Quantifying intercropping water advantages: A novel cosine similarity framework linking root water uptake patterns to productivity

Abstract

Context

Intercropping modifies soil water dynamics through complex interspecific interactions crucial for enhancing water productivity. However, quantitative assessment of its productivity based on underlying water utilization processes remains a critical gap. Thus, novel methodologies are needed to evaluate water use patterns-productivity relationships in agricultural systems with interactions.

Objective

This study aimed to develop and validate a novel quantitative framework, using cosine similarity metrics derived from stable isotope data, to evaluate water use complementarity and competition in different intercropping systems.

Methods

Stable isotope combined with the MixSIAR Bayesian mixing model quantified root water uptake (RWU) and differentiated water use strategies. The Relative Difference in RWU (RDRWU) was introduced to quantify water deficits or advantages in intercropping compared to monocultures. Four cosine similarity metrics, θ_CS, RDSW_CS, RWU_CS, and RDRWU_CS, were proposed linking to water productivity.

Results and conclusions

The cosine similarity metric based on RDRWU (RDRWU_CS) demonstrated the strongest linear relationship with water productivity, proving to be a robust and effective indicator for linking intercropping water use complementarity and water productivity.

Significance

The stable isotope method linked with cosine similarity metrics establishes a novel quantitative framework for water utilization patterns in intercropping. They hold significant potential for simulating and optimizing water productivity across irrigation regimes.