Readers' Rating:

Rate this article

Manure management has become an important topic because of its environmental implications. However, economic and agronomic opportunities exist with little risk to the environment if manure is applied to the land properly.

Manure as a Fertilizer

Like any fertilizer, it is important to know what substances are present in the manure, in what form, and in what amounts. These substances should be monitored to avoid build up in the soil to excess or toxic levels. This information is available from a laboratory manure analysis and should be monitored by soil testing where manure has been applied.

Nutrients in manure exist in two forms: organic and inorganic. Since only inorganic forms of nitrogen and phosphorus are available to plants, only a portion of the total nutrients can be utilized in the year of application. The organic forms must first be converted to an inorganic form (mineralized) which occurs naturally in the soil. This can be advantageous for the crop because not all of the nutients from manure are immediately available. The slow release of nutrients minimizes possible crop injury and prevents excess nutrients from being lost before plant uptake occurs. Availability of manure nutrients to the crop is dependent on the organic/inorganic makeup of the manure. With nitrogen, three different measurements are given in a manure analysis:

• Total Kjeldahl Nitrogen (TKN) is the total amount of organic and ammonia nitrogen in the sample.
• Ammonia nitrogen (NH3) is the amount of inorganic nitrogen that is readily converted to plant available forms.
• Organic nitrogen is determined by the difference between total nitrogen and ammonia nitrogen.

The general rule of thumb for nitrogen mineralization from manure is to expect 25-30% of the organic nitrogen to be available to plants in the first year, with the remainder becoming available during the next three years at a decreasing rate. Soil testing should be conducted to confirm the actual amount of available nitrogen in any specific situation. When considering application rates of manure based on nitrogen content, consider the amount of readily available nitrogen (ammonia) relative to the amount of gradually available organic nitrogen. In some cases, it may be necessary to add a starter fertilizer to ensure the crop has enough nutrients available during its early growth stages.

Field and laboratory methods of manure analysis are available. Field test kits allow for immediate estimation of nitrogen content and should be checked against a laboratory analysis first. Manure analysis from an operation should change very little from year to year if there are no major changes in feed ration or manure storage. Nutrient content of manure samples may vary greatly if not thoroughly agitated, since solids usually settle out during storage.

Sampling manure as close to time of application as possible provides the most accurate reading of nutrient levels in manure. However, this practice is limited by the turnaround time to receive a laboratory manure analysis to adjust current application rates. The previous year's manure analysis can be used and the application rate adjusted based on a current soil test.



Manure Sample Handling Instructions

• Half fill enclosed plastic jar with manure and close lid tightly.
• Place jar in plastic bag and close with twist tie.
• Place plastic bag containing jar of manure in packing box. Store in a cool place until shipping.
• Contact the laboratory of your choice for shipping information.
• Place cheque made out to the laboratory performing the analysis along with an information sheet with your name, address and type of manure in the packing box.
• Ship to laboratory as quickly as possible (by courier, prepaid).
• Be certain that sample spends no more than two days in transit. A courier service can provide delivery in less than two days. The mail service frequently does not. If sample must be stored before shipping keep refrigerated.

Manure Analysis and Costs

Manure can be analyzed for several components, some of which have more agronomic importance than others. Manure analyses of these components fall into one of three general categories:

• Top Priority - % moisture/%dry matter (DM), Total N, ammonia/ammonium-N, P, K;
• Secondary Priority - E.C. (total salts), pH;
• Low Priority - S, Na, Ca, Mg, total micronutrients (Cu, Mn, Zn, Fe, etc.)

These constituents exist in relatively low levels in manure and are not completely or immediately available for plant uptake.

Following is a list of available laboratories that conduct manure analyses. This is not necessarily a complete list and Manitoba Agriculture and Food is not promoting one laboratory over another by including some laboratories and failing to include others. Costs for manure analysis can vary from $20 to $85 per sample depending on the laboratory and the type of analysis conducted.

The agronomic value of manure can vary widely from place to place, according to feed ration, management practices, storage facilities and weather conditions. Data bases of information pertaining to the nutrient contents of manures are currently being developed and expanded, such as in Table 1:

Table 1. 1996 Summary of Hog Manure Analysis - Norwest Labs, Winnipeg
	TKN	Ammonia	Organic Nitrogen	P2O5	K2O	Na	EC	Moisture
	-----	-----------	lb/1000 gal	----	------	------	mS/cm	%
# samples	90	78	78	89	89	89	89	89
high*	30.7	21.9	8.8	23.5	17.3	5.1	16.1	97.9
average	27.3	19.2	8.1	18.6	15.6	4.5	14.8	97.3
low*	23.9	16.5	7.4	14.0	13.9	4.0	13.4	96.8
*Extreme values have been disregarded. 9 times out of 10 the sampled values fall between the high and low values listed above.

Conclusion
Treat livestock manure as a fertilizer. Once its nutrient content is determined, manure can be managed to benefit crop production with minimal risk to soil and groundwater contamination. The three key managmement points to remember are:

• Soil Test
• Manure Analysis
• Adjust fertilizer rates accordingly
  
  Author: Manitoba, Agriculture and Food
  
  

  Readers' Rating:

  Rate this article

  
        
  
  Who saw this article? ^New!
  
  

  ---

  
  MAKE A COMMENT ABOUT THIS ISSUE.