[Effects of different genotypes soybean and maize intercropping on soil phosphorus fractions and crop phosphorus uptake].

Abstract

Reasonable soybean-maize intercropping mode can effectively promote soil phosphorus turnover and crop phosphorus absorption, and reduce phosphorus fertilizer input. To optimize phosphorus (P)-use efficiency in soybean/maize intercropping system, we intercropped two genotypes of soybean with maize to investigate the rhizosphere processes and mechanisms underlying soil biological P fractions and crop P uptake. The results showed that intercropping significantly depleted the rhizosphere soluble inorganic P (CaCl₂-P) content in soybean genotype Yuechun 03-3, without impact on the P fractions in the rhizosphere of soybean Essex. Similarly, intercropping significantly increased biomass and P uptake of soybean genotype Yuechun 03-3 by 42.2% and 46.9%, respectively, compared to monoculture. However, it did not affect P uptake and biomass of soybean Essex and maize. Intercropping significantly increased both the total root length and the quantity of root exudates in Yuechun 03-3 by 19.7% and 138.1%, respectively. There was a significant positive correlation between P uptake and total root length in Yuechun 03-3, while a significant negative correlation between soluble inorganic P content and P uptake. In summary, intercropping of soybean and maize exhibited noticeable genotype differences in its impact on soil P fractions and crop P uptake. Intercropping has the potential to improve soybean P uptake and rhizosphere P turnover, mainly by increasing root length and root exudates of P-efficient genotype. The study would provide scientific evidence for optimizing the pairing of soybean and maize varieties in intercropping systems, thereby enhancing phosphorus utilization efficiency and reducing fertilizer inputs.