High carbon content in soil tends to result in better crop yields and greater resilience to weather-related crop failure. In regions like sub-Saharan Africa, this important information can be challenging to get, however, due to the high cost and complexity of measuring carbon in soil.

To assist with providing this data, Michigan State University researchers tested a device that inexpensively provides fast, accurate soil carbon measurements. The findings have been published in the Soil Science Society of America Journal.

"Soil organic carbon varies at fine scales across fields. Farmers require detailed information to better understand how crops will respond to nutrients and water management. Both processes are regulated by soil organic carbon," said researcher Sieglinde Snapp.

She explained that farm sizes in this region are typically under one hectare (about 2.5 acres). Known as Researchers calibrated data collected by reflectance to lab soil samples. The application developed provides accurate information to farmers in real time. Source: Regis ChikowoResearchers calibrated data collected by reflectance to lab soil samples. The application developed provides accurate information to farmers in real time. Source: Regis Chikowosmallholder farms, they are often divided even more across many smaller fields. Soil characteristics vary greatly here and fertility is quite sensitive to management, and farms are managed with limited resources and often have degraded soils. “This can cause unstable food supplies in the region. Restoring the soils' productivity through management that increases soil carbon is a major policy goal."

A highly accurate laboratory method for measuring carbon can be over $100,000 in equipment costs. The researchers evaluated a portable device known as a reflectometer with a $400 hardware cost and calibrated it with lab tests to verify the data they collected.

"We found that the reflectometer predicted soil carbon levels precisely. It gave sufficient accuracy to inform soil management practices. What is unique about this handheld sensor is that it provides the data directly in the field, in the absence of a good phone connection,” said Snapp. "With minimal training, extension staff can use the reflectometer to carry out assessment of soil carbon in real time with farmers in their field. This represents a significant step forward in improving agronomic management in data-poor locations. Access to such immediate and locally relevant soil data can empower Malawian farmers to make more informed management decisions based on their unique contexts."

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