Good manure management is good economics and good for environment

2012-02-10T15:29:00Z Good manure management is good economics and good for environmentBy Jose A. Hernandez and William Lazarus, University of Minnesota Extension Minnesota Farm Guide

Livestock producers face uncertain markets and narrow margins. This situation has motivated them to optimize production methods, utilizing all resources including manure.

In addition, increases in the price of commercial fertilizer experienced in the last five years has heightened interest in the use of livestock manure for supplying crop nutrients and has significantly increased its value.

Over the past year more producers have been considering the contribution of manure's value to their cash flow in livestock operation budgets, and seeking an appropriate market value in exchange with crop producers. More crop producers also are seeking livestock manure as a major nutrient source, either by purchasing from a livestock producer or by adding livestock to their operations.

Determining the economic value of the nutrients in livestock manure can be tricky. Nutrients in commercial fertilizer are acquired by paying for the nutrients and a small application charge.

Additionally, commercial fertilizer supplies the amount and ratio of nutrients you need or ordered. With manure you, in effect, "acquire" nutrients by paying for the cost of application, even if you already have ownership of the manure. With manure, you get the amount and ratio of nutrients that it contains, which complicates the determination of a value.

Even when a rate that supplies the correct amount of nitrogen is applied, the amount of phosphorous and potash applied may not match what you would have purchased commercially, and amounts applied above crop need probably have no value.

In the past, manure application costs often exceeded the value of the nutrients applied. Now, in many situations, the nutrient value in the manure exceeds the cost of application.

Maximizing the value of manure first requires understanding how economic value is gained from manure. In most cases the greatest contribution comes from the value of commercial fertilizer that manure would replace in the crop year after application.

In some situations, another opportunity can come from second year credits, particularly with low fertility fields.

Increased crop yield is another possible source of value created from manure application. Where it is realized, that value has increased in the past year with higher crop prices.

Finally, net value can be maximized by avoiding over-application. Over-application beyond what the crop needs, or beyond what commercial fertilizer the crop producer would have purchased will usually increase application cost per acre without gaining additional income.

Management strategies to increase manure value can be looked at in the same way as how value is determined. First, for the "Value of Year 1 Fertilizer and Application Costs Replaced" (the replacement of nutrients that would have been purchased) use the following management practices:

- Apply for a nitrogen requiring crop.

- Apply to crops and fields that need P and K.

- Incorporate manure to reduce N volatilization losses.

- Use high nutrient concentration manure which requires fewer gallons or tons to haul to meet crop needs, reducing application cost.

- Avoid unnecessary dilution in liquid manures from factors such as drinker wastage.

- Consider lower rates (P based applications) with supplemental commercial N. This practice can potentially increase efficiency of nutrient use, spread yield benefits of manure over more acres, and avoid over-application of these nutrients. However, be sure that the application equipment used can apply the lower rate uniformly.

- Develop a multiyear set of manure tests for each barn to better estimate nutrient levels in manure.

- To gain residual value, apply manure to low P and K soil testing fields. Value is gained by replacing fertilizer that would be purchased for the next year.

- To gain yield response apply to fields that do not have a recent manure history. If possible select fields with lower organic matter.

- To limit manure application costs use equipment that have a range of application levels and that can be calibrated so that application accuracy is achieved. Avoid over-application which wastes nutrients and increases application costs per acre.

Another factor regarding N management with manure is the time of application. Many times the logistics of livestock operations, with their unique handling systems, etc, determine when the manure must be applied.

Fall manure applications, either injected or broadcast, allow more time for the organic portions to break down before the plant needs the nutrients as compared to spring application.

In contrast, fall applications also provide more time for potential loss of N. Fall applications should be avoided on coarser-textured soils where N leaching can be an issue. If fall application is necessary, it should be done when soil temperatures are below 50 degrees F.

There is a useful spreadsheet and an online "Value of Manure" calculator, developed by Dr. Bill Lazarus at the University of Minnesota. The spreadsheet considers first year fertilizer replacement value, possible residual value, and yield impacts, along with application cost, and calculates net manure value.

More information is available at or to learn more.

Copyright 2016 Minnesota Farm Guide. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

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