Cereal and oil seed crops response to organic nitrogen when grown in rotation with annual aerial-seeded pasture legumes

Abstract

Nitrogen fixation from pasture legumes is a fundamental process that contributes to the profitability and sustainability of dryland agricultural systems. The aim of this research was to determine whether well-managed pastures, based on aerial-seeding pasture legumes, could partially or wholly meet the nitrogen (N) requirements of subsequent grain crops in an annual rotation. Fifteen experiments were conducted in Western Australia with wheat, barley or canola crops grown in a rotation that included the pasture legume species French serradella (Ornithopus sativus), biserrula (Biserrula pelecinus), bladder clover (Trifolium spumosum), annual medics (Medicago spp.) and the non-aerial seeded subterranean clover (Trifolium subterraneum). After the pasture phase, five rates of inorganic N fertilizer (Urea, applied at 0, 23, 46, 69 and 92 kg/ha) were applied to subsequent cereal and oil seed crops. The yields of wheat grown after serradella, biserrula and bladder clover, without the use of applied N fertilizer, were consistent with the target yields for growing conditions of the trials (2.3 to 5.4 t/ha). Crop yields after phases of these pasture legume species were similar or higher than those following subterranean clover or annual medics. The results of this study suggest a single season of a legume-dominant pasture may provide sufficient organic N in the soil to grow at least one crop, without the need for inorganic N fertilizer application. This has implications for reducing inorganic N requirements and the carbon footprint of cropping in dryland agricultural systems.

Nutritional Content Analysis of Crop Residues in Three Agroecologies in East Gojjam Zone

“…In comparison to cereal crops, the contribution of grain yield from pulse and oil crops was low (4.9% and 0.1%, respectively) and was lower than 12.9% and 5.9% recorded by the CSA in 2021. This might be attributed to environmental conditions such as climate, disease, and soil fertility, as well as the small area of land allocated for pulse and oil seed crops [ 21 ]. However, in the ML, as compared to HL and LL agroecologies, the contribution of the yield of the vetch crop was significantly greater ( P < 0.05) ( Table 2 ).…”