Adaptation of the crop model STICS to intercropping. Theoretical basis and parameterisation

Abstract

International audienceGiven the complexity of intercropping systems, models can be especially helpful to analyse them comprehensively. The present work puts forward a modelling approach based on an extension of sole crop models, considering the system to be composed of two species instead of one. The chosen sole crop model is STICS and its adaptation to intercropping relies first on a simplified definition of the complex agronomic system, which is subdivided into three sub-systems: the dominant canopy, and the shaded and sunlit parts of the understorey canopy. It is assumed that no inversion of dominancy occurs during the cycle of the shorter duration crop. Each of the sub-systems is embedded in a different light microclimate, estimated from a radiative balance module, assuming that a simple geometric shape can represent the dominant canopy. This radiative balance pilots the differential behaviours of the sub-systems in terms of growth, LAI dynamics, water and nitrogen uptakes and stress indices. The estimation of the water requirements for both crops relies on light partitioning coupled to a resistive scheme and applied at a daily time-step. In the soil, the horizontal differentiation is neglected in favour of the vertical one. As far as below-ground competition for water and nitrogen is concerned, it is assumed that the interactions between the two root systems result from the influence of the soil on each crop root profile through its water content dynamics. Data sets from three different intercrops, two annual and one perennial systems grown in French Antilles, were used for parameterisation of the model and verification of its consistency. The intercrop-specific modules of the model are described and discussed in comparison with the other existing models

Ecological principles underlying the increase of productivity achieved by cereal-grain legume intercrops in organic farming. A review

“…However, it is difficult to propose fundamentally based and generic crop technical strategies because of the multitude of possible production objectives and hence of combinations of species, varieties, densities, structure and organic manure strategies. This shows the limitations of experiments and the value of modelling multi-species cropping systems (Brisson et al 2004;Corre-Hellou et al 2009;Launay et al 2009). In fact, for a given production objective, modelling would allow the following: (i) the performance and behaviour of intercrops to be evaluated under a wide range of conditions, (ii) to help with the determination of varietal characteristics suited to intercropping (Barillot et al 2012(Barillot et al , 2014a(Barillot et al , 2014b, (iii) to optimize the crop technical protocols according to multiple criteria and (iv) to devise a decision-aid model.…”

Mixing Plant Species in Cropping Systems: Concepts, Tools and Models: A Review

“…Hi-sAFe (Dupraz et al, 2007) and mixtures of herbaceous species (Brisson et al, 2004;Caldwell and Hansen, 1993;Carberry et al, 1996;Tsubo et al,2005), including crop-weed models (Deen et al, 2003), but even fewer for mixtures of trees and crops (Garcia-Barrios and Ong, 2004;Mobbs et al, 1998). Competition models for trees only usually run on a yearly time step, while competition models for crops only, or crops and trees, run on a daily time step.…”

“…In the second group of models, a first level of spatial heterogeneity is introduced through discretisation of the system into some linear or circular areas between which flows of mass or energy occur. Some intercropping models such as STICS-CA (Brisson et al, 2004) and most tree belt-crop models (Huth et al, 2003) follow that approach. The WaNuLCas model (Van Noordwijk and Lusiana, 1998) includes 4 zones of tree-crop interactions with decreasing intensity.…”

Assessment of Root System Dynamics of Species Grown in Mixtures under Field Conditions using Herbicide Injection and 15N Natural Abundance Methods: A Case Study with Pea, Barley and Mustard

“…This experimental approach can be also helpful to improve the simulation of root growth in mixtures with process-oriented models. Several models have been developed to simulate competition for various resources during weed competition or in intercropping systems (Ball and Shaffer, 1993;Brisson et al, 2004;Caldwell, 1995;Kiniry et al, 1992). These are based on existing crop simulation models used for sole crops.…”