# Presentation: 939313

## Optimization of Whole Farm Nutrient Balance:N-CyCLE

- Michel A. Wattiaux1
- 1Department of Dairy Science, UW-Madison
- wattiaux@wisc.edu

**Notes:**
This presentation will be about integration of knowledge in various disciplines to help researchers, consultants and students gain a vision of the flow and balance of nutrient throughout a dairy farm as if they were producers themselves.

## Background

- Planning nutrient management:
- What are the options for producers to maximize export of nutrients in economically valuable products while:
- minimizing imports of nutrients onto the farm, and
- minimizing environmental risks ?
- Holistic approach:
- Need for integrated feeding, cropping and manure management strategies

**Notes:**
One way to address environmental management of farm starts with asking the question of...

.. Answering this question demand a “holistic” approach.  In other words, any proposed BMPs must integrate at least the feeding program with the cropping strategies on the farm as one unit of management with manure nutrient management as a key link between the two. 

## N-CyCLE

- Tool name:
- 	  **N****utrient-****Cy****cling ****C****rops ****L****ivestock ****E****nvironment**
- Developers:
- Michel Wattiaux*, Doris Pellerin**, Edith Chabornneau**, Sally A. Flis*, Vinicius R. Moreira*
- Stage of development:
- Not released
- http://dairynutrient.wisc.edu

- * University of Wisconsin-Madison
- ** Université de Laval, Quebèc, CN

**Notes:**
The tool that we have begun developing two years ago is called N-CyCLE, which stands for 

Contributors of the development of the tool includes...

It has not been released but will be made available as a free to download spreadsheet at

## Outline

- N-CyCLE v.1.0
- Model Objectives and Description
- Strengths and Limitations
- N-CyCLE v.2.0
- Conceptual approach of the model
- N-CyCLE v.2.5
- Inputs, objective functions and constraints, and outputs
- Example
- Vision for the future

**Notes:**
We’ll start with a short history of the model and a short description of the first version of the model
Then, we’ll proceed to discussing the conceptual approach that was built in the second version of the model
..  which remains current
Version 2.5 is the latest version that I will describe in further details here
..  And finally, we will conclude and try to provide you with a vision for the future.

## N-CyCLE v.1.0

## A Simple Model to  Optimize Feeding Program and Crop Rotation of Dairy Farms

- M. A. Wattiaux. 2001. Proc. Nutr. Mgt Conf Pp 54-69. 3rd Babcock Institute Tech.           Workshop, University of Wisconsin-Madison

**Notes:**
The first version of the model was presented at a conference here in Madison a couple of years ago as a simple model to optimize feeding program and crop rotation of dairy farms. 
The model was in essence an extented leastcost ration formulation software which picked the best combination of crops to grown on a farm given a land base and the type and amount of purchased feed required to formulate rations that meet nutritional requirement of the herd. In addition, N-CyCLE 1 estimated manure nutrient production and compared nutrient requirement of the proposed crops to nutrient availability in manure. 

## Strengths and Limitations of v.1.0

- The model was a first successful step in moving from balancing rations to balancing home-grown and purchased nutrients as one unit of management
- The model objective was to minimize purchased feeds; thus an implicit model assumption was that home-grown feeds were cheaper and were less environmentally threatening than purchased feed
- The model worked as if the farm was one field and one animal group
- The model worked on a discrete-year basis (no 2nd and 3rd year nutrient credit)
- The model did not assess economic impact of management decisions in response to changes motivated by excess nutrient imports and related environmental concerns.

