Observation-constrained assessment of long-term cropland productivity trends and drivers at the global scale

Abstract

The cropland ecosystem is closely linked to global food security and carbon budget dynamics. Understanding the trends and drivers of cropland gross primary productivity (GPP) is essential for evaluating potential agricultural yields and for formulating effective adaptation and even mitigation strategies. However, existing GPP assessments have largely focused on natural ecosystems, with limited attention paid to the long-term evolution of cropland productivity and its attribution. Our study presents a global analysis of cropland GPP from 1982 to 2016, with an attribution analysis constrained by multi-source observational datasets. Findings reveal a notable increase in cropland GPP, averaging 10.4 Pg C yr −1 , which accounts for 8.6% of global GPP and contributes 18.8% to its overall rise, only followed by evergreen broadleaf forests. Since 2000, croplands have emerged as the largest contributor to global GPP gains (22.5%). Attribution analysis indicates that vegetation structural changes explain approximately 43% of the cropland GPP increase, while climate variability imposes a negative −9% effect. The remaining increase is dominated by residual term that combines rising atmospheric CO 2 , intensified management, crop breeding and differences among GPP products. By further quantifying the plant-assisted weathering efficiency (PAWE), we show that the biological enhancement of weathering rises nonlinearly with productivity, yielding a 2.5–4.5-fold biological amplification across major breadbaskets. Realized carbon removal nonetheless remains contingent on mineral supply, soil chemistry, hydrology, and alkalinity export.