The Potential of Green Manure Mixtures to Provide Nutrients to a Subsequent Lettuce Crop

Abstract

The objectives of this greenhouse experiment were to quantify the benefits of green manure (GM) diversity and to assess effect of GM on a succeeding lettuce crop. Species included barley (B), field pea (P), sunn hemp (S), and buckwheat (U). Treatments included single plantings of B and P and mixtures of B and P (BP), B, P, and S (BPS), and B, P, S, and U (BPSU). The pea GM had the highest shoot concentration of potassium, calcium, magnesium, manganese, zinc, and iron. Roots had higher concentrations of nutrients than shoots. Accumulation of nutrients in legumes was higher than in barley. The CO2 flux from the soil suggests that the most intensive mineralization period occurred within two weeks after incorporation of GMs. The mixtures and single planting of P mixtures had a significant benefit over single planting of B regarding fresh and dry weight of the lettuce.