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Manure Nutrient Recycling /Recovery 
Processes and Systems


Commentary on Nutrient Recovery Systems 

Phosphorus Recovery
Nitrogen (ammonia) Recovery
Nutrient Recovery - General

Nutrient Recycling (nutrient flows in Agriculture)

Whole Farm Nutrient Balances(Accounting) 
    North America
Europe & Australia

  graphic: Dr. Mark Powell, USDA-ARS,
                 Madison, Wisconsin.
See Also:

Nutrient Recovery Systems for Manure Handling

(May 23, 2003; updated May 13, 2004)


There has recently been a number of papers and reports promoting the principle of "biological nutrient removal" for nitrogen in animal wastes, in which ammonia nitrogen is removed through nitrification to nitrate (or nitrite) followed by subsequent denitrification to nitrogen gas (N2), and lost back to the atmosphere.

This is NOT a sustainable practice and should not be recommended.   Much of the nitrogen fertilizer used in agriculture is produced by the energy-intensive Haber process for producing urea, which also has greenhouse gas emissions associated with it. It makes no sense to promote strategies that "purposely exhaust" nitrogen back to the atmosphere as N2, when more atmospheric nitrogen will have to be re-captured elsewhere to make new nitrogen fertilizers! 

Instead, practices should be promoted that conserve nitrogen from fertilizers and livestock manures, recognizing that there will be some leakage into water bodies, and developing practices that minimize these processes.

As livestock producers move towards more sustainable management systems, they need greater flexibility for managing the valuable nutrients contained in livestock and poultry manures.

Historically, most livestock manures have been land-applied, and this will continue to be the preferred practice. However, with the intensification of livestock production, there are increasing instances where the importation of nutrients (primarily the major nutrients, nitrogen (N)  phosphorus (P) and potash (K)) to the farm for crop production continually exceed the export of nutrients through products leaving the farmstead (e.g. meat, poultry, milk & dairy products, grains and other products). (See: " Whole Farm Nutrient Balances" Section).  In time, this will lead to nutrient excesses in some areas of the farm, especially for phosphorus which tends to accumulate more than nitrogen. Such excesses increase the risk of elevated nutrient loadings to nearby water bodies, including near-surface groundwater. A sustainable farming system should have, as a target, a reasonably balanced nutrient import/export scenario.

There is currently a nationwide initiative towards the development of comprehensive nutrient management plans (NMPs), which assist farmers in more effectively [economically and environmentally] managing major nutrients (N,P,K) for crop production. Although some management strategies are based on N-limits, there is a move towards the adoption of both N & P limits, based on a range of soil, crop production, topographic and environmental considerations.

Thus a farmer may be limited in the amount of manure can be applied, not based only on volume, but also on the nutrient content.  In the long-term, P will become the more limiting nutrient for land application.  Before reaching this point, the farmer may wish to adopt one or more of the following strategies:

  1. Reduce nutrient inputs to balance nutrient exports from the land base,
  2. Increase the land base for applying [manure] nutrients (buy, rent more land or, contract with neighbouring farms to receive excess manure),
  3. Export excess nutrients from the farm in the form of value-added products.

This commentary will focus on the third option, which becomes an increasingly important strategy as land values increase, and NMPs limit additional nutrient applications.

The basic concept of nutrient recovery (recycling, scavenging) from liquid manure slurries involves the transfer of the nutrients from the liquid to the solid phase.  Often, the first step will be the separation of the solids from the liquids, using a variety of methods, covered under "Manure Processing Technologies".   The amount (fraction) of nutrients removed with the manure solids will depend upon the method (equipment) used for solid-liquid separation process.

Scavenging the remaining nutrients from the remaining "watery" slurry is the main focus of this entire section. Europeans appear to be somewhat more advanced in investigating chemical processes for "cleaning" the remaining watery phase, especially P recovery. A number of technology providers are now promoting various processes for producing water clean enough to be discharged from the facility. However in many jurisdictions, this will trigger the requirement for the farmer to obtain a "C of A" (Certificate of Approval) for the discharge, which can be a rather rigorous and time-consuming process.

The degree to which the water phase is purified should usually be driven by the "value" of the recovered nutrients, rather than by the need to produce pure water, unless of course the farm is in a very arid area, and there is a great economic requirement to recover and recycle the limited water resource.  In most cases the "cleaned-up" water can be re-used within the barn facility for flushing, or land-applied without exceeding nutrient application limits.

There are mechanical filter / membrane systems that can separate the solids from the liquid phase. The finer the membrane, the smaller the particle size removed. The cost usually skyrockets when the minimum particle size to be removed (including bacteria, viruses, etc) is below 1micron (1 micrometer).

There is another nutrient recovery technology available for manure slurries, referred to as "vacuum cascade drying" (GBU, Germany), which is essentially a low-temperature (55 - 70°C) water condensation process under a partial vacuum, which de-waters manure slurries, producing semi-dry solids (containing virtually all of the nutrients), and relatively pure water which can be re-used or discharged. Excess heat from an anaerobic digester greatly reduces the energy inputs required. Providing the pH of the manure slurry is adjusted to near neutral (pH 7), virtually all of the ammonia will be in the non-volatile ammonium (NH4+) form and should not be stripped by the vacuum condensation process.

Some nutrient scavenging processes have migrated from the municipal and industrial waste water sectors, where coagulation/separation techniques have been employed for many decades in sewage plants.  From an agricultural perspective, there is one interesting process that involves the addition of magnesium (Mg) to the manure slurry, usually in the form of MgCl2. This causes the formation of a mineral called Struvite, MgNH4PO4.(H2O)6, which is a white crystalline substance. What is of real interest to agriculture is that struvite is a slow-release fertilizer containing equal molar amounts of N & P, and may have real potential as an agricultural fertilizer. (see several links below to struvite-related documents). It is not clear whether costs of adding magnesium salts to manure slurries to recover struvite would be currently economic.

If the scavenged nutrients from the manure slurry are added back into the solid manure separated from the original slurry, then there is an opportunity to control the nutrient content of final "value-added" product which can be sold off-site as an organic amendment, or as an organic fertilizer (guaranteed minimum analysis).  However, before these value-added products can be marketed, there would probably be a requirement for them to be "pathogen-free". If the manure slurry has been treated by digestion techniques, in which there has been a thermophilic treatment step, then then the final product could be assured of being free of harmful pathogens.