**Notes:**
The first attempts at using the model to predict the optimal feeding and cropping system given different farm situations were very encouraging.  The model outputs were realistic.
However the model has a number of limitations.  For example,

## N-CyCLE v.2.0

## Modeling Nitrogen Cycling and Balance

**Notes:**
Any tool that arguably describes the cycling of nutrients on farm must include the major pools and flow of these nutrients in the systems. 
It doesn’t matter where you start, but conceptually, N, P and K cycles around the farm from the crops to the feed storage units then to the herd than to the manure and back to the crop.
The maximization of the efficiency of nutrient cycling is key to farm profitability and key to reducing environmental risks because in most of our farming conditions in the US., maximization of nutrient efficiency on farm, can be brought about by reduction of unnecessary import on the farm. AND THUS THE NECCESSITY TO STUDY BOTH  THE BALANCE AND THE CYCLING OF NUTRIENT AT THE SAME TIME
Meeting these two objectives should lead to a minimization of what is very difficult to measure directly: the losses of nutrient to the atmosphere and to water resources.

## Modeling Nitrogen Cycling and Balance

- Feeds
- Bedding

- Fertilizer

- Purchased / Imported
- Inputs

- Manure

- Milk
- Animal

- Crops

- Sold / Exported
- Outputs

**Notes:**
Although complementary to each other, estimating the balance is appear to be a much easier exercise that estimating the cycling of nutrient.  To develop a farm balance, one can look at the farm as a black box and ignore all internal interactions as long as one has access to amount of nutrient containing products that have been purchased/imported and the nutrient containing products that were sold/exported from the farm.

In the case of P, economic valuable inputs and outputs suffice to describe the overall balance of the farm.  But in the case of N, the biological N fixation and the atmospheric deposition of N with rain complicates the establishment of Nitrogen Balance on the farm.
Trying to minimize whole farm N balance would lead to different recommendations is BNF is included or not the calculation of the whole farm balance.

## N-CyCLE Conceptual Framework

**Notes:**
So, given this conceptual framework, we constructed N-CyCLE 2.0 As a tool that “looks at optimizing the flow of N and P in as many as five groups of animals in the herd and five groups of fields (referred to as land management unit) in order to minimize the overall  balance on the farm.  As indicated earlier, we felt we needed to explore the impact of including or excluding BNF in the balance and create the option of letting the producer export or not some of the manure produced by the herd. 
Another major difference between N CyCLE 1 and N-CyCLE 2 is the fact that here, we optimize the whole farm balance as opposed to the nutrition of the herd.

## N-CyCLE 2.0 and Above

- Purposes:
- To describe Nitrogen, Phosphorus and Potassium (pools), flows and balances across units of management within a farm
- Optimization of the whole-farm model:
- Net income (maximization)
- P balance (minimization)
- N balance (minimization)
- Research and Educational tool:
- Teaching, Research, Extension
- Private consultants
- Documentation: in progress

## N-CyCLE v.2.0 and Above

- Developed on Microsoft® Excel® using:
*Solver Function*  that solves linear and integer models by the *Simplex* algorithm
- Five worksheets (N-CyCLE v.2.5):
- Four Input sheets
- Herd and Rations
- Feed
- Land Units and Crop Rotations
- Manure and Fertilizers
- Optimization sheet
- Output sheet

## Current versionN-CyCLE v.2.5

## Herd Description

## Herd Description

-  Herd Structure
-  Herd Production
-  Ration Composition (5 groups)
-  Milk price

- INPUTS

## Herd

- Herd Structure:
- Total # cows
- Mature body weight
- Calving interval
- Culling rate
- Mortality rate (heifers<1yr)
- Age at first calving

- INPUTS

## Herd

- Herd Production:
- Peak milk production, Kg/d
- Fat, %
- Protein, %
- Other solids, %
- Management groups (n **≤** 5):
- 1 or 2 lactating, 1 dry, and 2 heifer groups
- 1 or 2 lactating, 2 dry, and 1 heifer groups
- 3 lactating and 2 heifer groups
- Milk Price

- INPUTS

## Herd

- Ration Composition:
- Fiber/Energy
- Neutral Detergent Fiber (NDF)
- Forage NDF
- Non Fiber Carbohydrates (NFC)
- Nitrogen
- Rumen Undegraded Protein (RUP)
- Rumen Degraded Protein (RDP)
- Minerals
- P
- Ca
- (K + Na) – (Cl + S)

