Root Parameters Show How Management Alters Resource Distribution and Soil Quality in Conventional and Low-Input...

Area of Science:

• Agricultural Science
• Soil Science
• Agronomy

Background:

• Low-external input (LEI) diversified cropping systems are often more efficient than conventional systems, but the underlying plant-soil relations require elucidation.
• Understanding how management practices influence soil quality and root responses is crucial for optimizing agricultural sustainability.

Purpose of the Study:

• To investigate the links between management practices, soil quality indicators (SQIs), and root responses in long-term LEI and conventional cropping systems.
• To determine if soil organic matter inputs explain observed differences in soil quality and root growth.

Main Methods:

• A long-term cropping systems experiment in Iowa comparing 2-year conventional and 3- & 4-year LEI rotations.
• Measurement of soil quality indicators (particulate organic matter carbon, potentially mineralizable nitrogen) and root characteristics at two depths across crop phases.
• Construction of a carbon budget to assess organic carbon inputs.

Main Results:

• LEI systems exhibited greater and more evenly distributed stocks of particulate organic matter carbon (POM-C) and potentially mineralizable nitrogen (PMN) compared to conventional systems.
• While organic carbon inputs were higher in LEI systems, they did not fully account for the observed differences in SQIs.
• Biochemical SQIs were more stratified in conventional soils, with lower POM-C and PMN in the 10-20 cm depth compared to LEI systems.
• Maize root length density was concentrated in the top 10 cm in conventional plots but evenly distributed in LEI systems.

Conclusions:

• The plow-down of organic amendments and manures in LEI systems significantly improved soil quality indicators and extended root distribution.
• Enhanced resource distribution, not just abundance, is a key factor in the functional efficiency of LEI cropping systems.
• LEI systems can maintain or exceed conventional yields with fewer inputs due to improved soil function and resource utilization.