Nitrogen benefits from four green-manure legumes in dryland cropping systems

Partial replacement of fallow with legume green manures has the potential to improve cereal production and agricultural sustainability in the northern Great Plains. This is possible if N gains by annual legumes and enhancement of soil N availability are optimized. The objectives of the study were to (i) determine the N distribution in different vegetative components of four annual legumes; (ii) estimate their ability to accumulate N through fixation; and (iii) compare the N uptake of the cereal crop that follows legume green manure with that of cereal grown on fallow or of cereal receiving N fertilizer. Black lentil (Lens culinaris Medik.), Tangier flatpea (Lathyrus tingitanus L.), chickling vetch (Lathyrus sativus L.), and feedpea (Pisum sativum L.) were grown in rotation with spring wheat (Tnticum aestivum L.). Nitrogen concentration in legume nodules was several times greater than in any other plant part. However, N concentration in legume shoots was, on average, 27% greater than in legume roots. Total...