scholarly journals Correction to: Supporting Student System Modelling Practice Through Curriculum and Technology Design

2021 ◽  
Author(s):  
Tom Bielik ◽  
Lynn Stephens ◽  
Cynthia McIntyre ◽  
Daniel Damelin ◽  
Joseph S. Krajcik
Keyword(s):  
System Modelling ◽  
Technology Design

Quantifying the value proposition for white clover persistence on a New Zealand summer-dry hill-country farm

2020 ◽  
Vol 82 ◽  
pp. 199-209
Author(s):  
Mike B. Dodd ◽  
Katherine N. Tozer ◽  
Iris Vogeler ◽  
Rose Greenfield ◽  
David R. Stevens ◽  
...  
Keyword(s):  
White Clover ◽  
Net Present Value ◽  
Moisture Stress ◽  
Simulation Modelling ◽  
Low Fertility ◽  
System Modelling ◽  
Value Proposition ◽  
Hill Country ◽  
The North ◽  
Farm System

The improvement in forage quality and quantity of summer-dry hill country pasture resulting from the introduction of clover is well recognised. However, ensuring the persistence of the commonly availablecultivars is challenging, in the face of seasonal moisture stress, intensive grazing, competition from established well-adapted pasture species, low soil fertility and low soil pH – conditions typical of the East Coast of the North Island. Here we quantify the value proposition associated with the introduction of white clover into a case study on a Gisborne sheep and beef farm, using a six-step process. A topographically explicit approach is taken, using an understanding of the underlying spatial variability, based on a combination of soil and pasture measurements, APSIM simulation modelling of pasture growth and farm system modelling of enterprise performance. We show that from a baseline of a typical low-fertility, diverse species hill country pasture, white clover introduction can increase spring and summer forage consumption by 17%, enabling inclusion of an additional 6-month bull finishing enterprise generating a 32% greater carcass weight production and leading to a 49% improvement in farm system EBIT. This represents a positive net present value of over $360,000 for the original investment in white clover establishment into existing pastures.

Constrained Time-Varying System Modelling

1988 ◽  
Author(s):  
Jerome R. Bellegarda ◽  
David C. Farden
Keyword(s):  
System Modelling ◽  
Time Varying
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