Most agricultural soils in Manitoba and across the globe have lost soil organic carbon since agricultural production was initiated. A greater understanding is needed of the potential for various agricultural practices in various locations to rebuild the soil organic carbon. Soil scientists believe there is significant potential for agriculture to remove carbon dioxide from the atmosphere and sequester it as soil organic matter, leading to reduced atmospheric carbon dioxide levels while also improving the productivity of soils.
Monitoring for soil carbon relates directly to the agricultural productivity, or health, of the soil. Soil organic carbon levels are correlated to a number of factors related to productive soils, including aggregate stability, water holding capacity, water infiltration rate, nutrient exchange, and micobial activity. These factors usually increase if soil organic carbon levels increase.
This project will attempt to provide a demonstration of the impact of certain grazing practices on soil organic carbon over time by employing the Soil Carbon Coalition approach to soil carbon monitoring (Donovan. 2013. Measuring soil carbon change http://soilcarboncoalition.org/files/MeasuringSoilCarbonChange.pdf). This approach is being adopted by a number of cattle farmers in western Manitoba and after 3 years of monitoring some farmers have reported observing large increases in soil carbon.
Two distinct grazing systems have been established at the Brookdale Farm for the "Planned Grazing Demonstration Project" and the soil carbon will also be monitored in conjunction with that project. The planned grazing system employs a documented plan at the beginning of the season to guide when and where cattle will be moved as the grazing season progresses. Cattle are moved quickly during fast growth in early spring and slower during slowed growth in late summer and forage plants are observed to ensure full recover before they are grazed a second time. In contrast, the continuous grazing system allows the cattle to move throughout the same number of acres freely.