If the volumes of manure produced are quite large, then there is a good possibility that the diverted value-added organic amendment / fertilizer could become another revenue source for the farmer. At least, having this process available provides increased flexibility for the farmer in managing manure nutrients.. using them for crop production, or if in excess, diverting them to value-added off-site products. As part of a business plan, there should be up-front assessments conducted to determine potential markets for such products.

Value-added amendments (organic fertilizers) that are appropriately packaged (e.g. pellets, granules) will be the key to recycling excess livestock nutrients back to crop production areas currently dependent upon only mineral fertilizers. The continuing dependency upon mineral fertilizers has increased soil acidity, as well as increasing global nutrient loads in water bodies. (See also -Closing the Loop on Large-Scale Nutrient Flows).

If you have any questions or comments, please contact: Bruce T. Bowman



Phosphorus Recovery (from manure slurries)

 European Sustainable Phosphorus Platform - Sustainable management of Phosphorus is crucial for agriculture, food, industry, water and the environment. ESPP brings together companies and stakeholders to address the Phosphorus Challenge and its opportunities.

SCOPE Newsletter. The phosphate industry's research foundation and a sector group of CEFIC (the European Chemical Industry Council.  The  Newsletter seeks to promote a better understanding of the sustainable use of phosphate and the role of phosphate in the environment.

IWAR Phosphorus Recovery, Technical Univ. of Darmstadt, Germany.  Site aims to provide an information basis for the development of phosphorus recycling, necessary for sustainable development. (extensive library of technical documents on the subject).

Phosphorus in Agriculture and in Relation to Water Quality. Controlling the risk of phosphorus transfer from soil to water ... Past effort and expenditure in the UK to tackle phosphorus pollution in rivers and lakes.

Enhanced Biological Phosphorus Removal (EBPR) for Liquid Dairy Manure (2008). Jactone Arogo Ogejo, Katharine F Knowlton, Nancy G Love, Yanjuan Hong, Kevin Gilmore, Kerem Gungor; Amer. Soc. of Agric. & Biol. Eng. - Objective of this study was to evaluate the efficiency of P removal from separated liquid dairy manure by a research scale (16 L) EBPR system. EBPR was successful, as demonstrated by up to 98% reduction of the dissolved reactive phosphorus (DRP) when the manure was diluted 1:5 with tap water. When the dilution was reduced to 1:4, the DRP reduction efficiency dropped to 70%. Successful EBPR was demonstrated with dairy manure, but efficiency was affected by dilution.

Chemical Phosphorus Removal for Separated Flushed Dairy Manure.  Applied Eng. in Agric. 24(4):499-506. (2008). J.A. DeBusk, J. Arogo Ogejo, K.F. Knowlton, N.G. Love. Objective of this study was to determine effective and economical dosages of chemicals to remove phosphorus (P) from liquid dairy manure, the corresponding chemical and polymer dosages to treat manure in a full-scale case study at the Virginia Tech dairy, and the cost of manure treatment and land application of P-rich sludge produced.

The Physico-Chemical Conditions For The Precipitation Of Phosphate With Calcium. William A. House, Inst. of Freshwater Ecology, River Laboratory, East Stoke, Wareham, Dorset, BH20 6BB, England, UK. - The most important factors controlling the chemical speciation of calcium and inorganic phosphate in fresh waters and waste waters are discussed. Solubility diagrams are used to illustrate the range of compositions that are predicted to be stable with respect to the formation of key calcium phosphate minerals and calcite.

Removal of Phosphate from Sewage as Amorphous Calcium Phosphate. Robert Angel, Process and Industrial Chemists consultants, Australia - The pilot process demonstrated that phosphate could be effectively removed from sewage and that this was recoverable into a low grade (ca. 2%) phosphorus containing product. However, in treating sewage it was found that although removal of the bicarbonate (ubiquitous in such streams) should have enhanced utilisation of the magnesium oxide, (the primary reagent used in the process), the opposite was observed.

Prospects For The Recovery Of Phosphorus From Animal Manures: A Review. Julian Greaves, Phil Hobbs, David Chadwick and Phil Haygarth. Biological, Environmental & Rural Sciences ( IBERS)North Wyke, Devon, EX20 2SB UK;  paper reviews the potential for P recovery from animal manures as a method of increasing the sustainability of the global P cycle. The P content of animal manures produced annually in the UK is currently estimated at over 120,000 t. Similar quantities of P are produced in manures in the Netherlands and an estimated 600,500 t are produced annually in the US. Up to 65% of manure P may be associated with an organic moiety. However, current methods to identify these including HPLC and 31P NMR are under developed while P fractionation procedures give only operational definitions. Combinations of current technologies developed for the treatment of sewage are likely to prove effective in the recovery of P from manures.

Phosphate recovery from animal manure: The possibilities in the Netherlands (Nov. 1998) [396 KB pdf]. Van Ruiten Adviesbureau/Projectbureau BMA, for Phosphate Recovery.  This inventory of current knowledge is accompanied by a description of the anticipated technical and economic prospects, and an estimate of the amount of phosphate from animal manure that will in principle be available for recycling.

Particulate and Dissolved Phosphorus Chemical Separation and Phosphorus Release from Treated Dairy Manure [183 KB pdf]. Thanh H. Dao,  Beltsville Agric. Res. Ctr, Animal Manure and By-Products Lab., Beltsville, MD 20705, & Tommy C. Daniel, Crop, Soil, and Env. Sci. Dep., 115 Plant Sci., U. of Arkansas, Fayetteville, AR 72701;  J.  of Env. Qual. 31:1388-1398 (2002) - Water treatment polymers and mineral phosphorus (P) immobilizing chemicals [Al2(SO4)3·18H2O, FeCl3·6H2O, and Class C fly ash] were used to determine particulate and dissolved reactive phosphorus (DRP) reduction mechanisms in high total suspended solid (TSS) dairy manure and the P release from treated manure and amended soils.

Struvite Precipitation Potential For Nutrient Recovery From Anaerobically Treated Wastes [2784 KB pdf]- Ann Miles*, Timothy G. Ellis**, *HDR Engineering, Inc., 8404 Indian Hills Drive, Omaha, NE 68114; ** Dept. of Civil and Construction Eng., Iowa State University, Ames, IA 50011-3232 - Geochemical equilibrium speciation modeling was used to determine optimum conditions for precipitation of magnesium ammonium phosphate, or struvite, for the recovery of nutrients from anaerobically digested wastes. Despite a wide range of pH values with the potential to precipitate struvite, the optimum pH was determined to be 9.0. Bench experiments conducted on effluent from an anaerobic sequencing batch reactor (ASBR) treating swine wastes achieved a maximum of 88% ammonia removal at a pH of 9.5 with added magnesium and phosphate to achieve an ammonium: magnesium: phosphate molar ratio of 1:1.25:1.

