Diversifying Agronomic Systems to Improve Soil health Through Intercropping

Diversifying agronomic systems has the potential of increasing nutrient and water use efficiencies. Intercropping, the practice of growing two or more crops simultaneously in the same field, takes advantage of facilitatory and complementary traits of crop species to capture resources. We established a four-year intercropping experiment in the fields of southern Idaho. We intercropped pulses (lentils, chickpeas, and spring pea) with barley in full and deficit irrigation conditions. We measured available soil nitrogen and carbon throughout the soil profile, root distributions, yield, and microbial groups (PLFA). During the first season we isotopically labeled (13C and 15N) pulse plants to compare intercropping treatments. We found extractable N to decrease across all depths that corresponded with aboveground yields. Microbially available carbon was greater at deeper depths in the horizon. Lentil harbored a unique microbial community. Monocrops tended to have greater biomass at deeper depths compared to the intercrop plots. Root distributions of all plants were primarily located at deeper depths (>15 cm) within the soil profile. Lentil was sensitive to the deficit irrigation treatment. Lentil and pea differed substantially in their nitrogen and carbon allocation. Even within pulses, the species' traits were of primary importance in the utilization of nitrogen and carbon.