Based on current prices (Fig. 2) and the uncer-tain future, we must become more conscious about how we apply fertilizer and the return in forage systems. Forage crops export far more nutrients off the field than grain crops because most of the above-ground growth is removed as hay. Forage and livestock producers are used to applying fertilizers without knowing the needs of existing forage crops and without knowing the soil nutrient reserves that are available. Most of the losses in a forage production system are due to improper fertilization that is done by imple-menting a blanket application. To have a better understanding of fertilizer needs and cost, producers should concentrate on getting a soil sample that could allow developing an efficient production system. Producers should collect a repre-sentative soil sample in field sections no greater than 10 acres and to a minimum depth of six inches. If legumes are present in the pasture, the percent of legumes and species in the stand should be included to obtain a more effective fertilizer recommendation.
Fertilizer efficiency will depend on several factors such as soil type, weather conditions, existing soil nutrient levels, soil pH, fertilizer type, application rate, forage type, etc. Figure 3 represents the possible yield responses based on your soil nutrient levels. Commonly, there is a linear in-crease in forage production with nitrogen (N) appli-cation. On the other hand, phosphorous (P) and potassium (K) had a 95 to 100% response with a very low soil level, 70 to 95% response at a low level, and 40 to 70% response with a medium level.
Financial constraints commonly limit fertilizer use by forage and livestock producers as they strive to maximize net returns on their investments. Under-standing soil test levels will help develop a fertilizer plan to make the wisest economic application. There are different fertilizer sources and some blended fertilizers like triple 13, triple 17, and poul-try litter that might be easier to apply, but you might be applying a nutrient source that you might not need if a soil sample is properly collected. Keep in mind that poultry litter could be a good source of P
and K when tested to determine the application rate. Most of the nitrogen in the poultry litter is trapped in the organic matter which requires microbial activity to break it down over time and some might be used by the microbes. Nitrogen availability in poultry litter ranges from 30 to 40% depending on poultry litter source and meaning that an additional N application might be required to achieve the recommended N rate. Table 1 provides an example in which a soil sample can cut costs and help choose the correct fertilizer source. In this example, there is the as-sumption that pH is optimal. If a soil sample recom-mend a lime application, it might be best to concen-trate on adjusting the pH before considering the ap-plication of other nutrients. Values in Table 1 indi-cate that choosing a blended fertilizer is 43% more expensive than developing a fertilizer mix. Produc-ers are paying for a convenience that we cannot af-ford these days. On the other hand, if a producer chooses to apply poultry litter and assumes that 40% of the nitrogen will be available, there will be a need to apply 2.1 tons per acre. That means that this approach will be 27.1% more costly than using a mixed fertilizer.
Developing a well-managed and effi-cient forage fertilization program that can increase profitability routinely depends on soil testing as well as maintaining records of the applied fertilizers and nutrient removal. Choose a fertilizer mix that can give you the needed nutrients, but also provides an economic advantage. Contact your local County Extension Office to collect the proper soil sam-ple and develop a suitable fertilizer plan.
Sheep and Goat Production Webinar Series (6:00 PM to 7:00 PM CST) - Registration Required
Jan 18, 2022— Addressing Reproductive Issues in Goats - Registration here
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For upcoming forage related events visit: forages.pss.msstate.edu/events