Managing nitrogen fertility in Mediterranean agricultural systems is complex due to their distinct climate and soil characteristics. High temperatures and oxygen levels during the growing season lead to low soil organic matter, while cold and rainy winters increase nutrient leaching, particularly of nitrogen. These conditions create challenges in synchronizing nitrogen availability with crop demand, especially in organic systems where external inputs are limited.
To address these issues, Pilot Study 13 investigates innovative, agroecological nitrogen management practices using legumes as fertility-building crops. Conducted within the Biosyst Long-Term Agronomic Experiment (LTE) in Perugia, Italy—ongoing since 1996—this study compares an organic legume-based system (ORG) with a conventional low-input system (CON). Strategies tested include cover cropping (CC) with legumes before spring crops, and temporary intercropping (TIC) of legumes with winter cereals to enhance nitrogen availability and reduce reliance on external inputs.
Specific objectives are:
- Assess the impact on soil fertility of legume-rich cropping systems (ORG) compared to legume-poor systems (CON).
- Explore the relationship between cash crop yields and the above-ground biomass of different legumes used in CC and TIC.
- Estimate a simple relationship between legume biomass (from CC or TIC) and the yield, grain quality, and total biomass of the subsequent cash crops.
- Quantify the nitrogen replacement value of legumes used as fertility-building crops.