Effect of Anaerobic Digestion on Struvite Production for Nutrient Removal From Swine Waste Prior to Land Application. Lara J. Beal1 Robert T. Burns1, Kenneth J. Stalder2 - 1 Agric. & Biosystems Eng. Dept.,2Animal Sci. Dept., U. of Tennessee, Knoxville, TN; Presented at 1999 ASAE Ann. Int'l Meeting, Toronto, Canada (July 18 – 21, 1999).  Concentrating and transporting excess P to P-deficient cropping areas may be economically viable. Forced precipitation of struvite (MgNH4PO4.6H2O) is one option for phosphorus concentration and removal. Using raw swine manure, testing has demonstrated that up to 92% of the reactive phosphorus (PO43-) can be removed by the addition of Mg2+ to the waste in the form of MgO and by heating to 35°C to force the formation of struvite. Up to 98% of the reactive phosphorus (PO43-) can be removed by using the same procedure with anaerobically digested swine manure.

Laboratory and In-Situ Reductions of Soluble Phosphorus in Liquid Swine Waste Slurries.  Robert T. Burns, Lara B. Moody, Forbes R. Walker, D. Raj Raman, Biosystems Eng. & Environ. Sci., Univ of Tennessee, Knoxville, TN 37996. 865-974-8080 (ph). 865-974-8086 (fax); Environmental Technology. 22(11): 1273-1278  - The forced precipitation of struvite (MgNH4PO4·6H2O) from animal waste slurries prior to land application can reduce soluble phosphorus (SP) levels in manure slurries. It offers the potential to concentrate and remove P from the system. Using this approach, the recovered P could then be transferred to cropping locations that are P deficient.

Phosphorus Recovery from Animal Manures using Optimized Struvite Precipitation [191  KB pdf] (May 2002). Robert T. Burns & Lara B. Moody, U. of Tennessee, Biosystems Eng. & Environ. Sci.  The recovery of phosphorus from animal waste as a struvite containing precipitate has been successfully demonstrated. The next step in the development of this technology is the development of a field-scale recovery unit at a commercial animal production unit. The operation of a field-scale recovery unit would supply the necessary data to complete a cost/benefit analysis to investigate the economics of the technology.

Optimization of phosphorus precipitation from swine manure slurries to enhance recovery  (2003) R.T. Burns, L.B. Moody, I. Celen and J.R. Buchanan, U. of Tennessee, Biosystems Eng. & Env. Sci., 2506 E.J. Chapman Dr., Knoxville, TN 37996-4531 USA - Water Sci. & Technol. 48 (1): 139 - 146. Laboratory experiments were conducted using magnesium chloride (MgCl2·6H2O, 64% solution) to force the precipitation of phosphorus and reduce the concentration of soluble phosphorus (PO4 3–) in two swine wastes. For the high and low concentration waste, a 10-minute reaction time at a pH of 8.6 was sufficient to remove 98 and 96% of the PO43– from solution.

Optimization of Phosphorus partitioning in Dairy Manure using Aluminium sulfate with a Mechanical Solids Separator (July 2003) [235 KB pdf]. I. Oh, L.B. Moody, I. Celen, J. Lee, & R.T. Burns - U. of Tennessee, Biosystems Eng. & Env. Sci., 2506 E.J. Chapman Dr., Knoxville, TN 37996-4531 USA - Paper 032266 ASAE Meeting, Las Vegas NV - Total suspended solids in the chemically amended supernatant were 56, 86 and 93% less than in the supernatant from the control. The soluble P conc. was immediately reduced in the screw press influent after addition of chemical, where it remained in the precipitate form throughout the separation process.

Enhanced Phosphorus Removal from Swine-Nursery Manure in Aerated Batch Reactors. (2003). P.M. Ndegwa,Biosystems & Agric. Eng., Oklahoma State U., Stillwater, OK; J. Zhu, A. Luo & D. W. Hamilton. Trans. ASAE 46(3): 797-803 - P-based land application of swine manure slurry results in under-application of nitrogen (N), while N-based application leads to over-application of P. This study compared three schemes of soluble orthophosphate (ortho-P) reduction from liquid swine nursery manure during batch aeration: (1) solids-liquid separation before aeration (pre-aeration solids-liquid, or PASL, separation), (2) solids-liquid separation in the middle of aeration (mid-aeration solids-liquid, or MASL, separation) and (3) no solids-liquid separation (control).

Precipitating swine manure phosphorous using fine limestone dust. (2004) [pdf]. S.F. Barrington, S. Kaoser1, M. Shin and J.B. Gélinas - Dept of Agric. & Biosystems Eng., Macdonald Campus, McGill U., 21111 Lakeshore, Ste. Anne de Bellevue, QC  H9X 3V9; and 2OMYA St. Armand, 2020 University St., Suite 1700, Montreal, QC H3A 2A5.  Can. Biosystems Eng. 46: 601-6.6 - The addition of 2% limestone improved TP and TS precipitation by 4% and  greatly improved sludge density and sludge separation from the supernatant.

The Phosphate Fertilizer Industry: An Environmental Overview. Michael Connett, Fluoride Action Network (May 2003) - They call them "wet scrubbers" - the pollution control devices used by the phosphate industry to capture fluoride gases produced in the production of commercial fertilizer. Fluoride has been, and remains to this day, one of the largest environmental liabilities of the phosphate industry. The source of the problem lies in the fact that raw phosphate ore contains high concentrations of fluoride, usually between 20,000 to 40,000 parts per million (equivalent to 2 to 4% of the ore).

Environmental Aspects of Phosphate and Potash Mining [1779 KB pdf]. United Nations Environment Program & International Fertilizer Industry Association. This publication completes a series that looks at environmental aspects of the fertilizer industry throughout the life-cycle of mineral fertilizer products. In this volume, the holistic way of looking at an issue is applied to the activities of the fertilizer raw materials sector, incorporating the concept of the whole-of-mine-life thinking and planning.

Phosphate Primer. Florida Institute of Phosphate Research (FIPR) - information regarding phosphate mining in South Florida - Publications from FIPR   

MAP Precipitation for Recovering Nutrients from Manure [204 KB pdf]   R. Schulze-Rettmer, Soerser Winkel 22, D-52070 Aachen, Germany, P. Metzen, Petra Alfer & B. Simbach - In Germany, the phosphate load of manure is more than three times higher than the phosphate load, that is excreted by the population. Phosphate in manure should be precipitated by adding a surplus of magnesium ions in presence of ammonium, where struvite and some byproducts are formed, called MAP - mono-ammonium phosphate.

