Simulating Carbon Dynamics in Orchard Systems Using the Century Model.

Orchard systems can be an important sink for atmospheric C. Fruit trees grow over several decades fixing a significant amount of atmospheric CO₂, incorporating it as biomass. Concurrently, management practices of the orchard floor can help to increase soil organic carbon (SOC) levels. Specifically, the use of cover crops (e.g. legumes, grasses or mixes) together with no-tillage can significantly raise SOC stocks in these agroecosystems. The use of ecological models such as Century is an interesting and viable option for predicting and testing management practices on C dynamics in orchard systems. The Century model was originally developed to simulate soil organic matter dynamics on the Great Plains grasslands of North America and has several submodels to predict net primary production, nitrogen mineralization and soil organic matter dynamics. Century has been widely applied to grasslands, perennial forests, savanna systems, and annual cropping systems. We present a new modification of the Century model for simulating C and N dynamics in orchard systems with special attention to the relationship between fruit trees and cover crops.