Introduction to N-CyCLES (Nutrient Cycling: Crops, Livestock, Environment and Soil)

Economic and Environmental Optimization of Whole-Farm Balance: N-CyCLE.

The N-CyCLE spreadsheet was developed through a collaborative efforts between researchers at the "Département des Sciences Animales, Université Laval, Québec" and the Department of Dairy Science, University of Wisconsin-Madison.
  • As an analytical decision-making tool, N-CyCLES (Nutrient-Cycling Crops-Livestock-Environment-Soil), was developed using the linear programming feature of Microsoft Excel to optimize feeding program, cropping system and manure allocation as a single unit of management within a farm.

  • In N-CyCLE v5, nutritional requirements for 5 feeding groups can be met with 10 home-grown feeds and/or 15 purchased feeds. Nutrients needed for any of 5 different crop rotations to apply in 5 different land units (set of fields with similar soil characteristics) can be met with manure nutrients and (or) 4 purchased fertilizers.

  • The model maximizes income, minimizes P balance, or minimizes N balance of the whole-farm by choosing the mix of home-grown feed and purchased feed to meet nutritional requirements of each pre-defined animal group, selecting a crop rotation for each land unit, and allocating manure and fertilizers as needed for each rotation.

  • Program outputs include farm net income, whole-farm N and P balances, and other minerals (K, Cl, Na and S), a crop fertilization plan for each land unit, diet composition for each animal group, and more.

  • Click here to download N-CyCLE v5 (1.06 MB Excel File).

More about N-CyCLES


N-CyCLES is a research and education decision-making tool that allows users to analyze the economic implications and alternative management options of reducing whole-farm balance of nitrogen, phosphorus and potassium.

Fig1-N-CyCLES.jpg
Overview of N-CyCLES (Nutrient-Cycling, Crops, Livestock, Environement and Soils) describing resources whose allocation are subject to simultaneous optimization, the N and P imports and exports (solid lines) to establish balance across the boundary of the livestock-crop component of a farm (dotted line), and cycling within the boundary (dashed line).


What does it do? N-CyLCES allows the user to determine the balance (flow across farm boundary) and the cycling (flow within farm boundary) of nutrients (N, P, K and Cl, Na, and S) assuming that herd nutrition, manure handling and crop fertilization is a SINGLE UNIT OF MANAGEMENT rather than three separate and loosely associated areas of decision-making (see Figure below).
You can use the model to maximize net farm income, minimize P balance, or minimize N balance of the whole-farm. To describe a farm you will be asked to input farm-specific descriptors under six main categories:
  1. herd description including five animal groups, each with its specific characteristics,
  2. economic inputs,
  3. ration composition,
  4. feed inputs,
  5. manure and fertilizers, and
  6. crops and rotations including five land units, each with its specific characteristics.
Given your objective, the program will seek a set of management practices that, among others, meet the following constraints simultaneously:
  1. rations of each animal group must be formulated to meet nutritional requirement of the herd, but not excess a user-defined excess in nitrogen or phosphorus;
  2. crop fertilization plan must make the best allocation of manure and purchased fertilizer to meet UW- recommendation for fertilization of crops according to soil P test (and other characteristics) but within a user-defined maximum excess application.
By comparing program outputs under each objective, you will be able:
  • to estimate the average cost of reducing whole-farm nutrient balance and
  • to determine the best management practices associated with a given objective.
What N-CyCLES does not do... This version of N-CyCLES does not allow the user to explore "what if" scenarios. However we plan on creating this option in the next version.

What are some of the main assumptions built in the model? In essence, N-CyCLE assumes that a producer follows the current (NRC) guidelines to meet nutritional requirement of the herd and follows the UW recommendations for N,P,K crop fertilization. In addition the model assumes that crop fertilization plan include credits for manure nutrients. You can use N-CyCLE to estimate cost-savings resulting from reducing excess dietary protein or phosphorus by setting high minimum nutrient concentration in the diet of any group of animal on the farm.

What you need to be aware of as you learn to use N-CyCLES... In a linear programming model, calculus is used to derive the maximum or minimum of an objective function under a number of constraints. In essence, N-CyCLES solver gives us the "EXTREMES" in balances associated management practices. The feasibility of the proposed solutions may or may not be realistic. However careful interpretation of extremes will allow the user to determine the main trends in management practices associated with a particular objective. In addition advance users will be able to modify the constraints to explore conditions that represent "COMPROMISES."



Keywords:Whole-Farm Nutrient Balance Software: N-CyCLE   Doc ID:60349
Owner:Michel W.Group:DS Dairy Nutrient Main
Created:2016-02-01 19:27 CSTUpdated:2016-02-01 19:44 CST
Sites:DS Dairy Nutrient Main
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