Reducing Phosphorus Runoff from Swine Manure with Dietary Phytase and Aluminum Chloride (2004). D. R. Smitha, P. A. Moore, Jr.b, C. V. Maxwellc,B. E. Haggardb and T. C. Danield  - a USDA-ARS, National Soil Erosion Res. Lab., Purdue U., 275 South Russell Street, West Lafayette, IN 47907; b USDA-ARS Poultry Production & Product Safety Res. Unit, U. of Arkansas, Fayetteville, AR 72701; c Dept of Animal Sci., U. of Arkansas, Fayetteville, AR 72701; d Dept of Crop, Soil & Env. Sci., U. of Arkansas, Fayetteville, AR 72701; J. Environ. Qual. 33:1048-1054  - study was conducted to compare the effects of dietary modification and aluminum chloride (AlCl3) manure amendments on reducing P in swine manure and runoff. Phytase reduced manure soluble reactive phosphorus (SRP) by 17%, while AlCl3 reduced manure SRP by as much as 73% compared with normal manure. P runoff was reduced from 5.7 to 2.6 mg P L–1 (a 53% reduction) using AlCl3.


Nitrogen / Ammonia Recovery (from manure slurries)

Ammonia Recovery Process [7264 KB pdf] (Jan. 2000). Environmental Technology Evaluation Center (EvTech) Report;  ThermoEnergy Corp, Little Rock AR 72201 Tel. 501-376-6477 Alex G. Fassbender, -  A low-cost, environmentally responsible method of recovering nitrogen, in the form of ammonia, from various dilute waste streams and converting it into concentrated ammonium sulfate. The ThermoEnergy Biogas System utilizes the new chemisorption-based ARP to recover ammonia from anaerobically digested wastes. The process provides for optimal biogas production and significantly reduced nitrogen levels in the treated water discharge. destruction technologies.

Air stripping of ammonia from pig slurry: characterisation and feasibility as a pre- or post-treatment to mesophilic anaerobic digestion. August Bonmatí and Xavier Flotats, Lab.  of Environ. Eng., Dept of Env. & Soil Sci., U. of Lleida, Av. Rovira Roure 177, E-25198, Lleida, Spain; Waste Management 23(3): 261-272, 2003  - Objective: to study the effect of pig slurry waste type, fresh or anaerobically digested, and the effect of initial pH on ammonia air stripping from pig slurry waste at high temperature (80 °C). Batch anaerobic tests showed that ammonia air stripping is not an advisable pre-treatment to pig slurry anaerobic digestion.

Effect of Adding Alum or Zeolite to Dairy Slurry on Ammonia Volatilization and Chemical Composition [102 KB pdf] (2001). A. M. Lefcourt and J. J. Meisinger, Agricultural Research Service, USDA, Animal and Natural Resources Institute, Beltsville, MD 20705 -  J. Dairy Sci. 84:1814–1821 - measured ammonia emissions and resulting chemical changes in the slurry in response to the addition of amendments (alum or zeolite) at 0.4, 1.0, 2.5, and 6.25% by weight; alum or zeolites as on-farm amendment to dairy slurry offers the potential for reducing ammonia emissions and soluble phosphorus in dairy slurry.

Nitrogen recovery and reuse [215 KB pdf] (2001). M. Maurer, J. Muncke  [In: Lens P., et al. Water and Resource Recovery in Industry] . Novaquatis, EAWAG, P.O. Box 611, Ueberlandstrasse 133, CH-8600 Duebendorf, Switzerland Phone +41-1-823 55 11, Fax +41-1-823 50 28 - excellent technical document on chemical and biological reactions of the various forms of nitrogen in a variety of waste management scenarios.


Nutrient Recovery-General

Energy and Nutrient Recovery from Swine Manures. (April, 2010). Wendy J. Powers, Iowa State U.; Robert T. Burns, U. of Tennessee. Objectives: 1) Summarize processes that extract energy from animal manures (urine and/or feces) as a mechanism to recover value from manure by providing on- or off-site energy; 2) Summarize the economic feasibility of energy recovery and describe the non-economic benefits that may accompany several of these technologies; 3) Summarize opportunities and approaches that enhance the ability to recover nutrients in order to avoid over-application of nutrients to cropland.

Opportunities for Nutrient Recovery in Handling of Animal Residuals (2000) [143 KB pdf] Eberhard Morgenroth, Dept of Civil & Env. Eng. & Dept of Animal Sci., U. of Illinois at Urbana-Champaign, Urbana, IL 61801, USA; Tel: (217) 333-6965, Fax: (217) 333-6968 - Treatment methods are presented that can be used for nutrient recovery from animal manure and these processes are compared to the current practice. Both aerobic and anaerobic process can be used to produce a valuable product from animal manure that can be reused. Phosphorus can be recovered by precipitation in combination with a biological phosphorus removing activated sludge system or by membrane separation in combination with anaerobic digestion.

A review of membrane bioreactors and their potential application in the treatment of agricultural wastewater (2003) [pdf]. N. Cicek, Biosystems Eng., U. of Manitoba, Winnipeg, MB  R3T 5V6; Can. Biosystems Eng. 45: 6.37 - 6.49 - defined as systems integrating biological degradation of waste products with membrane filtration. They have proven quite effective in removing organic and inorganic contaminants as well as biological entities from wastewater; paper summarizes the potential applications of the MBR technology for the treatment of wastewater from agricultural sources.

Agri-Clean™ System. Press Technology & Mfg. Inc., 1315 Lagonda Ave., Springfield, OH 45503; Tel: 937-327-0755; Fax: 937-327-0756;  removes solids and nutrients from animal manure wastewater. System consists of an Internal Drum Thickener (IDT), an Agri-Press® Screw Press, a Dissolved Air Floatation (DAF) Clarifier, a twin polymer make-down system, a chemical feed system, a PLC control, a data collection system and a telephone modem.  The IDT pre-thickens the low consistency raw manure slurry to 10-12% solids. The thickened slurry flows into the Agri-Press® and is dewatered to 35-40% solids. The liquid filtrate from the IDT and Agri-Press® is pumped to a DAF clarifier. Chemistry is added to the liquid filtrate before being injected into the DAF. The chemicals are a coagulant and a flocculent. The coagulant is used to remove soluble phosphorus and ammonia while reducing the pH & neutralizing the negatively charged suspended solids. Solids from the DAF are returned to the IDT and Agri-Press®.