- INPUTS

## Feed (and Bedding) Inputs

- Feed Composition and Prices (n **≤** 20):
- Home-grown feed (and bedding) defined by crop rotation (n **≤** 10)
- Corn silage, alfalfa silage, grass legume mix, grass silage
- Corn stover, straw
- Corn grain, wheat (barley),
- Soybean (for roasting)
- Purchased feeds (n **≤** 10)
- Energy sources (e.g. CaFat, WCS)
- By-products (e.g. CoDi, CGM)
- RUP and RDP sources (e.g. Sbex, Sbsol, Urea)
- Minerals (e.g. CaCO3, Ca2PO4)

- INPUTS

## Land Units and Crop Rotations

- Land Units (n **≤** 5):
-  Areas
-  (Distance from facilities)
- Crop rotations (n **≤** 5):
-  User-defined (CCC; SCC; CCAAA; CCCSCAAA; CCCSWAAA)
-  Yield of each crop in each rotation
-  N, P, K requirements
- Adjusted for Legume credits
- Soil test P
-  Cost of production ($/ha)

- INPUTS

## Manure (N) Management

- Type of Manure (Liquid & Solid)
-  Type of Storage Facility
-  Method of Manure Spreading
-  Costs Related to Manure Management

- INPUTS

## Manure (N) Management

- Type of Manure & Storage Facility:
- Liquid
- Daily Haul
- Liquid Storage:
- Covered
- Uncov. Top Loaded
- Uncov. Bottom Loaded
- Solid
- Bedded Pack
- Stack
- Compost

- INPUTS

## Manure (N) Management

- Method of Manure Spreading:
- Liquid:
- Broadcast, no incorporation
- Broadcast, incorporated within 2h
- Band spreading
- Injection in open slots
- Knifing in
- Solid:
- Box spreader, incorporated within 2h
- Box spreader, no incorporation

- INPUTS

## Manure Management

- Cost Related to Manure Management:
- Cost of production ($/t 0)
- Cost for exporting ($/t 100)
- Cost of spreading (distance from storage)

- INPUTS

## Fertilizers

- Purchased Fertilizers (n=4):
- User-defined (e.g.: 18-46-0; 27-0-0; 0-46-0; 0-0-60)
- Nutrient contents (N, P & K)
- Market prices
- Variable spreading costs per Land Unit

- INPUTS

## Objective Functions

- To find the best combination of:
- Rotations for each of the pre-defined land units,
- Manure allocation and fertilizer application,
- Diets ingredient mix for each pre-defined group of animals,
- with the objective to either:
- maximize net income ($), or
- minimize whole farm phosphorus balance (kg/yr), or
- minimize whole farm nitrogen balance (kg/yr)

- Optimization worksheet

## Land / Crop Constraints 

- Land Use:
- (Land available - cropped area) **≥** 0 (i.e., crop required land only)
- 						       =  0 (i.e., crop all available land)
- 						            crop sold **≤** user defined limit
- Crop rotation Assignment:
- If binary constraint: one rotation per field
- If no binary constraint: fractional rotation per field is allowed
- Crop requirements:
- 0 **≤** (N, P, K supplied - N,P,K needed) **≥**  Legal limits
- 							      **≥**  Agronomic limits

- Optimization worksheet

## Feed / Herd /Manure Constraints

- Manure produced - manure used – (manure exported) = 0
- Nutritional Need (per animal group basis)
-        Min < 	Total amount of DM					< Max
-        Min < 	NDF, NFC, Absorbable P, Absorbable Ca	< Max
-        Min <	FNDF, RUP, RDP, and K				--------
-        ------	CP							< Max
- Adjustable Losses
- Home-grown (Field and storage losses)
- Purchased feed (Shrinkage losses)
- Adjustable feed refusals

|  |
| --- |

- Optimization worksheet

## Outputs 

- Main Outputs:
- Income ($)
- P balance (kg/yr)
- N balance (kg/yr)
- Optimal rotation:
- w/ binary constraint: One of the five rotation for each land unit
- w/o binary constraint: Acres of each selected crop as a fraction of the cropland of the farm

