Effects of crop species on soil functions and soil multifunctionality are species-specific

Soil multifunctionality is essential for sustainable agriculture, as soils
not only need to support crop growth but also maintain soil biodiversity
and sustain other critical ecosystem functions. However, the focus of
intensive agriculture on maximizing crop yield has reduced the
multifunctional capacity of soil. Here, we examined how crop species can
be used to enhance individual soil functions and multifunctionality. We
grew twelve common crop species, organized into four groups: legumes
(broad bean, green bean, soybean), crucifers (broccoli, Chinese cabbage,
cabbage), cereals (wheat, maize, oat), and a vegetable mix (eggplant,
chili pepper, leek) under controlled conditions. We measured how crop
species affected individual soil functions (plant biomass production,
nutrient cycling, carbon storage, and disease suppressiveness), soil
multifunctionality, and the balance in the performance of these functions,
expressed as evenness of functionality. We found that crop species have
specific impacts on soil functions and multifunctionality. Broad bean
enhanced multifunctionality by enhancing biomass production and nutrient
cycling, while Chinese cabbage and broccoli increased multifunctionality
via disease suppressiveness and carbon storage functions. There was a
positive correlation between multifunctionality and the evenness of
functionality, suggesting that crops enhanced multiple soil functions
simultaneously. We conclude that no single crop species consistently
increased all soil functions. However, most crop species contributed to
soil multifunctionality by stimulating either a balanced combination of
nutrient and biomass production-related functions or disease and carbon
storage-related functions. Therefore, enhancing soil multifunctionality in
agricultural systems may require selecting crop species that are
complementary in their effects on soil functions. We propose that
optimizing the multifunctionality of entire crop rotations instead of
focusing only on yield offers a novel perspective for enhancing the
sustainability of food production. Such a multifunctional perspective on
crop rotations may also be applicable to intercropping, and both will
require attention to keep the agricultural system diversified.