Nutrient Recycling (nutrient flows) in Agriculture

Backgrounder -  Sustainable Nutrient Management in Agriculture and Closing the Loop on Large-Scale Nutrient Flows, Bruce T. Bowman, Former Chair,  CARC Expert Committee on Manure Management

See also: 
   Whole Farm Nutrient Balances
    Sustainable Livestock Development

    Large-Scale Livestock Nutrient Recycling: A Key Part of a Sustainable Nutrient Management Strategy

Comprehensive Systems For Managing Nutrient Flows And Gaseous Emissions In Relation To Dairy Manure John Meisinger, USDA/ARS, Beltsville, MD; - Res. Project - 2000-2005.  Redirect whole-animal carbon & nitrogen to reduce C and N emissions/unit animal product and enhance environmental sensitivity. Develop efficient strategies for management of nutrient flows and gaseous emissions by identifying major loss pathways. Develop manure treatment, handling, and use practices that reduce release of nutrients, ammonia, odors, bioaerosols and dust particles to air & water. Develop rapid methods of analysis for both inorganic and organic nitrogen in manures.

Creating Markets for Manure: Basin-wide Management in the Chesapeake Bay Region [63 KB pdf] (June 2004). Doug Parker,Agric. & Resource Econ., U. of Maryland, College Park, MD (presented at the joint Ann. Meet of the NE Agric. & Resource Econ. Assoc. & Can. Agric. Econ. Soc., Halifax, NS, June 20 - 23, 2004) - Historically, animal and crop production systems were often integrated on a single farm. With the introduction of cheap commercial fertilizers, farms were able to increase crop production by supplementing animal manure sources. Abandoning animal manure as a source of nutrients and switching to commercial fertilizer inputs to gain high crop yields allowed for the separation of animal production from feed production.

Phosphorus: Global Transfers. (2002). [97 KB pdf]. Vaclav Smil, Winnipeg, Canada. In: Causes and Consequences of Global Environmental Change I. Douglas, ed. Vol. 3. of Encyclopedia of Global Environmental Change, T. Munn, ed., John Wiley, Chichester, pp. 536-542. Phosphorus – unlike carbon, C, nitrogen, N and sulfur, S – does not form any long-lived atmospheric compounds and hence its global cycle is just a part of the grand, and slow, process of denudation and geotectonic uplift. But on a small scale the element is rapidly recycled between organic and inorganic forms in soils and water bodies. Human activities now annually move more than four times as much phosphorus as did the natural processes during the pre-agricultural era. See also: Phosphorus Cycle

Decision Making on Integrated Nutrient Management Through the Eyes of the Scientist, the Land-User and the Policy Maker (2002) [260 KB pdf] E.M.A. Smaling, J.J. Stoorvogel  Wageningen Univ., Soil Science,  PO Box 37, 6700 AA Wageningen, NL) and A. de Jager, Agric. Economics Res. Inst., PO Box 29703, 2502 LS The Hague, NL)  CAB International 2002. Integrated Plant Nutrient Management in Sub-Sahara Africa. Nutrient imbalances are substantial, but researchers, land-users and policy makers all react individually, and focus on different spatial scales.

Phosphorus in the environment: natural flows and human interferences. (2000). [476 KB pdf]. Smil, V. Annual Review of Energy and Environment 25:53-88. P has a number of indispensable biochemical roles, but it does not have a rapid global cycle akin to the circulations of C or N. Natural mobilization of the element, a part of the grand geotectonic denudation-uplift cycle, is slow, and low solubility of phosphates and their rapid transformation to insoluble forms make the element commonly the growth-limiting nutrient, particularly in aquatic ecosystems. Human activities have intensified releases of P. By the year 2000 the global mobilization of the nutrient has roughly tripled compared to its natural flows:

Integrated Nutrient Management, Soil Fertility, and Sustainable Agriculture: Current Issues and Future Challenges. [158 KB pdf] (Sept 2000) Peter Gruhn, Francesco Goletti, and Montague Yudelman, Int. Food Policy Research Inst., 2033 K Street, N.W., Washington, D.C. 20006 U.S.A.   As long as agriculture remains a soil-based industry, major increases in productivity are unlikely to be attained without ensuring that plants have an adequate and balanced supply of nutrients. They call for an Integrated Nutrient Management approach to the management of plant nutrients for maintaining and enhancing soil, where both natural and man-made sources of plant nutrients are used. The key components of this approach are described; the roles and responsibilities of various actors, including farmers and institutions, are delineated; and recommendations for improving the management of plant nutrients and soil fertility are presented.

Integrated Plant Nutrition System - Key To Soil Productivity Enhancement And Sustainable Agricultural Production [116 KB pdf] (2001). M. Velayutham, Consultant, FAO Regional Office for Asia and the Pacific, Bangkok, Thailand. Integrated Plant Nutrition System (IPNS) as a concept and farm management strategy embraces and transcends from single season crop fertilization efforts to planning and management of plant nutrients in crop rotations and farming systems on a long-term basis for enhanced productivity, profitability and sustainability.

Land Spreading of Animal Manures, Farm Wastes & Non-Agricultural Organic Wastes, Part 1: Manure (and Other Organic Wastes)Management Guidelines for Intensive Agricultural Enterprises. (1999). Owen T. Carton1 and William L. Magette2, 1Teagasc, Johnstown Castle Research Centre, Wexford;  2 Dept. of Agricultural and Food Engineering, UCD, Earlsfort Terrace, Dublin2. (May 1999) ISBN 1 84170 23 8 - Johnstown Castle Research Centre Wexford - Properly managing manure (liquid and solid) and other organic wastes on farms is essential to achieving sustainability, both in environmental and economic terms. Recycling animal manures back to the land is the most sensible management option.  Full report in PDF (801 KB).

Recycling Organic Waste: From Urban Pollutant to Farm Resource (August 1997) - Worldwatch Paper #135: Gary Gardner ISBN: 1-878071-37-8 59 pages - Today, we normally send organic garbage and sewage to landfills and incinerators, or dump them into rivers, bays, and oceans. And manure is increasingly dumped or overapplied to farmland because of large, centralized livestock production. These disposal methods clog landfills, pollute air and drinking water, and encourage cities to invest in costly, water-intensive sewage infrastructure.

Recycling Organic Waste: From Urban Pollutant to Farm Resource. (1997) Gary Gardner, WorldwatchPaper 135. Recycling organic wastes and returning them to productive soils would be a large step toward sustainability for the world's cities and national economies. But the current trend in most of the world--toward greater dependence on extended, one-way nutrient flows facilitated by heavy fertilizer use--promises increased ecosystem disruption, greater waste disposal problems, and eventually a negative effect on food production itself.

