Effect of fertilizer and legume mixture on oat cultivation and nitrogen storage in an alpine region

To reveal the effects of oat variety, fertilizer, and legume mixture on plant nitrogen storage and allocation patterns, we examined the effects of four levels of nutrient addition and four legume mixture levels on four oat varieties in an orthogonal experiment L₁₆(4⁵). Results showed that aboveground and belowground plant nitrogen storage was affected by variety, fertilizer, and mixture. Fertilizer had the largest influence on oat leaf nitrogen storage, and both variety and fertilizer influenced root nitrogen storage in oats. The legume mixture had a large influence on stem, leaf, and root nitrogen storage in legumes. Under the Avena sativa ‘Qinghai’, urea + diammonium phosphate + organic fertilizer and a mixture level 75 kg·ha^–1, above and belowground nitrogen storage increased during the milk period. Aboveground plant nitrogen storage increased during the growth period, but belowground nitrogen storage decreased. Variation in the aboveground biomass increased, stem and leaf increased first and decreased later, and root nitrogen storage of oats, decrease. The aboveground biomass, stem nitrogen storage, and leaf nitrogen storage of legumes increased, but root nitrogen storage decreased during the growth period.