class attention, just like peanuts, cotton, corn or vegetables. The following management practices often limit double-crop soybean yield and/or quality.
SOIL TEST RESULTS: Each field should be tested at least every third year. The nutrient reservoir should be in the medium to high range for phosphorus and potassium. Soil acidity should be between pH 6.2 and 6.5. Remember, soybeans are a legume and best use atmospheric nitrogen in this pH range. If in the mid 5’s, or the field has not been in beans for a few years, consider inoculating the seed with Rhizobium bacteria. Also, lime needs can be applied anytime, but still take a month or more to react and neutralize soil acidity. As always, lime works best if incorporated into the soil.
VARIETY SELECTION: Ask your seed dealer for varieties proven in your region, population targets and seeding suggestions. Remember, each day of delay at planting can erode yield potential. A heavier seeding rate often results in a taller plant, higher pod set and earlier ground cover.
RESIDUE: Quality wheat straw can have significant market value. Removal of straw from the field raises several management issues. It can result in a day or two delay in planting beans. Straw can conserve some soil moisture by shading the future seedbed. Straw will tie up some nitrogen as it begins to decay. Straw contains a considerable amount of potassium. So, one must weigh the advantages of straw removal vs. remaining on the field.
NUTRIENT BALANCE: If both wheat grain and straw are removed from the field, it raises several concerns for the soybean crop. Nutrient removal from the field will likely exceed the fertilizer nutrients applied to wheat for both the wheat and soybean crop. According to the IPNI crop removal figures, each bushel of wheat removes 0.6 pounds of P205 and 0.34 pounds of K20. Soybean removal is higher, 0.84 and 1.3 pounds per bushel, resp. Thus, for a 60 bushel wheat crop plus 50 bushels of double crop soybean, removal from the field will total 78 pounds of P2O5 and 85 pounds of K2O. Straw removal takes another 13 pounds of phosphate and 96 pounds of potash for a total of about 90 pounds of P2O5 and 180 pounds of K2O. Thus, double cropping places considerable demand on soil phosphate and potash reserves. A shortage, especially of potash, is most likely to affect the soybean crop and the crop to follow. Both nutrients are essential for photosynthesis, water use efficiency, energy relations, as well as grain development.
HARVEST: Combine wheat as early as possible to allow early soybean planting. Bale wheat straw right away, while it is bright and then store under cover. Timeliness of operations are as vital for wheat/soybeans as for any other crop.
KNOWLEDGE: “Knowledge is Power” continues to be true. “Experience” is a good companion. Improvement is often the result of “Change”. So, contact your crop input provider, retail dealer, county extension agent, Certified Crop Adviser (CCA) or neighboring grower for more input about developing a top-profit, double cropping systems.
Balanced Nutrition is vital for both plants and animals alike. It is essential for optimum growth as well as for resistance to stress. Eighteen nutrients have been proven essential for crop development. Of these, Nitrogen (N) is needed in the largest amounts by most non-legume crops like corn, wheat, cotton, pecans or forage grasses. Potassium (K) often comes in a close second, especially as we strive for top-profit crop yields. But let’s focus upon a few N facts for this Spring. (more…)
Apply For Your G.A.T.E Card Now!
Apply for your Georgia Agricultural Tax Exemption Card (G.A.T.E.) Now
Many growers already know that the Georgia laws governing Sales Tax on agricultural products have changed. On January 1, 2013, all ST-1 Sales Tax Exemption certificates became invalid. These are the certificates Growers have furnished to their various input suppliers. (more…)