Integrated Animal Waste Management (USA) [1479 KB pdf](1996). Council for Agricultural Science and Technology (CAST). Co-Chairs - Dr. Alan L. Sutton, Dept of Animal Sci., Purdue University, West Lafayette, Indiana, and Dr. Jim F. Power, U.S. D. A., Agricultural Research Service, University of Nebraska, Lincoln, NE 


Livestock and Sustainable Nutrient Cycling in Mixed Farming Systems of sub-Saharan Africa, Volume II. (1993) [2748 KB pdf]. Technical Papers- Proceedings of an Int'l Conference, Int'l Livestock Centre for Africa (ILCA), Addis Ababa, Ethiopia; 22–26 November 1993 - Edited by J. M. Powell, S. Fernández-Rivera, T.O. Williams and C. Renard (ISBN 92–9053–294–7). An efficient cycling of nutrients among crops, animals and soil is crucial to the sustained productivity of low-input mixed farming systems in sub-Saharan Africa.





Whole Farm Nutrient Balances (Accounting)

Net Nutrient balance (Inputs/Outputs) on farms can be a good indicator of the sustainability of nutrient management practices being used at whole-farm scale, and provide some indication of the risks for water contamination by excess nutrients.  The purpose of this section is to document studies / reports dealing with on-farm nutrient accounting/balances.

See also: Life Cycle Assessment in Nutrient Management

North America

Whole Farm Nutrient Balance Spreadsheet (2009) Cornell U. Nutrient Management Spear Program.  Spreadsheet is designed to assist in the evaluation of sources of nutrient arriving on farm, degree of nutrient concentration or imbalance, and appropriate strategies for correcting nutrient concentration concerns (Instructions included for Excel spreadsheet).

What is Whole Farm Nutrient Balance? (2008). U.S. Cooperative Extension System. Whole farm nutrient balance considers the location and flow of nutrients onto, within and off the entire farm. Whole farm nutrient balance involves taking a step back and also comparing the amount of nitrogen (N), phosphorus (P), and potassium (K) and other nutrients entering the farm as purchased feed, fertilizer, animals etc. with the amount of nutrients leaving the farm as milk, animals, crops, manure exports to other farms, etc.

Whole Farm Nutrient Planning [848 KB pdf] (2003). Livestock and Poultry Environmental Stewardship (LPES) Curriculum.  Rick Koelsch, Dept. Biological Systems Eng., U. of Nebraska, Lincoln, NE - Excellent course outline and general information on whole-farm nutrient balance. Whole farm nutrient imbalances are common for modern livestock operations.

Nutrient Balance on Nebraska Livestock Confinement Systems (1999) [1343 KB pdf]. Rick Koelsch1 & Gary Lesoing2. 1 Dept. Biological Systems Eng., U. of Nebraska-Lincoln 68585-0726; 2U. of Missouri Outreach and Extension, Richmond, MO 64085. A nitrogen and phosphorus balance was constructed for 33 Nebraska confinement livestock operations. Twenty-five and 17 of these operations experienced significant nitrogen and phosphorus imbalances, respectively (50% more nutrient inputs than outputs).

Whole Farm Nutrient Flow and Manure Management [30  KB pdf] (1999). C.G. Cogger1, T.N. Cramer2, A.I. Bary1, and D.C. Grusenmeyer2; 1Washington State University, Puyallup Research and Extension Center;2 Formerly with Washington State University Cooperative Extension, Whatcom County -  Even the best on-farm management cannot prevent excess nutrient accumulation if nutrient flows are greatly out of balance. Nutrient flows must be better understood to help determine the best approaches to sustaining long-term dairy productivity and water quality. By measuring whole-farm nutrient flows – imports, exports, and major on-farm transformations, we can gain a better grasp of the situation that we face, and of potential solutions.

Whole-Farm Nutrient Budgeting: A Nutritional Approach to Manure Management. Wendy Powers, Dept of Animal Sci., Iowa State U.; H.H. (Jack) Van Horn, Dept of Animal Sci., U. of Florida. Consideration of nutritional management in nutrient management practices allows a producer to tailor the nutrient budget to more accurately reflect the operation's management practices. Wide variation in manure production may occur as a result of nutritional strategies.

Developing Whole-Farm Nutrient Plans for Feedlots [59  KB pdf]. Wendy Powers, Dept of Animal Sci., Iowa State Univ., Ames IA.  Nutrient management has become necessary for all livestock producers. It is important to keep a balance between nutrients produced and nutrients needed. The steps outlined above can help a producer become more actively involved in the nutrients his farm produces and how to manage them. To achieve environmentally acceptable nutrient balances, many animal production facilities will have to export manure or manure products in the future or change nutrient production to match nutrient needs.

Using an On-Farm Nutrient Balance as a Monitoring Tool. Mark Muller, Inst. for Agriculture and Trade Policy,  2105 1st Avenue S., Minneapolis, MN. Initial results indicate that on-farm nutrient balance tools are an effective method of measuring the potential for adverse environmental impacts due to nutrient losses.  Perhaps most importantly, on-farm nutrient balances could be used to improve public awareness of the benefits of environmentally sound agriculture.

A Mass Balance of Nitrogen, Phosphorus and Potassium On Farms in a Dairy Watershed in Northeast Wisconsin.  [KB pdf] Kevin A. Erb, U. of Wisconsin-Green Bay, WI.  A mass balance of 13 dairy farms, ranging in herd size from 50 to 500 head and 4 cash grain operations was conducted in the Lower Fox River Basin over a two year period to determine the per-hectare rate of nitrogen, phosphorus and potassium loading on farms in the basin. Incoming sources of these nutrients were quantified from feed, fertilizer and livestock purchases, as well as natural sources of nitrogen. Economic nutrient export was calculated, as well as an estimate of environmental phosphorus losses.

Using Nutrient Balances to Benefit Farmers and the Environment [84 KB pdf]. Mark Muller, Institute for Agriculture and Trade Policy, Minneapolis, MN 55404;  The Nutrient Management Yardstick is a series of worksheets that provides information on nutrient flows on a farm. It provides a method of calculating the amount of nutrients in animals and crops that enter and leave the farm. Processes that take place within the farm, such as the farm’s crops being fed to the farm’s animals, do not have to be accounted for.

