|
When Fertilizer is Expensive, Think Manure! Improve soil quality while applying this nitrogen source. With nitrogen (N) fertilizer prices high, it’s a good time to reconsider having manure hauled in and applied to your farm ground. Different types of manure have varying nitrogen contents, and even within a manure type, there is a lot of variation depending on feeding and management practices. Table 5 shows average nutrient concentrations for different kinds of manure. Based on the current value of the nitrogen and phosphorus in the manure alone, beef manure is worth $13.60 per ton. So if you can get manure for less than that, consider that a good deal! Sheep and poultry manures would be valued even higher due to their higher nutrient concentrations. But be careful to avoid spring applications of fresh poultry or swine manures due to their high ammonium levels that can burn plants. Of course, manure’s value is actually greater than the numbers shown above since manure is also a good source of potassium and micronutrients such as zinc, iron, sulfur, and boron. Plus, manure is a terrific soil amendment. By increasing soil organic matter levels, manure can improve a soil’s water and nutrient holding capacity and also improve drainage and aeration. Improved water holding capacity is especially important as we possible head into another year of drought. Manure also makes a good food source for the bacteria, fungi, and worms that recycle soil nutrients and improve soil physical properties. One important thing to remember about manure nitrogen is that it will mineralize or become available to crops more slowly than commercial fertilizers. In effect, manure acts as a slow release N source, releasing the N over about a three year period. So will applying manure now (in the spring) delay the availability of the manure N even more? Dr. Merle Vigil of the USDA Great Plains Research Center in Akron and Brad Jakubowski (CSU graduate student) studied N availability from fall and spring applied beef manure. Under irrigated conditions, N availability to corn was identical for either application time (measured at both V6 and tassle growth stages). On the other hand, under dryland conditions, fall applications had significantly more N available at V6 than spring applications. By the time corn was tasseling, there was no significant difference in N availability from fall and spring applications, even under dryland. This research demonstrates that under irrigated conditions, manuring now (in the spring) will not delay N release from manure. When you are spreading manure, choose fields with the lowest soil NO3-N levels and the highest N need, rather than those with a long-term manuring history. Choosing crops that will give you a yield response for the added manure nutrients makes the most out of the manure application, and saves you the most in fertilizer costs. If there are other yield limiting factors such as heavy weed populations, high water table, or poor irrigation uniformity, this will limit the impact of the manure nutrients on yields. Apply manure where nutrients are the greatest yield limiting factor to get the most bang out of your manure spreading dollar. If you value manure for its N content, it is critical to conserve that N so that plants can use it. It is important to minimize volatilization losses (losses of ammonia gas into the air). If manure is broadcast and not incorporated, up to 30% of the ammonium in the manure will be lost to the air within just four days of spreading. Incorporating immediately will reduce that loss to less than 5%. So to get the most N value from the manure, be sure to incorporate as soon as possible. If you manage a feedlot, leaving manure in open lots results in the greatest N losses to the air. Storing manure in a manure pack reduces N loss by about a third. Scraping pens and hauling manure out on a daily basis reduces N losses even more. So, if you value manure for its N content, manage manure to minimize N volatilization and add value to the manure. If you have a Concentrated Animal Feeding Operation, the new EPA regulation requires that you evaluate the risk for P runoff to occur from each field where you intend to apply manure. The best way to evaluate this risk in Colorado is with the Colorado Phosphorus Index, a simple tool that considers the texture and slope of the land, the soil test P, the amount of P applied, and how P is applied (more information available at your local NRCS field office). If the P Index is high, then manure has to be applied at rates to meet the crop’s P requirements, not the N requirements. This will significantly reduce application rates, and most crops will require N fertilizer supplementation. However, the new regulation does allow for multi-year P applications up to the agronomic N rate. In other words, you can apply three or four years’ worth of P at one time, as long as you do not apply P again until three or four years later and as long as this manure application rate does not exceed the N agronomic rate. We compared N-based and P-based manure application rates in a recently completed four-year study and found that although N-based rates significantly increased soil test P, there were no cases of soil NO3-N or NH4-N buildup in the N-based rates exceeding those for the P-based rates. Lastly, you’ll get the most out of the manure application if it is applied as uniformly as possible with properly calibrated equipment. When you load the spreader trucks, be sure to even out the load in the truck, because uneven loading results in uneven application. Monitor the distribution of manure as it comes out the back, so you can get the proper overlap to even out the application rate. Otherwise, you may end up with N deficiencies in some spots and too much N in other spots, even though over the whole field, the application rate was correct. You may have avoided manure application in the past because of high transportation costs. But check your figures again this year, since the fertilizer value of the manure may outweigh the transportation costs. And what other fertilizer increases soil organic matter and improves soil properties!
|
|
|