## Model Outputs

- Crop Fertilization plan:
- Type and amount of purchased fertilizer and manure to apply on each land unit
- Amount of manure to export (if allowed)
- Feeding program:
- Type and amount of purchased feed and home-grown feed to offer each animal group
- Amount of home grown feed to sell (if allowed)

## N-CyCLE 2.5Example

## Scenario

- 192.4 ha (50; 50; 50; 42.4 ha) with high soil P test
- 190-cow herd producing 10,000kg/lactation
- Hi group
- Lo group
- Far-off
- Pre-fresh
- 153 Heifers
- Rotations
- CS-CG-CG
- Soybean-CS-CG
- CS-CG-Alfalfa-Alfalfa-Alfalfa
- CS-CG-CS-Soybean-CG-Alfalfa-Alfalfa-Alfalfa
- CS-CG-CS-Soybean-Wheat-Alfalfa-Alfalfa-Alfalfa

## {

**N-CyCLE Output**
-  Farm description
-  Milk output
-  Economics
-  Balances

## {

**N-CyCLE Output**
-  Rations:
-  Feeds
-  Nutrient Composition

## {

**N-CyCLE Output**
- Allocations:
-      Rotation                Fertilizer                Manure

## Net income $ when maximizing Net income, minimizing P or N balances

- Lost income
- When P
- was minimized:
- = $95 / kg
- When N
- was minimized:
- = $25 / kg

## Income and Balances When Maximizing Income or Minimizing Balances

- Income, $

- P Balance, kg

- N Balance*, kg

- Maximize
- Income, $

- Minimize
- P Balance, kg

- Minimize
- N Balance, kg

- 76,000

- 4,158

- 32,211

- 30,303

- 3,676

- 34,710

- 33,199

- 5,798

- 30,509

- Objective Function

- * Manure export not allowed

## Rotations and Purchased Feed when Maximizing Net income, Minimizing P and N balances

- Maximizing Net income
- CCC; CCC; CCC; CCAAA
- Sbw, Sbsol, CGM, CoDi, Urea, CaFat, Ca2PO4, CaCO3, (298.4 ton/year)
- Minimizing P balance
- CCC; CCC; CCC; CCCSCAAA
- Sbex, Sbsol, CGM, Soyhulls, Cotton, Urea, CaFat, Ca2PO4 (424.8 ton/year)
- Minimizing N balance
- CCC; CCC; CCC; CCAAA
- Sbex, Sbsol, CGM, Soyhulls, Cotton, Wheat, Straw, Urea, CaFat, Ca2PO4 (551.5 ton/year)

## Summary

- N-CyCLE v.2.5 provides an economic evaluation of management practices including those related to “environmental management” of farms
- What is the cost/benefit of reducing N balance?
- What is the cost/benefit of reduction P balance?
- N-CyCLE v.2.5 provides a mean to compare current practices to an “optimal” set of “Best Management Practices”

## Summary and (near) Future

- N-Cycle allows:
- Land use studies
- Land requirement for different crop rotation systems
- Land requirement for farm of increasing animal density
- Sensitivity analyses
- Change in feed or fertilizer market prices on feeding and cropping strategies
- Change in BMP to maintain high N/P ratio in manure
- Forage quality
- Quantify losses and soil build-up
- Long term change in Soil test P
- Ammonia-N losses
- Evaluation of the economic impact of regulatory policies
- Limit P balance
- Limit Ammonia Loss

## Limitations

- Input intensive/knowledge intensive
- Not (yet) user friendly
- Limited usage
- Require additional validation
- Inherent limitation of Linear programming
- “Everything” is linear
- How can economies of scale be built in a linear programming?
- Incomplete estimates of environmental losses
- N leaching
- “Garbage in, Garbage out”

## Nutrient - Cycling Crops - Livestock - Environment