Simple soil test promises to predict yields

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An inexpensive new test may soon allow farmers to manage crops better and ascertain crop sizes accurately.

Farmers may soon be able to predict the size of their crop before it is planted, if the results of a new test are anything to go by. The test, developed by a team at Michigan State University, measures the active, labile fraction of organic matter in the soil.  “This is usually less than 20%,” explains researcher Steve Culman. “But it’s where soil nutrients are rapidly cycled and interact with microbial communities.”

The size of the labile pool can be a useful predictor of maize agronomic performance, but tests traditionally used to measure it, such as microbial biomass and particulate organic matter, are labour-intensive. So the researchers turned to a simple, inexpensive test for nitrogen and carbon mineralisation, measuring soils managed under three separate practices – conventional, integrated, and compost – and two crop rotations.

The results suggest that these measures of labile organic matter can reflect long-term management and short-term seasonal changes as well as predict maize performance. The team hopes to provide farmers with better tools to manage their lands and increase crop yields. “Most farmers don’t test soil for nitrogen. They just apply a rate based on their yield goals, and excess nitrogen may be applied. The long-term goal would be to offer this as a predictive test so that farmers can apply the nitrogen according to soil type and management.”