Whole-Farm Nutrient Budgeting on Twenty-Eight Farm Operations in Southern Wisconsin. D.R. Fisher, J. L. Posner, J.O. Baldock, Dept. of Agronomy, U. of Wisconsin, Madison WI.  28 Southern Wisconsin farms are applying nitrogen, phosphorus and  potassium at rates which are only slightly greater than crop offtake.  Where nutrient imbalance exists, common causes include heavy stocking rates, high starter fertilizer application rates, under-crediting of manure and legume nutrient additions, and excess nutrient concentration (especially  P) in the dairy ration. View document as PDF[333KB]

Whole farm nutrient planning. Jeff Lorimor, Dept of Agric. & Biosystems Eng., Iowa State U.   Whole farm nutrient planning is not a new concept. Many producers are already doing it by using a good nutrient management plan and carefully controlling rations. It is simply another way to understand the basic relationships between farm imports and exports. If the two do not match, Mother Nature will make them.

Whole Farm Nitrogen Balance: Partners prove best management practices can help handle nitrogen [875 KB pdf]. Stew Hilts, Land Resource Sci., U. of Guelph, Guelph, ON N1G 2W1; Nitrogen leaching is a major concern of the agricultural industry. But what's the best method to measure the problem? Researchers compared seven approaches, with these observations:

Regional Nutrient Balances (MLMMI 02-HERS-04)   Full Report [3619 KB pdf]. A nutrient balance model was developed for the Municipalities of Hanover, La Broquerie, Roland and Sifton in Manitoba. The model tracks and estimates all nutrient (nitrogen and phosphorous) inputs, outputs, and losses to the environment for the agricultural industry.  The study found that in areas such as Hanover and La Broquerie, which have a significant intensive livestock industry, the importation of large quantities of nutrients in feed is contributing to a build-up of nutrients in the soil on a regional basis.

Evaluating Livestock System Environmental Performance with Whole-Farm Nutrient Balance (2005). J. Env. Qual. 34:149-155 (2005); Rick Koelsch, U. of Nebraska-Lincoln, Biol. Systems Eng. & Animal Sci. Dept, East Campus, Lincoln, NE 68583-0726  - A review of 2 mandatory and 2 voluntary nutrient management strategies is made by comparing whole-farm nutrient balance for a case-study beef cattle feedlot. The results suggest that voluntary BMPs, such as modification to animal feeding program and exporting of manure, can have greater environmental benefits (30–60% reduction in P accumulation for case-study farm) than mandatory NMPs and buffers (5–7% reduction in P accumulation for case-study farm) for a typical beef cattle feedlot.

Whole-Farm Perspectives of Nutrient Flows in Grassland Agriculture. Crop Sci 45:2139-2159 (2005). C. A. Rotz (USDA, PA), F. Taube (U. of Kiel, Germany), M. P. Russelle (USDA, MN), J. Oenema, (Wageningen, NL),  M. A. Sanderson (USDA, PA), and M. Wachendorf (U. of Kassel, Germany) - review the principles of nutrient cycling in grassland agriculture, discuss examples of grassland farming systems research, and demonstrate the usefulness of whole-farm simulation for integrating economic and environmental components.

Whole-Farm Nutrient Management on Dairy Farms to Improve Profitability and Reduce Environmental Impacts [1444 KB pdf] (April, 2004). Cornell University, University of Wisconsin-Madison, USDA-Agricultural Research Service, Dairy Forage Research Center - A collaborative project to define and evaluate nutrient management tools developed and used in New York and Wisconsin that are applicable across regions, and tools or models that are region specific but whose approach and structure may be applicable across regions - document contains outlines of nine nutrient management tools used in NY or Wisc. and provides readers with comparative reviews of the tools to aid in tool selection. Model developers and agricultural educators can use this information to improve their nutrient management research and teaching efforts.

Whole-Farm Management to Reduce Nitrogen Losses from Dairy Farms  (2003). C. Alan Rotz, USDA/ARS, Curtin Road, University Park, PA 16802.; Jouke Oenema & Herman van Keulen, Plant Research Int'l, Box 16, 6700 AA Wageningen, the Netherlands; 2003 ASAE Annual Meeting, Las Vegas, Nevada, USA - Whole farm simulation provides a tool for evaluating the impact of nutrient conservation technologies and strategies on dairy farms. Technology such as a low nitrogen emission barn floor, a covered manure storage, manure injection, and the interseeding of grass on corn land to absorb excess nitrogen were used on this farm to reduce nitrogen loss. 

Planning For Whole Farm Management: Lessons From Midwest Farmers [1510 KB pdf] (Sept 2003). The Minnesota Project and The Great Lakes Whole Farm Planning Network - Michelle Miller, Diane Jensen, Steve Bonney, Laura Ann Bergman - stories of farmers in this 12-state region. These farmers who are purposefully experimenting with new management approaches that integrate the opportunities on their farm with the needs of their families and communities.

Whole-Farm Nitrogen Balance on Western Dairy Farms (2003). R. A. Spears1R. A Kohn2 & A. J. Young1-1 Animal, Dairy, & Vet.  Sci. Dept, 4815 Old Main Hill, Utah State U., Logan UT 84322-4815;  2Dept of Animal & Avian Sci., Animal Science Ctr, U. of Maryland, College Park MD 20742-2311. J. Dairy Sci. 86:4178-4186.  Environmental legislation has made it necessary for livestock producers to be able to quantify and adjust the N balance on their farms. Whole-farm N balance and efficiencies were computed for 41 commercial dairies in Utah and Idaho using the University of Maryland Nutrient Balancer.

Whole-Farm Phosphorus Balance on Western Dairy Farms (2003).  R. A. Spears1,A. J. Young1 and R. A. Kohn2; 1Animal, Dairy, & Vet.  Sci. Dept, 4815 Old Main Hill, Utah State U., Logan UT 84322-4815;  2Dept of Animal & Avian Sci., Animal Science Ctr, U. of Maryland, College Park MD 20742-2311.  J. Dairy Sci. 86:688-695 - Environmental concerns have focused attention on animal agriculture and its contribution to P accumulation in soils and runoff to surface waters. Monitoring P inputs and outputs on farms is a means of calculating the potential P build-up in farm soils. The objective of this study was to determine whole-farm P balance and the relative importance of the farm components (herd, manure storage, cropping systems) that contribute to it in dairies of the western United States.

