Intercropping Simulation Using the SWAP Model: Development of a 2×1D Algorithm

Victor Meriguetti Pinto,Klaus Reichardt,Jos C Van Dam,Quirijn De Jong Van Lier

doi:10.3390/agriculture9060126

Victor Meriguetti Pinto, Klaus Reichardt + Show 2 more

Open Access

https://doi.org/10.3390/agriculture9060126

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Journal: Agriculture	Publication Date: Jun 16, 2019
Citations: 10	License type: CC BY 4.0

Affiliation: Universidade de São Paulo

Abstract

Intercropping is a common cultivation system in sustainable agriculture, allowing crop diversity and better soil surface exploitation. Simulation of intercropped plants with integrated soil–plant–atmosphere models is a challenging procedure due to the requirement of a second spatial dimension for calculating the soil water lateral flux. Evaluations of more straightforward approaches for intercrop modeling are, therefore, mandatory. An adaptation of the 1D model Soil, Water, Atmosphere and Plant coupled to the World Food Studies (SWAP/WOFOST) to simulate intercropping (SWAP 2×1D) based on solar radiation and water partitioning between plant strips was developed and the outcomes are presented. An application of SWAP 2×1D to maize–soybean (MS) strip intercropping was evaluated against the monocropping maize (M) and soybean (S) simulated with the 1D model SWAP/WOFOST, and a sensitivity analysis of SWAP 2×1D was carried out for the intercropping MS. SWAP 2×1D was able to simulate the radiation interception by both crops in the intercropping MS and also to determine the effect of the radiation attenuation by maize on soybean plants. Intercropped plants presented higher transpiration and resulted in lower soil evaporation when compared to their equivalent monocropping cultivation. A numerical issue involving model instability caused by the simulated lateral water flux in the soil from one strip to the other was solved. The most sensitive plant parameters were those related to the taller plant strips in the intercropping, and soil retention curve parameters were overall all significantly sensitive for the water balance simulation. This implementation of the SWAP model presents an opportunity to simulate strip intercropping with a limited number of parameters, including the partitioning of radiation by a well-validated radiation sharing model and of soil water by simulating the lateral soil water fluxes between strips in the 2×1D environment.

Highlights

Intercropping is a method employed for agricultural sustainability in which two or more plant species are simultaneously cultivated together on the same land [1,2,3] Intercropping systems are favored by a better land occupation, a decrease in the use of agrochemicals, better soil conservation, and yield diversification, among other benefits [4,5,6,7]
Intercropped maize leaf area index (LAI) simulated by SWAP 2×1D was lower than in maize monocropping (Figure 5A) for most of the simulation period
SWAP 2×1D was able to reproduce the reduction in the intercrop LAI compared to the monocropping system, to the behavior of the intercropping

Summary

Introduction

Intercropping is a method employed for agricultural sustainability in which two or more plant species are simultaneously cultivated together on the same land [1,2,3] Intercropping systems are favored by a better land occupation, a decrease in the use of agrochemicals, better soil conservation, and yield diversification, among other benefits [4,5,6,7]. Models for intercropping systems have been developed using several approaches [10] simulating the competition of intercrop plants mainly for water and radiation. Chimonyo [18] pointed out the difficulties of evaluating the root systems and water extraction dynamics of multicropping systems are the main reason for the modeling of the processes belowground to be put aside. Another reason for avoiding the belowground modeling in intercropping is the difficulty of integrating two spatial dimensions for the simulation of the vertical and horizontal soil water fluxes [19]

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Results

Conclusion