1. General Model Information

Name: PARCH: Predicting Arable Resource Capture in Hostile environments

Acronym: PARCH

Contact:

Author(s):

(1):
Physiology and Environmental Science
University of Nottingham,
Sutton Bonington,
LE12 5RD, UK

(2):
School of Agriculture Food and Environment,
Cranfield University,
Silsoe,
MK45 4DT, UK

Abstract:

The PARCH model consists of 4 main sub-models:

• Crop Model
• Soil Water Balance
• Soil Nitrogen Model
• Soil Phosphorus Model

Although the model is general it has been developed for applications in the dry tropics and, to emphasise this, the model has the acronym PARCH (Predicting Arable Resource Capture in Hostile environments). Therefore considerable attention has been paid to the crop's water supply. A multi-layer water balance simulation is a key component of the model. This simulates vertical redistribution of soil water, infiltration, drainage and soil evaporation.

Within PARCH the influence of soil nitrogen supply on crop growth can be simulated. Nitrate is distributed vertically between the soil profile layers from where it is available for both leaching and crop uptake. The mineralisation and immobilisation of nitrogen by soil organic matter is modelled using approaches derived from the CERES models (Jones & Kiniry 1986). These account for the influence of soil moisture, temperature, and C:N ratio. Crop uptake is controlled by nitrogen availability within the soil, crop root distribution and crop nitrogen content. The crops response to nitrogen deficiency is simulated using a nitrogen stress index similar in principle to the water stress index. The model allows for the addition of nitrogen, either in the form of mineral fertiliser, or as an organic manure. In the case of manures it is necessary to define the characteristics of the manure.
Limitation by phosphate is also included although this is considered in less detail.

The model has been calibrated for four cultivars, CSH-6, CSH-8, M-35-1, and DK55 using data from 17 experiments selected from a larger dataset of 68 yield and 59 total biomass observations. The calibrated model has been tested against the remaining 51 yield and 42 biomass observations. Overall there is good agreement between the model and observation with the model accounting for >80% of the observed variation in crop yield and biomass with a residual standard deviation of 0.53 tha-1 for yield and 1.66 tha-1 for biomass The model shows no significant bias in prediction although there is a tendancy to underpredict yield. The model undoubtedly requires further testing of the model, in particular for situations of low yield.

A version of the model for rainwater harvesting has been developed at Newcastle University by Damion Young and co-workers: PARCHED-THIRST

A combination of the HYBRID tree/forest model with PARCH, named HyPAR (v.2.7), was developed by D. Mobbs et al. at the Institute of Terrestrial Ecology, UK, to model a simple, theoretical agroforestry system.

Sources of abstract:
Environmental Modelling at Nottingham University
Manual/User Guide/ Tutorial Download Page

II. Technical Information

II.1 Executables:

II.2 Source-code:

II.3 Manuals:

II.4 Data:

III. Mathematical Information

III.1 Mathematics

III.2 Quantities

III.2.1 Input

III.2.2 Output

IV. References