Managing Material Transfer and Nutrient Flow in an Agricultural Watershed  [220  KB pdf] (2003). E. A. Nord and L. E. Lanyon, J. Environ. Qual. 32:562–570Dept. of Crop and Soil Sciences, The Pennsylvania State Univ., Univ. Park, PA. - monitored the agricultural area of a 740-ha watershed to determine the nature and scale  of farm material transfers, N and P balances, and farmer decisions that influenced them. 3 of 15 farms, emphasizing hog, dairy, or cash crops with poultry production, accounted for more than 80% of the inputs and outputs of N and P for the 362-ha agricultural area.

Whole-Farm Phosphorus Management On Dairy Farms (2002) [47 KB pdf]. J. Mark Powell1, Douglas B. Jackson-Smith, Larry D. Satter and Larry G. Bundy;  1USDA-ARS Dairy Forage Research Center, 1925 Linden Drive West, Madison, WI 53706 - Balancing phosphorus inputs and outputs through integrated feed, fertilizer and manure management are quickly becoming the principal regulatory challenges facing the US dairy industry. The needed integrated approach to nutrient management on dairy farms necessitates close interaction between farmers and the feed and fertilizer consultants and veterinarians hired by farmers to make nutrient management decisions.

Nitrogen Budgets For Your Dairy [156 KB pdf] (Sept. 2002). Allen Young, Utah State U. Extension, Logan, Utah - it is important to know the nitrogen balance on your farm and to use this information to identify areas that could lower excess nitrogen lose that might cause pollution. Each farm is unique, but it is helpful to look at whole-farm nitrogen balances from other farms in order to have a reference from which to compare your farm.

CEEOT-LP Application to Environmental Issues in Poultry Production [243  KB pdf] (March 2000). Joju Abraham and Ron Kepford, Texas Inst. for Applied Env. Res., Tarleton State U., Box T0410, Tarleton Stn., Stephenville, TX 76402;  - A watershed-level evaluation tool called the Comprehensive Economic and Environmental Optimization Tool-Livestock and Poultry (CEEOT–LP), earlier developed, and successfully applied, to evaluate environmental and economic impacts of alternative management methods in dairy and swine operations, will be developed and adapted for poultry operations to evaluate similar objectives.

Whole-Farm Planning for Economic and Environmental Sustainability (MF2403, Aug. 2000) [47 KB pdf]. Rhonda R. Janke, Dept of Horticulture, Kansas State Univ. The goal of whole-farm planning is simply to find a way to tie all of the various parts of a plan (economic, environmental, & social) together into an integrated whole.

Estimating Feedlot Nutrient Budgets and Managing Manure Output [160 KB pdf] (1997). C. M. Zehnder and A. DiCostanzo, Dept of Animal Science, U. of Minnesota, St. Paul, MN - This paper will focus on ways cattle feeders can minimize, measure, manage and control N and P as these nutrients move through the cycle in a cattle feeding operation.




Europe and Australia and New Zealand

Study on Input/Output Accounting Systems on EU agricultural holdings [209  KB pdf] (Mar. 2001) (CLM 489 - 2001).  Gillian Goodlass (ADAS), Niels Halberg (DIAS), Gerwin Verschuur (CLM), Centre for Agriculture and Environment, Utrecht; PO Box 10015,  Utrecht NL-3505 AA  The Netherlands  - The objective of the project is to provide Commission services (DG agriculture and DG environment) with a critical assessment of current experiences with Input/Output (nutrient) Accounting at farm level. This report will hopefully contribute to a better understanding of the strengths and weaknesses of IOA systems to make farming in Europe more environmentally friendly.

Integration of organic poultry in whole farm systems: manure nutrient budgets [21  KB pdf]. Susan H Gordon, Anne Bhogal, Andrew W Walker, ADAS Gleadthorpe, Meden Vale, Mansfield, Nottinghamshire, NG20 9PF, UK - The aim of this project is to examine how rotations incorporating organic poultry use the cycling of nutrients and waste between the soil, crops and birds. It will be important for organic farmers to know whether quantities and availability of N, P and K within the system are likely to be limiting, or whether there will be a surplus.

Nutrient balances on organic pig farms. Jørgen Eriksen,DARCOF, Danish Inst. of Agric. Sci., Dept of Plant Growth and Soil Sci., Research Centre Foulum, Box 50, DK 8830 Tjele; Tel: +45 8999 1900. Fax: +45 8999 1719 - This project examines the removal and loss of nutrients from out-door sow herds with a view to establishing the possibilities of retaining nutrients to benefit subsequent crops.

Evaluating nitrogen taxation scenarios using the dynamic whole farm simulation model FASSET [226 KB pdf] (4 July 2002). J. Berntsen, B.M. Petersen, Brian H. Jacobsen, J.E. Olesen, N.J. Hutchings - Danish Institute of Agricultural Sciences, Dept of Crop Physiology & Soil Science, Res. Centre Foulum, Box 50, DK-8830 Tjele, Denmark; Danish Research Inst. of Food & Resource Economics, Rolighedsvej 25, 1958 Frederiksberg C, Denmark - whole farm model FASSET ver. 1.0 was used for evaluation of the environmental and economic consequences of implementing different nitrogen taxes. The taxation policies analysed were a tax on nitrogen in mineral fertiliser, a tax on nitrogen in mineral fertiliser and imported animal feedstuff, and a tax on the farm nitrogen surplus.

Nutrient budgets as a tool for researchers and farmers [18 KB pdf]. Stephen P. Cuttle, Inst. of Grassland & Env. Research, Plas Gogerddan, Aberystwyth, Ceredigion SY23 3EB, UK - Whole-farm budgets for N, P and K have been determined for the organic dairy farm at Trawsgoed in mid-Wales and used to assess the potential value of budgets as a management tool for optimising nutrient use. Most of the information needed by farmers to calculate whole-farm budgets is available on commercial farms but an important limitation is the difficulty of estimating N fixation.

A Whole Farm Nutrient Plan: Nutrient Management for farmers and the environment [1082 KB pdf] UK. This booklet aims to provide guidelines on the aspects of food production that relate to the fertility of the soil and the use of nutrients; - A 10-page check list for various management practices.

Nutrient management strategies on Dutch dairy farms: An empirical analysis. [1582 KB pdf] (2002) PhD Thesis; Ondersteijn, C.J.M.; Wageningen Univ., The Netherlands. 200 pp.; Research presented in this thesis describes all empirical analysis of the relationship between farm and farmer characteristics, the way nutrients are managed on the farm. and the financial consequences, based on the bookkeeping and survey data of specialised dairy farms collected by the EDP-project.

European Journal of Agronomy - Vol 20 (1-2) devoted to on-farm nutrient budget issues.




Bruce T. Bowman, Archivist
Last Updated: Saturday, December 24, 2016 10:11:26 AM